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Hey all, after building my custom pipes and installing the K&N intake, I added the PC5. Downloaded some maps, but really need dyno time. Question is, how lean can our motors handle? It was a bit lean, maybe a lot, I richness up the mixture, lost a lot of mpg, split the difference, got pinging, added a bit more... Don't want to damage anything.

Second question for poncho or anyone with additional info. Wife's first bike, Suzuki S40. Odd reaction to high speen running on the highway. Shut off throttle to exit, it dies, won't idle, but can be kept alive by use of the right wrist. Thought carb, cleaned it, rebuilt petcock, what else? Only change was custom open muffler. Keep it running for a bit and it calms down and runs great. I can twist throttle to keep her running, so I know fuel is available... So is spark and air.
 

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wocka, wocka, wocka
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Question is, how lean can our motors handle?

Second question for poncho or anyone with additional info. Wife's first bike, Suzuki S40. Odd reaction to high speen running on the highway. Shut off throttle to exit, it dies, won't idle, but can be kept alive by use of the right wrist. Thought carb, cleaned it, rebuilt petcock, what else? Only change was custom open muffler. Keep it running for a bit and it calms down and runs great. I can twist throttle to keep her running, so I know fuel is available... So is spark and air.
hw, your motor can be leaned all the way over till you scrape yor boards and then a bit more?
as for the fuel mix.. 14:1 is good. but you dont have those tools,, so watch yor plugs. front one is ez. White is NO good tooo lean hot. Tan/Brown is mor better. dark brown/Black is NO good tooo rich. which also yor mileage will suk.
stock these motors are probly 15-16'ish. being water cooled, kaw can get away with such dryness..
pix my plugs. changed them this summer at 50k. they is as good as new.


zookie issues. some carb bikes have fuel flow issues at high speed when the tank gets less than half full. the weight of the gas affects rate of fuel flow and can starve the motor. if you have pump or fuel filter restriction issues, exasperates this phenomenom.
Yes, some carb bikes have fuel pumps. our yammers Roadstars have em. many us strippers.. strip em off and go with the gravity feed. worx fine mos time. I removed the two pre filters in the tank and line. left just the final filter at the carb float bowl.

fixes include: clean tank, clean fittings, line, keep full tank, dont ride full throttle, cetera.
 

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Hey all, after building my custom pipes and installing the K&N intake, I added the PC5. Downloaded some maps, but really need dyno time. Question is, how lean can our motors handle? It was a bit lean, maybe a lot, I richness up the mixture, lost a lot of mpg, split the difference, got pinging, added a bit more... Don't want to damage anything.
I think auto tune will work on the 08 with pc-v.
 

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wocka, wocka, wocka
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Zuki, sounds like chopping the throttle induces cut off of fuel flow? Is there some throttle carb linkage hanging up? Look at the idle cam on carb, accelerator pump, anything mechanical that mite hang up when the throttle is chopped shut? A good cleaning of linkage with carb spray can free up sticky stuff.
 

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Burt, the Suzuki sounds like it is running a little lean on the idle circuit. This was probably caused by you opening up the exhaust. I would try to richen up the idle mixture, if you can't adjust it out with the idle air screw then you may have to go up a size or two on the pilot jet.
 

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Discussion Starter #6
Thanks for the ideas. On the v2k, I have considered the autotune, still thinkin on it. Want the dual channel. Dyno time would run $200 for a tune session.

On the Zuki, been sperimentin'. Ran in prime one day, no issues. Put it in "on", induced the issue. AH HA! Sez I. Did the same the next day. No die either way. Scratching me head bumfuzzled... Have had the carb apart three times. Will try richnin' the mix a bit to see what that does.

Worried Belle might be gettin jealous with me mountin' 'nother bike...
 

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Burt, the Suzuki sounds like it is running a little lean on the idle circuit. This was probably caused by you opening up the exhaust. I would try to richen up the idle mixture, if you can't adjust it out with the idle air screw then you may have to go up a size or two on the pilot jet.

Yep bang on, sorted a mates one out a while back. Modified exhaust and same issues. These bikes run horrendously lean. Idle screw adjustment does little to sort things.

We had to rejet the sod with loads of mucking about. Jets are cheap as chips (fleabay) its just trying to get the right combination. Once sorted it ran like a top but did suffer considerably in the mpg dept.

As soon as Dave's license was done the horrid little S40 was traded for a vstar. Ando


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