Valves hitting piston after rebuild

[G601950cc]

If it's Chinese its a through away design. However I used to make gaskets for a Suzuki ts 185er using cereal box and vauxhalls green gasket rtv worked fine. Tapping a little hammer against card whilst resting it on head to indent shape.

[bikemach]

hi m8 am a bike mechanic and own cleveland county scooters in teesside NE,
have you got the piston the right way round as the inlet valve (think it is) is bigger and the piston has a bider grove to take it,

[G601950cc]

I've spoken to a couple of people and recon you might get away with putting 2 gaskets together to make up the difference. Not guaranteeing that though. But another point if relevant if fitted with a cam chain is it going to be long enough to fit with taller head gasket thickness?

[golf-sib]

Piston is correct way round, it seems a common issue with these bore kits. What I've decided to do is make a 2mm gasket at bottom end and use stock 0.6mm head gasket if that doesn't give enough clearance then I will use the cb150 gasket for head at 1.5mm

 only worry is timing chain should slip on but the more you space things out the more you knock timing out.

[golf-sib]

I also have an entertaining video of how we removed the camshaft

www.youtube.com/watch?v=bCYtyGaRIB8

[golf-sib]

Right!

Build the gasket, yada yada, got the engine running but the timing chain was under some stretch, when I cut the engine out it snapped the chain, no damage to valves etc, but now I'm in a dilemma can anything actually be done?

One idea is to add two more links to the chain, links are 8mm long and the stretch is 6mm overall, so with the tensioner in thory it may work, but I'm sure adding additional links would knock timing out, correct?

Other method is to put it all in the bin 

[danny_p]

extra links in the chain won't affect timeing.

have you thought about chmber volumes ect,   just wondering with spaceing th ebore up your effectivly lowering your compression ratio also doing the same with thick head gaskets.

another approach  is woud it be worth moveing the piston down the bore by doctoring the con rod or piston itself

[golf-sib]

In essence the compression should be fine as the 150 kit uses a shorter con-rod, but since no one has yet documented this upgrade its literally like walking in the dark too continuous surprises.

What is this doctoring you speak off?

Hmmm the link option is a high possibility then, can i break the links the same way as a bicycle chain by pushing the rivet out, or would it weaken the chain to much?

[gazareth]

I think if the chain has snapped once its fit for the bin. there is every chance it will break again.

[rallye_golf]

Would it be easier to look where the contact is on the piston and machine/grind a bit off so it clears?