TOPIC:

New spark plugs, checked valve lash, it is in spec, re-cleaned carbs and found last time I had separated them I didn't align the chokes quite correctly. So I fixed the choke, put everything back together and now I am clearly out of sync (based on how the bike runs). Before I re-sync the carburettors, I'm going to give them one last go-over.

Does anyone have a good solution to use for soaking carb bodies? I can inspect everything removable from the carburettor to make sure the holes are uniform and unplugged, the carb body is a little harder to verify though, since not all of the holes run straight through. I'm thinking soaking them may be a good next step (and then sync them when I put them back on). I've never done that though (never encountered an engine where I needed to soak the carb bodies to get to a good running condition), so I'm asking for 'best practices" for soaking the carburettor bodies (I do know about the hole between the two smaller ports in the bottom of the carb, so it's not as simple as sticking a wire through there to clean it out).

A good solution to dirty carbs is not to soak them but have them cleaned professionally in an ultrasound tank. Anything else will likely leave a residue and can even reblock your carb when some loosened gunk finally lets go. Also it's more effective at cleaning out air passages as it gets all the oxidation out. A shop will not charge much for the service. Remember to bring any loose jets and the float bowels and get them all dunked at the same time. Too many automotive cleaners are just too harsh for bike carbs. Avoid these.
Ultra sound uses good old H2O so it won't harm the metal in your carbs. Blow dry and you're good to go.
Dogfight.

Sounds like your bike is running way too lean. Check your intake boots. They will harden over time and fail at the head/boot junction. Test by starting up and warming until it will idle at least somewhat then spray some light oil s/a WD40 around the carb to boot and boot to motor joints. if you notice a change in RPM, probably lower, you need to either replace the boots or try re installing them with Three Bond or any good automotive gasket sealer. NOT silicone as it will dissolve in contact with petroleum products and enter your motor. Not good.
Air leakage will not only screw up your air/gas ratio, it will severely mess up the vacume sensitive slides and pretty much make them impossible to tune. Same issues as when going to pod type filters. Haven't seen this on other Japanese carbs but Kawis are known for it.
Good Luck.
Dogfight

If restricting the air flow to the carb improves the idle, then you have an intake leak downstream from where you are causing the restriction. Very likely in the old, hardened intake boots. Another common cause is over or under tightened carb to boot clamps. Yes you can over tighten them, causing the boot to distort and let in air. Idle the motor and spray the intake joints with a light oil. If it idles down and quits spitting back, you have found the problem. Otherwise, check the usual suspects s/a cam chain tension, valve clearances and valve timing. Also make sure that the vacume line to the petcock is not leaking and that the petcock diaphragm is not torn. And lastly check the Left Carb's vacume plug to make sure it's not cracked or missing.
Good Luck,
Dogfight

dogfight wrote: A good solution to dirty carbs is not to soak them but have them cleaned professionally in an ultrasound tank. Anything else will likely leave a residue and can even reblock your carb when some loosened gunk finally lets go. Also it's more effective at cleaning out air passages as it gets all the oxidation out. A shop will not charge much for the service. Remember to bring any loose jets and the float bowels and get them all dunked at the same time. Too many automotive cleaners are just too harsh for bike carbs. Avoid these.
Ultra sound uses good old H2O so it won't harm the metal in your carbs. Blow dry and you're good to go.
Dogfight.

They use more than water.

dogfight wrote: Sounds like your bike is running way too lean. Check your intake boots. They will harden over time and fail at the head/boot junction. Test by starting up and warming until it will idle at least somewhat then spray some light oil s/a WD40 around the carb to boot and boot to motor joints. if you notice a change in RPM, probably lower, you need to either replace the boots or try re installing them with Three Bond or any good automotive gasket sealer. NOT silicone as it will dissolve in contact with petroleum products and enter your motor. Not good.
Air leakage will not only screw up your air/gas ratio, it will severely mess up the vacume sensitive slides and pretty much make them impossible to tune. . . . [[[[ [[[[[[[ [ Same issues as when going to pod type filters. Haven't seen this on other Japanese carbs but Kawis are known for it. ]]]]]]]]]]
Good Luck.
Dogfight

B.S.


.

Somewhere around here I found a document someone had assembled on carb adjustment, went through it, and the bike has been running to my satisfaction for months. I suspect that something is partially blocking channel after the air mix screw on the left side carburettor, or maybe just a bit of oxidation build-up. To get the best running condition, the left side air mix screw is out quite a bit further than the right side air mix screw (don't remember exact turns), When I originally got the bike, the o-ring at the bottom of the mix screw on the left side came out tough, and was a little chewed up, Since then, I've put a kit in it, and the new o-ring does the same thing and is starting to get chewed up. So at some point in the future, I'll probably buy a new left carb body. In the meantime though, it runs well enough that the adjustment seems to be sufficient for the frequency I ride it (been checking compression regularly, no change, and plugs continue to look fine).

Also, I'm pretty sure I've already pointed out more than once in this thread that I've replaced the carb boots relatively recently, and went to great lengths to seal things up. I wish there was a way to permanently block people who bring up air leaks every time they see a carb thread. While it's good advice, I'm pretty sure everyone who's owned a vintage motorcycle for more than about 30 seconds has heard that one.

Right now, I'm in the middle of buying a house and moving, so I consider this thread closed. Problem comes back I'll pick up a new left carb body, but I've got greater priorities right now.