How to set Fuel Mixture

[Brad]

I 'm working backwards, I've synced my carbs last week following the tech tips here with some home made equipment and she still wont idle. I also think that my throttle cable has something to do with it. The throttle cable "steel housing adjustment" under the throttle will not thread and is broken. I do know that I should buy a new one and replace that first. I should also try to set my butterflies. I should also clean my carbs and look for some info on how to set my fuel mixture. I haven't had much experence with motorcycles and have limmited resources. The home versions and how to secrets would greatly help.
I ran around today and it will run ok as long as you continue to rev slightly while stopped. Can someone also recomend a good size bigger tire with no mod's to the bike? The one I have on is not the size spec'd, and looks really skinny. I have a 1978 XS 1100E. Thanks

[Ken Talbot]

Whoa there, big fella! Working back to front like you're doing might be interesting, but it sure won't help you get where you want to be.

If you have any reason to think your carbs need cleaning, i.e. you do not know for absolute sure that they are clean, this is where you start. Take them off, read the various tech articles on what to do and what to watch out for, and take your time. While you're got them off, you will see there is an idle speed adjustment screw between #2 and #3. The adjustment at the handlebar is not for setting idle speed, it is only for setting cable slack.

Read a bit more about the sync procedure, and you will also sort out that this is in fact "adjusting the butterflies". You can start with the bread tie sync so it will at least run when you put it together, but remember that it will probably idle at 3000 or so rpm until you adjust it back down with the idle speed adjustment.

Get you idle back down, sync it properly, then do a 'colortune by ear' adjustment for the low speed circuits. The tech article for this is here. Check the sync once more, and you should be good to go.

Save yourself a lot of time and aggravation - try working forward!

BTW - say hi to my auntie!

[81xsproject]

Have you tried adjusting the idle set screw at the carbs? It's a little knob ended screw that sets the minimum throttle position. If is runs good otherwise, the first thing I would do, would be set the mixtures all to 2.5 turns out from LIGHTLY seated (turned in all the way). Then use the idle set screw to set the idle speed (1000 rpm or less). Poor half to a hole can of Sea Foam or B12 Chemtool in a full tank and run it through. If it still won't idle or runs poorly, it's time to pull and clean carbs. Carbs should be the LAST point of troubleshooting a poorly running engine. First you need to verify that you have good spark (and no pickup coil wire issues; common), good compression, and proper valve adjustment. If all this is straight, it could be your carbs.

[Brad]

Thanks for the response guy's, this help is greatly appreciated. The rear tire I have on the bike is 130/90-17 and the front looks godd, it's 100/90-19. This old baby need new rubber and was wondering if anyone has put a little bit wider tire on the back without any modification's? Suggestions would be great.

[psycoreefer]

do a search for "tires" and read until your eyes bleed, but the short answer is some brands you can fit a 140, maybe and it might or might not rub. To fit wider tires some have gone to chain drive or adapted other bike swing arms to fit, lots of work and time involved in both routes and you need to KNOW what your doing.

[fredintoon]

Thanks for the response guy's, this help is greatly appreciated. The rear tire I have on the bike is 130/90-17 and the front looks good, it's 100/90-19. This old baby need new rubber and was wondering if anyone has put a little bit wider tire on the back without any modification's? Suggestions would be great.

Hi Brad and welcome,
those are the stock tire sizes. Go to 110/90-19 on the front and there's precious little clearance left between the tire and the fender.
Go to 140/90-17 on the back and some mfrs tires in that size will rub against the swingarm.
And even if the front tire looks good, how old is it? Over-age tires get as hard as wood and don't grip worth a darn.

[Brad]

Thanks again guys...