No start

I have battery voltage with new battery i just rebuilt starter i have spark good compression and i have fuel any ideas why i am still getting a long fast crank but no start. thanks

 

Well, if you're sure you have air, spark, fuel, and compression, there are really only three possibilities:

1. Too much fuel and flooding
- Are the plugs wet?

2. Way too little fuel
- Have you tried a good spray of starting fluid into the air box then seeing if it'll start and run for a couple of seconds?

3. Timing
- Any backfires? Any chance the 1/4 and 2/3 coil pickup wires, coil drive wires, or plug wires are swapped somewhere? Orange should go to 1/4; Grey to 2/3.

By the way, I'm assuming you have a Yamaha XJ since you posted on this forum, but it's a good idea, and good form, to let people know what model and year bike you're asking about.

Cheers,
Paul

 

the bike i am working on is 1982 yamaha 750 maxim. no backfires and the plugs are not wet but what happens sometimes which i just noticed this morning was carb number 3 dumps fuel out the air filter cone. but why would that make it not start? it should still fire right....

thanks

 

You have a hung float valve. You need to pull your carbs and clean them meticulously. Check out how to clean your carbs and the whole nine yards by Rick-O-Matic.

 

-Is this bike equipped with "pod" filters rather than the stock airbox?

-Has the exhaust system been modified?

-Has it ever run, that you've seen?

-Have you recently performed some modifications?

The more info the better; you're not giving us much to go on.