Guys, I fully understand the carb tuning/troubleshooting process but have an issue I thought I'd bounce off you in prep to digging into it. I firmly believe that two or more heads are better than one.
My CL77 runs great and once warm, idles fine. But, I've had issues with one cylinder not firing and then it would start working and I thought it was fixed by snipping a bit off the ends of the plug wires. But it came back, and this time bike just would not start. Changed the plugs and she started and ran great. Since I have not had time to tinker with it, it's remained with this intermittent problem.
Another piece of info is the engine won't run well on standard main jets. I'm running one size lower. Exhausts are straight pipes with my home made baffles. I would say they have less than or similar restriction to a stock exhaust. Probably less since it is not as quiet. Air filters are stock.
The issue seems to be that if I putt around the yard with the bike and don't take it out and run it, the plugs foul. They get a nice uniform coating of dry soot on them. Now the bike does burn a tad of oil, but I don't think this is the problem, although it might play a role. My oil level does not budge and there is no blue cloud. Just a slight blue tint to the exhaust if I rev the engine in neutral.
Since I need to run one size below std main, I'm guessing that I have an oversize condition in the mid or low speed range. I'm thinking either needle needs to be lowered or the needle jet is worn. If I remember correctly, the needle is correct and a Keihin needle.
The problem appeared again this week. Took the bike out, fired her up and took her out back to shoot some pictures. Putted around the yard with her and then put her away. Next day decided to take her on a shakedown ride prior to the upcoming Motogiro and she fired on the first kick and then quit. Fired once more and then nothing. Pulled the plugs and they were wet and black. Dried them off with compresses air and still nothing. Checked for spark and had spark all over the surface of the plug, except the electrode or at one point, no spark. Hit both plugs quickly in the bead blast cabinet and had spark at both tips. Put them back in and the engine started and ran like a raped ape. Went for a ride and noticed a flat spot at the bottom of the throttle range when at speed. Back off and coast and then slowly open the throttle and nothing until throttle was open maybe 1/8th. I tried adding choke in that range and no change. So that tells me it is too rich. The strange thing is she idles fine.
Now, I have a theory that fuel is playing a role here as well. I have lots of carbon deposits on the end of the muffler on my fuel injected Harley. I've been told this is from all the additivies in our crummy gas. So I might have a combination of crummy fuel making a slightly rich mixture a problem. But the small main is also telling me I have something going on here.
Any thoughts would be appreciated. Weak spark, tired coils, tired condensers, don't limit yourself to fuel. I'm looking for experience here with similar problems and what the root cause was found to be. Everything on the bike is stock short of the exhausts. I need to recheck all the jetting.
My first attempt is going to be lowering the needle and making sure fuel is not bypassing anywhere. Since both plugs are fouling, I'm not confident I'll find a "mistake" like a loose jet or similar. It's a configuation issue if it is carburetion.
Thanks in advance. I'll be digging into this next week. Giro is the following weekend. Nothing like waiting until the last minute, huh?
regards,
Rob
Plugs foulingHi,
again : (like in your thread "Interesting CL77 ignition problem") In the other thread you didn't reply on my suggestions, why not ? I took the time to think about it and write it up, and all you did was not giving any feedback. I don't say this is your problem, but at least I was expecting some response, just as you are expecting responses now. Sorry Jensen. I cannot say why I did not respond to your suggestions except to say that I never got around to doing much more testing once the giro was over. As I mentioned in this inquiry, I've not touched the bike since the giro last spring.
I did check all the connections for clean and uncorroded connections. I had all the various grounds off the bike when I pulled the coils. I eluded to that in my ignition post, but did not cover all the details. What I did do is pull out my DMM and measure for resistance. That definitely needs to go on my to do list. Your suggestions are good ones and I do need to go back and check everything again. The problem has been no time to dig into the problem and work on it continuously until I uncover the root cause(s). I do think it is fuel related now, or at least includes the fuel system. Things might be changing for me and I'll have more time to dedicate to working thru issues like this and setting them right. I always try to provide feedback on what the problem or solution turned out to be. Since I never got around to doing any more checks, there was nothing to report. Might have something to report by the end of this coming week. And even if I determine the suspected cause, probably won't have parts in time for the giro. I'm hoping the needle change may at the very least improve things. Once the giro is over, it will have to wait until I finish the restoration on my '66 T120R. I have this personal rule about starting to tear into a bike when I have one that needs to be finished. I broke the rule this year when I did the CB160. But I justified it because it was just a spruce up, not a restoration. But the Triumph should be done by now and instead it's just an engine with no head bolted into a bare frame. regards, Rob Assume you are suggesting this for the small main jet condition. I know the levels are spot on from previous checks. But that does not mean they are right for this engine/set-up. Good thing to keep on my list.
The more I think about this, the more I expect to find worn needle jets. Wonder if they are still available. Thanks, Rob I've never seen a worn needle jet, although others claim to have... It's the fuel level, not the float height that's important. It's been suggested many times (correctly) that the floats should be even with the jet holder as the tang just hits the pin. This puts you right at Honda spec. I have a couple of examples however, of fairly high mileage carbs where they ran much better with the floats set a few mm higher (close to even with the end of the jet). The best thing is, it doesn't cost anything to try, and its reversible if it doesn't work. Good Luck!
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