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Old May 25th, 2023, 02:36 PM   #1
dan151
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2012 Ninja 250R Bogging/Sputtering On Take Off Running Rich

Hi Folks,
Took a chance and bought a low mileage 100% stock non-running 250r that sat garaged for a number of years. New battery and fresh gas, bike started but died when the choke was closed. Removed carbs to find no varnish, just some light debris. Thoroughly cleaned the carbs ensuring all jets and passages were clear and now the bike will idle fine at around 1300 rpms and revs smoothly in neutral, however when you hold the throttle steady above idle, the bike bogs down and shuts off. The same symptoms occur when you try and move forward in gear. I was able to start moving once but it bogged and sputtered severely and could not pick up any speed.

Details thus far:
-All troubleshooting and adjustments on a fully warmed engine
-Spark plugs were very dark and exhaust smells rich
-All jets stock
-Needle orientation correct: N9VU-left N9VW-right
-Float heights 17mm +/- 0.5mm
-Removed mixture screw caps and set both to 2.5 turns out
-Diaphragms undamaged
-Petcock is functioning properly, no change when running on "prime"
-No vacuum leaks found, all tubes secured and undamaged
-Air filter and air box are clean
-Tried lowering the floats by 1mm, symptoms remain

Any suggestions where next to troubleshoot?
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Old May 25th, 2023, 03:58 PM   #2
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Welcome to the board, Dan! Have you seen these diagrams?

https://n4mwd.blogspot.com/2013/10/s...-passages.html
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Old May 26th, 2023, 05:41 PM   #3
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Quote:
Originally Posted by Triple Jim View Post
Welcome to the board, Dan! Have you seen these diagrams?

https://n4mwd.blogspot.com/2013/10/s...-passages.html
Thank you! I just disassembled the carbs and meticulously cleaned them following the diagrams you provided. I reset the float bowls to exactly 17mm and 2.5 turns out on the mixture screws.

I was able to ride a short distance but the bogging/stuttering and rich running condition from idle to around 3000 rpms persists. You can visible see a small amount of black exhaust fumes coming out of the exhaust. Once the bogging starts, the bike will eventually die out not matter the throttle position and the choke has no effect. Once restarted you can move again, but eventually the bogging returns.

Any suggestions where to troubleshoot next? Is it possible that ignition spark may be cutting out in these conditions? The battery that I replaced was completely dead when I got the bike and would not take a charge. Concerned that the previous owner may have caused damage with a reversed polarity jump start.
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Old May 26th, 2023, 08:08 PM   #4
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It sounds like a carburetor problem, like float valves sticking open, for example.
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Old May 26th, 2023, 08:22 PM   #5
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@dan151 have you actually replaced the float valves with brandy new?
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Old May 27th, 2023, 07:51 AM   #6
dan151
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Quote:
Originally Posted by Triple Jim View Post
It sounds like a carburetor problem, like float valves sticking open, for example.
Quote:
Originally Posted by ducatiman View Post
@dan151 have you actually replaced the float valves with brandy new?
Needle valves and seats are spotless and confirmed functioning properly. No damage to the rubber cone tips. I tested them when the carburetor was off the bike. With very light compressed air, no flow through when the the needles rise into the seats. They open back up without issue as well.
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Old May 27th, 2023, 07:55 AM   #7
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Is there any chance there's too much oil on the air filter element? I'm trying to think of something that is causing the richness.

Just to confirm, when it's trying to stall or bogging when trying to accelerate, does opening the enricher make it worse?
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Old May 27th, 2023, 08:33 AM   #8
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Is there any chance there's too much oil on the air filter element? I'm trying to think of something that is causing the richness.

Just to confirm, when it's trying to stall or bogging when trying to accelerate, does opening the enricher make it worse?
Just tried running with the air filter removed with the side cover on. No change in symptoms. Bogging, stuttering and light black soot out the tail pipe .

