So now we get to the bad news. Just before I left on the trip I noticed a sound coming from the top end. It was a ticking noise that had a ring to it, almost like a rattle. It sounded like it was coming form the valve cover and only on the right side. I checked all the valve clearances, and and checked the cam journals with plastiguage and everything seemed to be fine, cam chain looked ok. I thought it might be the cam sprockets making extra noise since i removed the rubber dampers from them in order to slot the sprockets to time the cams. The sound got worse over the course of the trip and I noticed the oil level was low, and dark. Indicating some blow by. Compression was still good though - 220 psi on both cylinders. Blow by got so bad that riding around in LA after the trip I burned through 1.5L in about 50 miles, which ended up running low on oil without realizing it. :
I tore the top end off to find the wrist pins galling and nearly seized in the pistons again this may have been from the low oil levels, but I cannot be sure. Also an incredible amount of carbon on the piston domes and in the chambers. I guess the cheap piston rings weren't a good bet. either that or the 1 piece oil ring was doomed from the start. The wrist pin bore on the pistons are trashed so I have been exploring other piston options. I dunno if it was my poor assembly, the one accidental 11k over rev I had on the fresh build or something else that caused the problem but either way it will not be a cheap mistake to remedy.
I have been doing a bunch of research on piston options to move forward with. As far as I can tell there are 4 choices to move forward.
1) find some OEM overbore pistons - about $350-400 with rings and wrist pins depending on what deals I can find. I'm not really considering this because I want MORE POWER!!
2) Custom JE pistons at 80mm bore - 783cc . custom pistons w/ pins and rings - $400 for two - min order of 4 pistons, I could probably sell the other set. This allows me to use the stock sleeves and stock head gasket.
Anything bigger than 80mm bore will require new sleeves. the cost of new sleeves is 65-150 each depending on what needs to be done, plus an additional $65 to bore the cylinder for new sleeves. It will also require the cases bored for the bigger sleeves - Something I can safely do myself either on a friends mill or with a die grinder. Cometic already has a 85mm gasket for this bike for $55 each. That is about what I was paying for the OEM green gaskets.
3) Other platform piston -ie. Raptor 350 84mm piston - 864cc $260 for two. May or may not work with what i have, probably less than ideal for the combustion chamber design I have.
4) Custom JE piston at 85cc - 884cc again I end up with a second set
The total price breakdown with boring and a gasket will be
1)OEM $570-620
2)custom 80mm $620 + $400 in pistons that i may or may not be able to sell
3)Raptor 84mm $735-915
4)Custom 85mm $855-1055 + $400 in pistons that i may or may not be able to sell
The benefits of getting custom pistons are they will be optimized for the combustion chamber design, and I can have custom features included to help with wrist pin galling, as this is the second time its happend on this bike. for example - forced pin oiling - where a hole is machined from the oil ring to the wrist pin so as the piston drops in the cylinder it forces oil directly to the wrist pin bore.
I'm going to drop my cylinders off at LA Sleeve which is like 1/4 mile from my work. When I get a hard number on the cost of the sleeves, this will give me a concrete budget to look at.
Any thoughts or suggestions?