Bucking and Stuttering, Take two  By  rcq92130 (Read 4,867 times)

Hi Shannen

I don't know if you are having the same interferance problem with your 30mm carb -- but here is the issue I am dealing with.

The bottom of the carb - on the right side (seen when sitting on the scooter; carb installed facing to the rear) has a round protrusion that is the pump.  It's all a part of the carb casting - not a separate piece.

With the carb installed this round "pump" part hits against the main engine mounting ear of the right side (a part of the crankcase casting).  The solution if to have the carb sit slightly not upright so the pump protrusion is canted slightly to the left, and does not hit the mounting ear.  

I thought of grinding the ear down a bnit - or the pump protrusion - but it would have meant taking too much metal away.  Anyway, I'm hoping the slight off-vertical install will not cause problems.  So far it seems OK.

The cross brace is the shape of a "C" facing down (curves up in the middle), and the intake duct comes in from the rear.  Right now the duct fits UNDER the "C".

I'd have to raise the carb maybe 6 inches to allow the duct to go over the TOP of the "C".

I don;t know if that makes any sense ...

Like one of these - Intake Manifold Insulator - if it doesn't already have one (and not a bad idea, anyways, if it doesn't).

Of course, you'd need enough clearance beneath the crossmember for it all to fit properly. And likely longer mount studs.

Intake pipe/bracket looks nice!

Bob

(oops... missed Alley's post...)

rcq92130 My motor had a small spacer already on it. So once I did as you suggested and ditched the rubber carb attachment on the polished intake I bought, it fit right up and cleared that engine mount. Putting it on is a little tricky as you have to kind of put them on separately and then at the last push towards the engine let them come together.

I still want the 3" riser just because it will make working on the carb a whole lot easier. Granted I don't plan on taking my carb off and on much, but it's still necessary every once in a wile to pull the carb off and give it a good cleaning.

That's great that you figured your problem out...now I'm still left scratching my head as to whats causing my issue. My scoot is a 2008 with only 2K miles on it. This tells me it sat for a good bit here and there. So my issue could very well be the fuel pump. I know I'm not lean and I know it's not my air filter. Remember it did this same thing with the original air box hooked up. So.... guess I'll start by replacing my fuel pump. I'm thinking about going with a 6-8 psi unit with a regulator on it. The whole shebang will only cost me 30 bucks so. ehh.. At least if it doesn't cure my problem I'll know that the pump should never be an issue in the future.

Wanted to wait and check to make sure (already have a 1/4 inch spacer between the manifold and the head)...

in MY case the carb would have to be raise about 1-1/8 inches for the pump casting to clear the crankcase mounting ear:

MOUNTING EAR CAUSING INTERFERANCE:


PART OF CARB THAT IS HITTING:



And there is only about another 3/8 inch above the carb inlet before the cross brace would then interfere with the intake duct.  

Would have to raise the carb 4 inches or so to get it high enough that the duct could pass OVER the cross brace --- which is doable, but I'd lose my underseat storage (important to me).  Anyway, I'm thinking maybe the slight (5 degree) cant to the carb from vertical will not cause fuel starvation, since the scooter must lean far more than that when cornering.

At least that's the situation with the GY6 and carb I have.

One thing I COULD do is trim off maybe 1/4 inch of the intake manifold so the carb would move FORWARD, maybe clearing the ear to the front, not clearing the ear above it.  But that would leave a pretty narrow amount to secure the rubber piece connecting the manifold to the carb .... and if things are OK as they currently are I'd rather not do that.

Whew.  Thought I was going to embarrass myself making yet another stupid comment.

Alley - asked in another thread and would really appreciate your thoughts on good break-in procedure.  The web is full of conflicting theories - probably from people who don't know much more than me.  So, I'd appreciate a real expert's viewpoint before i go and mess the new setup up.