Once it starts bogging it struggles to recover or get past 2500-3000 rpms. If it can get past that rpm range which is rare, it does seem to run fairly well. The only way to return to idle is let it die out or stall and restart the engine.
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Old May 27th, 2023, 08:56 AM   #9
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How many miles, and has it had its valves adjusted?
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Old May 27th, 2023, 10:10 AM   #10
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How many miles, and has it had its valves adjusted?
Only 400 miles on the bike, I received no service history but would gather they are untouched given the low mileage. If I had to guess it probably has the original engine oil as well. I'm guessing it was parked for years due to the issue I am dealing with now.
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Old May 27th, 2023, 10:36 AM   #11
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How about the enricher I asked about above? When it's bogging and you open the enricher, does it get better or worse?
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Old May 27th, 2023, 11:16 AM   #12
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Originally Posted by Triple Jim View Post
How about the enricher I asked about above? When it's bogging and you open the enricher, does it get better or worse?
Just tried opening the choke slowly as the symptoms start and it has no effect. The bike bogs down at steady throttle below 3000 rpms and dies out. If you hold engine speed at above 3000 rpms, it will hold there without issue.
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Old May 27th, 2023, 11:40 AM   #13
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Is the engine oil level steady, as in not rising from gasoline dilution?
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Old May 27th, 2023, 02:33 PM   #14
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Is the engine oil level steady, as in not rising from gasoline dilution?
The oil level was high when I first got the bike and I had to siphon out about 1/2 of a quart of oil so that it was at the proper level on a warm engine. It did not smell contaminated to me.

I took a short ride on the bike a few moments ago, if you clutch out at 4,000 rpms and keep it above that the bike will accelerate but stutters bad when you settle to cruising speed and bogs down below that.
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Old May 28th, 2023, 05:46 PM   #15
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Same Exact problem I ran into after having Gordon clean my carbs
...however we changed the main jets to 95's and put 2 shims under the needles
and I opened the fuel/air mixture screws to somewhere around 3 to 3.5 turns out and now it runs....
when it is cold it still has a slight bog around 4,500 to 6,000 RPM
but when it warms up that bog goes away....
this is totally bazaar and in my mind should not happen in any way or form
as it is Mechanical and it can't do that... but it does.... what went bad to cause this is so far UNKNOWN to me.... if you put it all back to stock you would expect it to run like a stock bike but it will not take any throttle then ...really strange !
I went as far as isolating all the smogg **** on the bike and had no change at all. what seemed to make the biggest difference is the shims under the needle jets ( remember the left and right needles are different from each other, don't mix them up !)
... if you are lucky enough to find the culprit please POST it as this has been cropping up all over the place.... a problem that should not be occurring, but does.... and I for one want to know what causes it.
Bob......
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Old May 28th, 2023, 07:14 PM   #16
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Should measure actual jet sizes. Many have been drilled out by POs.
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Old May 28th, 2023, 10:18 PM   #17
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Good thinking Danno.... I had a 250cc DT1 yamaha that I drilled out the main jet to many decades ago and I thought nothing of it... the Main jet was stamped... and I thought you know if I ever sell this thing that is going to confuse the hell out of the next guy so I took a file and removed the stamp marks.... so with no markings on it at all he would at least know something is up.... but most guys won't do that...you want it a bit richer so you just go to the next size up in your drill index, and drill the holes bigger...
they know about it... but no one else ever will !
....
I have a feeling like a leak in the diaphragm might cause this problem ...these symptoms are indeed rare but they do happen .... and the only way I know of testing a diaphragm is just replace it with a new one...and their expensive things !

