Ninja 250 idles fine idle increases drastically as it warms up

[Deathjunior]

I have a 2005 ninja 250, I've installed a new timing chain, a manual tensioner and the engine is running really well. It starts up and idles well but as it heats up the rpm at idle increases drastically to 3-4k rpm. So I turn the idle adjustment screw down to lower it to the 1300-1500 rpm range. I should mention this is with the choke off. The chokw seems like it has enough play though I'll look at it again tonight. The bike runs great til I get to a stop sign or a light then if I let off the throttle it dies and won't start back up until it cools down or if I open up the idle adjuster on the side of the bike a whole lot, when I do that the engine starts then climbs to an extremely high rpm until I close the screw. These seems like a pilot jet or an idle adjustment issue.

The bike has a k and n pod filter, 3 washers on the fuel needles and 110 main jets. As I was taking apart the carb to clean it I found perforation at the edge of one of the slide vacuums that I've sealed (I have a new vacuum on the way). I'm not sure if this is the issue as it runs perfectly at every rpm and it doesn't have an eratic idle the idle just increases as if its getting more fuel than it needs. But it only does it if the main jets aren't engaged. Any suggestions would be great I'm going to check the choke cable play tonight and pull the carb to check the pilot jets.

- I've googled all I can but I'm really tired of the bike dieing at lights and not starting without fiddling with it

[Motofool]

It sounds like valves with insufficient clearance, combined with a dirty carburetor, including stuck slides.

Please, read this:
http://faq.ninja250.org/wiki/Trouble...roubleshooting

http://faq.ninja250.org/wiki/How_do_..._the_valves%3F

[Deathjunior]

Carbs cleaned, valves are adjusted to .004 inches intake and .005 inches exhaust per the service manual (adjusted them 15 miles ago) . Slide vacuum seems probable (like I said 1 is on the way) but wouldn't the slide vacuum effect every rpm?

[choneofakind]

Check for vacuum leaks on the hoses. They can have a huge effect in idle oddities.

[Motofool]

Originally Posted by Deathjunior

Carbs cleaned, valves are adjusted to .004 inches intake and .005 inches exhaust per the service manual (adjusted them 15 miles ago) . Slide vacuum seems probable (like I said 1 is on the way) but wouldn't the slide vacuum effect every rpm?

How did you install a new timing chain?
I mean, how much surgery did you do?

The cause of a new problem is always the last work we did.
If all jets and passages of the carburetor are clean, mix needles adjusted to 2.5~3 turns, guides (part 16017) properly oriented, floats adjusted to 17 mm, slides free, all vacuum tubes leak free and needles properly installed in diaphragms, there should not be reason for what is happening, as the valves are working properly.

As the problem is a function of temperature, either the engine is losing compression (improper timing / leaking valve) or the air/fuel mix is becoming too reach (less volume of air is flowing in).

For re-starting you don't need to manipulate the idle knob, all you need to do is to open the throttle a little because that knob only pushed the closed-throttle (butterfly valves) limit up or down.

The damaged diaphragm should not be the cause because the engine should behave with only one cylinder working, it only becomes less powerful.

[ducatiman]

Deathjunior-

I'd suggest to focus some attention on the vac hose take off points *between* the carbs. Splitting the carbset will be necessary to fully examine the hoses for swelling or not being pushed on *all the way* at the barbs. If swollen ends...snip a 1/4" off the swollen end to reveal a tight section again, unless you decide to replace the hose(s) entirely.

In doing some (and splitting) 250 carbs, i've noticed a trend in this problematic area, the heart of the vacuum system at the carb bodies.

Assure this area is secure first...then further diagnose/eliminate vac leaks working outwards.

