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1981 Honda CB650C Clutch Rattle

Posted: Sun Dec 03, 2017 4:51 am
by Whacky Wheels
Hi guys! So this is my first post on this website, I do apologise if there has already been a thread opened for this topic, but I am wondering if anybody has had a similiar problem:

Upon startup and low revs, there is an immense rattle that sounds like it is coming from the the clutch, but when I pull the clutch lever in, or when I put the bike in gear and start riding, the rattle suddenly disappears. Does anyone perhaps have any advice on this? I bought the bike second hand from a shop here in the Cape Town area in South Africa. (Also live in SA). I have a vague suspicion it is the carbs that are not synced properly, but some advice would be great thanks!

Some details about the bike: 1981 Honda CB650, 53 000km on the clock, looks as original as can come except for a view paint changes! Still has original frame stickers for chain slack and tire pressure.

Thanks in advance!

Re: 1981 Honda CB650C Clutch Rattle

Posted: Sun Dec 03, 2017 8:43 am
by Folsoml
Welcome to the forum!

Your clutch dampers may need replacing. Here is a link to a tutorial on replacing them. The tutorial is for a CB900C, but the procedure is the same:

http://www.cb750c.com/modules.php?name= ... ic&t=23512

Re: 1981 Honda CB650C Clutch Rattle

Posted: Sun Dec 03, 2017 11:11 am
by cb650
Try adjusting it and if it works properly and idles smooth just run it. The 650 clutches do make some noise anyway.

Re: 1981 Honda CB650C Clutch Rattle

Posted: Mon Dec 04, 2017 8:30 am
by Ox Moto
Also best to open up that cover
Sometimes things come loose
Or break off

Sent from my SM-G870W using Tapatalk

Re: 1981 Honda CB650C Clutch Rattle

Posted: Wed Jan 17, 2018 3:55 am
by Whacky Wheels
HI guys! Thank you so much for your replies, sorry that I dissapeared. Work became hectic. I opened up the clutch and found everything to be in order. Turns out it was the carbs, the main jets (4 of them), were odd: 3 were the same and original, 1 was odd. So the cylinders fired differently with every revolution. Thanks again!!

Re: 1981 Honda CB650C Clutch Rattle

Posted: Wed Jan 17, 2018 6:24 am
by Folsoml
Whacky Wheels wrote:HI guys! Thank you so much for your replies, sorry that I dissapeared. Work became hectic. I opened up the clutch and found everything to be in order. Turns out it was the carbs, the main jets (4 of them), were odd: 3 were the same and original, 1 was odd. So the cylinders fired differently with every revolution. Thanks again!!


Now you have my curiosity wanting to know what was "odd."

Re: 1981 Honda CB650C Clutch Rattle

Posted: Tue Dec 31, 2019 2:39 am
by Whacky Wheels
Folsoml wrote:
Whacky Wheels wrote:HI guys! Thank you so much for your replies, sorry that I dissapeared. Work became hectic. I opened up the clutch and found everything to be in order. Turns out it was the carbs, the main jets (4 of them), were odd: 3 were the same and original, 1 was odd. So the cylinders fired differently with every revolution. Thanks again!!


Now you have my curiosity wanting to know what was "odd."


I actually sourced another set of carbs, but the original ones had different size jets in the each of the 4 carbs. And they were filed down to different lengths with a metal file and the brass shavings where just lying in the carb bowls!! Can you believe it. Have stripped the engine since then, as I have zero trust in the previous mechanical work on this engine.