1979 Yamaha XS1100 fuel/ignition problem

Having problems with the bike running past 4500rpms. Bike hits a wall at 4500rpms and sounds like a rev limiter. Can't figure out the problem

Category:

Autos & Vehicles

Tags:

• 1979
• Yamaha
• XS1100
• motorcycle

[ejoy1220]

The vacuum advance is working correctly, and there are no breaks in the wiring. Ignition unit is functioning properly. Prior to this, carbs were removed, flushed cleaned and rebuilt, with new gaskets, float valves, main/pilot jets were replaced with brand new ones.

[Mojorising5150]

My 79 eleven special does that too. Carbs fresh outta the shop. The tack will bounce around 4000-5000,. Defiantly electrical

[roshans124]

I'm having the exact issue on my XS1100 after i cleaned the carbs. Did you solve the issue?? If so, how??

[dirtydogvideo]

float level adjustment is critical in carbs....get 3' of new fuel line and cut in half. remove old fuel line going to carb and attach new line going into a container. remove old vacum line to petcock and attach new one. now suck on the new vacuum line, turn on gas and make sure it flows freely in the on and reserve position. if it dosent, drain tank and rehab the petcocks, install new inline filters and lines. then check carb syncronization with vacuum gauges...good luck!

[tripplesrule]

Hey there, I had a 78 xs1100 that looks just like yours. I had a problem with spark plugs filing from the carbs needing rejetting. The previous owner had taken off the old airbox and put UNI filters on and the bike ran good for a while then 2 or 3 outta 4 cylinders would fire. Get it rejetted if you changed the filters to smaller filters and make sure you are running NGK plugs only BP6ES. My Haynes manual said BP8ES but they were wrong. Let me know how that works out for ya. Enjoy!!!

[dirtripper25]

i had the same problem with my 550 right at 4000-5000!

it was my carbs, i know u said they were rebuilt and all, but check again.

Also, make sure the screen in you tank isn't clogged or your tank isn't full of crud. That could be a problem

[Gazza61253]

it's a retarded spark under presure.....check plug leads and caps sounds like it's arking out somewhere! the problem's electrical...

[jucamo007]

either valvs not calibrated or carb balancing....

thats always the problem with the xs.

-former yamaha xs 650 and 1100c.c owner.-

[desmomotorrad]

Probably a bad ignition module.

[bamper42069]

Also it could be the mains are plugged because thats when it relies fully on the mains under 4500 is pilots.