77 750K high revs

[jhort]

This question is similar to some of the other postings I've seen here, however it does differ slightly.
I have a 77' CB750 which has started to idle high after the engine warms up a bit. I got it back from the shop where they said they syc'ed the carbs. The bike was running perfectly, but all of a sudden it shot up to 5k rpms. For the past few days when I start the bike it's idling around 2k, but as the bike warms up the revs increase 3k then in 10mins 4k then in 10 more minutes 5k. Would this have anything to do with the floats as well? Also a new voltage regulator was just installed. BTW I've already tried to adjust it with the idling screw, but it's turnned out all the way already. Just strange that it was perfect one second and the next it's not.

[fasterjimmy]

Hello jhort.
I recently had this same issue. The bike shop mechanic started it up... it idled high... he grabbed the throttle and twisted it backwards and the idle came down to normal. Something about heat and expansion. I removed the tank and adjusted some slack into the throttle cables and my problem is gone.
Hope this is your fix too.

[jhort]

Thanks for the insight. It probably could have been a number of things. What I eventually assumed was that the mechanic adjusted the carbs to rev too high when he sync'ed them. I had the shop do a "tune up" which in fact screwed the bike up worse then when I brought it in. I found out through questioning that when the mechanic sync'ed the carbs he did it when the bike was cold or not warmmed up yet. That is why it started so easily even with out the choke, but when hot the bike was reving so high. They readjusted it for free since it was their mistake and things are as they should be. The trials a tribulations of owning a 30 year old machine. Love riding it now though, even in Manhattan where not only do you have to keep your eyes out for squirrels but also for your occational bum or woman with shopping bag or stockbroker on cell phone.

Cheers and have a great weekend.

[rm56-2]

Glad they fixed it right, my 74 is stubbern to start. She does'nt want to start when cold. You have to play with the choke while blipping the throttle.
But after she warms up she runs perfect and idles at 1100.
PS-run over the broker ;)
rm

[jk333]

its gotta be the intake bands going from the carbs to the intake manifold. My 81 750 has the same problem.