I've never seen a diaphragm go bad except one time... the bike set so long in the weather that the diaphragm was cracked all around the bend when it was folded up.... and I think the leak in a diaphragm would have to be huge to effect the running of the bike a pin hole wouldn't do it I don't think...
so you would not be able to see or feel the difference in the running of the engine.... however if the vacuum hole that operates the diaphragm was plugged or simi plugged that might do it !
.... or a massive vacuum leak....
I still think it's a vacuum leak but I can't find it and I've looked everywhere for it.
.....
it's like we're trying to patch the problem by other means rather than find the true problem's source..... because everything is correct.... it doesn't leave you with to many options other than re tune it to make it run right...
which shouldn't be nessary but in this case you have no choice putting it back to stock and it doesn't run worth a darn something is amiss..... but WHAT....that is the big question....
.....
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Old May 29th, 2023, 04:48 AM   #18
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Originally Posted by DannoXYZ View Post
Should measure actual jet sizes. Many have been drilled out by POs.
Or replaced by UNMARKED jets supplied in junk jet "kits"
Measurement (and replacement with marked OEM) becomes imperative!
I'd suggest to avoid and correct these unmarked "situations" whenever encountered.

AVOID.....DO NOT USE UNMARKED JETS! PERIOD
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Old May 29th, 2023, 06:29 AM   #19
dan151
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Quote:
Originally Posted by DannoXYZ View Post
Should measure actual jet sizes. Many have been drilled out by POs.
Quote:
Originally Posted by Bob KellyIII View Post
Same Exact problem I ran into after having Gordon clean my carbs
...however we changed the main jets to 95's and put 2 shims under the needles
and I opened the fuel/air mixture screws to somewhere around 3 to 3.5 turns out and now it runs....
when it is cold it still has a slight bog around 4,500 to 6,000 RPM
but when it warms up that bog goes away....
this is totally bazaar and in my mind should not happen in any way or form
as it is Mechanical and it can't do that... but it does.... what went bad to cause this is so far UNKNOWN to me.... if you put it all back to stock you would expect it to run like a stock bike but it will not take any throttle then ...really strange !
I went as far as isolating all the smogg **** on the bike and had no change at all. what seemed to make the biggest difference is the shims under the needle jets ( remember the left and right needles are different from each other, don't mix them up !)
... if you are lucky enough to find the culprit please POST it as this has been cropping up all over the place.... a problem that should not be occurring, but does.... and I for one want to know what causes it.
Bob......
Quote:
Originally Posted by ducatiman View Post
Or replaced by UNMARKED jets supplied in junk jet "kits"
Measurement (and replacement with marked OEM) becomes imperative!
I'd suggest to avoid and correct these unmarked "situations" whenever encountered.

AVOID.....DO NOT USE UNMARKED JETS! PERIOD
The bike was completely untouched when I bought it, factory paint markings on screws and bolts still. The thought of drilled jets did cross my mind when the carburetors were disassembled. Although I did not measure them, the factory stamped jets were in new condition with no evidence that they had been tampered with.

I thoroughly inspected the diaphragms when removed and found no defects or damage. No vacuum tube/line leaks were evident following a spray down with carburetor cleaner.

