January 17th, 2018, 09:59 AM | #1 |
ninjette.org member
Name: Bill
Location: Central Texas
Join Date: Jan 2018 Motorcycle(s): 1992 250R Ninja Posts: 27
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Looking for Definitive Short Answer to Carb Setup for K&N R-0990 Pod Conversion
Hi:
I have a 1992 Ninja 250r that was given to me that I am trying to get running. It was last registered in 2003, so assuming it hasn't run since then. Drained tank of "gel", cleaned with muratic acid (works great on steel car tanks) to remove gunk and rust, then coated inside with WD-40 until I am ready to install. Now onto carbs. I am getting rid of airbox (need new rear tire anyhow), putting on K&N R-0900. Have carbs torn down and chem-dip cleaned them. Now I need to know how to set up the carbs with this filter (more airflow means more fuel needed as well to keep air-fuel mix in balance). To summarize what I know: Main Jets: *either a 110 or a 112 (100 is stock? *which one? *most say 110 is still a little too lean, 112 too rich, but better too rich than too lean) Slow Jets: *either a 35 or 38 (35 is stock? *most say it doesn't matter, some recommend 38: which one?) Idle Air Screws: *Left 2 1/2 turns out, Right 1 3/4 turns out (stock, most say no need to change?) Needle Jet: *2-3 shims, click position 3? It's the needle jet settings that I really don't understand. When I took apart the carbs, the needle jet had no shims on it, though it looks like the shim/washer for the idle air screw is a perfect fit and could be used as a "shim". And folks talk about a "click position" on the needle, usually 2 or 3. *What is this? *It is often but not always mentioned in conjunction with "FP", which I am assuming means "Factory Pro"? Can anyone provide some insight on this needle setting (and the others)? *Do I need to upgrade to some kind of adjustable needle from Factory Pro or is the stock needle OK? Looking for short answer. *Some threads on this topic have 200+ posts, just looking for "cliff notes". Thanks in advance. |
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January 17th, 2018, 11:01 AM | #2 |
Rev Limiter
Name: Jay
Location: WI
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1990 Ninja 250 - K&N pod filter and stock (leaky) exhaust, running 87 ethanol-free.
Pilots - 38 Needles - stock with 2 washers Mains - 108 Idle Mixture screws - 2.5 turns out +/- depending on temp Idled well and pulled strong all the way up to the limiter. |
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January 17th, 2018, 11:59 AM | #3 |
ninjette.org member
Name: Bill
Location: Central Texas
Join Date: Jan 2018 Motorcycle(s): 1992 250R Ninja Posts: 27
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Thanks for the reply. Given your stable of bikes, you've got some experience certainly more than me -- I haven't had a motorcycle since 1977 and then it was a 250 Maico (sunburst head, coffin tank and a 4 speed).
So it pulls strong to the redline with a 108 jet? And the plugs look good (brown, not white)? Most folks say 110 minimum and some a 112 to avoid a lean condition. Do you think your location (WI -- cooler weather) makes a difference? And out of curiosity, where did you get the idea/advice for the two washers under the needle in the first place as that is not stock? I wonder who first came up with that adjustment? Any idea what that does? Guessing it allows more fuel into the mix by raising the needle base, maybe that's why a 108 works for you. Perhaps the 110-112 needle guys aren't shimming the needle or not as much. So maybe the theory/rule could be for main jets 112 with no shims, 110 with 1 shim, 108 with 2 shims? And for pilot jet, 38 with 2 shims, 40 with 1 shim, 42 with 2 shims? |
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January 17th, 2018, 12:43 PM | #4 | |
Rev Limiter
Name: Jay
Location: WI
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Quote:
Pulled to redline and beyond to the limiter just fine. Plugs were tan. Non-ethanol gas does give you a richer mixture than gas with ethanol, but I think a lot of people go overboard with the Main Jet size. What exhaust will you be using? That can make a difference as well. 108 is a good place to start. Temperature and elevation also alter the mixture. There are plenty of variables. Shimming the needles gives a richer mixture sooner, and compensates for a stock mid-range that is on the lean side. 1 to 2 shims is common. Adjustable needles do the same thing, but aren't really necessary. The needle adjustment doesn't effect the mixture at WOT, as they (needles) are completely out of the Main Jet by then. Shims don't effect the Pilot Jet size or Idle Mixture setting either because the fuel is not being drawn up through the Main Jet at that point. Not sure all the info is definitive, but it has worked for us. There is plenty info on carb tuning, and much more, here - https://faq.ninja250.org/wiki/Ninja250_Howto |
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January 17th, 2018, 01:35 PM | #5 |
ninjette.org member
Name: Bill
Location: Central Texas
Join Date: Jan 2018 Motorcycle(s): 1992 250R Ninja Posts: 27
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It was actually a 400, not a 250, I was 14 years old when I owned it, weighed all of 125lbs, and it scared the hell out of me compared to the Suzuki RS 125 I moved up from. Sold it and moved down to a CR250 for a very short while before I got interested in other things.
