Well I thought it was a carb issue...

[Stoneman]

 

[Frankenstein]

That piston has some really bad build up on the exhaust side or you have very bad blow by on that side.

Did you have an exhaust leak perhaps instead of a or in addition to the head leak?

I'm going to guess you didn't clean up your ports at all before starting the bike... Maybe a phantom bad edge job on the exhaust port in the cylinder was left untouched from the factory. That would chew up one side of a piston and rings pretty fast.

You'll want to get a cylinder and piston, rings all that. I highly recommend bicycle_motor_works on ebay for that, you specifically need a type A piston and cylinder, there's a type B but you don't want that, the wrist pin hole is higher up in the piston, basically half way up, yours is below mid way.

He supplies a new cylinder, rings, piston, bearing, wrist pin, and clips. All good quality stuff, and willing to set things right should things go a funky.

Good luck.

 

[Stoneman]

Thank again jake

It's what I was thinking now
No I never cleaned anything....lesson learnt
The edges where terrible when we pulled it down
I've got all the gear already so back to the beginning I guess
At least we picked up a bit of knowledge

Cheers and thanks all for the help

 

[gary55]

That piston has some really bad build up on the exhaust side or you have very bad blow by on that side.

Did you have an exhaust leak perhaps instead of a or in addition to the head leak?

I'm going to guess you didn't clean up your ports at all before starting the bike... Maybe a phantom bad edge job on the exhaust port in the cylinder was left untouched from the factory. That would chew up one side of a piston and rings pretty fast.

You'll want to get a cylinder and piston, rings all that. I highly recommend bicycle_motor_works on ebay for that, you specifically need a type A piston and cylinder, there's a type B but you don't want that, the wrist pin hole is higher up in the piston, basically half way up, yours is below mid way.

He supplies a new cylinder, rings, piston, bearing, wrist pin, and clips. All good quality stuff, and willing to set things right should things go a funky.

Good luck.

His son ran it for a half hour with the carb loose sucking air, and fried it.

 

[gary55]

View attachment 76966 View attachment 76967 View attachment 76968

I had a feeling. Like Jake said new top end. Get one with a slant plug head. The center hole stock head is 10cc. The slant plug stock head is 6cc. Big diff. in performance with the slant. Keep the carb tignt. Change the nut on the clamp screw to a nylock, and the screw to a allen head.

 

[Stoneman]

Thanks Gary
Yeah was obvious the difference in heads after reading your post
I'm glad I've joined now as I know so much more about the different types of parts

And than jake had me reading for hours again on the pistons! Lol
Just got to find a little on the connecting rods and decking the jug

Checked out bike bicycle motor works (nice engines!)but don't seem to come up for me in AUS eBay
But could get to there site. Problem is our dollars ain't worth much ATM so to keep the cost in reason I'll try and do it myself, plus I enjoy tinkering......but but the wifey doesn't haha

Cleaned the new jug up last night so will bolt her all up today hopefully with new gaskets and the slant head.

Its my sons bike but I'm the one hooked on it!

 

[Stoneman]

I might be being lazy now but is there a thread on all the different combinations of parts and fitting and basic build types?
Something that connects the dots

In my hunting I found this

https://ozarkcruisers.com/resources/66cc_engine_specifications/cylinders-pistons/

 

[Stoneman]

This is the result of the new jug tidied up

I put two tiny little nix in the transfer ports but I'm hoping they won't cause any problems.

Des any one have any tricks to keeping it clean or is just practise?

 

[Stoneman]

Well it's got me!
Now I'm back to 90psi
New jug, piston, rings and head. Triple checked for burrs and still no joy

No problem going together?..

 

[Stoneman]

Is this normal? It seems like a 100psi is all I can get
These are picture of the old jug but shows TDC one the sleeve