Hey all, just joined looking for some help with my struggles. I just completed a frameoff restore on a 92 lt250r. FMF fatty pipe, power core 2 silencer, boysen reeds and a wiseco standard bore piston. I have done everything on this thing and it looks amazing, but... I can't get it to run right. I have a beautiful bottom end and several spare motors that I'm going to fully rebuild to put in this thing, but for now I threw a top end on one of the spare bottom ends I had hoping to be riding weeks ago. I have been trying to troubleshoot this thing for weeks and I'm out of ideas. As stated it has the above components and upgrades and here is the full background on the motor. Bottom end is an 87 that the top end blew up on. The top end is a 92 and I have 125 psi compression test (though I have to kick it quite a bit to get the max pressure is that normal?) Carb is fully rebuilt and I started with 37.5 pilot and 260 main. When I started it it smokes a lot, but runs. Idle screw all the way in and it idles, idle air screw if screwed in motor dies but I can remove that and it still idles no problem. When I revved it it smokes a ton!!! So... reading the forums I've replaced the head gasket, replaced the crank seals, fired it up again and no different. I tried a 140 main jet and it did make a difference. I can turn the idle screw out 1 turn before it dies, air bleed screw adjustment remains ineffective. I throw in a 30 pilot jet, no difference. What am I looking at here? I'm at a loss; I don't have any idea what to try now. I'm mixing 32:1 and my 88 doesn't smoke hardly at all, but this thing just acts like its running really rich. HELP PLEASE!!!
Oh, its a stock mikuni carb too
Just a few weeks. Mixed it fresh non ethanol when I was ready to start it up. Logging in today I see I posted under the 500 section; sorry.
125# compression seems low. Should only take two or three good kicks with the throttle wide open to get a good reading.
OK. That's what I thought, but I'm kicking it like 6 times. What are symptoms of low compression with these things? Is low compression symptomatic of these issues? I've had 4 strokes until recently so I'm learning the mechanics of them now.
Was the cylinder bored or at least honed for the new piston. It sounds like your not getting a good ring seal to start with.
You should be in the 140 s for compression. On a stock cylinder unless it a ported cylinder and a stock head then you will read low.
Did you do a leak down test ? Are the crank seals in good condition. If the crank seal on the clutch side is bad it will suck oil and smoke like hell and not run rite.
Yeah I replaced the crank seals. I have ordered everything to do a leak down test, not done yet.
I didn't do anything with the cylinder. The top end was off of a running motor with a
**** case so I figured it would make till next fall. Guess it must have been a poor running motor :-/ When I bought it the guy didn't even have a pipe on it so I know it ran, but doing know anything else. Guess I'll do the leak down and if the low end isn't leaking I'll just rebuild the top end.
This may seem to be an offensive question but... Are you aware of how much a 2stroke should smoke? I only ask because you say you just switched over.... Try running it a little leaner... I know when I ran 32:1 My quad smoked quite a bit and I just switched over to 36:1 and it made a huge difference. Ran a lot better and smoked less.
This comparison isnt a good one but... Take my weed eater for instance lol...
Wont run right if at all if I run it 32:1... But when I run it 40:1 it runs perfect.
hello did you replace the orings in the carb. also vacuum test the float valve inplace and adjust float level.