sleeper06

I've shattered every clutch plate known to man. I also play with the clutch a lot . How much weight is on your lockout and which lockout do you have, time release or regular

I've shattered every clutch plate known to man. I also play with the clutch a lot . How much weight is on your lockout and which lockout do you have, time release or regular . Excessive heat can do crazy things

Can you post pics of harness problem. The electronics are pretty resilient on these bikes, might wanna try oem shit loosely before using the after market

O rings do break down over time. Fuels/temp/coolant used all plays into it

I wouldn't sand the fire rings but definitely check them. Occasionally I will see electrolysis

What programmer? Check static compression

Don't hurt your self by pressure testing the motor to rule out your problems. It would tell you everything you need to know

Leave it closed . Just send it.

Noss machine style, fast racing sells them. The best imo

Where are you from?

68 mm wsm pistons have a banshee crown. I have some measurements written down at home I'll check it out later

I will tell you it's not gonna fix itself

It's your money invested, if you wanna roll the dice go ahead. I'll bet you whatever you want there its got some form of an air leak.ive also had reeds cause a backfire. If it was a reed it would look like the motor tried to eat it

As stated above. Leakdown test compression test post pic of the carb areas so we can make sure everything is in place. With separate k/n filters in the winter you should be like 300 main 27.5 pilot , 1/2 to 1 turn out on air screws. If you don't have toomey needle in there already I would get some. Stock needle won't give as much fine tuning capabilities with the bigger main jets in there. Most importantly stop running it before you grenade a brand new set up.

Having one idle screw could be an issue

Look through the spark plugs holes with a good light n tell me the numbers on them, I've had a rash of people lately with wrong pistons in there causing same condition your explaining

What numbers do the pistons say on top of them? Have you pressure tested this motor yet.

Follow it down behind radiator and unplug it, remove parking brake cable, install a block off on caliper. You could just unplug it but what the hell

380s are def not uncommon in a ported engine . For some reason fmf takes hella fuel to be happy compared to other pipes ,t5 are not far off. Since it's been milled he should def do a compression test n a squish test . I couldn't make out if he has a stock head modified for domes or just a milled head .

What needle do you have, toomey pipes work best with toomey needle. You could have some oddball needle ,off idle usually is a taper issue once you start using bigger jets. Use the smallest pilot you can without a hanging idle , change the needle, leave the 300 main for now . Also make sure your cable retainers on the top of slide are in correctly with vent hole visible

If the float is off or getting stuck on that side , you could be sucking it dry and it's not rebounding quickly enough. Since its only one side I would definitely do your basic testing, compare compression, pressure test crankcase, check for burnback on plug wires and ohm coil

After the preparation suggestions above I usually take a porting tool and wedge the groove. For some reason every time I weld these shit cases, it works best with the tungsten almost even with the cup . Once you start to get new material in there your contamination should rise to the top and then you can make it pretty. Pre heating helps. I'm not a pro welder by any means but I've repaired quite a few of these with no problem. Your welder also might act differently . Do you have a cooler on your tig?

Not many people have the rite jig to do the center section. Welding has nothing to do with it, I crack open welded cranks all the time. IMO it should be looked at by someone with the rite tools. Since you blew a piston there was most likely excessive heat n strain put on the big end rod bearings n centers.

IMO the crank should at least be broken down and gone through, nothing hurts more than erasing everything you did with a bad crank component. Then get a cheap set of stockers for$150 and put some pistons in. Then you have a solid piece.

If you're plugs are black with those jets you're not burning fuel correctly. Ohm out all your electronics . I would start with a 350 main or 360 to be safe. Depending on the porting/pipe combo and how efficient it is you might need to run more than most . Start big n work down . The plugs could clean up once you give it some fuel.