Regards, Duc

[Deathjunior]

The thing is its nothing to do with heat in the block because the engine starts back up no problem if I turn the idle adjustment knob all the way to the right it will start back up. This leads me to believe its a carb problem and not necessarily heat but perhaps just a factor of time.
I picked the bike up with with a noise coming from the timing chain. Found out the tensioner spring had been broken in half somehow, the timing chain was loose inside the case and has ground away bits of the metal on both stays, this meant the chain wouldn't move very fluidly with bits of metal between the links causing them to be stiff the grinding also stretched the chain in a few places.
I tried first by installing a manual tensioner, still not enough tension as the tensioner bottomed out and it still made a bit of noise. The bottom chain stay is mostly gone and the top chain stay is worn enough that the chain can be removed with a bit of wiggling.

So I swapped out the chains, adjusted the valves put it back together and it runs extemely well though its this idle thats the problem. If I let it idle at the 3k mark it runs perfectly well doesn't die at lights or anything but it will probably overheat at lights if I don't fix it. I've got the carb on my desk right now so I'm going to check the hoses

[spooph]

it probably won't overheat sitting at idle @3K in traffic - just FYI. The Pre-gens are exceedingly cold blooded. However, that doesn't mean you shouldn't fix the problem.

Lots of good suggestions from folks on here. Have you synched the carbs? I've experienced very similar problems with out of synch carbs.

Also, 110 main jet might be too much, especially with your needle level being so high - you might actually be so rich that your main jet circuit is bleeding over into your off-idle circuit which would also cause the issue you're having.

Do you have a full exhaust on the bike?

You might also want to check the slide springs, as they could have rotated and covered up the vacuum hole in the bottom of the slide, which could cause this issue as well.

and last, but not least, let's hope this is not the case, but you might have pinched the slide vacuum seal with the seal cover (which holds the slide spring down), in which case, it would create a vacuum leak and result in exactly what you're experiencing... Let's hope not, as those puppies aren't cheap.

[Deathjunior]

I have the carb out on my desk and I'm going to pull the washers off of the needles just to remove one factor. I hadn't thought about the spring covering the vacuum hole. So I'll check on that as well. The hole I had in the slide vacuum is on the outside edge where it seals but it still has just as much vacuum as the flawless one next to it. I've got another vacuum that gets here thursday if it is indeed my problem. I'm thinking its perhaps the boots that seal the carb to the engine. The idle adjustment knob just opens and closes the butterfly valves enough to let in a little bit of air for idling. I'm having to almost completely close them as the engine warms up leading me to believe its sucking air from the engine side of the carb. I'm going to check the boots today , reinstall the carb and run it with the pod filter on loosely til the engine RPM rises (if it does), then pop the pod filter off and see if the slides have raised. If its a problem with the bad seal on the one then i should see one side higher than the other. If its the carb boots shouldn't I be able to spray water on them and listen for RPM drops if they are leaking?

[spooph]

Originally Posted by Deathjunior

If its the carb boots shouldn't I be able to spray water on them and listen for RPM drops if they are leaking?

yes, in fact, don't plan on popping the pod filters off, no way you're fast enough for all of that... Just install everything as it should be, and get starting fluid and methodically spray a little bit here, and a little bit there. If the idles goes up, you've found your leak. If you spray everywhere and the idle doesn't change, no leak. Keep in mind, if you get any starting fluid (ether) on your pod filters, the idle will go up, as it's getting into the carbs, so be very cognizant of where you're spraying.

[Deathjunior]

Well I reinstalled the carb and it still has the issue. I ran the engine up to 175 and I thought it was fine so I took it for a spin and by the time it hit 185 it was having the issue again. Then I let it cool down to 160 and it started no problem revved it to 185 ish and it died at idle again so I stopped turn the idle screw up to 3000 at idle and road it home like that. I picked up some new spark plugs. I checked the tanks air relief line.