It has a stock exhaust. The shims thing makes sense now that you've explained it. I am guessing that there are also these adjustable needles -- position 1, 2, 3, etc. -- that can be turned to be higher or lower right at the exposed part of the needle in the venturi without having to pop the top on the vacuum diaphragm? Everyone seems to be between 108 and 112 on the main jet, so I am going to split the difference and go with a 110 ands cross my fingers. Same with slow jet: everyone's between 38 and 42. I was thinking of a 40 just to be on the rich side a bit, unless you think that is overkill. And I'll go with 2 shims on the needles. |
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January 17th, 2018, 02:10 PM | #6 | |
Rev Limiter
Name: Jay
Location: WI
Join Date: Jul 2013 Motorcycle(s): '06 SV650n, '00 Derbi GPR, '64 CA77 Dream 305, '70 CL450 Scrambler, numerous dirt bikes Posts: A lot.
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Quote:
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January 17th, 2018, 06:44 PM | #7 | |
ninjette.org certified postwhore
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Quote:
Bill
__________________________________________________
Insanity: doing the same thing over and over again expecting different results each time. Last futzed with by Ram Jet; January 17th, 2018 at 06:46 PM. Reason: additional info |
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January 18th, 2018, 05:20 PM | #8 |
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Short answer: YMMV. Test it yourself. Plenty of instructions online.
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January 18th, 2018, 07:11 PM | #9 | |
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Quote:
Bill
__________________________________________________
Insanity: doing the same thing over and over again expecting different results each time. |
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January 19th, 2018, 02:16 PM | #10 |
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January 19th, 2018, 02:52 PM | #11 |
ninjette.org member
Name: Bill
Location: Central Texas
Join Date: Jan 2018 Motorcycle(s): 1992 250R Ninja Posts: 27
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Going with:
Main: #110 Idle: #40 # of Needle Shims: 1 Idle Air Screws: 2.5 Turns for both Will let you know how it works with the K&N pod (BTW, why is it called a "pod"?) |
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February 19th, 2018, 03:31 PM | #12 |
ninjette.org member
Name: Bill
Location: Central Texas
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Ok, bike runs with the aforementioned carb setup -- first time since 2003 -- revs up to 13,000 redline and returns to a stable 1,500 rpm idle after first undershooting momentarily to 1,000 rpm.
Onto the brakes, then onto the road. |
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March 7th, 2018, 08:13 PM | #13 |
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Name: Adam
Location: Sardis
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the pod looks like a cold air intake cone that is usually on a performance vehicle to allow more airflow into the engine. cant remember what mains I'm running right now but all tuning can vary on your elevation. with a little trial and error you can tune it yourself quite easily buy a few sizes of jets from kawi i believe i went with 108 110 and 112 then install each one and test how the bike runs. once you find the best running jet start putting a couple washers/shims on your needles (one on each needle to start) then keep adding washers until you get a nice smooth power all the way to redline. i never needed to mess with the idle mixture screws i believe they're 2.5 turns out. mind you I am at sea level
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March 8th, 2018, 10:21 AM | #14 |
ninjette.org member
Name: Bill
Location: Central Texas
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Thanks.
Still haven't actually ridden the bike yet: rebuilt everything but the brake lines, but they were clogged/collapsed, so waiting for new ss braided ones. In meantime, I start it every couple of days. It is a bear to get warmed up, but once it is, the engine revs to the redline with no problem. I do have a question about the choke and idle though. When I first started working on the bike, the choke lever has some "friction" to it, that is it would stay wherever I set it. Now I have to hold it to keep the choke on. Does the choke lever have a friction plate or something similar that I just have to tighten up on the lever mechanism or is holding it in-place until warmed up the proper modis operandi? And it seems like I have to fiddle with the idle adjustment a little bit every time I start it up. Is this just a warm up issue or is something else going on here? |
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March 8th, 2018, 10:57 AM | #15 |
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Nope, like cold-start cycle on autos, using choke leads to idling at higher-RPMs. It will increases to +4000rpms as it warms up. So just dial back the choke gradually as it speeds up until you've got no more choke. I just use choke for 15-20s, then ride off. Turn off choke at 30s or so.
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March 8th, 2018, 12:03 PM | #16 |
ninjette.org member
Name: Bill
Location: Central Texas
Join Date: Jan 2018 Motorcycle(s): 1992 250R Ninja Posts: 27
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Thanks for that. Right now mine needs to be held open for a minute or two before the throttle will respond without "bogging".
Does your choke stay open/on at the lever or do you have to hold it open? Mine was doing that initially (staying open on its own), but once the rust wore off the lever plate (the bike hadn't been started in 14-15 years), the choke won't stay open/on unless I hold it there. |
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March 8th, 2018, 12:31 PM | #17 |
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There should be enough friction in the choke-lever to hold it. Perhaps push the handgrip closer to choke-lever to increase friction?
