Vintage Dirt Bike Q & A

I just got it running this weekend, but it smokes (white smoke). I noticed oil spitting out from the head and into the exhaust pipe.

I've read about jetting(?), timing and possibly crankcase seals being the culprit. I want to make certain the issue before I tear into the engine which is something I've never done before.

Any help would be greatly appreciated.

I've come so far...I'm almost there!!!

Kyle

White smoke sounds like timing. The excess oil may
be a by-product of incomplete combustion.

Ray, since this an MT, you want to jump in here?

dogger

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1973 CR250M
1979 CR250R
1993 CR250R
2008 CR500R
2009 CR250R

Kyle,

This is from a post you made on May 9th:


This sounds like a lot of oil. Several things spring to mind:

1) oil pump cable way out of adjustment
2) incorrect oil in injector tank
3) bad clutch-side crank seal
4) leaking center case gasket

My buddy's MT250 still smokes a bit (bluish-white smoke), probably due to some misadjustment of the pump cable. At first fire-up after 15+ years idle it smoked a lot, but I was running 40:1 premix until I verifed the oil pump still worked.

Below is the oil pump diagram; figure 69 shows the adjustment marks.

Ray

_________________
'74 CR125M (175cc), '75 MR175, '82 RM250Z, '08 YZ250F, '14 Zero FX electric, '14 Zero MX electric, '18 Alta MXR electric

I found out it was my clutch side crank seal by leaning the bike way over on the kick stand side and that alloweed the crank oil to run to the other side of the crank and the seal started to suck air in and leaned way out and the revs picked up once that happened I knew right what it was I had thought it was jetting the whole time and am lucky I didnt burn up the top end. I did this on accident but it worked to find the problem. I have no oil pump on my bike I took it off so I knew that wasnt the problem.