I just installed the plugs and I'm going to try this again. If it's not this I'm going to check the balance on the carbs check my valves and see if there okay. My new slide vacuum gets here Thursday (delayed shipping) and if that doesn't fix it I might have to give up. Thing was it idled for what seemed like forever now it's just having problems starting once it's warm and the idle cuts out when it's hot

[ducatiman]

Originally Posted by Deathjunior

if that doesn't fix it I might have to give up.

https://www.ninjette.org/forums/showthread.php?t=240826

[Deathjunior]

New plugs and the issue continues though the old plugs were a bit nasty so still worth it. It comes back down to idle better but it still stalls out around 185 degrees at idle. So now it's down to rechecking the valves, carb balancing, and then that vacuum because I've got nothing else really.

[ducatiman]

when you replaced the cam chain.....did you set, then check, then double check the valve timing?

note pic attached is generic, provided to show example...consult your service manual for your own year bike

But....did you?

[ducatiman]

additionally....have you actually pulled and cleared the pilot jets then confirmed the pilot *circuits* within the carbs are clear? And all other circuits?

Cleaned the float valves and seats, performed float and fuel level tweaks followed by wet testing?

In other words...were the carbs *inspected and prepped* or simply assumed ok and installed upon your initial repairs?

[Deathjunior]

Well the bike probably wouldn't run right to begin with if the timing was off so. But yes I've set it 3 different times now. So its fine and as I've said the engine runs extremely well. It was doing this before I replaced the timing chain.
The valves were check and double checked but I'll be checking them again tomorrow. I can't see how valves being out if range could cause this but who knows at this point. Im going to try testing my coils tomorrow once the bike is good and hot but if they are fine and the valves are fine then its going to come down to that vacuum or carb balance. If not that I'm taking it to a shop because I'm out of options.

[ducatiman]

Don't want to annoy you (on the contrary, I'm trying to provide help), but diagnosis via keyboard depends on info and feedback you're providing to questions that must be asked, issues that must be eliminated, point by point.

You have provided zero feedback to my specific carburetor questions.

As you've assured us valve timing and clearance are addressed, I'd then urge you point your efforts towards carb internal checks, corrections and setup.

Before throwing in the towel and turning to a shop (big $$$) you might consider the refurbed carbs i linked.

[Ghostt]

@Deathjunior by carburetor balance, do you mean carburetor synchronization? And if your attempting to do it with vacuum method, which I personally believe is the wrong way, and your carburetors and or motor has other issues, using the vacuum method is making things worse, if your trying to synchronize them.

The true method is bench synchronization.

[22R88]

Originally Posted by Deathjunior

Well the bike probably wouldn't run right to begin with if the timing was off so. But yes I've set it 3 different times now. So its fine and as I've said the engine runs extremely well. It was doing this before I replaced the timing chain.
The valves were check and double checked but I'll be checking them again tomorrow. I can't see how valves being out if range could cause this but who knows at this point. Im going to try testing my coils tomorrow once the bike is good and hot but if they are fine and the valves are fine then its going to come down to that vacuum or carb balance. If not that I'm taking it to a shop because I'm out of options.

Let me just chime in and tell ya if the timing and valves are right I would highly recommend Gordon (Ducatiman) as a place to send your carbs. I sent him mine a few months ago and they came back in new condition.. My 04 starts easy, idles perfectly and runs great. It runs like a bike off the showroom floor, no stalling, coughing, sputtering , etc that you would expect in a 11 year old bike. His work is very inexpensive and done right. I don't know him personally so this is only a plea to assist you in getting your bike right. If you get the carbs done by him and it still does not act right you will at least know that the issue is not carb related and help ya zero in from there.

Good Luck
22R

[jkv45]

I'm thinking it's a carb issue as well.

The 110 Main very well could be too much, but it sounds like there may be a vacuum leak or the you are getting fuel from the enrichening circuit when you don't need it.

We've also seen odd issues from incorrect assembly during carb servicing and incorrect placement of washers, etc.

Have you set the idle mixtures screws to 2.5 turns out? That's a good base. There are washers and o-rings on the adjustment screws that can also get damaged or out of place and cause odd problems. The screws need to be removed and passages cleaned when doing service.

