250 shifting ???

[Carl Hill]

Finished restoration on my 74 250 this year and rode it at VMD (my 1st ever vintage race) and had a good time. I did have multiple missed shifts including 1 that cost me a good start in 2nd Moto . I rode a 75 & 78 many years ago and don't recall any shifting issues. Of course my previous ride was a Berkshire so maybe anything would have seemed good. I do notice on this machine it shifts pretty good without using the clutch. What do you folks think? Ride it or pull it back apart?

[brian kirby]

I never have any missed shifts on the KTM engines that are not my fault. I dont use the clutch on any motorcycle, but I do chop the throttle as I shift, I never shift under a load or "power shift". Shifting without the clutch and "power shifting" are two different things. All you have to do is unload the transmission, whether its with the clutch or with chopping the throttle.

If you do have missed shifts that you do not think are because of your shifting technique, I would suspect the pin on the shift fork that rides in the groove of the shift drum. Because sometimes the shift lever is adjusted too low riders boots can push the lever up and put pressure on the fork, this causes the pin to become worn, the fork will shift good in one direction (downshifting) and will miss the up shift or it will make the up shift and then pop back out of gear when you let off the throttle, the back cut dogs will hold it in gear until the load is lifted and it will pop out.

Brian

[SouthRider]

Great explanation Brian.

Also - the early engines had welded steel shift drums that had wear problems. It's very possible that an engine this old has a worn out shift drum.

_____________________________________________________________________________________

"We the willing, led by the unknowing, are doing the impossible, for the ungrateful. We have done so much, for so long, with so little, that we are now qualified to do almost anything, with nothing."

1972 Penton Berkshire 100
1983 Husqvarna 250 XC
2011 Jayco 31.5 RLDS
2009 Chevy 2500 HD Duramax

[Toolsurfer]

My 74 1/2 shifts great and has never been apart. Just like the guys say, make sure shift lever is adjusted correctly for your riding style and if you are selecting correctly and getting false neutrals may have wear issues. My manual says always use clutch, keeps selector dog / cam wear down . I like shifting both ways as stated before.

[454MRW]

Most KTM engined MX bike racers gear their bikes so that 1st gear isn't used, starting in 2nd, so as to avoid the neutral between 1st & 2nd gear altogether. Mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1978-1979 MX-6 175 & 250 KTM's
1976-78 125-400 RM's & 79 PE250 Suzuki & 2012 DR650
2007 CR125R Honda
1977 MC250 Maico

[Carl Hill]

Thanks guys. It is always during up shift that false neutral is hit. Usually between 2-3. Guess I better tear into it and take a closer look at shift forks.

[454MRW]

There is an actual neutral between 2nd & 3rd in the transmission design, built in because of the ability to lock out 1st gear and convert the transmission to a 5 speed with the use of a lock out bolt installed on the RH side of the engine case by the clutch release mechanism. It may be that you are not using enough pressure to clearly shift into 3rd, knowing the neutral exists there, optimum shifter lever length or adjustment. Mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1978-1979 MX-6 175 & 250 KTM's
1976-78 125-400 RM's & 79 PE250 Suzuki & 2012 DR650
2007 CR125R Honda
1977 MC250 Maico

[brian kirby]

Yes, I forgot about that, there is a neutral in between 2-3.

Brian