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no bottom end power
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Posted by: ihillig---------------------
ive been running 40:1 yamalube oil in my bike for a year, and have not had any problems. yesterday i was in school and my brother was going to go out riding and called the local shop for the oil ratio and they said 32:1. he said it rode fine but no idle. so i went out riding today (with 32:1) and the bike would not idle, did not have much bottom end power and it might have just been me but i thought i felt a lack of compression?
thanks
Posted by: crazycr125---------------------
:think what is it jetted for? i would just run 40:1 if it worked before. did you hear a clinking sound at idle that progresstd as the rpms went up? if so it has no compression and has piston slap
but i doubt it.
Posted by: Lutz---------------------
If your bike is jetted for 40:1, running 32:1 would make your gas/air ratio a little bit leaner. This change could be large enough to make the bike not idle, but I doubt that it would make the bike so lean that it burned up your rings, unless you were already on the ragged edge. Try going back to 40:1, and everything should be OK.
For reference, my 95 KDX 200 was run on 40:1 up until this past summer, when I switched to 50:1 with Amsoil 2000. I still have the original piston and rings, and haven't had any problems.
Posted by: MN KDXer---------------------
You have a totally different problem than from the small air/fuel ratio change from switching to 32:1 from 40:1.
Here's some options-
1- He rode it hard without warm-up and cold scored the piston.
2- Your piston suffered a ring seizure.
3- The pilot jet is plugged.
4- Somebody was mucking with the idle screw.
5- The powervalve is stuck in the full open position. (this colder fall weather will make the goo that much thicker until the engine is warmed.)
6- He bought some bad fuel, which is causing the engine to idle weird.
7- It is much colder out, and your bike needs to be rejetted to compensate.
Good luck with it! 
Posted by: bud---------------------
Good list mnkdxer. I think I might be able to get a bike to behave like that by turning the air screw in all the way too. If it won't idle but will run as usual on top, I'd say that would rule out options 1,2 and 5 as the main cause.
Posted by: Grok---------------------
Turn off fuel tap, drain float bowel contents into a gas proof container. Examine what youv'e drained out.
If you find water, great! Just totally drain your tank and refill with clean premix.
If you find solid contaniments.......... bummer.
You have to drain tank, dismantle carb, clean and reassemble, also replace or clean all filters (don't forget fuel tap filter). Refill with clean premix.
Eliminate the source, ie -clean rusty tank.
Posted by: Lutz---------------------
Listen to MN KDXer and the others. I wasn't very clear in my previous post in my words or reasoning; what I meant is that the change in air fuel ratio probably isn't the big problem. A change in the mix ratio will affect the way the bike runs to a certain extent, but not result in a major change. By the way, have you checked the spark plug?
Good luck!
Posted by: feiloong71---------------------
Hi crazycr125,
i refer to your message
>>> did you hear a clinking sound at idle that progresstd as the rpms went up? if so it has no compression and has piston slap but i doubt it.
:think this sounds like my bike symptoms. What should i do then in this case?
thanks!
:D
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