Stumped! Please help.
 

Hey guys,

New here to the forum. I need some assistance.

I have a 1992 CBR 600F2 and am having some real anoying issue happen.

The bike seems to have a "misfire". Right when I start the bike it seems ok, but once I get a block down the street it starts acting up. It will run horribly up till about 8k RPMsafter which it will then run somewhat ok. It feels like one cylinder in not working until the 8k and then that cylinder will kick in and out for the above 8k RPMs.

Sorry for the horrible technical language.

Here's what I've done. I replaced all the plugs, it was still acting up. I then took the carbs apart and cleaned the jets as well as inspected the floats and float valves. All looks good. The mis is still there. I notice that after I start it cylinder number 3 is cooler than the other three. I then took the ignition coils off and have since tested them. I am within specs on the terminal side and a tiny off on the plug side. The manual says the max impedence on the plug side should be 25k I am getting 26.2....can this be causing the issue? If not does anyone have a clue????

Thanks much in advance for any advice.

Michael

2001 Honda CBR 929RR
2000 Yamaha YZF-R1
1992 Honda CBR 600F2

RE: Stumped! Please help.
 

I'd say the coil could be the problem. Your spark is weak at the plug and that is why the cylinder is cooler. Coils are cheap on eBay.

PS, did you measure at the coil terminals before the wires? It could be a bad wire.

RE: Stumped! Please help.
 

I checked after the wire. But do you think that little of a variation from normal impedence would make a difference? Also, the plug when removed has whitish deposits on it....which if I'm not mistaking would mean it is running a little lean on that cylinder....is this right? Could it still be a coil issue?

Mike

RE: Stumped! Please help.
 

The service manual provides the allowable ohm readings. Anything different is out of spec and needs to be fixed. Regarding the white, yes that means lean condition. I would get the carbs cleaned and adjusted as you could really screw up a piston or cylinder by running lean for extended periods.