intake manifold

[jedw79]

Hi I have a 700 polaris twin with a single 42mm CDKII keihin pumper carburetor. Problem is that while installing an ocean pro vortex flame arrestor I noticed that the gasket doesn't set right on the manifold. It's as if the mounting holes weren't tapped in the right place on the manifold. Once the carburetor is installed, you can see some of the intake if you open up the butterfly - basically there are two offset circles if you get what I'm saying. Will this take away from my performance significantly? I can't say how it was running before because I have never ridden the ski before; bought the ski as is and fixing engine. It's not a terrible offset, carburetor sits approximately 1/16" too close to engine. Also I put hi-tach on the gasket and am concerned that it could come off the exposed gasket and possibly stick in the reeds -- am I being too paranoid?

The other problem is that the ski will not idle. I suppose I can just idle it up, but should I readjust oil pump as well? Also ski runs good at 50% throttle and above, but is sluggish at anything lower. Should I lean out the low speed mixture screw now or wait to run through the first tank of 40:1 premix (put a lower end in ski).

[ April 15, 2003, 10:23 PM: Message edited by: jedw79 ]

[pcalonge]

Don't know if i read this correctly- you are talking about the carb base to intake manifold line up, right?
If you are saying that there is the possibility of an air leak (vaccumn leak) between the carb and the manifold, then don't run it till you have it sealed. if it is a slight alignment problem, it likely won't hurt.
It is not inconceivable that there is a "step" showing between the carb venturi and the intake manifold. See it all the time on auto and truck engines. It is difficult when mass producing cast pieces to have true uniformity, and both the manifold and carb body are cast. Can it effect air flow? Sure. Is enough to affect performance- possibly, but not a bunch. It would not be that hard to match everything up, this is basic blueprinting. Get a tube of prussian blue from the parts house and some long cotton swabs from an electronics supply. Hold the throttle open and paint the "step". Take your dremel and a very fine stone and *very carefully* hone down the step, work it in small steps and keep rechecking. Taking off too much will not give you any improvement, the step is just on the other side.
I don't think you will notice any huge improvement, maybe none at all. On the other hand, stuff like this is what racers do to give themselves that little bit of edge.

Far as the high tack goes, once that stuff is dry nothing but a scraper and adhesive remover can touch it. Even if some managed to flake off, i can't see it hurting the reeds or the bearings. If you have huge globs of dried sealant, pull them off with a long needlenose.

[jedw79]

You interpreted my problem correctly. It is a misalignment problem rather than a sealing problem. Thanks for the advice.