Stepping down a size in the pilot and main jets may be the next likely step in troubleshooting as I'm confident the carburetors are completely clean at this point. It just baffles me that a 100% stock bike with only 400 miles could potentially need to be rejetted.
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Old May 29th, 2023, 10:58 AM   #20
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Personally I think you shouldn't be confident that the carbs are clean. the carbs on these bikes are the hardest to clean that I have ever seen "THEY DO NOT COME CLEAN EASILY"
I am a retired Motorcycle mechanic but getting old at 70 yrs now, and I know bike carbs.
yet it took me 3 trys to get the carbs clean !!!! I used the time tested methods , not an ultrasonic cleaner, ( which I now have by the way) but after riding the bike all season I could tell the carbs were not as clean as I thought they were.
over the winter I did a valve adjustment and sent the carbs to Gordon (Ducattiman)
because I didn't want to fight these silly carbs again.... he cleaned them for me and this same problem cropped up He graciously offered to check them out again for me so I sent them back to him... he did a re clean and after discussing it we decided to put in smaller main jets and 2 shims under the needles.... and after much tinkering I think she is running alot better now.... I still haven't ridden it on the street but I think it is finally
back up and running right.
....
with all the smog garbage on these things and the settings so very fine to get them to pass smog they run on a razors edge.....any thing will screw up the running of these bikes, but once you get them tuned in they run fantastically and will stay that way for ages... My bike does not get alot of use it sets most of the time. it's only got 5600 miles on it and is in like new condition.... yet this same problem cropped up as what happened to you. you'll notice in the manual that each carb is slightly different right from left..... they have different jet needles and the mixture screws are set differently from each other.... this to me is very strange to see ! it is a highly tuned powerhouse
of a bike that develops alot more power than the average 250cc bike so any speck of dirt in the carbs can effect it's running. ( I put an in line fuel filter on my bike first thing. )
.....
I sujest pulling off the carbs and paying close attention to the passageways inside the carbs in cleaning them again....the pic. below helped me a bunch those passageways do not come clean easily.... and you can't poke a small spring wire through them yet they must be super clean.
....
Bob
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Old May 29th, 2023, 11:21 PM   #21
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What elevation are you at Bob?
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Old May 30th, 2023, 05:14 AM   #22
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Quote:
Originally Posted by dan151 View Post
The bike was completely untouched when I bought it, factory paint markings on screws and bolts still. The thought of drilled jets did cross my mind when the carburetors were disassembled. Although I did not measure them, the factory stamped jets were in new condition with no evidence that they had been tampered with.

I thoroughly inspected the diaphragms when removed and found no defects or damage. No vacuum tube/line leaks were evident following a spray down with carburetor cleaner.

Stepping down a size in the pilot and main jets may be the next likely step in troubleshooting as I'm confident the carburetors are completely clean at this point. It just baffles me that a 100% stock bike with only 400 miles could potentially need to be rejetted.
How, unless you measured, could you be absolutely sure of this?
Also suggest all brand new "consumables" (orings, float valves) and a full treatment to the float valve seats, followed by setting fuel levels based upon actual wet testing using a gravity fed fuel source, letting them set for 60 minutes to assure floats are fully sealing.

Best o' luck.
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Old May 30th, 2023, 06:11 AM   #23
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Danno... 3957' ASL according to the elevation sign ! at the summit about 1 mile away
so I figure sense we drop down a bit 3,400' at the very lowest ( I know it's higher than that!) FIGURE 3,500'asl which may have some bearing on the subject as my bike was running rich with stock jets and that is likely because of the elevation !
it starts now without making a full revolution and gains RPM slowly like it should on choke
....
I have NOT taken it for a ride yet as it has been raining off and on for the last 3 days
and it has cooled off dramatically ! I had a fire in the pellet stove last night !
....
I have been racking my brain trying to figure out this problem but Nothing fits.... I can't figure it out.
to have 2 or 3 guys out there come up with the same problem is really bazaar !
....
obviously it is not a common problem but it does happen...
couple that with "putting it back to stock and it hardly runs or barely will run if you beg it."..... it's like UH ? that can't be right ! but it is what it is, so something has to be done to make them run again..... maybe it is a symption of the electronic ignition failing ? because it should run no matter what if it's all put back to stock and the carbs are clean..... missing or stumbling at 5~6k RPM still plegs mine, but once it's warm it seems to quit that..... ( I did take the right coil off to check the valves)
I don't know, I am at a loss here !

....
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Old May 30th, 2023, 10:42 AM   #24
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Originally Posted by Bob KellyIII View Post
Danno... 3957' ASL according to the elevation sign ! at the summit about 1 mile away
so I figure sense we drop down a bit 3,400' at the very lowest ( I know it's higher than that!) FIGURE 3,500'asl which may have some bearing on the subject as my bike was running rich with stock jets and that is likely because of the elevation !
it starts now without making a full revolution and gains RPM slowly like it should on choke
That sounds about right. General rule-of-thumb is -1% mixture for every 1000-ft elevation. So you want about -4% fuel compared to stock. Good job on getting those mixtures fine-tuned!
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Old May 30th, 2023, 01:22 PM   #25
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Quote:
Originally Posted by ducatiman View Post
How, unless you measured, could you be absolutely sure of this?
Also suggest all brand new "consumables" (orings, float valves) and a full treatment to the float valve seats, followed by setting fuel levels based upon actual wet testing using a gravity fed fuel source, letting them set for 60 minutes to assure floats are fully sealing.

