Can't restart bike...what am I missing?

When using carb cleaner in a pressurized spray can to clean the pilot circuit, be sure that the cleaning spray passes through the small orifice into the carb bore.

If the pressurized spray can't get through the orifice into the carb bore, neither can the fuel mixture as it's supposed to do in normal operation.

The following illustration may not exactly match the carbs at hand, but shows the basic idea.





Good Fortune!

Back in the late 80's early 90's the local dealers would send the 10 year and older bikes to me. Didn't have time or room for them. I got to work on some interesting machines. I had a Yamaha 1100 come in with two of the back bone tubes cut out to accept a Honda peanut tank. The carbs were gunked up and I charged $40 per carb to clean and sync them. I warned him about the frame and when he picked up the bike I wrote on the job order, NOT FOR HIGH WAY USE. That was to protect my ass. Sometimes you think you've seen it all, then this.
Steve

Question... I know this would be a contributing factor to a poorly running motorcycle but would a plug with a cracked insulator running on the inside of the plug cause some of my symptoms? I pulled the plugs two days ago, while pulling the carbs, and decided to torch them to see what I could find out (one plug was oily and fueled soaked.) After burning the contamination off the plug I could see what looks like a crack running below the electrode (I'll post photos tonight.) the problem is, I'm not sure which cylinder I pulled it out of. If the plug is fouled, and the cylinder is not firing correctly, the cylinder would be running rich which would exhibit a cooler or hotter exhaust than the properly firing cylinder?

Get some new plugs.

Agreed. The cracked plug might be failing when it gets hot.

Here are a couple of photos.



If what you say may be true... It might be why the bike starts up really easy after a long day and run pretty well for the first 10 seconds then begins its shenanigans? Waiting for rain to pass before I go out and play with it some more, this time with functioning plugs.

Think about this. What if a piece of the porcelain broke off and lodged between your piston and cylinder? That would make for one F#%$ed up day!
When I first started to work on my own bikes in ER 71? I had a Climer manual that said a motorcycle engine could suck up a cut up chicken and still run to some degree. I never tried it. I did drop a valve in my Honda 350 and rode it home. That was expensive and I was learning. Still am. Somehow that makes it fun.
Oh, the noise made me want to get off and walk. I didn't. Now that was a F#%$ed up day.
Steve

Well, that didn't work. Through in some new B8ES plugs, gaped to about.30 and nothing really changed. Starts great and sounds great until she starts to warm up. Then the expected happens. Oh well, on to the next things.

Below are some photos of the new plugs after I called it a day.

Right cylinder...


Left cylinder...


I'm working in uploading the video I shot while I started it up with those new plugs, to follow shortly.

1 Too rich.
2 Oil fouled.
Have you checked the coils? Try switching them Plug to plug, wire to wire. See if it reverses.
The coils may be breaking down once they warm up. Points and condenser or EI?

Coil is brand new. Points and condenser stock setup. I should replace those next.

New coils can be defective. If the points look good it might be the condensers. Checking for arcing never worked for me. However you can start up the bike with the cover off and see if there is sparking at the points. If there is, replace the points and condensers. I added two early ford condensers up stream because the old stock ones were weak. The Ford ones were $5 each. It worked. I have a Dyna 1 now but have my old point set up in the bike just in case.

Nduetime wrote: ... ('77 KZ400 D4)... it started up. Idled around 2,500 rpm's for about 1-2 minutes. Then died...
Things I've done to date:

• Valve clearance checked (not fully confident, no previous experience)
....

Nduetime wrote: ... Starts great and sounds great until she starts to warm up. Then the expected happens....

Classic symptom of too tight valve clearance. Engine starts and runs when cold, but falters as engine approaches normal operating temperature, Especially noticeable at low rpm, where engine dies instead of idling.

Good Fortune!