03bansheeLE

I have not used FMF Fattys nor have I used the BB Shearer pipes but I do currently use the SB Shearers and I would not prefer any other pipe. I would personally go with the Shearers over the Fattys hands down seeing as how you said you ride dunes which means you are mostly using the upper portion of your rpm range. If you were riding in tight trails or MX then the Fattys would probably be a better choice but for your style of riding, Shearers all the way. I can't see the BB Shearers on your engine being worse at all in the top end, just the bottom end due to larger diameter pipe and stingers.

The size of the pipe right after the flange that slides onto the jug will determine BB or SB. The SB pipes have a "step down" to a smaller size than the flange while the BB pipes do not. The BB pipes also have a little bend right after the flange and have a smoother radius up into the expansion chamber. I am pretty sure the stinger tubes are larger on the BB pipes aswell. Small Bore Shearers Big Bore Shearers

I have a 4mm Dune ported banshee that I ride on the trails and gravel pits and I love the sound and power of the Shearers. I have heard CPI's make more mid range power but I much prefer the look of the Shearers.

How do you test a CDI box? I've heard from more than one person that you cannot test them. Or do I just have to suppliment a known good one?

Im using the complete 450 front end (a-arms, spindles, calipers, hubs) and I am using ltr450 shocks and they work amazing. Ive got some pretty good air where before I would have bottomed out hard but these shocks soaked it right up. Also, I would like to point out that I have noticed no bump steer at all going quickly down very bumpy rocky trails in 3rd and 4th gear. This would be due to the much more positive caster that the 450 front end gives the banshee also causing the tight steering that some complain about but it helps auto center the steering much better and eliminates bump steer. Also the +2 banshee tie rods work just fine for the 450 a-arm conversion, lots of thread contact in the tie rod.

What kind of octane are you using? Im pretty sure 110 octane is safe for that much compression but if your running pump gas like 94 octane then I think around 155 psi with +4 timing is about the limit. I use 21cc cut domes with my 4 mil for 155 psi.

I just tore them apart today and I cannot see any obvious signs for no fuel being supplied to that cylinder. The main and pilot jets are not blocked and the bike was running quite well, it was a sudden failure. Im going to jet up and mix in more oil, aswell im going to switch the sides the carbs were on and hope for the best.

Im using 94 octane pump gas so ill try 32:1. Have you heard of the cdi screwing up or something with the flywheel triggers causing the timing to advance too much?

If I were to use 32:1 instead of 40:1 I would have to use larger mains right? More oil = less gas per volume of air/fuel mixture that goes into the engine. Therefore it would essentially be running a leaner air/fuel mixture but with more oil. Correct me if Im wrong but I might try this.

Alright it was just a thought, how about leaking exhaust o rings at the jug? Im just getting ready to order pistons and gaskets so Im getting a pingle valve too. I think Im going to get nology coil and wires aswell, they are original so it can't hurt to change them.

Yea I totally thought of that after I tore it apart, it would have definately ruled out a vacuum leak but I will check it when I put it together again. Going to go up a couple sizes on the jets and be real careful this time.

I noticed this morning when I was cleanig the pipes off that there is burnt oil residue that has run down from a weld in the left pipe about half way between the jug flange and the expansion chamber. So there has to be a pinhole in the weld that is leaking exhaust, could this suck in air too? The hole is on the same side that melted the piston, I suppose It could just be a coincedence. One more thing, does anyone know the average running coolant temperature for a build like mine? I have a trail tech vapour mounted and riding through the trails it stayed around 140 - 150 degrees F but when I was riding in the sand pit it got up to about 185 degrees. I usually wait till it is up to 110 - 120 degrees before I even start riding.

Im using a stock fuel valve. I used a chariot cool head for this build and it is brand new, never used. When I disassembled the engine, all the o-rings looked fine and I didn't see any signs of coolant being burnt. The domes were spotless still, and the plugs didnt have any deposits, they were a dark brown colour ever since break in. I didn't check the piston to cylinder clearance because I assume that was done when the cylinder was bored and honed but I realize I should have. I believe the ring end gap was around 0.012" but I could be wrong, I have it written down. I'm at work right now so Ill look when I get home. I still cannot believe this happened, I was so careful and took my time putting the engine together because I have a lot of money into it this time. Both times it melted the right pistons it was pretty well a stock engine and now I have replaced almost everything.

I wipe down the cylinders with the premix oil, aswell as the piston skirt and lots around the rings and ring lands. Also, I put a bunch of drops down into the crank bearing lubrication holes.

Yes I did