Best o' luck.
Quote:
Originally Posted by Bob KellyIII View Post
Personally I think you shouldn't be confident that the carbs are clean. the carbs on these bikes are the hardest to clean that I have ever seen "THEY DO NOT COME CLEAN EASILY"
I am a retired Motorcycle mechanic but getting old at 70 yrs now, and I know bike carbs.
yet it took me 3 trys to get the carbs clean !!!! I used the time tested methods , not an ultrasonic cleaner, ( which I now have by the way) but after riding the bike all season I could tell the carbs were not as clean as I thought they were.
over the winter I did a valve adjustment and sent the carbs to Gordon (Ducattiman)
because I didn't want to fight these silly carbs again.... he cleaned them for me and this same problem cropped up He graciously offered to check them out again for me so I sent them back to him... he did a re clean and after discussing it we decided to put in smaller main jets and 2 shims under the needles.... and after much tinkering I think she is running alot better now.... I still haven't ridden it on the street but I think it is finally
back up and running right.
....
with all the smog garbage on these things and the settings so very fine to get them to pass smog they run on a razors edge.....any thing will screw up the running of these bikes, but once you get them tuned in they run fantastically and will stay that way for ages... My bike does not get alot of use it sets most of the time. it's only got 5600 miles on it and is in like new condition.... yet this same problem cropped up as what happened to you. you'll notice in the manual that each carb is slightly different right from left..... they have different jet needles and the mixture screws are set differently from each other.... this to me is very strange to see ! it is a highly tuned powerhouse
of a bike that develops alot more power than the average 250cc bike so any speck of dirt in the carbs can effect it's running. ( I put an in line fuel filter on my bike first thing. )
.....
I sujest pulling off the carbs and paying close attention to the passageways inside the carbs in cleaning them again....the pic. below helped me a bunch those passageways do not come clean easily.... and you can't poke a small spring wire through them yet they must be super clean.
....
Bob
As suggested, I'm going to try another carburetor cleaning, fluid fuel level check, and step down a size in the pilot and main jet. The stock Keihin CVK30 carbs on this bike have a #38 pilot and #98 main jet. Looks like the next step down would be a #35 pilot and #95 main. Could anyone confirm if these are the correct jet series? I am referencing the attached chart from Keihin.

