700 miles out of a pitbike motor... dayum

 

I have one that I bought last year. It's got very low hours and a couple of weeks ago it quit pulling in 2nd gear.
Very frustrating considering its bad very little use.

 

Try This:

[h=1]Shift Star - TBolt USA Tech Database![/h]A loose shift star and drum will cause miss shifts
Rare problem , but normally an easy fix
Sounds like a loose shift star
Pull the clutch cover and and the little black plug near the front sprocket
see bolt #5 and the bolt in the center of the shift star
tighten both ends of the shift drum

 

I wish the issue with my motor was that simple. The gears are slipping past each other.

 

Thanks for the tip!

I'll try it.

 

^ knuckel head!
If the star is loose, it's not holding the gears at the correct position... Causing them to not be fully engaged... Which makes them dogs bark! (<-- = slips) lol

 

Another common issue I've heard about for these when used as street machines...clutches. The clutches start slipping. Ususally the first thing you have to do is replace the springs with HD springs . Then absolutely manke sure that the thing is adjusted right with a little free play. Last make sure you are using wet-clutch oil...not conventional oil. Those three things are vital.

I had a GPX160 made into a 177v2 and ran it nearly 4000 trouble free miles on the street. I replaced the motor with a Honda Nice but I could have used that motor for a much longer time. Another thing is that you need to replace that oil about every 500 miles on these things. Just remember, finish machining on these motors is done by the user...when they are riding it.

 

My new yx160 slipped as soon as I got it. I put the springs from my zs150 in it which are nearly 1/8 longer and fixed that issue. The PP155 does have some valve float. I'll check the shift star, and hope thats it, but was not on previous 2 engines.

Oil probably gets changed at 300 or less.

 

We have HD spring for the Clutch AND Valves !!

 

Did the zs155 ho have a shifter drum upgrade?? If so about what year or version did that upgrade happen?

Fast

 

^ All gears slip in the same manor?

 

1st and 2nd for sure. I dont know if it does in 3rd or not but they dont really have the load on them.

 

Does the trans skip harshly or is a smooth slip. It may be a slipping clutch.

 

Definitely not the clutch. Its like the chain slipping on the sprocket and catching.

 

^^^^^ that's what mine feels like in 2nd gear. Problem is that I pulled motor off bike so I'd have to put it back in to try it.

 

Sounds like a trans problem, maybe a bent shifting fork or a loose shifting star. I would start at the easiest pace and remove the clutch cover. Check the shifting star and the spring laded shifter detent. Also check the oil pump screen for trans gear pieces. If that all looks good then I would split the cases

 

The shift fork upgrade can cure the second gear slip issue, which is usually caused by a bent or smoked shift fork, 1st 3rd and 4th are not usually effected by this issue as their design is different. If 1st gear is skipping the issue is something broken or just worn.

 

1st and 2nd for sure. Probably 3rd if ran hard enough. Only does it under full load but starting to get worse.

 

Replaced the neutral switch with a bolt and will see how that helps. It seemed to fix it but did not get to really ride it at ~35F.