Nearly at wit's end with this 380...

[jbswear]

I have spark at all plugs. The points barely spark at all when it's running. I know my condensers are good and I know that my gapping and timing is good.

I can get it to start by holding up the enricher tab (the ball to keep it in place was lost long ago), but if I let it go, the bike slowly dies. It's only running on the left cylinder.

It isn't running at all on the center and right cylinders. Both plugs are firing; I've pulled them off and checked. Big, fat, hungry sparks.

There is fuel in all three of the bowls. There is no vapor-lock. All three floats are set properly.

I have the pod filters pulled off (same performance when on the carbs). I can spray a bit of carb cleaner into the throat of the center carb (no throttle input; the slide is down) and the center cylinder starts firing as it sucks the fluid in. Spraying it into the right carb does nothing. When I crack the throttle open it sounds like the bike is stalling.

When I pull the center and right plugs, there is no fuel on them. They are gapped correctly.

I pulled the center and right carbs apart today and checked the pilot and main jets; they're both clean and clear. I used my air compressor to blow out all the passages in the carb bodies; I felt no obstructions.

Can anybody tell me what to do next before I give up for good?

[tz375]

Are the air passageways clear from the air jet through to the bleed holes? Pity you don't live closer - I'd tell you to bring the bike round so we could check it out.

Assuming that it has compression and that timing is correct, either the spark is insufficient or it's a lack of fuel and the trick with the starter fluid narrows that down to fuel supply.

[two-stroke-brit]

when i got my buffalo it had similar probs with not wanting to start ,it had good compression on all three cylinders but the plugs would be dry in the left and center ,it turned out to be the crankseals were shot so a complete rebuild was the only solution . why dont you try a leakdown test to rule out or in the crankseals.
hope this helps mark.

[Coyote]

Pull the center plug and dribble a few drops of FRESH gas into the plug hole. Replace the sparkler and fire the bike. if that cylinder is firing, the exhaust pipe will be hot a few inches out from the cylinder. Try the same thing on the right. If they fire, it's a fuel delivery problem. If they don't, I'm betting your timing is still a mile and a half out. Does the bike backfire? That's a dead giveaway.
Also, it's a good idea to pull out the SRIS valves and make sure the crankcase isn't filled with oil. That can play a big part in the induction area.

[Scorch]

What's involved with pulling the SRIS valves? I'm interested in checking these too. I've read about them in the service manual, but still not sure where they are on the engine. Anyone have any pics?

[Coyote]

Ask and ye shall recieve

The valves are located at the very bottom - front of the engine. They are nearly impossible to see with the exhaust pipes in place. If your bike is a 74 or later the valves are threaded in place. 72 and 73 were pressed in but still come out with the twist of a wrench. If you remove them, be extremely carefull with the little mesh filter attached to the rear of the valve. The valves are still available but the filters are NOT available anywhere on earth. I am running new valves with no filters. Part number for the valve is 16710-31012 and run about $15 each.

[Scorch]

Nice, thanks!

[jbswear]

Coyote--

I finally was able to get to the GT again. I pulled the right and center SRIS plugs. The right one drained a little oil, no more than a couple of cc's. The center drained nothing. I had the bike facing downhill so that gravity would work in my favor.

Looks like an over filled crank isn't my problem.

I've never performed a leak down test. What do I need to buy and how do I perform it? If I'm lucky sometime next week I'll borrow a buddy's sonic cleaner and redo the carbs again...After that, there's no telling when I'll be able to get to it again...I'm starting night classes again, so free time will be nill.

On a positive note, my Harley rebuild is making better progress!

[diamondj]

You can check your crank seals by doing a pressure test.

I built my test rig for around $25. Here's what I used:

A basketball type hand pump with gauge - I got mine at Sports Authority for $9.99. I can't find it on their website but I have seen plenty of these foot pumps as well for under $10 and they should work well for this application:



A set of HELP brand spark plug non-foulers - these are made to raise a spark plug up out of the cylinder head. You want the shorter ones with a 14mm outer thread from an auto parts store... Like these:



A long rubber tire valve stem - also from the auto parts store

Trim the edges of the valve stem seat with a pair of scissors, stick it into the female end of the non-fouler and seal it with JB Weld. Once it dries, you replace a spark plug with the non-fouler. You'll then need to remove the intake manifold and exhaust pipe on that cylinder and seal off the ports on that cylinder. I use pieces of scrap plexiglass from the local builder's supply with a dried bead of permatex that's the right size to seal the port and bolt holes drilled to match the bolts on the cylinders. Then I refit the intake manifold and the exhaust pipe collar minus the header pipe and run the bolts down until it's air tight. Attach your air pump to the valve stem/non-fouler that is screwed into your spark plug hole.

Pump up the cylinder to NO MORE THAN SIX LBS of air pressure. The rule of thumb is six PSI for six minutes. If it holds, your crank seals should be okay. Do all three.

Hope this helps.

Jim

[jbswear]

That sounds pretty ingenious. It'll take a while to do, so it may be a few weeks before I can get to it, but for the price, it really can't be beat.

[cyclebuster]

they almost have to have 100 psi minimum compression to start with any ease.
when its running stick your hand over the carbs not firing. If they are sucking, it should be running. switch the darn plug wires.
dry tells me its still a carb issue. something isnt getting fuel in.
a running 2 stroke even with bad seals will draw enough gas to run at higher ends.
i have seen dirt bikes you have to prime with gas, and then they run great, until they cool down, and then no start.
how big of an actual air gap do you suppose a worn out seal has? not much. the rapid movement of a superior volume of air will usually easily out pace any normal seal leaks. they have to be monumentally shot to make it not run.
verify timing as well.
if it wont run with carb cleaner in one of the cylinders, well thats not good. not close to good.