starting issues

If it's broken or just needs tweaked

Moderators: Volker_P, tidd650

amateur CB
Posts: 11
Joined: Wed Jun 08, 2016 9:51 pm

starting issues

Postby amateur CB » Fri Jun 24, 2016 7:46 pm

So I recently rebuilt my top end, actually just finished putting my bike back together and went to start it for the first time and I could get it to start and run for a short time but then It would clank kinda loud and then kill. is it possible that i put my camshaft in incorrectly and a piston is hitting a valve or is there something else i may have done wrong? any input is helpful!!!

thank-you :D

User avatar
tario
Posts: 166
Joined: Sat Mar 07, 2015 2:26 pm

Re: starting issues

Postby tario » Sat Jun 25, 2016 9:23 am

Are the valves set to proper clearances? If you're hitting valves you'll likely have to rebuild everything again and maybe replace bent valves. Hopefully that isn't happening. The cam chain is tensioned properly?

Your camshaft has a dot on it and maybe two lines to show how to orient it. These should have been lined up during reassembly with the engine in 1.4? position I think.
1979 cb650
1980 cb650

amateur CB
Posts: 11
Joined: Wed Jun 08, 2016 9:51 pm

Re: starting issues

Postby amateur CB » Sat Jun 25, 2016 6:28 pm

I was thinking it was the valves but the bike runs and I can get to idle without a problem but then when i start giving it gas it clunks and then dies. is it possible that the cam chain is skipping and then the engine is killing?

amateur CB
Posts: 11
Joined: Wed Jun 08, 2016 9:51 pm

Re: starting issues

Postby amateur CB » Sat Jun 25, 2016 6:40 pm

also how do you adjust the cam chain?

User avatar
Volker_P
Posts: 5508
Joined: Mon Mar 06, 2006 1:53 am
Location: southern Germany

Re: starting issues

Postby Volker_P » Wed Jun 29, 2016 1:11 am

You can check cam chain tension directly with a screwdriver at the opening shown here.
You will have to remove the center valve cover for access.
For adjustment, remove the right side crankshaft cover to turn the engine with a 24mm socket.
Release the adjustment nut and fix it during slow turning of the crankshaft.
Verify the result with a screwdriver as indicated above, it may require several efforts and even get worse again.
The text in the above link also provides some hints on possible additional problems with the tensioner.

BTW, a cold CB will typically die on the throttle without choke, often with a clunk. So to some limited extend of the sound this might even be still normal.
Cosky's great (free) online manual: http://cosky0.tripod.com

forum links to common technical issues

If you really like this site and you would not like to see it vanish soon, have a look there: Urgent: Future of HondaCB650.com Forum


Return to “Technical Discussion”

Who is online

Users browsing this forum: No registered users and 46 guests