New 2-stroke engine won't start

[Cisco]

my brand new 80cc 2 stroke bicycle engine

Where did you get your new engine?

 

[noah9988]

I could hear air being pushed out when the piston goes up.

My engine does this and I also have quite low compression. Is it supposed to happen? How do you fix it?

 

[DieselTech]

Yes you could sand the head down flush, but you are going to ruin your squish band & that will cause a bunch of problems, like head looses its efficiency of removing heat from the piston & cylinder. If you did sand it down flush, you would have to recut your squish band in the cylinder head.

 

[Chainlube]

Yes you could sand the head down flush, but you are going to ruin your squish band & that will cause a bunch of problems, like head looses its efficiency of removing heat from the piston & cylinder. If you did sand it down flush, you would have to recut your squish band in the cylinder head.

He might be able to get away with a thicker head gasket.

 

[DieselTech]

Yeah he could do that to adjust his squish clearance, but it wont do anything for the squish band, that's the width of the tapered area in cylinder head that matches your piston crown, the width should be 40%-50% of the cylinder bore diameter roughly.

 

[Dood Surfston]

Thanks for chipping in guys. I've ordered a new head, hopefully it'll arrive in better condition. In the meantime I'll experiment with the one I've got.

Where did you get your new engine?

It's a Zeda 80 from ebay. Here in the UK there's a lack of reputable resellers.

Wet base gaskets that you didn't personally oil to expedite seating and crush means your top end for sure isn't tight enough to seal.

Sounds like it came under-torqued from the seller. I'll torque it up and let you know the results!

 

[YetiWoodz]

Sounds like it came under-torqued from the seller. I'll torque it up and let you know the results!

Just don't go too crazy, I once snapped one of the studs, but it does need to be pretty tight.

 

[DAMIEN1307]

I'll torque it up and let you know the results!

Torque on the head bolts are set at 12 ft pounds, (if you use an inch pound torque wrench, it will be 144 inch pounds)...re-torque ocasionally during the first 2 or 3 hundred miles or so to those settings until it settles in...I have a Zeda 80 myself...DAMIEN

 

[Greg58]

If I may add, run the nuts down till they touch then torque in an x pattern about 6-7 lbs first. Then x again to 12lbs.

 

[HumanPerson]

and be sure the studs are all the way seated and torqued down as well.