You may also have a fuel-delivery issue. The engine temp may not be related, it could just be the timing of the problem. When it stops running you could open the floatbowl and see if you have adequate fuel coming out and also see if there's any debris. Junk in the tank can clog the screens and restrict fuel flow.

All just speculation, but it's hard to find a problem without going through all of the possibilities one by one and eliminating them - sometimes more than once.

[spooph]

Originally Posted by Ghostt

@Deathjunior by carburetor balance, do you mean carburetor synchronization? And if your attempting to do it with vacuum method, which I personally believe is the wrong way, and your carburetors and or motor has other issues, using the vacuum method is making things worse, if your trying to synchronize them.

The true method is bench synchronization.

Please do enlighten as to this bench synchronization...


@Deathjunior - before throwing in the towel, it might be time to tear the whole thing apart. Send the carbs off to Ducatiman, he knows his stuff. Then go through the tank, petcock, hoses, and airbox...

as others have said, one by one. If you're looking at a quick fix, the shop will gladly take your money, but if you're tenacious, you can fix this!

[Ghostt]

@spooph here is my official write-up, and why


You can sync with the carbs in hand. Back the idle adjustment off to close that carb then match the second carb to it with the sync screw. You can then turn the idle adjustment up while using a thin feeler gauge (maybe .002") between the throttle plate and the throttle bore, adjust to just fit, and then check the second one and adjust to match. If you have good feel for this it will run fine once installed.

It would do folks well to take a minute to review and understand what a sync tool does, how it works. And take another minute to look at the carb linkage and sync adjustments available to fix irregularities that might occur. It can help take some of the mystery out of this as well as stop unnecessary carb sync screwups.

Meaning, that the carbs were right once, the butterflies were matched and it performed well, but then changed. Undecided And the problem somehow occurred in the butterfly direct shafts, or the sync screw turned or wore that pad that it rests on, or the carburetor pairing/ bridging brackets twisted in relation to each other, and enough so that the butterflies no longer operated in sync, such that performance noticeably suffered. And a fix will be accomplished by changing the butterfly position, the only thing the sync adjustment does. Hmmm. Really? Undecided

Meanwhile, the tool measures vacuum at each individual runner. That's all it does, how it works. And vacuum is effected by a huge list of things, butterfly position being only one of them, and the only one addressed with that tool while turning those sync screws. The rest of that list includes, valve adjustment, jetting, float level, compression differences between cylinders caused by wear as well as factory CC differences in the head, intake runner, as well as flow by port variations, etc. Variations in cams, wear or factory tolerance. Then there's the potential big one, pilot jets and pilot screw mixture settings. All of those effect the vacuum and will be read by the sync tool, accurately identifyng the difference that exists, and with the only adjustment being used to "correct" the problem, move the butterfly relationship, one to the next.

It's that clear understanding that has me of the opinion and long time practice to not touch the sync screws on a set of carbs that were right once and were never dismantled from the rack. And jet cleaning as well as float needle changing doesn't require that they be dismantled. And further, if I DID dismantle a set of carbs, I just matched the butterflies on the bench at assembly, using a feeler gauge, and then never touched them again, never gave them another thought.

That method, properly executed, will have THAT portion of the complete equation, balanced flow to each cylinder in a multi-cylinder/ carb application due to butterfly position, satisfied entirely adequately. And in fact, it has worked for me every time I've done it on every bike (as well as individual runner/ butterfly V-8 intakes, all eight) that I've ever owned or any that I've fixed for others. And the times I fixed for others was usually after an attempt by others to sync the carbs, chasing a problem, or sometimes not even chasing a problem, but one they created wth a sync tool, chasing a problem from that list, that was never a butterfly position change problem. Those linkages are so direct and simple that they don't know how to screw themselves up. Not enough to care about.

I'm sure this will start a lot of controversy so I won't argue it, just offering it for those who understand the whole picture that I outlined and might make good use of it. It is what I've done, on every engine I ever worked on, including blue printed racing engines as well as regular old, high mileage street stuff. I've had at least four, four cylinder bikes with over 100,000 miles that ran quite well, the whole time, and never had a carb sync performed. When they did finally get a total disassembly, this is how I set them up, on the bench. Over the years I've straightened out at least a half dozen messed up ones, probably more, and on the bench, after fixing the original problem which was fouled pilot jets.