Main Jet Series: 99101-393
Pilot/Slow Jet: N424-25B

https://www.keihin-na.com/assets/1/7/jetlist.pdf
Attached Images
File Type: png Screen Shot 2023-05-30 at 4.32.35 PM.png (244.7 KB, 2 views)
File Type: png Screen Shot 2023-05-30 at 4.32.55 PM.png (257.6 KB, 3 views)
File Type: png Screen Shot 2023-05-30 at 4.33.12 PM.png (213.6 KB, 2 views)
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Old May 30th, 2023, 01:36 PM   #26
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yes correct series numbers, i'd suggest to source from jetsrus.com
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Old May 30th, 2023, 01:38 PM   #27
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Originally Posted by ducatiman View Post
yes correct series numbers, i'd suggest to source from jetsrus.com
Excellent, thank you for the quick response and recommendation! I will report back once I have completed the above work.
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Old May 30th, 2023, 03:45 PM   #28
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What is it .... #4 copper washers used for shims ????
you should pick up at least 4 of those too while your at it as you may need them. or just run to the hardware store for those...
I really didn't notice any difference in the running due to the Main jets just a tiny bit leaner... from 98's down to 95's is a very small change... I expect to see a change in plug color, but it won't be much... I really think the big change came from the shims.
....
when I was porting and polishing 2 strokes in my younger years it was not uncommon to go 3 to 4 sizes due to all the material I removed from the ports
and the engines were like a completely different animal ! though the big changes were adding tuned pipes ! that really changed the machine !
...
Bob....
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Old May 31st, 2023, 04:38 AM   #29
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I don't usually change pilot jets ever....unless the fuel/airscrew makes no change at all
which is usually not the case even with changing the main jet.....
however I have noticed that unlike the first adjustment I did to the bike that now for some reason the fuel/air screws don't seem to change anything as far as the idle goes which is very weird.... I suppose that the carbs could have been so dirty in the last year or so that they were dirty enough to actually be just right... LOL and now that their clean the hole is too big ! HAHAHAH
so I may also have to reduce the size of the pilot jet as well.
but I do have the fuel/air screws out a long way... 3 to 3.5 turns out but they did NOT change the RPM of the engine at all ...unlike the first time I got it running good I could easily tell the change in the RPM of the engine idling even without killing one cylinder
this time the fuel/air screws had no effect what so ever.....
Maybe that is a hint to the problem ? it only started running half way decent when I put the screws out to 3 turns out at 2 turns the flat spot was so big I couldn't get over it at all.... it started having a flat spot at 4,000 RPM and would not take any more throttle for love nor money ! once I opened the airscrews to 3~3.5 then I could get over the flat spot at 6,000 RPM and it ran ok from there to red line sense I got the carbs back from Gordon they were alot better but only after I opened up the fuel air screws.
.....
but Jets shouldn't change in a years time (asuming they arn't all gunked up and dirty)
so what could change the first tuning I gave it where the fuel air screws adjusted it perfectly.... to now ?... the main jet does not effect that circuit but it is not isolated from it
and it's my belief that the carb is designed so lean that it needs the pilot jets to be perfect in order to run top notch because they dump fuel into the airstream all the time
and they plan on that in the design of the carb..... adjust the fuel air screws too lean and the bike will fall on it's face trying to take throttle just off idle that is normal but even more so with these carbs it will carry on to mid range not just off idle....that is probably WHY the flat spot at 4~6k RPM the answer would be to dump in more fuel than usual into the air stream as soon as the throttle opens, hence the shims.
and it seems to have worked for the most part...because when the engine is good and warm (at operating temperature) it runs great ! it just takes 10 minutes to get that thing warm !
.......
Bob.......
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Old May 31st, 2023, 06:29 AM   #30
dan151
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Originally Posted by Bob KellyIII View Post
What is it .... #4 copper washers used for shims ????
you should pick up at least 4 of those too while your at it as you may need them. or just run to the hardware store for those...
I really didn't notice any difference in the running due to the Main jets just a tiny bit leaner... from 98's down to 95's is a very small change... I expect to see a change in plug color, but it won't be much... I really think the big change came from the shims.
....
when I was porting and polishing 2 strokes in my younger years it was not uncommon to go 3 to 4 sizes due to all the material I removed from the ports
and the engines were like a completely different animal ! though the big changes were adding tuned pipes ! that really changed the machine !
...
Bob....
Quote:
Originally Posted by Bob KellyIII View Post
I don't usually change pilot jets ever....unless the fuel/airscrew makes no change at all
which is usually not the case even with changing the main jet.....
however I have noticed that unlike the first adjustment I did to the bike that now for some reason the fuel/air screws don't seem to change anything as far as the idle goes which is very weird.... I suppose that the carbs could have been so dirty in the last year or so that they were dirty enough to actually be just right... LOL and now that their clean the hole is too big ! HAHAHAH
so I may also have to reduce the size of the pilot jet as well.
but I do have the fuel/air screws out a long way... 3 to 3.5 turns out but they did NOT change the RPM of the engine at all ...unlike the first time I got it running good I could easily tell the change in the RPM of the engine idling even without killing one cylinder
this time the fuel/air screws had no effect what so ever.....
Maybe that is a hint to the problem ? it only started running half way decent when I put the screws out to 3 turns out at 2 turns the flat spot was so big I couldn't get over it at all.... it started having a flat spot at 4,000 RPM and would not take any more throttle for love nor money ! once I opened the airscrews to 3~3.5 then I could get over the flat spot at 6,000 RPM and it ran ok from there to red line sense I got the carbs back from Gordon they were alot better but only after I opened up the fuel air screws.
.....
but Jets shouldn't change in a years time (asuming they arn't all gunked up and dirty)
so what could change the first tuning I gave it where the fuel air screws adjusted it perfectly.... to now ?... the main jet does not effect that circuit but it is not isolated from it
and it's my belief that the carb is designed so lean that it needs the pilot jets to be perfect in order to run top notch because they dump fuel into the airstream all the time
and they plan on that in the design of the carb..... adjust the fuel air screws too lean and the bike will fall on it's face trying to take throttle just off idle that is normal but even more so with these carbs it will carry on to mid range not just off idle....that is probably WHY the flat spot at 4~6k RPM the answer would be to dump in more fuel than usual into the air stream as soon as the throttle opens, hence the shims.
and it seems to have worked for the most part...because when the engine is good and warm (at operating temperature) it runs great ! it just takes 10 minutes to get that thing warm !
.......
Bob.......
Thanks Bob, I'm hopeful but not expecting a drastic change with the replacement jets given the severity of the rich running condition but it will be a good starting point to continue testing and reading the plugs until its running correctly.

