If it's broken or just needs tweaked
7 posts • Page 1 of 1
So I have a 1980 honda cb650. I got this bike not running so it's been rather difficult for me. I got it running for about 30 seconds and it was leaking oil from the head. So I replaced all seals made sure the valves and time correct. Have spark. However she won't start. I am however shooting gas out of the tubes of 5he back of the carbs. Not sure why this is happening any help would be greatly appreciated.
- The bottom two tubes is where the gas is shooting out.
- 20170817_175116.jpg (3.95 MiB) Viewed 1057 times
Hi Nic, is it all of the carbs or just one? If it is blowing when it should be sucking I would suspect inlet valves being open at the wrong time but you say you have set them. I would remove the valve covers just to see if there is anything obvious like a sticking tappet.
I do recall reading on the net (not sure if it was on this site) that a guy had a starting issue and he couldn't find anything wrong with his valves when he took the covers off but the bike just wouldn't start. It turned out that he had forgotten to put the cup shaped washers underneath his valve cover bolts, making the rear screws sit just low enough to interfere with the tappet and hold the valve slightly open. Might be a long shot but worth investigating.
The engine turns over fine by hand? I know my manual has misleading information on setting the valves, there is a little chart that shows the exhaust settings on bottom. When you stand over the bike the exhaust is on top. I've also dealt with the timing being off on the cam shaft. Make sure it's right on 1.4T and the notch is lined up on the front. I've fixed wrong timing twice on one of these(at the cam). Both times it was checked and double checked but... shit happens i guess.
I was afraid it was the cam. I've checked it three time and it all looks correct. The engine turns good by hand. But it won't even try to fire even if I use starting fluid. And I definitely has spark. I'm gonna have to try taking it apart again and check everything one more time
You do have the air box on the bike when you try to start it, right? The choke won't block enough air on its own. You could try blocking off the intakes with a sheet of something and just letting in a little air to get it to fire. The coils need to be hooked up a certain way too. If they are backwards they won't ignite the fuel. (it won't be compressed when they fire) If they haven't been changed you should be fine. Make sure you are using imperial .003 and .002 for the valves . Obviously .02 or .03 would be a problem as well... if you made that mistake.
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