Rebuilt Derbi variant wont start

Over this winter I rebuilt my pyramid reed variant and now that I finally have the engine back on the bike I have had trouble getting it started. It is a little tough to pedal but not much harder then it was before the rebuild. when I pedal it everything turns over, the starter clutch engages, the piston pumps and its got a fat spark. Ive tried swapping three different (known working) carbs on and get nothing, and the plug is wet with gas when I check it. Ive tried advancing and retarding the timing and still nothing, not even a little putt. also the compression seems good, it blows my finger out of the plug hole when I pedal it. The bike has brand new bearings, gaskets, and seals.

Ive never rebuilt a derbi before this nor has anyone in the local community. Idk if im just over looking something derbi specific, any suggestions greatly appreciated!

Re: Rebuilt Derbi variant wont start

its gotta be compression, leaky head, head bolts, de-comp, etc. plug probably fouled by now. i like drill starting.

Re: Rebuilt Derbi variant wont start

Too much choke drowning it out? Too much gas thru jets in carb?

Re: Rebuilt Derbi variant wont start

Did you use the treats gasket party case gasket? It doesnt fit right and is slightly undersized.

Re: Rebuilt Derbi variant wont start

I have a leak down tester you can borrow, if you don’t have one at the shop. There may be a massive air leak in one of the gaskets or seals. (edited)

Re: Rebuilt Derbi variant wont start

So I tried down jetting and that doesn't seem to be the case. And yes I did purchase the treats gasket party but realized its not the right size so I traced and cut my own from the original gaskets.

there is a hole on the metal head gasket, is that supposed to face up or down? if anyone knows.

Joe, I do not have one of those but I do have a basic compression tester. I may need to borrow that from ya if I cant pin point it tonight. gonna make sure those seals are in there right.

Re: Rebuilt Derbi variant wont start

Richard Eberline /

Get Frank to help you, I hope you have a bike that runs good. I need one at your rally.

Re: Rebuilt Derbi variant wont start

Hole in the gasket lines up with the hole on the jug. It should go above the exhaust port and the head should be sitting with the decomp tucked up towards the frame.

« Go to Topics — end of thread

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account