Built 416, 425, 440, 465ex v/s 450r and yfz450

[trxmaster]

Ran across this old thread Have you decked the cylinder (http://www.exriders.com/vbb/showthread.php?threadid=48435&perpage=20&pagenumber=11) and found it very interesting.

Just curious if anyone has anymore info to add to this, and also how these atv's compare to the newer ones out today (yfz, 450r, pred, gas gas etc) as it seemed some of the posters in that thread knew their stuff and were getting some decent power from the xr400 engine used in the 400ex.

Also dont seem to recognize many of the people in that thread and anyone know what happened to them or if they are still working and riding the quads that were discussed etc.

So what ya think?

[trxmaster]

Oh well maybe no one is interested in the internals of their engines anymore :)

[khen]

I just put a 416 11:1 compression Wisco piston in mine this weekend. I asked C&D if they had a gasket that will make it a true 11:1 and they sent me out some Cometic gaskets that they stated would get me there. I did this in conjunction with putting in a Hotcam stg 2 and ported and polished my own head.

I took it to the track today and I was amazed at the power difference! It will pull out of corners a whole lot better. I no longer have to stress out on short run doubles fearing I might not get the speed I need to clear them, there's plenty of power on tap.

I was racing my brother on his piped KFX and a buddy on his pipe YFZ. They all competed really well, if we all got a good start the YFZ would usually get the holeshot, but it is a long way to the first sweeping corner on this track. Once out on the track I could run with the YFZ, it all came down to rider. And this is a fairly fast track we were on.

[torqen2k1]

Originally posted by khen
I just put a 416 11:1 compression Wisco piston in mine this weekend. I asked C&D if they had a gasket that will make it a true 11:1 and they sent me out some Cometic gaskets that they stated would get me there. I did this in conjunction with putting in a Hotcam stg 2 and ported and polished my own head.

I took it to the track today and I was amazed at the power difference! It will pull out of corners a whole lot better. I no longer have to stress out on short run doubles fearing I might not get the speed I need to clear them, there's plenty of power on tap.

I was racing my brother on his piped KFX and a buddy on his pipe YFZ. They all competed really well, if we all got a good start the YFZ would usually get the holeshot, but it is a long way to the first sweeping corner on this track. Once out on the track I could run with the YFZ, it all came down to rider. And this is a fairly fast track we were on.

I did the same as you with the Cosmetic gaskets. Their good becuase their metal so you dont have to worry about blowing the gaskets "nock on wood". Plus 11:1 is not that high of a compression ratio.

[RIDER11X]

I am getting ready to have a 416 kit done on mine, so I am curious as well. Mine stock with pipe and jetting, will run about a quad legnth and a half behind a piped YFZ up to about a hundred yards, then it gets toasted.......But, only 1 out of 4 YFZ's got me in a dead engine start at a local harescramble to the first turn...... I hope a 416 kit will even the odds a bit.;)

[khen]

I think the biggest difference I noticed was that the powerband was a lot larger.. The 416 pulled from the bottom all the way up to where it was bouncing off of the rev limiter(I was running the stock CDI). It makes riding the track sooo much easier when your not always shifting up and down. I was going to put on an aftermarket carb, but now I'm thinking I'll hold off for a bit.


One thing I did notice, with the thinner gaskets the scribes on the cam sprocket were not lined up with the head. They were retarded a slight bit, like the referenced thread indicates. Does anyone have a suggestion for this? I'm debating on either leaving it as is, sloting the cam sprocket bolt holes or buying a sparks advance key.

[cals400ex]

oh yes, it will pull to the stock rev limiter. i have hit the stock rev limiter in 4th gear before when i had my 406. i couldn't get it in 5th though. :D then again, i was running taller gearing so maybe that is why i couldn't get there.:devil: