Topic: Bike not starting

[tuckholladay]

I was going to clean my carbs.  My bike started first time out of winter storage but then wouldn’t start again.  I was assuming something got stirred and the carbs got clogged. 

I’ve had the bike (1977 CB400f) for two years and haven’t cleaned the carbs yet.  I am pretty sure it came from a good home.  Anyway I was looking into cleaning the carbs and someone said diagnose the spark plugs. 

So I pulled them and they are pretty fried. 

Judging from this chart .  I’d say they are oil or carbon fouled. 



Any thoughts?  Do I have a bigger problem here than carbs?  What’s my next step?


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[piefairy]

Clean the plugs and try again. Is the gas new or old? From my limited knowledge, it could be a number of things, but cleaning the plugs and new gas shouldn't hurt the situation provided it started earlier. But I could be wrong.

[calj737]

Don’t clean them, replace them. Use fresh plugs and pull an idle chop. Evaluate those. That will tell you whether the pilot circuit is functioning properly.

[tuckholladay]

Don’t clean them, replace them. Use fresh plugs and pull an idle chop. Evaluate those. That will tell you whether the pilot circuit is functioning properly.

Ok after looking idle chop, assuming it starts after I get new plugs in there, I take the bike out, get it up to high revs in like 4th on the way back to the driveway, then kill it with the clutch pulled in, push the bike back up to the garage and pull the plugs again? 


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[Vintageguy]

Those plugs look way rich to me. Too much running on full choke due to carb issues, I'd bet.

[tuckholladay]

Those plugs look way rich to me. Too much running on full choke due to carb issues, I'd bet.

So you think I should just try cleaning the carbs first without trying new plugs? 

[tuckholladay]

Those plugs look way rich to me. Too much running on full choke due to carb issues, I'd bet.

Took out the carbs today.  My first time ever.  They look very clean, I’ve never put gas with ethanol in the tank, but I noticed I couldn’t see through any of the pilot jets without carb cleaner and compressed air. 

Another thing I noticed is the choke openings are not synced.  Two of them have play and don’t close all the way with the other two.  Will that be fixed by bench syncing? 

The float bowl gaskets are impossible to get back in.  I don’t know how they were in there before, they are too big.  I ordered new shaped ones online, but I would be open to tips for fitting them in so I don’t have to wait for the mail. 


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[calj737]

A bench sync will help the slides and choke butterflies. The stock bowl gaskets, once removed, are nearly impossible to reuse. You’ll have to await new ones.

You can try some super glue on the old gaskets to hold them in place.

[BRG-BIRD]

They may shrink back to size if left out for a day or two. I experienced the same thing on a CB350 twin last year and the gaskets shrank back to size.

[PeWe]

Floats are correctly set?
All plugs sooty like that can be floading floats. Check that before new plugs that will look the same after 5 min idle.

[tuckholladay]

The carbs and the throttle came out together.  I don’t think I can remove and clean the needle with this attached.  Anyone have a preferred method of separating these two parts?  I swear I tried to google.  I guess I might have to hit the books


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[Bodi]

The chokes closing are not critical - use the adjusters to get them as close as possible to dead flat across the throat with choke fully OFF. Minimizing airflow disturbance with choke off is much more important than having them all close fully.
Odd that the gaskets blew up with no ethanol fuel, that stuff usually does it.
You can use weatherstrip adhesive or "krazy glue" to stick new ones in the groove.

[tuckholladay]

The chokes closing are not critical - use the adjusters to get them as close as possible to dead flat across the throat with choke fully OFF. Minimizing airflow disturbance with choke off is much more important than having them all close fully.
Odd that the gaskets blew up with no ethanol fuel, that stuff usually does it.
You can use weatherstrip adhesive or "krazy glue" to stick new ones in the groove.

The gaskets shrunk back down after a few hours actually


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