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I remember seeing an italian TGM 125 from the late 70's in a magazine. It was said to be the first 125 with 30 HP and it looked so cool with a slim tank and huge rear sprocket. That was my dream bike for a while back then.

I can understand that It's hard to really guess what is happening, since I did cut off a little too much all way around. Now, as I said, the exhaust opens into the crank area, but the port timing on the intake is of course way off too. I have basically ported it for high revs cutting the piston, combined with this exhaust opening it really doesn't perform very well [B)]

Anyway, problem identified and a new piston should do it. I have replaced all jets and the needle in the carb as well.

I will adjust the skirt using the John Durrill "line'em up" method this time [:I]

Richard, no need to apologize. That could very well have been the case.

I have lined them up using the pin just as you suggest John. But since I cleverly enough did cut off the bottom of the skirt I cannot see how much too long it was before. All I can say is that the stock Suzuki piston i a bit longer on the skirt, and when I did this I didn't pay attention.

But really, the question is if anyone have experience on how bad the engine can run when the piston opens the exhaust on the underside a bit?

Wiseco and Wössner pistons fits both bikes, but I am using a stock Suzuki (only) piston. They probably didn't care if it did fit the maico or not. I shaved a little off the skirt and took away too much.

Of course I didn't mount it backwards.

Anyway, a new one on ebay can be found for $20 - $40.

Thanks,

I hope you will enjoy yours as much as I enjoy mine.

EDIT: The 400 is mine and the other one is my buddys 420 1981.

Dave Hurley, my 400 shaft is from a 250 engine so they are the same.
Why is the bike a problem child? Do you have other problems than the shaft?

brian kirby, I have noticed that the seals seem to seal and last longer when there is some air in the fork. It seem to help keeping the dirt out and the seal lip tighter around the tube.

Does anybody have the same experience, or am I imagining things?

I also use ATF but I think my fork is a little underdamped. It doesn't bottom and seem alright but it feels to lively. I have heard others claim that 20wt fork oil is better. So that was what I was planning to use.

There is no quick fix unfortunately.

Here are a serie of pics of my 400 rebuild:
http://tinyurl.com/ktm400mc

SouthRider, yes, of course I did. 1,8 mm BTDC.

TedG, Ok, I can buy that explanation. Timing was late, but my head is
torqued exactly according to the specifications with my
quality and calibrated torque wrench.

The seal is perfectly seated though. Took everything off to
polish the cone.

SouthRider, yes, of course I did. 1,8 mm BTDC.

TedG, Ok, I can buy that explanation. Timing was late, but my head is
torqued exactly according to the specifications with my
quality and calibrated torque wrench.

The seal is perfectly seated though. Took everything off to
polish the cone.

I agree. Too tight fit between piston and cylinder. There are some other strange things that can be going on as well, such as a defect piston that expands non-uniform, or a bore that is not straight, or even 2 cases from different engines that doesn't form a straigt base for the cylinder bottom, so it leans over slight and the bore isn't perpendicular to the crank shaft.

Most of those where sold with Öhlins over here but they are 357 mm eye to eye whereas 13,75" is 350 mm. So I would say 14"

I found Kees Van Der Ven at Facebook and sent him a friend request today. He was a factory rider in the 250 class back then. Even though he might not know, maybe he can help to locate a mechanic or someone with the answer.

Adrian, wow.. she's nice!!