Diagnostic help needed

Helping a friend with a early 70's street CL175.

It starts with lots of throttle wringing and full choke. Will not idle but revs. No weird sounds.

Turn off choke, it dies immediately, no matter what I do. I pulled the plugs. They look dark and wet. Looks a lot like oil and/or fuel.

New plugs, carbs cleaned, jets cleaned, air screws checked (need to double check idle screws), good battery, gas in the tank. I haven't measured the float level, but it looks okay. Float bowls seem to fill just fine.

I have not done a compression test. I'm wondering if oil is getting past the rings. Could it be valves? Hoping to check those tomorrow night. Timing?

Just trying to assemble some ideas so I can try several things next time I go to the shop.

Thanks in advance for your help/suggestions.

 

Sounds to me like the pilot circuits in the carbs are still blocked.

 

I agree. They are so small it's hard to check visually. Most people just soak them and assume. Best bet is just get new ones. If not the Yamaha brand carb dip is pretty amazing. 50/50 with water and soak overnight. But new ones are best

 

Flame away, but I've never heard the words "pilot circuit " before. Does that mean take the carbs off and soak the whole thing? I confess that i just removed the jets. Didn't remove the carbs and go through them completely.

Thanks for the replies.

 

If it won't idle it has to be the pilots. Don't dick around trying to clean them, just get new ones for $5 each or less.

 

I like to blow starting fluid through pilot circuits to confirm that the circuit is clean. Just because you replace the pilot jets doesn't necessarily mean that the circuit is free of debris. I dismantle the carb completely, then start squirting fluid through all of the orifices, starting with the intake bell. Plug the big holes with your finger to direct the fluid to the different passages and make sure that the fluid comes out somewhere familiar. Wear goggles and gloves.

 

Cool. Thanks guys. This is really helpful. Will dig in tonight and report back on how it goes.

 

Buy a can (like a 1 gallon paint can) of Berryman's carb cleaner at your local wally world. It comes with it's own dip bucket. The stuff looks like maple syrup and you'd think it was contaminated...but the stuff is the tits. It has never failed me and I've every solution out there....even better than Yamaha stuff....IMHO.

 

Thank you Moto. I'll try that if the clean up I did last night doesn't seem to work.