Bike not running.

[Firstbuild408]

So I was able to remove the head and found the problem. A big hole in the piston which I’m thinking was caused by the new spark plug. So new cylinder head and piston. Any suggestions how I would go about this? I know I gotta clean the crankcase for any metal that fell down.

 

[GreasyChris]

Yup you were running way to lean and burnt a hole thru the piston. You'll need to properly tune it when you get it back together or it will happen again.
Lean mixture = hot combustion temperature
Rich mixture = cooler combustion temperatures

 

[Firstbuild408]

Thanks for the feedback really helped. I have a question though it did say this engine is an 80 cc which is a 66cc but by the look of the bottom of the cylinder it looks like a 48cc. How can I tell the difference before I purchase parts?

 

[Firstbuild408]

Very much appreciated it is in fact a 66

 

[GreasyChris]

What is stamped on your connecting rod?

 

[Firstbuild408]

The connecting rod is stamped with FM80

 

[gary55]

The connecting rod is stamped with FM80

This would work well. When you get it started if it is idling high find the vacuum leak before you blow it up again. If it's idling high and unadjustable with screw it is too lean. First you need to lower the clip on the carb and if that don't work you have a leak somewhere. The B6HS plug should work fine with this top end. You will need to buy some studs, head nuts, and 4 ea. flat and lock washers for the new top end. Might want to call Matt or send a email to make sure you get the right ones.

Professionally Ported ZEDA80 or GT5 Cylinder + Piston | Bicycle Motor Works

 

[Firstbuild408]

Ok I’m ordering a set but I also need a stud set. Are the studs universal or are there different sizes. If so how would I measure them?

 

[Ralpho]

Ok I’m ordering a set but I also need a stud set. Are the studs universal or are there different sizes. If so how would I measure them?

I have the same engine that uses 6mm Allen bolts for the head if they look the same as the exhaust bolts then yours does too. You'll need some long 6mm bolts if you go with the two piece design. I believe the threads are 1.0 ? But don't know for sure.

 

[GreasyChris]

You'll need something like this. And some m8 flat washers and lock washers.

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