Kick start issue - gearbox output shaft axial position?

[NewKidOnTheBlock]

Hi Guys,

It's been a while i know... Finally making some space in the garage and i pulled out the Single (engine is a Spanish 250cc), couldn't get it started even new fuel, checked spark, valve clearances good, cleaned carb. But I've had an issue with a slipping kickstart for a long time so i thought that can't help. I found I'd got a coil spring conversion kit laying around so went to fit.

After getting access I found that the gear in the clutch casing seems to be rubbing on the crank case. It doesn't feel like it fully engages the gear on the output shaft. I'm wondering if somehow this is shimmed incorrectly inside the crank casing causing it to be set back somewhat. Does anyone have any ideas before i take the engine out and split it? I tried attaching a photo where you can see the lump from the kick start mechanism has been rubbing against the casing but it's too large to upload. Will have another attempt later!

[NewKidOnTheBlock]

Attached image now!

[NewKidOnTheBlock]

This lump is rubbing against the casing

[Jon Pegler]

Your photo looks like you have a 4-speed Mototrans 250.
I would guess that the gearbox shaft does need re-shimming, mainly on the RHS.
Try removing the final drive sprocket and see if you can tap the output gearbox shaft through from the RHS towards the LHS.
This may push the output shaft 1st gear further into it's bearing, allowing the kickstart pawls to engage further.
If it does move a fair way, a re-shim is required.
Be careful with the LH output shaft bearing. You can't get replacements.

Jon

[NewKidOnTheBlock]

Hi Jon, thanks for the help. You are correct that it's a 4 speed mototrans. I think in fact i bought that kickstart gear (and some gearbox bearings) from you those years back when i built this engine.

I'll try moving it from the sprocket end and see if there is some play. Any tips on reshimming the gearbox? I've never dared to touch those before (unless i did inadvertently last time!)