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1981 CB650C Carbs

Posted: Mon Sep 25, 2017 7:37 pm
by Europamarc673
Hi there,
This subject might have been discussed already but here I go again: Was given a free bike 1981 CB650C without carbs. Trying to make it a track bike for our rent-to-race program.
I put a set of Keihin V357-DF07 carbs on that I had laying around in the shop. Starts, idles but won't get past 1/2 throttle without sputtering. Played with different jets (110, 125, 130 mains) and needle positions. No change. It has some sort of "open" 4 into 1 exhaust on it and pod airfilter. Took the carbs several times apart to clean and inspect. Changed spark plugs, replaced both CDI boxes.
Unfortunately there are no OEM Honda carbs for this bike anywhere. Original parts number 16100-460-771.
Any chance that someone here figured this issue out? Could it be the ignition trigger which is also NLA 30300-426-154

Thank you,


Marc Beyer
OCD Custom Cycles and Auto Repair LLC
Kraut Racing
Santa Fe, NM

Re: 1981 CB650C Carbs

Posted: Tue Sep 26, 2017 4:50 am
by Folsoml
Welcome to the forum! I wish I had a suggestion for you. :(

Re: 1981 CB650C Carbs

Posted: Tue Sep 26, 2017 4:56 am
by cb650
did you check the gap on the ignition pick ups?

Re: 1981 CB650C Carbs

Posted: Tue Sep 26, 2017 4:59 am
by GeorgeSweety
Hi Europamarc, have you removed and cleaned the auto advancer from behind the ignition pulser plate? right hand side of the engine behind the round cover? Relatively simple job, you will have to disassemble it to clean it properly. It will require lubricating with a high melting point grease, just make sure that it is really free moving before assembling.

Re: 1981 CB650C Carbs

Posted: Tue Sep 26, 2017 5:12 am
by GeorgeSweety
Hi again, I googled that part number and they appear to be VB44 carbs, you should have no problem finding a set on ebay. It might be a good idea to measure the distance between your inlets before you buy a set though, just in case your bike was fitted with an earlier engine, if it was they won't fit the head.

Re: 1981 CB650C Carbs

Posted: Tue Sep 26, 2017 8:07 am
by GeorgeSweety
https://www.ebay.co.uk/p/Genuine-Honda- ... 2015716352

But it ain't cheap :shock: The thing is I don't think it is your pulse generator as the bike runs, my money is on your auto advance behind it :wink: