Topic: 1970 CL350, cleaned carbs, now float bowls bone dry.

[marty]

it was running this morning, but as I rode it it was as if I had "cruise control": after riding only for a minute I would stop and the
engine would rev up to 4K or so. I thought that a float was sticking since the throttle cable seemed fine. Some gas would drain out of the drain tube after I shut the bike off, not much just a little. I adjusted the idle screw and the throttle cable stops and it idles just fine, but after riding it revs up again.

So I proceeded to pull off both carbs, clean them out, I was a bit confused setting the float height since the manual said the spec was 21mm for my engine #, however the person I bought it from had it set around 26mm. The clymer says lists 26mm as an option but it's for later models I believe, the person I got it from had swapped the cylinder head from a different bike. So I thought I'd set them both at 26mm, thinking the cylinder head came from a later model.. maybe this was a mistake on my part?

I put the carbs back on the bike, and the bike won't start. After some trouble shooting, I discovered the float bowls are bone dry even with the gas turned on and flowing through the fuel line. Gas will not enter the carb. I was thinking that there isn't any suction pulling gas into the carb, or there is an obstruction preventing gas from getting in. Even though I just cleaned them! I pulled off one of the float bowls while everything was connected to see if the float was still sticking or to see if by moving the floats with my finger, I could possibly get the gas to flow through, but it didn't.

Any suggestions?

[BeSeeingYou]

Did you clean out the needle valve seats and are the needle valves moving up and down with the float?  Is the tank clean?  Any inline filters that may be plugged?  Kinked fuel line? Wrong float setting or float in upsidedown? It's just a simple gravity feed to the carb so if it's not flowing it has to be one of these issues.

[dylboss]

I had this same problem on 2 separate occassions with both carbs on my 450.  It ended up being a clogged fuel inlet.  I sprayed some carb cleaner down the inlet, then used compressed air to clean it out, so that the air would push though to the bowl area.  When you see the air/cleaner spray through, you're there.

[marty]

So I ended up sorting out the gas issue, by blowing through where the gas enters the carbs. There was something plugging up that hold that the carb cleaner couldn't get out, it ended up taking an air compressor to get it out.

Now with that resolved, I'm back to the original problem which is the bike revving up to 3 or 4 thousand rpms. Whenever I ride the bike it's as if there's cruise control. I'm going to try to spray some carb cleaner on the intake boots and see if this calms the engine, in which case it's probably an air leak. But if not, I'm not sure what's next. Maybe a hole in the diaphragm? There was one jet in one of the carbs that was stuck in there and I couldn't get it out. That may just be my problem.

[MoMo]

You could have a hole in the diaphragm or the slide could be sticking.  Have you removed them and polished the slides and body?...Larry

[marty]

I pulled the slides and they are clean, there was a 3/8" tear on one of them that was repaired with some kind of tape. So I pulled off that tape and repaired it with hondabond non hardening gasket sealer. So it should be flexible and not stiff (I don't want it to crack). I'm letting this set overnight so tomorrow morning we'll know whether that was the cause.

Thanks for the advise!

[marty]

when i say "tear" just for clarification there was a tear in the diaphragm, not the slide. As i read my last post I thought it sounded a bit unclear.

[MoMo]

The slide diaphragm is no longer available from Honda.  There is a company in Canada that sells the rubber part for 70$ plus shipping.  Good used slides usually sell for fairly large dollars on Ebay so I hope your repair works...Larry

[marty]

I put the repaired slide back in this morning and it did not change the problem. I'm not sure where to go from here.

[MoMo]

Did you check the slides to see if they were freely moving when you had the carbs off?  Also, is there adequate slack in the throttle cables?...Larry

[marty]

Yes I checked to make sure the slides moved freely and there is adequate play with the throttle cables. There's even a little slack, I wanted to make sure they aren't tight, but when I twist the throttle both cables lift simultaneously.

[marty]

I ended up pulling apart the right side carb and cleaned out the jet that the slide needle moves through. Put it back together and the revving issue significantly decreased, it's almost non existent now. Success!

[MoMo]

Congrats,  good work....Larry