Carburetor and Fuel System
Title: Linkert
lean condition
Right now the bike usually starts on 1 kick, hot or cold, it seams I have the combination right. The problem is, whenever I accelerate, a little or a lot, at any speed above idle, I can feel the bike going lean and hesitating and surging. I have had the high speed needle in all positions while riding, it helps a little, but it is about three clicks from being wide open! If I add one notch of choke, it runs and accelerates like a bandit!, but when slowing down or idling, I can tell it is way too rich. Today I tried taking the choke plate out, to see if the choke was helping, or the increase in the low speed circuit that one notch of choke gives. Without the choke plate, I saw no improvement, so, cutting down on the air (with the choke) makes the problem go away (but too rich at low speed)?!?
Not that I specifically checked the throttle shaft bore or other areas of the carb for leaks, I don't think the carb overall is worn out? I double checked the manifold seal (with air pressure), all is tight.
The plugs, before the carb work were oil and gas fouled, now a nice tan, but only a couple of hundred miles.
I ASSUME (you know what that means) the main jet is whatever HD put in it. In my opinion, it is either the main jet too small, or an air leak somewhere. All opinions are welcome, I am really scratching my head on this one.
Thanks
PS..I read a tech tip somewhere on the net about using the stock spiral single throttle cable with an S&S, now I have searched and can't find it, anyone know where I can find it?
Thanks
Post by Cotten on Dec 30, 2005, 3:33pm
64Duo!
We must eliminate one variable at a time, without making assumptions: Did you pressuretest your manifold after reassembly?
(Fresh O-rings are by no means a guarantee of a perfect assembly; bubbletesting while installing often reveals that it will seal in only one position or "sweet spot", and the carb support must be massaged to mate with it.)
There are (at least) four common places for air "leaks" concerning the Linkert itself.
First, always dress the manifold flange flat on emery or a large stone. They are nearly always distorted from fastener stress, as is the manifold's flange as well.
Second is the throttleshaft/bushing wear you mentioned. Grab the lever and see how much it wiggles sideways. It should not move up and down much at all.
Next is the wear that results from the shaft slop: The throttle disc will wear an eyebrow-shaped groove into the bore of the carb. This messes with the mixture entering from the idle bleed holes. Although the holes govern lowrange operation, their effect overlaps into the mid, causing you to attempt to compensate with the needles, with no happy medium. Evidence of the degree of wear is the protruding "key' that forms on the disc where the shaft protects it.
Fourth is that the venturi has nearly always shrank to allow a gap between it and the carb body. Clean the venturi and bore, tap it in, and observe for 'daylight' around it.
If it falls in, you may have enough air bypassing it to affect your mid and highrange.
Straightening out these concerns will return original performance, but I still suspect your manifold is the problem.
....Cotten
PS: It's weird that so many insist on setting their floats out-of-spec. It's double-weird that it doesn't seem to make any difference with the ultralight floats!
