new to me 1970 CB750

[_DK_]

Hello

I recently picked up a heavily customized 1970 CB750, It's in decent shape I think... I just need to work out a few bugs I think.
One problem is this... I'm not a mechanic, but I dont have any money to pay anyone to tweak the bike so I'll need to learn to do it myself.

It seems to run pretty strong, I've put 300 miles on it or so in the last month.

My main concern for now is after everythings all warmed up, say 15-20 minutes of city riding the RPM's seem to stay high. If I throttle up and then down quickly I can get it to drop to acceptable levels, but otherwise it hangs around 5000rpms then slowly drops


Can anyone suggest some good sources of info on identifing and self diagnosing the parts and problems?

Thank's

Rob, Aka _DK_

[Re-run]

That is very customized! I would say that you might want to sell the front rim and get a stock front. You can use some of the cash to do maintenance then. Just a thought.
First thing is to get a manual. Any is better than none.
For the idle, 2 things I can think of. First, how easy does your throttle turn? If it is very stiff, lube the cables and see if that helps. This takes a few minutes just so you know. You cant put in a drop of oil and have it work right away. Get a cable lube tool and some spray lube. Spray it and slide the cable back and forth. Once they move quite easily, see if the throttle closes better.
Another common issue is the rubber manifolds between the carbs and engine leak air. You can try to spray some carb cleaner on those boots and see if the rpm changes.

[_DK_]

I'll take some up close pic's this weekend.

The grips are new, they seem to be smooth. I have the idle screw backed all they way off(its not touching) and even the Idle seems alittle high. If I push on the lever I can get the idle to drop. I just don't know whats holding it up... There's an inline fuel filter that is right up against the throttle cable. I was going to see if I cant make those lines abit longer and tie them up out of the way to see if thats holding it up in some way.

I found a guy who's got a chiltions book, I just have to go get it.

My last bike was a NH450... I came late to riding , about 2 years ago(I'm 38)... Better late than never though.



(Sorry about the email, I'm not use to this sort of "forum" system)

[Re-run]

Best option might be to remove the carbs and clean things up. Make sure everything moves freely and nothing binds. The manual should give basic tune up steps.