Help needed with 78E - At wit's end and don't know what else to try...

[crazy steve]

...Any ideas out there on what specifically I should check on the floats except for free movement.

If the carbs were rebuilt with new float bowl gaskets, some are larger than the OEM ones were. The gasket can actually cause the floats to hang up, some careful trimming with a razor blade at the sides will fix this...

[natemoen]

I just think your plugs are fouling out and then the cylinder stops firing.

You need to figure out why you are fouling plugs out.

[jetmechmarty]

Is it possible that this thing is running out of fuel? Let it run with the gas cap open and see what happens. Maybe the cap isn't venting?

[CK]

Steve, good idea - I did have the carbs rebuilt by a mechanic and unsure if he put in new bowl gaskets are not but will check - thanks

Nathan, I'll double check, but I think when I took them out they were just oily. I didn't see the they had actually fouled out, but definitely worth another check. If they are fouling, what carb adjustment would you make - the idle mixture is all that I know of. Thanks for commenting.

Marty, I thought about that earlier and rebuilt the gas cap. I ran it today also with the gas cap open just in case and it behaved as usual. Good suggestion though, thanks for commenting.

Guys, out of town for next two weeks - will update you after then. Thanks again


Chris

[natemoen]

Nathan, I'll double check, but I think when I took them out they were just oily. I didn't see the they had actually fouled out, but definitely worth another check. If they are fouling, what carb adjustment would you make - the idle mixture is all that I know of. Thanks for commenting.

Carbon fouled, oil fouled...doesn't matter. Fouled is fouled. Is it is oil then you need to figure out how/why oil is getting in there.

[foreda]

Petcocks

Ok.. The 78E has vacuum operated petcocks. Here is a really dumb question, did you try turning the right side petcock to the prime posisition? These petcocks have been known to be evil.Don't ask me how I know this!
Dale

[GLoweVA]

My 2Cents

Would it help to open up the idle-mixture jets - the manuals say to leave them alone.

It sounds like you haven't touched your idle mix screws.
They HAVE TO COME OUT for a good clean of the idle circuit.
Then you set them back to the 1 -1/2 turns like you later said you did.
If the idle circuit is dirty then of course those cylinders won't get any fuel.

I do agree with looking to see if the floats (#3,4) are hanging up in the up/closed position.

You could try a test off the bike to see.
Basically with the carbs out, hook an external fuel source to the #3,4 fuel inlet, let the carbs fill and then drain some out via the bowl drains and see if flow continues or stops. That will tell you if the floats aren't allowing the needle to open and allow fuel in.