I'm looking for a 416 kit for my ex. But I would like to stay around or under $250 dollars. I know I can get the kit from Powroll that is a 415 and it's $234. Any more that anyone knows of?

 

You don't need a "kit". All you need is an 87mm piston set (rings and wristpin) and a top end gasket set. Should cost (at most) around $150~175 for all the parts.

 

hey Gabe, What did you give for the XR400 cam? I think my Honda dealer is trying to rip me off...Did it come with all the extra parts and did you use them?

 

If memory serves me correctly the XR cam cost between $110 and $120. It cam as the cam only, with decompression stuff (just like the cam you will remove). Yes, I dropped it in as it came.

 

86atc250R;
With the XR400 cam, is the for horsepower, torque gains or midrange?
Nick

 

Mostly midrange with gains on top as well.

I run the 87mm 10.8:1 JE piston, an XR cam, mildly ported head, XR250 CDI, and stock exhaust.

My throttle response is vastly improved. With a little more bottom end, much more responsive mid and a mildly better top. The engine feels restricted thru the uppermid and top - a pipe would probably correct that.

 

Gabe do use race fuel? What compression can i get to without using race fuel?

 

I run a 50/50 mix of premium and anywhere from 110-114 octane race fuel.

I don't really believe that is necessary - I think 92-94 premium would be fine. I just like the added safety margin - especially when riding in the sand, or racing.

About 11:1 (depending on many other factors) seems to be the limit on pump gas on a typical 400EX.

Some engines like the YZF426 get away with 12.5:1 on premium with their high overlap cams and more precise timing maps (via TPS information). This just goes to show there are many factors that go into it.

The higher your altitude the more likely you will be able to run higher compression without trouble as well.

 

Gabe, just curious but why don't you throw a slip on to improve the air flow (not to mention the savings in weight)?? Or do you just want a 'sleeper'? Also, how difficult is the upgrade/install to a 416?? Drew.

 

The sleeper factor is cool, but I ride in areas where the bike needs to be quiet.

I am planning some mods on the stock silencer soon. I think there is a lot more flow to be had without increasing the noise level significantly. I'll report back my findings when finished.

Yes, the mods I have done are very easy and affordable. The 416 (87mm) piston can be installed by simply having your cylinder bored by a machine shop.