One-side starting and idling

[Dizerens5]

Hello people, I think my beautiful 79 R65 seems to be jinxed. With ignition problem solved by junking the cheapo pattern coils and replacing with Bosch items, the bike ran really well....for about 2 weeks, now has exactly the same problem reported by Dontron on July 8 and worked on so well by you all - running fine on the main road, but bad misfiring at small throttle openings, gradually got worse. Now the left cylinder will not fire at all on starting - engine runs ok on right side (thump thump thump!) but will usually stall on opening throttle. If I can get it to speed up, the left cylinder picks up, though. But it’s no longer road usable.
So this is what I’ve checked:
Brilliant sparks on left plug (c.b. ignltion so easy to check that!)
Float bowl with fuel up to correct level it seems, fuel completely clean, no garbage.
Idle adjustment played with, now back to standard, makes no difference.
Idle jet clean, none of the tiny holes blocked.
O-rings on idle jet and idle mixture screw look fine.
Spark plug in left cylinder looks totally dry even after numerous attempts to start.
Valve clearances ok.
Idle air inlet at the main carb air inlet seems clear to the end.
It seems that the l.h. cylinder just isn’t getting any fuel at all with throttle closed or near-closed, but why? What’s left to try? Any ideas gratefully received! Thank you all.

[Bob_Roller]

I problems somewhat similar to yours, drove me crazy until I found it .

The idle jet has two holes drilled 90 degrees to each other in about the middle of the jet, the very end of the jet, there's a small opening, I had that hole clogged, sprayed carb cleaner from the screwdriver slot area, cleaner came out of the holes, so I thought it was good .

Take a real good look at the very end of the jet, it's a bit difficult to tell wether it's open or not .

[montmil]

The fuel pickup tube for the enrichener circuit has its own small fuel bowl. At the bottom, there is a small passageway for fuel from the main bowl to pass through and maintain a similar level... as long as this passage does not become clogged.

It's not actually a jet, so a thin copper wire will usually dislodge the clog. When plugged up, there is no fuel available for the starting circuit on that particular cylinder. The engine will idle rough until some temperature get s in the engine and then the dead cylinder will kick in.

Perhaps drop the float bowl and give a look-see. Hope this helps.

Monte

[Dizerens5]

Just for info: Bob I've rechecked the idle jet and all the tiny holes are clear, looks like they would stop anything short of a virus!  Monte I had noticed the fuel passage in a corner of the float bowl - big drillings, looked clear at a glance. Having read your post I took another look and sure enough there's a small brass restrictor, looks like a jet as you say, at the bottom of the vertical drilling. I unscrewed it and took it out, it seemed partly blocked, to clear it needed the smallest pin I could find in the house! Put it all back together, feeling pleased - pushed starter button - result no difference at all.
I'm running out of options now. Looks like a blockage in one of those very small drillings in the carb body. Clearing those looks like a job for a professional with some powerful chemical and an air compressor.....right?

[Rob Valdez 79 R65]

Have you tried swapping your spark plug wires to each side, to see if the problem moves?

[Dizerens5]

Did not think of that Rob. So I tried it. Gave me the chance to re-route the ignition leads in more neat way but otherwise no difference....engine still fires up instantly but on right cylinder only. As before, after letting right side warm up for 30 secs. becomes possible to open the throttle to about 1/3....then left cylinder comes in with a roar. Close throttle and it dies. Frustrating!

[Justin B.]

You can get a 1 gallon can of Berrymans Chem Dip to soak your carb bodies in and then blow all passages out with Berrymans B-12.