1981 GS650L will not rev over 4500 rpm

[adrianvee]

Hi,had all four carburetors rebuilt and balanced; new battery; new plugs, caps and leads installed. Two coils were checked. Outside cover taken off CDI and automatic advance mechanism; everything appears OK. Fuel line and vacuum line replaced. Fuel flows freely when petcock is set on prime. Inside petcock screen perfectly clean. Gas cap is vented. When started, bike idles,when given gas it will rev to 4500 rpm but not higher! All suggestions appreciated! Thanks, adrianvee

[tkent02]

Do the carbs yourself this time.

[romero]

double chk the advance, make sure it is

[jabcb]

Am a newbie with working on the GS bikes, but it sounds somewhat similar to my 1982 GS550L.
See:http://www.thegsresources.com/_forum...d.php?t=212772

After doing lots of work like you, the bike rev limited around 5k rpm.
Problem was a combination of voltage drops & the igniter.

Solved with the relay mod & Dyna S ignition.
Relay was something like $10 at an auto parts store & Dyna was about $120 at eBay.
Dyna replaces the ignitor & the "CDI coils" you looked at.

The experts have posted good info on the relay mod & Dyna S.
(Has been a long day & don't remember where at the moment.)
The experts are very helpful on this site, so just ask if you don't find the info & need more help.

[tom203]

Do you have the stock airbox/airfilter setup?? When you cold start, do you need "choke" and if so how far will rpms go up after bike fires?

[adrianvee]

1981 GS650L will not rev above 4500 rpm

Yes, it has a choke + cable.It is positioned in the center above the handlebars; it is pulled out when starting from cold. Bike idles fine with it on or off.It has astandard air filter but even without air filter in place it and side cover off it does not rev beyond 4500.adrianvee

[adrianvee]

Thanks for all the suggestions!adrianvee

[tom203]

It needs airfilter in and cover on or it won't be happy at 4k- actually any leaks in the airbox itself (section that attaches to carbs) will cause problems with 4k rpms- bike/stock carbs were designed to run with tight intake system.

[Nessism]

It needs airfilter in and cover on or it won't be happy at 4k- actually any leaks in the airbox itself (section that attaches to carbs) will cause problems with 4k rpms- bike/stock carbs were designed to run with tight intake system.

This...

Better check the newbie mistakes thread linked in my signature. Trying to run the bike with drastic intake mods is on the list. There may be others...