Quote:
Originally Posted by sportysrock
I was adjusting mine the other day (1st time in a long time) and following the manual. I backed off the adjusters and then checked the throttle pull cable. The manual made no sense to me because I was able to crank it around until the cam hit the stop. After cussing a bit because the procedure outlined doesn't quite make sense, I adjusted the cables back close to where it was previously. There is a bit less slack in the throttle cable, less turning before gas activation, and the idle cable seems fine.
This is one adjustment that I don't quite get.
|
There are two things you have to be concerned with when adjusting the cables.
1. Make sure the throttle cable (pull open) is adjusted so that it opens the butterfly 100% and cannot pull the throttle wheel any further than against the stop. If it's not opening the butterfly all the way, then you don't have 100% performance. If it can pull hard against the throttle stop when wide open, you are stressing the cable, and it will break. So, one performance issue and one safety/reliability issue on the throttle cable.
2. Make sure there is a minimum amount of free play in the throttle sleeve when moving the handlebars from side to side through the normal range of motion. If there is too much free play, then you have to crank the throttle sleeve too far before the butterfly opens. That is annoying and could be a safety issue if the throttle doesn't make the bike "go" when you want it to. Freeplay is set with the idle cable. If you don't have enough free play, then when you turn the bars side to side, the cable will pull the butterfly open more, resulting in an unexpected rise in RPM. This is really bad in a parking lot during tight maneuvers when you're not expecting it. The bike just takes off when you're turned all the way to one side or the other. The other problem with an idle cable that's too tight is that the carb might not return to idle when you let off throttle sleeve. Some people like that as a poor man's cruise, but I think that's a safety issue too.
So, put slack in both cables, then adjust the open (throttle) cable until the throttle wheel hits the stop when the throttle sleeve is cranked WFO. Now, lock down the throttle cable adjuster, you're done with that cable. Then, adjust the idle cable so the throttle snaps back when you let off, and there's not an excessive amount of freeplay in it. Turn the bars from side to side, and make sure it snaps back in all positions. If you can't get it to snap back when turned full left or right, and there is already a lot of freeplay in the sleeve, then you might have them routed oddly, hanging up on something, or they need to be lubed. If you want cables that snap back with the minimum safe possible amount of freeplay, your cables need to be well lubed.
In case it wasn't clear, the throttle cable determines how far the butterfly opens, and the idle cable is used to set the freeplay.
None of these adjustments have anything to do with
idle speed. When you're all done with the cables, set the idle speed with the idle adjustment screw. If the idle speed raises as you're turning the bars from side to side, then your cables are too tight.
Disclaimers: this is for a CV carb and a stock throttle from since about 1982. The procedure is the same for other carbs, but there might be a slide rather than a butterfly (HSR42). And aftermarket throttles like the Gunnar Gasser have just one throttle cable and freeplay is totally different. OEM single throttle cable systems are different too. These instructions are for current bikes, not antiques
And, if you crank on the throttle quite a few times getting this right, the accelerator pump is going to shoot a bunch of fuel into the cylinders. Be prepared for black smoke when you start it up. The bike will probably start with no enrichener due to all the extra fuel in the cylinders.
Of course, being a safety issue, you should follow the instructions in the manual, and not listen to a word I've said.
HTH,
Chris