I only posted this because it seems like its coming up fairly often, especially with problems from a sync gone bad. One I would suggest was never a sync problem to begin with. A big or sudden change in performance is NEVER a sync problem. NEVER. Remember that. Cool If there is a problem, and you connect the gauges? YES, there will definitely be an imbalance indicated. But because that hole has a problem that is from the rest of the list. A bad plug, a plugged pilot jet, a screwed up float, a bad valve or setting, etc. Every one of them effecting the vacuum in the intake but NOT from a sudden move of a butterfly position, a sync adjustment.

[Deathjunior]

I'll try to give the best description I can for what I did when pulled out the carbs. There a little different than the standard 4 barrels I'm used to so I'm not the most knowledgeable person in the world on cv carbs but I do know how they work. I cleaned out every jet and made sure all of them were clear, pilot jets were double checked yesterday I checked and rechecked the adjustment screws at 2.5 turns so those should be fine.

I'm going to put in the factory jets and just see what happens. This should cause the bikes rpm to hang more than it already does when i let it off the throttle but if its a problem with the jets being to big it should alleviate it.
The floats seem clean I went though that side of the carburetor and it seemed like new. This whole carb looks quite good on the inside and its really clean on the outside. I didn't change anything inside of the carburetor I just cleaned it and put everything back where it came from its wasn't really that dirty to begin with. The more surprising part is there is no inline filter on the carb and this carbs been messed with before since I didn't have to drill the plugs on the idle screws.

I was thinking it could be a factor of time. What basically happens now is that one you rev the engine enough to get it hot the bike won't idle. It just dies. It turns over just fine though and if you really open up the idle thumb screw (the butterfly valves) then it will restart and then rev stupidly high until you let the idle thumb screw back down. That leads me to believe that its a factor of to much fuel and not enough air and that letting the bike sit allows the excess fuel to evaporate.

I'm just converting knowledge from cars so you'll have to give me a bit of a break if this is wrong. I've pretty much just been wrenching on old muscle cars since i was a kid basically anything with a bowtie or an arrowhead. I'd like to ask my dad for help with this one (harley mechanic of many years) but he can't know I have a bike lol. Thats a story for a different day though.

[spooph]

@ducatiman - what do you say about @Ghostt 's explanation?

Scott, it makes perfect sense to me. Following from your explanation then, if I then sync the carbs with a vacuum gauge, then remove them and measure the gap on the butterfly valves I can get an idea of which cylinder is having some issues, no?

Also, how does this affect the 250 specifically, as the cylinders are different in their power delivery - cylinder 1 being the torque cylinder and 2 being the power cylinder. I'm sure they pull slightly different amounts of air at different RPM's?

I see your method working brilliantly on any engine where each cylinder is doing the same thing, but could it be different for an engine where each cylinder has a slightly different output, or does this fall under your "not enough to worry about" comment?

[jkv45]

Originally Posted by Deathjunior

I'm going to put in the factory jets and just see what happens. This should cause the bikes rpm to hang more than it already does when i let it off the throttle but if its a problem with the jets being to big it should alleviate it.

If you are talking Main Jet, changing it won't effect the idle mixture/idle speed/idle issues significantly. That's controlled by the Pilot Jet, the setting of the idle mixture screws, and the idle speed screw. I would start with the stock Main Jet (105) if you have it. If the PO installed Dynojet jets the numbers won't mean much. Do you have the stock exhaust?

I'd pull the plugs and take a look at them for a better understanding of what's going on. Are they the same color? Are they black or wet? It may help head you in the right direction.

[spooph]

Originally Posted by jkv45

If you are talking Main Jet, changing it won't effect the idle mixture/idle speed/idle issues significantly. That's controlled by the Pilot Jet, the setting of the idle mixture screws, and the idle speed screw.