As suggested, I will plan to acquire some #4 shims for experimenting. This article suggests you are correct on the shim size:

https://faq.ninja250.org/wiki/Washers_for_carb_needles

Last futzed with by dan151; June 1st, 2023 at 10:23 AM.
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Old June 3rd, 2023, 01:54 PM   #31
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Just installed the #35 pilot and #95 main jets. After a warm up, target idle was achieved with 3.5 turns of the mixture screws.

Proceeded on a 10 mile ride with speeds averaging 30-40 mph and rpms 3000-4500rpms:
-Bogging on takeoff has been reduced but still occurs slightly until rpms increase.
-Bogging down and rich running while cruising below 4,000 rpms feels improved but still there
-Both conditions above seem to worsen by riding up an incline
-Overall slight improvement on smoothness of running, less shuddering
-Spark plugs appear the same, heavy black soot but not wet with fuel

My thoughts are that I will leave the #35 pilot jet alone for now and step down another size in the main jet to #92. The incline factor has me thinking there is an issue with my float heights now too.
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Old June 3rd, 2023, 02:20 PM   #32
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Check your slides and see if they've been drilled...

For floats, do final wet-test. Measurements aren't always accurate due to sloppy fit of parts.
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Old June 3rd, 2023, 02:55 PM   #33
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See if you can relate throttle position to the problem areas. Correlation that way is generally much better that trying to relate RPM to them, and it can help to figure out which carb circuit(s) are causing trouble. Sometimes it helps to put tape on the twist-grip and mark 1/8, 1/4, 1/2, etc.
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Old June 3rd, 2023, 08:58 PM   #34
Bob KellyIII
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that is a great idea Jim !.... Mine is reacting poorly from half throttle down, everything above that is great.
I just took my 250R out for a test run and it ran terribly..... bottom end is really bad but anything over 6~7,000 RPM she ran great... best yet in fact ! smooth power hard pulling and it really hauls ! I did 70mph in a 50mph coming back home !
but on the bottom end a cylinder wanted to drop out and it was farting and fuming just trying to get the RPM's up....
I just ran up to the gas station here in town and filled up and came straight back.
it feels lean.....on the bottom end I didn't think to apply the choke, I wish I had darn it!
but that is an enricher technically not a choke but it would have added more fuel on the bottom end of the RPM scale and that would have told me if it was lean or rich by how it reacted....
.... I think next is pilot jets !
Bob........
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