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March 8th, 2018, 01:10 PM | #18 |
ninjette.org member
Name: Bill
Location: Central Texas
Join Date: Jan 2018 Motorcycle(s): 1992 250R Ninja Posts: 27
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Thanks for that. Right now mine needs to be held open for a minute or two before the throttle will respond without "bogging".
Does your choke stay open/on at the lever or do you have to hold it open? Mine was doing that initially (staying open on its own), but once the rust wore off the lever plate (the bike hadn't been started in 14-15 years), the choke won't stay open/on unless I hold it there. |
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March 8th, 2018, 01:26 PM | #19 |
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Don't have to hold choke-lever. There's enough friction in the mechanism to hold it in place.
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March 8th, 2018, 03:47 PM | #20 | |
ninjette.org certified postwhore
Name: Bill
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Quote:
Bill
__________________________________________________
Insanity: doing the same thing over and over again expecting different results each time. |
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March 9th, 2018, 12:10 PM | #21 |
ninjette.org member
Name: Bill
Location: Central Texas
Join Date: Jan 2018 Motorcycle(s): 1992 250R Ninja Posts: 27
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Well, unfortunately, I rebuilt the carbs -- including especially the choke mechanism -- and lubricated all the cables. Oh well.
Good news is that the new SS braided brake lines finally allowed me to bleed the front and rear brakes thru the rebuilt master cylinders and calipers, so I was scooting around the neighborhood last night. Rev'ed up to about 12,000, really can't tell yet how well or not it is running as I don't have any kind of recent basis for comparison. Literally I hadn't been on a bike since around '78 -- 250 Maico, I was a motocross guy, AMA amateur license and all, but not very good (not fearless/crazy enough) -- and I couldn't get this 250 up over 50mph without it scaring me: even though I never had a problem running that Maico at 70+ on dirt. Ah, to be young, invincible -- and stupid. Now time for some tuning/refining. Now that is is fully operational, bought a nice red, white and blue helmet, channeling the whole Evel Kienevel thing I guess. |
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March 9th, 2018, 01:10 PM | #22 | |
ninjette.org certified postwhore
Name: Bill
Location: Port Huron, Michigan
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Quote:
Bill
__________________________________________________
Insanity: doing the same thing over and over again expecting different results each time. |
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March 9th, 2018, 01:31 PM | #23 |
ninjette.org member
Name: Bill
Location: Central Texas
Join Date: Jan 2018 Motorcycle(s): 1992 250R Ninja Posts: 27
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Maybe once I have a brain bucket, I'll feel more confident. Is there a way to raise the ride height (maybe a rear shock adjustment/change) as it rides a little low for a six footer?
Will be fun to run to the store on it to get milk, but I think my Honda Insights (I have 2 identical silver ones: one manual, one automatic, manual is much better) will get better gas mileage Hopefully, the more I run and "blow it out" after 15ish years of sitting in a barn, the faster it will warm up, better it will idle, etc., but so far, so good. Thanks again to everyone for all the help, advice, etc. I'll post pictures of the battery box we had to build when we replaced the airbox with a pod. If anyone wants one, I am sure my brother will bend one up for you for a small fee (like he charged me) :-) |
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March 9th, 2018, 01:46 PM | #24 | |
Rev Limiter
Name: Jay
Location: WI
Join Date: Jul 2013 Motorcycle(s): '06 SV650n, '00 Derbi GPR, '64 CA77 Dream 305, '70 CL450 Scrambler, numerous dirt bikes Posts: A lot.
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Quote:
Generally an improvement, and very inexpensive. A true quality aftermarket replacement shock is pretty expensive, though there is a new thread here (https://www.ninjette.org/forums/showthread.php?t=312824) about an inexpensive aftermarket shock that might be worth looking into. Fork springs are too light for most as well. Sonic Springs is a good choice for those. |
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March 9th, 2018, 02:01 PM | #25 |
ninjette.org member
Name: Bill
Location: Central Texas
Join Date: Jan 2018 Motorcycle(s): 1992 250R Ninja Posts: 27
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Thanks for the suspension advice.
Will the post-gen shock raise the rear of the bike at all or is it just stiffer/more responsive? |
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March 9th, 2018, 02:14 PM | #26 |
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Raises about an inch iirc.
Be careful messing with suspension geometry in the name of rider fit. There's a definite end to stability if you go too far. |
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March 9th, 2018, 06:36 PM | #27 |
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Problem with raising bike itself is you'll still feel cramped when riding because the distance between seat and foot-peg is still the same. Better to add padding to the seat to raise it and put it further away from pegs and ground.
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March 9th, 2018, 08:13 PM | #28 | |
Rev Limiter
Name: Jay
Location: WI
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Quote:
I believe the New Gen shock also has preload adjustment, where the original one doesn't. |
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