one carb races

[2wheelindave]

I am working on a 1980 XS400 special. I cleaned the carbs throughly, replaced the float needs, and went one up on the main jets, also have replaced both intake rubber going to the head, BRAND NEW not used. My problem is one of the carbs races when I start the bike. I have un plugged the plug wire on each to find out which one is racing, it is the left side. There is NO intake leak. I am looking into mechanical adjustments now, I have ruled out anything hanging up with the throttle cable. Any Ideas??? Or better yet how do you adjust or sync these CV carbs?

Thanks... Dave

 

[willem]

what do you mean exactly with one of the carbs races? You mean your bike goes into very high revs when you start?

And are you running pod filters and aftermarket exhausts? I'm guessing you are since you are re-jetting. It might not have been enough to go up one size, if you're having high revs. That's a symptom of your bike running lean. Take your plugs out and read them (or take a pic and post) to check. White plugs= lean, black n sooty = rich, slightly tan=good, oily brown = oil leak.

and you say you ruled out the throttle cable. I've had some issues with this one myself, and thought I had ruled it out completely as well when I hadn't. To make absolutely sure, detach it from the carbs next time to see if there's any difference.

 

[2wheelindave]

ONE Clyinder races that means it is at full throttle, NO mainjet will do that. it is either a sticking linkage or a stuck cable, and if it were the cable or mainjet, why is it when I pull the wire off the cylinder that revs the other side runs fine and normal? And NO I only put a set of pods on, it has stock exhaust, till I get the carbs fixed the plugs won't be much help. It has to run longer than 20-30 seconds, and running like it does, I will not let that happen. maybe if I used that rock hammer on the picture here it might help. lol

Thanks

 

[willem]

did you sync your carbs? sounds like seriously out of sync carbs

 

[Scorpio1963]

My bike had the same problem turns out it was the cable sticking.It was full of corrosion on the inside full of white junk from the braded cable and condensation getting in there.I took the cable compltely off spray some graphite lubricant and work the wire back and forth.Then I sprayed liquid wrench inside of and work it back and forth some more.Also I had to adjust the cable where it goes onto the handle bars.Works fine now.Lookup youtube on how to bench sync your carbs that will get you close.Then make a home made nanometer which is describe how to here on this site.Sync your carbs perfect.Best of luck.

 

[phate]

I would check the cable and sync as well (plenty of how to info for this just use the search. Also I hope you were grounding the unplugged boot as it is very bad for the TCI unit to be left ungrounded (wouldnt want this problem to turn into a new TCI box problem)