Piston and Mod questions

[alnessp]

I am getting ready to start building a 426 and I have a couple questions. #1 what is the better piston JE or the Wesico pro lite? I am planning on using either a JE 10.8:1 or Wesico 11:1 with the XR base gasket. #2 is there a signifigant difference in output between lapping the valves or having a 3 angle job done? #3 is a port & polish going to be worth the $175? I have enjoyed reading the forums and I know you guys will be able to give me the advice needed to make a killer 426ex. By the way here is what I have written in stone so far.

Punch cylinder out 3mm (of course its gonna be a 426!)
W/B stage 2 cam (is this just a rebadged hotcam?)
Heavy duty clutch springs
450r carb
any other suggestions would be greatly appreciated

Paul

go with the wiseco

[BSTURDIVANT]

JE piston at 13 to 1, stage 1 hotcam, 450 carb,port and yes definately a good valve job to open the seats for max flow, Go with 1mm larger intakes while your in there! Max Hp for the money! Hotcam doesn't require heavy springs which rob some of the gained HP, and also doesn't require hardened rockers. Save your money on clutch springs- stock springs will handle 50HP and the clutch pull is much easier!
JE pistons are right on on compression ratio where Wiseco is 1 point lower than actual measured compression.

[enduro400rider]

go with wiseco and XR gaskets. some other things you might want to do are the CRF cam chain, and HD head studs for extra insurance. porting and polish is definatly worth it if your going to build a strong motor. what kind of pipe and filter are you running? if your running stock definatly get a pipe and an UNI

[alnessp]

Thanks to all for the great advice, Just 5 mins ago I popped off the head and found that I have one exhaust valve in pretty bad shape. The piston is good and clean so I assume the damage happend awhile ago. I like the 13:1 idea will the stock rod handle it? are there valve interferance issues at that compression? By the way I have an HMF sport series slip-on with the "ridge taken out of the head pipe. I also run a K&N and outerwears BUT I noticed some dust in the intake so I must need to use more grease for the seal or get the adapter. (not trying to set off a filter debate just telling ya what I saw tonight)

[TC426EX]

If you are gonna go any higher than 11:1 dont even THINK of using the stock rod. I just spent over a grand to completely rebuild my TC engine after being stupid and running 12:1` compression on a stock rod. If you need proof, just do a search on thrown rod* and see the pictures of the carnage. If you are a rec rider and dont race seriously then dont do the 13:1, stick around 11:1. If you go 13 youll have to use straight race gas, and you will not be able to really reliably ride your bike all day hard without taking breaks to let it rest (it generates more heat). In any event, I would do the JE piston, and add HD head studs from GT Thunder + a CRF cam chain from service honda. both are cheap mods but pay big dividends in the reliability department. If you do decide to go high compression, then go with a Carrillo rod as well, which of course you will have to have professionally installed in your stock crank. Basically as has been said many times in threads like these, it all comes down to your budget. The 400ex engine is one of the most mod-friendly engines out there, but it starts to add up fast...

[enduro400rider]

if your goin to be doing this build up and you want to get the most out of it you definatly need to loose that slip on and put a good full pipe on it

[QuadJunkies]

Originally posted by enduro400rider
if your goin to be doing this build up and you want to get the most out of it you definatly need to loose that slip on and put a good full pipe on it I agree.