what to do to my motor? got 1500 to spend

[kodie]

I'm getting ready to get a killer deal on a 450r that needs a new top end. So I'm going to go threw the whole motor to make sure nothin is wrong with the crank or shift drum or anything like that. I'm wanting to put a high compression piston in it but I wanna stay on 94 pump gas. What piston should I get?

I will also be getting a port job on it as well and put in a cam. Is there anything else I should do to the motor while its out? I'm going to have about 1500 bucks to throw into this thing after I buy it.

[250x_kyle]

cam 300
port job 500
piston 200
crank 300
gaskets 150

I beleive 11:1 the highes compression you should run on pump. your probably going to need to replace valves and spings and need a shim kit wich is another big chunk of mulah.

Originally posted by 250x_kyle
I beleive 11:1 the highes compression you should run on pump. your probably going to need to replace valves and spings and need a shim kit wich is another big chunk of mulah.

you have got to be a 400ex guy lol. Every motors tolerances for a certain compression ratio and octane are different. 11:1 is limit on pump gas for a 400ex but for a 450r stock they are over that. Heres what I would do. If it didnt have suspension done to it yet then thats what i would do and I would only fix what was needed on the motor. Unless all you are is a drag racer then put all of it ino the motor.

[Butter]

Originally posted by FlewByU352
you have got to be a 400ex guy lol. Every motors tolerances for a certain compression ratio and octane are different. 11:1 is limit on pump gas for a 400ex but for a 450r stock they are over that. Heres what I would do. If it didnt have suspension done to it yet then thats what i would do and I would only fix what was needed on the motor. Unless all you are is a drag racer then put all of it ino the motor.

Well said. Suspension is everything. Get that done first. If its already done. price out what it needs first, then look around for port and polish. You can run 13.5:1 and run pump gas with no problems. My bro has done it for 3 years with his MX race bike, and he only puts a new piston in over the winter to freshen it up.

[kodie]

Ya Ill find out whats done to it first. But figured since I was in there might as well take care of some stuff.

and are you sure about the 13 5:1? I was told 12 5:1 is cut off.

[Butter]

Like I said my bro has been running that comp. piston for 3 years in his MX race bike. He's been racing since he was 16 (33 now) and is not the easiest on the bike as he rides (A-class Pro-Am) and he has had no problems what so ever. No pinging, no damage to the cylinder, nothing. Changes the oil every 2nd ride, and continues on. He also runs a Hot Rods crank and rod, a Hot Cam Stage II, Kibblewhite oversized vavles, and a port and polish, all on 93 octane pump gas.

People will go against what I said, and I expect that. Each person has their own experiences with their vehicles. Just sharing what he's experienced and had, so you can hopefully gain something from it. Good luck with whatever you get done.

[trxzeth]

u can probably get buy runnin pump gas wit the 13.1 alot people do and its jus if u can get it tuned in right im runnin the +3mm hot rod stroker with my 13.1. all u can do is try if u cant get it to work go to the lower compression

[Tommy Warren]

Originally posted by FlewByU352
you have got to be a 400ex guy lol. Every motors tolerances for a certain compression ratio and octane are different. 11:1 is limit on pump gas for a 400ex but for a 450r stock they are over that. Heres what I would do. If it didnt have suspension done to it yet then thats what i would do and I would only fix what was needed on the motor. Unless all you are is a drag racer then put all of it ino the motor.

just put a turbo on it I know someone who can do it......^^^

[k265r]

depends on the year for compression

[duneboy64]

still run 11:1 compression piston but make it a high compression stock size one, make sense? its smaller and pumps faster, i would also get kibble white valves and better springs so you can put a cam in and the springs can hold all of the power given off of the cam make sense? depending on detonation, you can still run 91-94 octane fuel

[RobRacing]

I would consider a 3 angle valve job as well. You should look into supsension I am pretty sure you could get your stock shocks re-valved for under $600 and it would make a huge difference.

[RideRaceLive93]

dont go with kw valves ill never ever ever runt hem in my engine

[pro-rider46]

Originally posted by RideRaceLive93
dont go with kw valves ill never ever ever runt hem in my engine

if you dont run them, then how do you know they will hold up. ive been running without any problems for a year plus

[Ruf Racing]

Originally posted by RideRaceLive93
dont go with kw valves ill never ever ever runt hem in my engine

No personal expericence with KW, but lately I have been hearing
horror stories about breakage with these valves. Talk to Chad at
DRG.