[68grandprix]

I rode my cl all over today, and it has a few problems. I can't get it to idle, but it runs good everywhere else. I've cleaned the carbs (good) and I can hold it at about 1500rpm with the throttle, but it won't idle at 1500 with the idle speed screws (it will idle at around 3500rpm for some reason, but I back off the right carb screw a little and the rpm drops until it dies). What's the stock mixture screw setting (I have it at 750 spec 1 1/8 turns out)?
I did get it going 70mph on the way back from a friend's house about 15mi away. When I got to my other friend's house he said, "What's that bubbling sound?" and I noticed it sounded like my oil was boiling in the crankcase (I WAS riding full throttle at 60-70 on gravel for about 15 minutes straight). I had added stp oil treatment because the bike was burning oil and it would foul the right plug after a while. After adding the stp it didn't foul the plug anymore, but I'm wondering if it contributed to the bubbling sound? My friend said it probably saved my motor.
Finally, the motor did rev freely to redline all day, but tonight in my garage it would only rev to about 9000rpm and just sit there. I hear a little ticking, so I was wondering how to set the valves and camchain tensioner. I know how to do it on a 750, but didn't know if it was the same. Thanks (and sorry for the long post) Jimmy.



Edited by - 68grandprix on Apr 13 2006 02:58:32 AM

 

[jbranson]

Jimmy,
It's been my experience that with a whole lot of small displacement vintage bikes that the carbs are usually pretty messed up. I almost always install carb rebuild kits. I rarely see a small old bike without the idle screws messed up, pilot jets hogged out with a piece of wire, slides in backwards, floats messed up etc. If you plan on riding the bike any substantial amount you need to invest in the kits.

As for the boiling oil....did you change the oil yet? Is it possible you have enough moisture in the oil to have the water boil off? Cause if you got it hot enough to boil the oil...the motor is done, cooked, finished. Sounds almost like it's on the border of siezing up. It also possible if the fuel was low that it was boiling fuel in the tank..but again...if it got that hot you have some problems.

How many miles on it when you got it? I've disassembled over a dozen of these engines...if they have over 10k miles they are usually pretty messed up...not from wear but from neglect and kids screwing around with them. Most people aren't as anal as me...but it's rare that I find a bike that in my opinion doesn't need the engine partially disassembled and gone through pretty good.
JohnnyB



Edited by - jbranson on Apr 13 2006 06:57:19 AM

 

[UngaWunga]

The bubbling sound could also be your battery... lead/acid batteries do that sometimes when they've been getting one helluva charge.

 

[68grandprix]

The bike has just over 10,000 miles (somewhere around 10,400). Thw carbs looked really clean, but I guess the jets could have been hogged out or something like that. It's almost like the right cylinder isn't running at idle, because that pipe doesn't get really hot until I go ride the bike around, and that would explain why it won't idle below around 3500rpm, because by then that carb would be off the idle circuit (and almost off the pilot circuit too, I think).
The bike didn't seem to have any oil in it when I got it (at least it didn't show on the dipstick). I put in about a quart and a half, then I added a small bottle of the stp (which treats four quarts, but my friends said, just dump the whole thing in. It did stop the plug fouling). The bike also leaks a good amount of oil, but I can't fix that yet because the side cover screws are stripped so I need to use my friend's impact driver.
The bubbling sound was coming from the engine, and it sounded like the crankcase, but I was also thinking it could have been the carbs. The clutch was slipping pretty bad (it was moving with the clutch pulled in, so I adjusted it out until that stopped, but then it started slipping). Maybe it was hot and was boiling the oil near it?
Is the valve adjustment the same as the 750 (15* past TDC on that cylinder, then adjust)? I saw an old post by you (jbranson) that said to set both int and exh to .002". Jimmy

 

[jbranson]

Yeah a slipping clutch would have heated things up tremendously. And like Rob said...bubbling battery is pretty common.

10,400 miles isn't bad....would think it would still be in decent shape. The NO oil when you got it....that part is scary. I would guess that the STP didn't do anyting....the plug probably stopped fouling because of some other change, or just because it hadn't ran in a long time. Typically I change the oil very soon after the first run time....treat it as just a flush.
Was it smoking bad at any point? If the cylinder that was fouling was also smoking I guess the STP could have helped seal of a old valve seat or something.

Yes....Honda spec for the valves is .002" both intake and exhaust. That's very tight...if you have any doubts.....003" is better than .001.
JohnnyB

 

[mikeo]

look at the possibility that one of the carb intake rubbers is leaking air. I've had the experiance that it will cause some symptoms you describe as far a idle is concerned. Check the plugs and see if one is burning significantly hotter or leaner than the other. I think that the ride you described should have burned off any crap off them left over from sitting around or just getting dirty from screwing around trying to get it to idle.

Also if it is leaking a bit of oil that may explain the "boiling" noise if some were to leak out on or near the exhaust pipes. I also had one bike that I started after sitting quite a while and where I had some difficulty starting it. I ran it for a while and noticed a weird noise when I shut it off. Tracing the noise, which did sound a little like something boiling, I found that one muffler apparently had soaked up a lot of oil and fuel that ignited when I was riding it and was still burning.

For cleaning carbs I found that Yamaha's carb cleaning fluid works wonders. You mix it 3 to one with gas and fill the float bowls up, crank the engine a little to draw it up into the jets and then let it set for a couple of hours. Drain the stuff out and start it up. Worked wonders on every dirty carb I've ever tried it on. The problem is that you have buy about a quart of the stuff and its not the cheapest quart of stuff you'll ever buy and its enough stuff to clean about 300 carbs. I highly reccomend it anyway.

Mike O