I'd pull the plugs and take a look at them for a better understanding of what's going on. Are they the same color? Are they black or wet? It may help head you in the right direction.

Great suggestion on checking the plugs, however, if a main jet is too large, and the needle is too far removed, it acts as a secondary idle circuit and can affect the overall mixture. I only mentioned it as 110 are large jets. I know RacerX didn't put those in until he'd done extensive work on his bike, so just pods and an exhaust shouldn't need them. Just one more factor to consider.

[ducatiman]

short of actually being there and diagnosing personally, judging by your descriptions I'm now convinced a comprehensive pro carb service and setup
would be your solution.

Re: carb cleaning...you cannot compete within a home work environment against modern pro equipment. Heated ultrasonic and soda blast machines......accompanied by some parts replacement and followed by careful setup (with checks to confirm separate circuits are clear) would make short order of your carb issues.

Again, look at and consider my refurbed carbs, PM me for details if you like.
A fraction of what $$ a shop will nail you for. You've got a leg up, as you can provide install.

[Ghostt]

From my understanding of the NewGen carburetors, they use different needles, which would make a difference, without effecting the throttle butterflies.

But I could be wrong. As far as methods are used, I do believe Ducatiman does it the same way, as I have done for a lot of years as I stated in my write-up, I've used this method from bikes, cars etc...

Yes you can do the vacuum method, BUT user beware that you might be making a problem worse, or not dealing with the original cause of the problem.

I've seen and fixed many attempts at vacuum method, and while setting the butterflies properly, found the causes like clogged pilot jets, floats out of adjustment, valves out of adjustment, even dirty spark plug caps, bad petcock, bad vacuum line, etc....... All of which wasn't originally caused by the butterflies being out of synchronization.

[Ninjinsky]

As Spooph says they are cold blooded engines and mine certainly was very unhappy if you tried to ride it straight off from cold.
I would also habitually use the idle knob as a dynamic control, backing it of a little as the engine warmed and turning it back at the end of the day.
Conversely the idle would go ballistic on full choke and needed constant nudging until things settled down
I used to envy those lucky boys and girls on later bikes with fuel injection

[Ghostt]

Stupid question time, did you check the inline filter filter, located in the fuel inlet on the carburetor?

[Deathjunior]

Ducatiman, I'm going to put the stock jets in and then when the vacuum slide shows up on Thursday I'll install that. If I'm still having problems after than I'll pm you, is there any chance I could just send you my carb and you send me the refurb for less than 165?

[MAZ 80]

Originally Posted by Deathjunior

It starts up and idles well but as it heats up the rpm at idle increases drastically to 3-4k rpm. I should mention this is with the choke off.

It has always been my understanding that if a motor starts and runs well when cold, without any choke (enrichener), it's rich. If the ambient temperature is cold, it's very rich. If moderate or warm out, it's just a bit rich.

[ducatiman]

^ Deathjunior, those type of negotiations best done via PM, I'll contact you.

[spooph]

Originally Posted by Ninjinsky

As Spooph says they are cold blooded engines and mine certainly was very unhappy if you tried to ride it straight off from cold.
I would also habitually use the idle knob as a dynamic control, backing it of a little as the engine warmed and turning it back at the end of the day.
Conversely the idle would go ballistic on full choke and needed constant nudging until things settled down
I used to envy those lucky boys and girls on later bikes with fuel injection

This can be compensated for by doing the below:

Originally Posted by MAZ 80

It has always been my understanding that if a motor starts and runs well when cold, without any choke (enrichener), it's rich. If the ambient temperature is cold, it's very rich. If moderate or warm out, it's just a bit rich.

I have been known to run a 40 jet in the winter time for just this reason. Without changing the rest of the setting, just swapping out the idle jet made it so much easier to ride in sub-freezing temps.

