high compresion piston?

[trx400EXtreme]

is it ok to have one in a stock motor with jets and a s/o? worth it? thanx.

[zrpilot]

Compression is a nice upgrade, but if your going to buy a new piston, why not bore it for $60-$75 more and have a fresh top end?

[trx400EXtreme]

if i did i wouldnt wanna go any bigger than a 416 cuz i dont wanna have to rebuild it every year. would i lose any bottem end?

[zrpilot]

A rebuild, done right should be very reliable. If you simply put a 10.8:1 or 11:1 416 piston in it, everything else equal, you will not lose any bottom end, maybe gain some. Also higher compression makes a bigger cam a nice upgrade..

[trx400EXtreme]

srry to keep dragin on but... if i were to get a 416, wuts the average cost on that kind of stuff?

[NacsMXer]

Typical high comp piston kits are around the $100 dollar range. Then there's the costs of boring/honing, gaskets,etc. If you want to reap the benefits of a high comp piston a cam is a good choice like said above. Check with C&D racing the site sponsor, they can hook you up with what you need.

FYI, on the piston: 11:1 compression is the highest you want to go with the stock connecting rod. Any higher and you risk breaking it/shredding your motor. It is also the highest compression you can run on premium 93 without being dependent on high octane race fuel. Just things to keep in mind...

[trx400EXtreme]

thanks guys.

[tgreenz400]

you should get it:D

[CT400exRIDER]

im in the same position...wanting to bore out my quad but dont know what to get........how powerful are the 416's? if i had full exaust 11:1 k&n could i beat a stock 660? because thats what im looking for out of my 400

[eliasxr400]

I just installed a std. bore 11.1 wiseco and stage 1 hotcam yesterday.
This really woke the bike up! I still need to break it in but couldnt help getting into the throttle. I gave me enough low end improvement that I think I will go up 1 tooth in the front.(I'm down to a 13th so I will put stock 14th back on).
I had the cam and the piston cost $100 and the cometic gaskets cost $30.
It was about 3hrs of work. I really took the time to clean everything, hone the cylinder, and then torq everything to specs. This was well worth the $130. The cam cost $110, but I took that out of my bike to put into the EX. I did not want to bore yet because the bike is not very old, I bought it in late 2006. My other mods are in my sig. I aslo run straight 100LL AV gas.

IMO this mod is well worth the time and money!

If you do it make sure you clean off all the old gaskets and deglaze the cylinder. Get a good top end gasket set and torq everything to specs. I reused the valve cover gasket and put some ThreeBond liquid gasket on it because I have had them leak on 400s before.

[DOHC]

Originally posted by trx400EXtreme
if i did i wouldnt wanna go any bigger than a 416 cuz i dont wanna have to rebuild it every year. would i lose any bottem end?
My 440 is 2 years old and its still fine. Where did u get the idea that u have to rebuild every year?

[Def-e-nition]

excessive wear and tear perhaps ? from a modded engine , the old stigma of once something has been modded it gives trouble ??

[Varmit57]

If you got very big on the compresstion you may want to beef up the front head bolt. They tend to stretch and blow gaskets. Its very easy and cheap fix.

[trx400EXtreme]

Originally posted by DOHC
My 440 is 2 years old and its still fine. Where did u get the idea that u have to rebuild every year?

the reason i say that is because i always hear peolple talking about staying away from 440's b/c thay dont hold together. im sure u probably know wut ur doing when it comes to rebuilding motors. ive never done it before. i wasn't saying that if u have a 440 that u will have to rebuild it alot, but if i built it by myself, i might have to just b/c ive neer done it before.

[XtremelyCrazy]

Originally posted by trx400EXtreme
if i did i wouldnt wanna go any bigger than a 416 cuz i dont wanna have to rebuild it every year. would i lose any bottem end?

I got the 416 10.8:1 piston with a Hotcam 172 / 42 jets and a Powercore4 s/o and I think it runs stronger everywhere.

I only got about 10 hours on it, so I can't speak from personal experience as to reliability yet. But I've heard lots of good stuff....

[trx400EXtreme]

Originally posted by XtremelyCrazy
I got the 416 10.8:1 piston with a Hotcam 172 / 42 jets and a Powercore4 s/o and I think it runs stronger everywhere.

I only got about 10 hours on it, so I can't speak from personal experience as to reliability yet. But I've heard lots of good stuff....

ur quad sounds sweet. if u dont mind me asking, how much did it cost for every thing not including the jets?

[XtremelyCrazy]

Originally posted by trx400EXtreme
ur quad sounds sweet. if u dont mind me asking, how much did it cost for every thing not including the jets?

$135 for the hotcam, $135 for the JE piston, $200 labor to install.

Gaskets were $35 and the jets were like $20.

Check with C&D Performance. They are awesome.



The FMF pipe was on the bike when I got it, but they run like $200.

I also put a UM airbox on it for $185.

The Twin Air filter was already on the bike.

[trx400EXtreme]

thank u.

[weekendracer91]

go with the 440kit you will not regret it, you will have to put in a cam though! it depends if you want to go cheap or do it right!

i have an 03 motor in my 99 ex, it has a 440 kit, hot cams stage2, titanium valves, 12.5:1 compression piston and a full LRD system it has over 20 race hours and hasnt let me down yet!