Vintage and Classic Hondas

Left cylinders dead

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Thom

Left cylinders dead

1980 750C
Just got the bike in the Fall. Never had a chance to ride it due to snow. Fired up after winter (Stabil-ized) storage and the left two cylinders are dead. Exhaust coming out is cold. I figure they are not getting gas or spark. Anyone have any suggestions for chasing down either of these possibilities? (am new to all of this). Are the two left carbs on a separate fuel line? Are there two (left and right) coils? Where do I start???

Thanks...

1980 CB 750C, 25,000 kms
2009 HD Electraglide Classic

TOOLS1

Re: Left cylinders dead

Administrator

Start with checking for spark by pulling the spark plugs, then reconnecting them to the wires, then ground them to the engine, and crank it over. Look for them to spark. However since the No#1-4 and No#2-3 cylinders are grouped together in the ignition system, and your cold on No#1-2 I am guessing that it is a carb problem. Most likely the pilot jets are plugged from sitting.
TOOLS

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1976 CB 750-A X 2
1977 CB 750-A X 4
1977 CB 750-K
1976 CB 750 F
1981 CB 750
1966 Kawasaki SG 250
1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
1982 Honda XL 80
South of Eden (Kansas City MO)

Thom

Re: Left cylinders dead

>Tools1: Good to learn about the ignition pairing. That helps a lot. Thanks.

1980 CB 750C, 25,000 kms
2009 HD Electraglide Classic

hellsford

Re: Left cylinders dead

In reply to this post by Thom

As a previous lurker to this forum, it seemes like tools always knows what's going on. But to answer your question, no, only one carb gets gas from the tank. the rest rely on the accelerator pump in carb#2 (correct me if I'm wrong). Carb #2 is directly connected to the throttle, and to reduce an anomoly similar to that known as turbo lag, the accell pump in carb #two pressurizes carb 1,3,&4, so that when you twist that throttle, all four gas chuggers are reading from the same page.

hellsford

Re: Left cylinders dead

In reply to this post by TOOLS1

Woah, sorry, confusing your post with others I've read recently, if
you're getting cold pipes on #1&2 then, again, tools is right. I would start with a carb rebuild, and compare the condition of the specific carbs with the corresponding intake hoses from the air box. The hoses on mine looked great except #4 which looked like crap and what do ya know, compared to the other three clean carbs, #4 had a,lot of this going on air cur

Re-run

Re: Left cylinders dead

Administrator

In reply to this post by hellsford

Well, all 4 carbs get gas, they use fuel tubes to distribute. The accel pump squirts gas from little noxxles on all 4 carbs.

I 3rd a carb clean. It depends on what stabilizer you used. I used Sta-bil in the past and it preserved the gas so it became nice and gummy and fouled up my jets. Notably the idle jet.

The ride IS the adventure. The destination is just to get gas!

shinyribs

Re: Left cylinders dead

Administrator

In reply to this post by hellsford

hellsford wrote

Woah, sorry, confusing your post with others I've read recently, if
you're getting cold pipes on #1&2 then, again, tools is right. I would start with a carb rebuild, and compare the condition of the specific carbs with the corresponding intake hoses from the air box. The hoses on mine looked great except #4 which looked like crap and what do ya know, compared to the other three clean carbs, #4 had a,lot of this going on f

Is that your air cut-off valve cover? If it looks like that it's a pretty good chance the valves are bad. If so,they aren't cheap,but the you can bypass them and run without them.

Search for defeating the air cut-off valves. Or something along those lines.