TOPIC:

Yes, the seats are pressed in, and it looks like they may not be serviceable...I don't know. They do have a separate number stamped on them...but If they aren't serviceable then that means replacing the carb body, which is pretty nutty (might as well replace the carbs at that point). If you can obtain new seats somehow, then the seat can still be replaced - tap the old seat, insert a machine screw, and pull out with a slide hammer...but where to get a new seat? It might be worth while to contact Keihin directly. If it were mine, and I had no alternative, I would try and modify the carb body to accept a standard threaded seat and needle pair, but that is easier for me than most people, I would think...

Before that, I would eliminate any other possible problem or be good and sure the valve is leaking. The upside down test is very good, but not certain beyond doubt. I've used a precision low pressure air regulator form an airbrush to check the valves. I think the seats should be able to close against 7-9 psig while doing the upside down test.

Funny story...I have another set of carbs right here! These aren't in as good of shape but I think I'll swap some parts over and give em a shot. Can't hurt.

Just re read your first post above.

Does the "kicking and bucking" happen at any particular rpm range ? If only at the lower end of the rpm range then it may mean some dirt in the pilot circuit. About 10 years ago I had a similar problem which varied from small hiccups at 2500 to 3000 rpm to intermittent kicking and bucking at idle to the point of cut out. It took several attempts at cleaning before I found crud at 5 in the diagram below. I used a fine pin with the tip bent at 90 degrees to poke out the 3 holes at this point. You could try spraying carb cleaner in 8 and make sureit exits at 5. Wear yey protection. Carb cleaner in the eye is nasty.



I have a 750/4 and you have 440 but the carbs are very similar and the pilot assages are often overlooked when cleaning

You can see those holes by opening the throttle butterfly and looking up. pilot holes are circled in red in the photo below

THANK YOU!! Huge help! Didn't have a chance to pull the carbs today but tomorrow after work I should have some time to work on it. Totally overlooked #5.

As for the kicking and bucking: it was doing it at all RPMs. Then it would randomly clear and the bike would run like a bat out of hell. That's when it was actually running though, hasn't been on the road in about a month

If the problem happens at all rpms then its unlikely to be the pilot circuit. Still may be some crud in some circuit and a thorough cleaning where every hole is poked with a wire (guitar string) and blown with compressed air wouldnt hurt. It still may be as suggested by Ed and Kray-Z but just thought i'd make the suggestion.
Good luck

I actually thought about compressed air...didn't do it because I thought it could hurt something. It's okay to use compressed air then?

Compressed air is fine. I much prefer the airline at my local gas station to the little cans from the office supply store for cleaning keyboards

For a good cleaning take the disphragms out , remove jets. Keep parts for each carb separate. Poke all jets and passageways with stiff bristle or gently with guitar string. Blow in carb cleaner from spray can. Use eye protection as it will exit carb where you lesst expect it. Blow everything out with airline.

Small Chinese air compressors are so cheap at discount tool stores (sale price approx. $30) that there is really no reason why any home / shade tree mechanic shouldn't own one - at least to clean parts and do other handy things (fill tires, impact wrench, leak down tester) I have three air compressors - 3.5 hp 60 gallon in the shop - $500, a 1 HP 30 gallon in my basement workshop - $200, and a 1/4 HP 3 gallon "oil-less" portable I use for everything I can't get an air line to from the other two - $30.

Our compressor is down right now but I have a portable air tank I can go fill. Here's a little update...

So a couple days ago I threw the carbs back in. It ran for about 2 minutes, I took it out on the street and it sputtered and died right down the road. Definitely a fuel issue. Take the carbs off, clean all the passages well with a thin wire, check to make sure needles are seating, etc...put it back together yesterday and it wouldn't fire off. Turns out, only the right side was lighting. Left side was totally cold. I used to have the same issue but I fixed it with new plugs....so today, I think I'll take the carbs out, totally take them apart, and blow compressed air through all of the passages. I'm really convinced this is an issue in the carbs because I have great flow out of the tank and it's perfectly clean. Let me know what you guys think

-Jim

Is an aftermarket in-line fuel filter fitted?

Good Fortune!

No, it had one fitted when I bought the bike. It caused more harm than good so I took it out, never had any issues after that. Just for good measure, when I totally clean the carbs all out today, I think I'll take the petcock out and drain and clean the tank well.

Jmcjunkin3 wrote: ...So a couple days ago I threw the carbs back in. It ran for about 2 minutes, I took it out on the street and it sputtered and died right down the road. Definitely a fuel issue....

And will very likely persist until an aftermarket in-line fuel filter is installed whereby no gasoline will ever enter the carbs without having first passed through the in-line filter.

Far too many perfectly clean as-new carbs have been instantly recontaminated with gasoline entering the carbs without having first passed through an in-line filter.

The answer -- Clean'm again. And this time install a brand new aftermarket in-line fuel filter before allowing any gasoline to enter the carbs without having first passed through the in-line filter.

It doesn't matter that the tank interior and petcock are perfectly as-new clean, because the gasoline supplied into the tank may itself contain impurities.

Good Fortune!