[Deathjunior]

Yea the bike never needs any choke on start up. But its at 2.5 turns on the start? When it gets warm I can crank down the idle adjustment screw to about the 5k mark and it starts right back up and then revs to 5k til I loosen the idle screw. So its a problem with the idle circuit? That narrows the field a bit? I'm kinda at my wits end with this. I'm hoping it has something to do with that vacuum seal because otherwise the carb will be exactly as I got it after I install that seal.

[ducatiman]

Originally Posted by Deathjunior

Yea the bike never needs any choke on start up. But its at 2.5 turns on the start? When it gets warm I can crank down the idle adjustment screw to about the 5k mark and it starts right back up and then revs to 5k til I loosen the idle screw. So its a problem with the idle circuit? That narrows the field a bit? I'm kinda at my wits end with this. I'm hoping it has something to do with that vacuum seal because otherwise the carb will be exactly as I got it after I install that seal.

there is no way you can achieve a lower idle by loosening the idle screw? engine stalls out? Then will only start by cranking the idle screw back inwards?

Thee may be multiple faults within the carbs...vacuum leak, idle circuit plugged, synch, assembly errors? At this point dunno, would have to closely inspect carbs.

[MAZ 80]

What, exactly, is the best way to adjust the floats?
The manual lists two methods.
The first is using a level tube which has a quite tight tolerance (-.5 to +1.5mm). This sounds good but they are talking about doing it on the bike. I don't see how this is going to work when the carbs are not level.
The second is the traditional method of measuring them while off the bike. The tolerance here is very generous (17mm plus or minus 2mm).
To muddy up the water even further, Factory Pro lists float height adjustment as a key factor in tuning the carb.

Opinions? Comments?

[Ghostt]

Float height is very important for tuning the carburetors, and bike.

Setting them off the bike, and verify with the tube once back on the bike.

The trick is setting the floats properly.

http://faq.ninja250.org/wiki/How_do_..._the_floats%3F

[MAZ 80]

I see I didn't explain myself very well. Let me try again.

I don't dispute the importance of setting the float, that goes without saying.

The method you pointed out is what I would consider the 'standard'. It probably came over on the Mayflower. My only question there is why the tolerance is so large. Particularly since the subsequent method has half that tolerance.

The follow-up method of using a level tube does look very accurate if the carb is setting nice and level like the picture in the manual. But it's not. It's setting at a 20 degree angle so the only place that level tube works is dead center. If you take your reading as much as 1/8" off center, you're out of tolerance.

But what I was really hoping someone had experience with is the Factory Pro system. If it actually works there's no sense in bothering with trying to get it super accurate with the level tube since you're going to be changing it anyway. To quote " You should be able to apply FULL THROTTLE at LOW RPM in TOP gear without ANY misfire of bogging or stumble.......". That's very impressive. Is it possible? More to the point, is it possible with the Ninja 250? How many people can actually do that?

[spooph]

Originally Posted by MAZ 80

I see I didn't explain myself very well. Let me try again.

I don't dispute the importance of setting the float, that goes without saying.

The method you pointed out is what I would consider the 'standard'. It probably came over on the Mayflower. My only question there is why the tolerance is so large. Particularly since the subsequent method has half that tolerance.

The follow-up method of using a level tube does look very accurate if the carb is setting nice and level like the picture in the manual. But it's not. It's setting at a 20 degree angle so the only place that level tube works is dead center. If you take your reading as much as 1/8" off center, you're out of tolerance.

But what I was really hoping someone had experience with is the Factory Pro system. If it actually works there's no sense in bothering with trying to get it super accurate with the level tube since you're going to be changing it anyway. To quote " You should be able to apply FULL THROTTLE at LOW RPM in TOP gear without ANY misfire of bogging or stumble.......". That's very impressive. Is it possible? More to the point, is it possible with the Ninja 250? How many people can actually do that?

Yes, my bike and RacerX's I know for certain can do this. Just wack it wide open and it screams! However, change the ambient temp 20F and that's no longer the case, lol.

I don't think this would be possible with a slide carb though...