Blaster jumps & dies when put in first gear

[OlyOlson]

I have ready all the existing threads and there is good advice but my build is interesting:

I built two identical blaster. The first run everything is perfect. The second one runs perfect also but it doesn’t drive. When shifting from neutral into first it lurches forward and dies.

brand new engine rebuild gaskets, bearings, crank. New everything. New clutch basket, boss, discs/plates and springs.

I have a new clutch lever and cable. The clutch actuator arm and spring/washer/seal are new as well. I have a new pressure plate as well. Both push rods and bb are installed and new as well. This was built side by side with the twin bike.

with the clutch cover off you can pull the clutch lever and see everything working properly. Pressure plates and discs/plates moving fine.

bike idles perfectly and carb is tuned properly. Compression is perfect and leakdown test also held 6psi.

I’m completely stumped. I know others say oil but trans oil is Motul 10w30 specific for 2-stroke transmissions. I have built/restored over a dozen blasters and never had this issue that couldn’t be solved with cable/arm adjustment.

Sorry for being long winded but I wanted to make sure folks knew I have tried just about everything, I think.

 

[Larry's Shee]

It could be a manufacturing difference/tolerance in one or more of the parts. You could take every part from the working sister machine and compare them to the non-functioning one, but that would take a long time, because you’d even have to compare the cases. The throw out lever could be a couple thousands further away from the clutch.
The easiest way would be to adjust the center screw at the pressure plate. Ya, Lining the pointers up is the “ correct” way to adjust it, but that might not be what this engine needs/wants.
While the cover is off, pull the clutch lever and see how much the clutch actually moves.
I don’t recall if any of the washers in the clutch are cupped, but if there is , maybe it’s in backwards?

In manufacturing there is what’s called
“tolerance stacking” where , let’s say each individual part is to the small side and the pusher is further away, clutch plates are a hair thicker, it all adds up to the clutch not disengaging.

I hope this makes it clear as mud

 

[OlyOlson]

It could be a manufacturing difference/tolerance in one or more of the parts. You could take every part from the working sister machine and compare them to the non-functioning one, but that would take a long time, because you’d even have to compare the cases. The throw out lever could be a couple thousands further away from the clutch.
The easiest way would be to adjust the center screw at the pressure plate. Ya, Lining the pointers up is the “ correct” way to adjust it, but that might not be what this engine needs/wants.
While the cover is off, pull the clutch lever and see how much the clutch actually moves.
I don’t recall if any of the washers in the clutch are cupped, but if there is , maybe it’s in backwards?

In manufacturing there is what’s called
“tolerance stacking” where , let’s say each individual part is to the small side and the pusher is further away, clutch plates are a hair thicker, it all adds up to the clutch not disengaging.

I hope this makes it clear as mud

It makes sense and thank you for your reply. The convex washer is in correctly as well. A few things I might try are adjusting the screw to pressure instead of the set arrow and I also think I’m going to put the old entire clutch back in. I will also start measuring plates and stuff per factory tolerances.

 

[Larry's Shee]

I would just start with adjusting the pressure plate screw. It’s the easiest and fastest thing to do. I’ve seen a lot of Banshee owners have to adjust outside of lining up the arrows. That’s just a relative starting point.

Please let us know what you find out !!

Because I actually read what you posted I didn’t automatically say
“Grooved clutch basket” , because that causes near identical symptoms

 

[OlyOlson]

I would just start with adjusting the pressure plate screw. It’s the easiest and fastest thing to do. I’ve seen a lot of Banshee owners have to adjust outside of lining up the arrows. That’s just a relative starting point.

Please let us know what you find out !!

Because I actually read what you posted I didn’t automatically say
“Grooved clutch basket” , because that causes near identical symptoms

Yeah all new clutch basket, boss, plates &springs. I’m going to adjust the screw way out/in to see if that works, try older known working clutch parts and maybe a few other things. Thanks for responding.