Vacation is over... bad acceleration

bountyhunter wrote:

LineArtist wrote: Hello again. I took a long vacation from wrenching after some new problems came up at the end of last year. My 79/650/B3 was running tops all of last year until about 15 miles into a ride, going about 40-mph the motor started to slightly surge. ?

Could be a lot of things, on mine it was caused by crap in the fuel tank going into a jet.

I'm pulling carbs this week (just order a rebuild kit for the fuel accelerator). Problem happened about 5 miles after filling up. Gas was/is suspect, so the carbs are coming apart. Being that I only cleaned the carbs once before, this is a good opportunity to inspect all the pieces for real this time.

thanks

Check the petcock strainer.

LineArtist wrote:

bountyhunter wrote:

LineArtist wrote: Hello again. I took a long vacation from wrenching after some new problems came up at the end of last year. My 79/650/B3 was running tops all of last year until about 15 miles into a ride, going about 40-mph the motor started to slightly surge. ?

Could be a lot of things, on mine it was caused by crap in the fuel tank going into a jet.

I'm pulling carbs this week (just order a rebuild kit for the fuel accelerator). Problem happened about 5 miles after filling up. Gas was/is suspect, so the carbs are coming apart. Being that I only cleaned the carbs once before, this is a good opportunity to inspect all the pieces for real this time.

thanks

Be sure to clean all the crud out of the tank and petcock assembly and install good filters or cleaning carbs becomes a permanent hobby.

Pulling the clutch apart is no biggie....I would change the oil for a start and then really inspect that oil for contaminants. I doubt you would need new springs unless one broke. Sometimes friction plates can get dry from little use (winter hibernation) but again I doubt you would need new plates unless they were out of service limits. The steel ones should be good forever unless they got bent. If it were me I would drain/change oil, pull out all clutch plates and springs and check them all and reinstall to proper torque. Then make sure the clutch cable is lubed up well and adjusted properly and while you're at it pull out the long clutch actuator rod and check that is not dry or bent or has any nicks in it that would cause binding.....I'm going to bet a buck that the clutch is the issue.
Everyone seems to be stuck on fuel as being the issue....then how come the engine runs like a kitten when not under load? :huh: Mind you, all their suggestions are definitely worth doing anyway under the "general maintenance" flag

One problem I have with the clutch is that it will definitely slip if I add too much oil. This happens most often after an oil change with adding oil on the center stand. When I take the bike off the stand, the oil level ends up slightly higher in the window. If I don't have a air bubble in the window, with the bike on the ground, the clutch will slip under high stress. That is usually in higher gears under heavy throttle.

Clutch cable replaced - clutch adjusted no change

Points and Timing - having numerous issues dialing in the timing and dwell. Will start chasing wires and voltage through the system and most likely changing over to a Dyna S (DS2-2) setup with 3.0 coils once the issue is sorted.

Suspect bad coils or lack of power at the points.

Cleaning carbs. Last time I took them off like this was early 2014. I suspected the accelerator pump to be in question and it certainly is. One of the diaphragm screens disintegrated (new diaphragm kit is going it). #2 carb blacked out/dirty on the intake side, not sure what got in but I'm inclined to say the original hoses are hardened and leaking, new set is going on.




Exhaust side of the #2 plunger, most likely will keep me up at night until I sort what happened here.



This is the intake side of #2

Are you sure you don't have a bent or burned intake valve??
Go borrow or rent a compression gauge and crank that thing over a few times to see where you are....

Looks like it to me. :dry:
Steve

I'm afraid that's also on my list. I can do a compression test first. According to my notes, last time I checked (before all this happened) all were +125. The #2 has always been and off/on issue on my bike from running cold to fouling the spark plug. I believe there might be a combination of piston and/or valve issues on #2. I've suspected bad rings and up top have noted the valve clearance was on the lower end. There had to be a reason this bike was parked and left for nearly 20 years.

Thanks guys, I'm going to keep moving forward on this. I have a parts engine to swap parts but will source out the work if need be to have everything done right.

It couldn't have run very well that way.
Steve

swest wrote: It couldn't have run very well that way.
Steve

Based on the visual of that slider, and perhaps a bent or burned valve... how would the bike/engine behave?