430 wr running bad

Hi all, I rode my 82 430 at Unadilla a couple weeks ago and it ran great. Unfortunately the shift spring came off and I couldn't down shift from 4th. I got home and repaired the shift problem and took it for a test ride. Now the bike runs like crap. It feels like its stumbling and running very rough. It will hit a spot where it will take off and then fall off again. Could this be the SEM ignition going bad? I have a PVL on the shelf from a 79 390. Would the PVL fit the 430wr?

could be a few things. i would pull the bowl from the carb and give it a good cleaning, especially if you dont have an inline filter. next would be plug wire and/or cap, as the cap can become loose or go bad. as always check the kill switch, and dont forget about the plug

I did change the plug and no difference. The cap looks good but I will look closer. I'll try and tinker with it tonight.

Does it still have the old gas in it?
If so, dump it and go with new gas.
Also, clean the carb, jets and reset the float.

Paw Paw

The gas is a couple weeks old, non ethanol. The carb has new jets. I had just gone thru the carb before unadilla.

Since you had trouble at the track , did you get a chance to run the fuel out or did you just wheel it in the trailer and forget about it ?
If so , this could be just crap gas that gummed up in carb. ?

No I didn't run the fuel out. You really think it could go bad that fast? I got it on the way to unadilla so now it's about 2 weeks old. The bike starts fine, 3 or 4 kicks cold. Just runs like crap.

Check the head bolts, retorque, maybe base gasket?

It sounds like a possible ignition problem but lets explore another fuel system problem first. I know it seem impossible for well managed fuel to get contaminated but things do happen. Checking the carb bowl when its full of fuel will reveal debris or even the smallest amount of water. This is worth doing.

I don't have any experience with 79 and 82 ignition compatibility so I can't advise you there. Maybe just take a few hours to try and see if they'll interchange otherwise send the PVL out to have it checked.

I'm curious, based on your first post is the point where it will take off and then fall off again in the same RPM range every time? Is it different whether the engine is cold or hot? Does it rev up okay when in neutral? Anything characteristic you notice will help.

Ok, I just rode it for 15 minutes. Idles good and starts good hot and cold. I pulled the plug and it's brownish gray. I drained the float bowl. Nothing in the bowl plug, no dirt or water present. From idle to almost 1/4 throttle it runs pretty good. Blip the throttle from idle and it lifts the front wheel. Went down the road and 1/2 to full throttle it's breaking up and runs like it's way rich. The needle is dropped all the way down, 440 main, 50 pilot. I tried a 45 pilot a few weeks ago and it ran lean.
It's almost like the choke is on. I pulled the choke out and nothing blocking it from closing. At this point it feels like is running rich but the plug looks good and it ran good 2 weeks ago. The next smaller main that I have is a 410 and I tried that a few weeks ago and it fell off on wide open throttle. Maybe the main is to big. I'll have to order a couple smaller ones. But that still leaves me wondering why it ran so good 2 weeks ago.

Bigbill, head bolts are tight

Crash, it would be breaking up and then for a split second it felt like it cleared up and then broke up again.

What will it run like with bad reeds? That's about the only thing I haven't messed with.

Check the reeds anyway to be safe. Them rejet. The weather is warming up.

Thats what I will do.

Did you check the stop switch for a short underneath it?

No, I didn't. I'll check it

Just for haha's I pulled the flywheel to look at the ignition. I've never had a SEM before. The flywheel has 2 magnets around the inside. The inner magnet has a piece of it missing. I'm thinking this is my problem. It seemed odd that the bike ran good a couple weeks ago and now runs bad. That piece of magnet missing must be causing it to run bad. Would anyone have a good flywheel they would sell?

While test riding do you ever have the feeling like your running out of fuel ? Like when you go from half throttle and up .
One other thing to check is make sure the plug wire is not bouncing around and grounding out some where maybe zip tie it to something.

Was the piece of magnet laying in there some where? if not I would'nt think that is it.

On the husky chainsaws with the SEM ignition we epoxy the magnets when they show the separation.

husky saws have SEMs ??

some years of the saws have ignitions made by SEM, yes

Will it run a set of lights as well?