crank seal?

[elcamino12sec]

My bike has a real high cold start idle and also idles high with the idle screw all the way out (not complelely out) all the time. It seems like a lean condition because it takes a long time for the rpm to drop. For example, if Im riding in the power band and then let off the throttle and pull in thte clutch it takes longer than it should to drop down the rpms, on the way down it fires quite a bit. Its a 1994 kx250 with stock jets and procircuit pipe and silencer. For good measure Im going to replace the crank seal and flywheel seal next weekend. I have already inspected the carb and reeds, replaced the reed cage gasket. Is there somthing else I should look at before I remove the clutch and flywheel to replace seals? Is there any other known place these motors can get air leaks from. thanks in advance for any responses!

 

[wornknobby]

i'm not sure on your budget, but they do make leak down testers for 2-strokes.

 

[elcamino12sec]

Does anyone else have any other sudgestion on where an air leak can be, I plan on building a leak down tester this week.

 

[nickyd]

the leak can be anywhere 2 surfaces meet that go into the crank cavity - ie base gasket, reeds, etc. sounds like you are on the right track - what does the plug look like? I'm also assuming that you ruled out the easy stuff - slide hanging up in the carb, torn intake boot, etc.

 

[elcamino12sec]

Before I tear into it this weekend Im going to spray starting fluid on the gasket areas from the outside, Im gonna bet that if there is a leak I will see an increase in RPM. Again to rule out the obvious. If no leaks are found I will do my leak down test and go from there. I was just hopeing that someone in this forum had this problem with the same kind of bike that could tell me what they did to trouble shoot and fix the problem before I start throwing parts at it. Im sure its a simple fix, I just hate taking a whole Saturday working on the bike instead of riding. I live in Florida and we can ride all year long.

 

[xprojectstevex]

I am experiencing something similar on my 97 rm250 right now. I found that if I turned the air screw all the way in the problem just went away which further confirms the fact that it's a lean condition and I am getting ready to head in that direction(crank seals) as well because it's getting air from somewhere. Unfortunately I've ran into other problems on this bike I need to tend to before I worry about it. How long has your bike been doing this? A guy at my local shop told me before I wasted my time on anything else to loosen the nut on the top of the carb cap and tighten that adjuster down where the throttle cable enters the cap because alot of times it will vibrate loose over time and will gradually raise your idle until it gets unruly one day.

 

[elcamino12sec]

Thanks allot, I will try that before I preform surgery.