Have you Decked the cylinder

[Leo]

Good thread..!

I was just going to slap my piston in and call it good enough.. but now...



Leo

[86atc250r]

Yes, the JE "10.8:1" 87mm piston has a dome - I believe I have the specs at home if anyone is interested.

I assume that the 89mm JE is also domed, as the catalog I have shows it to be. I believe they use practically the same dome on all their "off the shelf" pistons, which also reflects in the compression rising as you go up in bore size with JE off the shelf pistons.

Great news on the Ross pistons Matt.... Have you weighed the assembly yet?

[86atc250r]

First they claim to only manufacturer pistons for the EX400 (89mm 440) up to 10:1 under the J&E name.

That's odd, the JE catalog I have states otherwise....

Well, maybe he's technically right - my catalog only lists pistons for the XR400...

[86atc250r]

Matt, the flange is splined & got one wide one so it can't be oriented incorrectly...

I'd also be interested to hear why the decompressor can't be used.

[86atc250r]

Looks like you beat me to it Mike.

Here's a question on the hardweld rocker topic...

If you get your rockers hardwelded unnecessarily - and the cam is not, does the cam then become the wear item?

[86atc250r]

The FCR carb, Hetricks pipe, and port work will all work best in the upper rpm ranges anyway.

Actually, Matt, I noticed more bottom end gain with the FCR than I ever expected (actually I was expecting to lose a little bottom)... That's going by the seat of the pants dyno.

Must have something to do with less disruptions in the air path than the stock carb (Really, it has none, the stock carb has two)... But there was a large difference in the low end & mid with the FCR. I didn't notice much on top, but my limiting factor I'm sure is the cam I run. I'm sure there would be a huge diff in top end with a more aggressive cam - we've got one engine like mine with the GTT cam, but never ran it on the stock carb - mine's been run on both.

[86atc250r]

Hey Matt.. Just for the record, my "off the shelf" JE 87mm piston is domed - VERY similarly to the Ross we got....

It's advertised as the 10.8:1 piston.

[86atc250r]

Personally, mine starts easier with the FCR, even though it does not have a choke.

Sometimes when it's really cold, sub 20 deg, it will lean out pretty badly until you get a little heat built up, but if that's the case, you really shouldn't be putting the engine under load until it warms up anyhow.

That would also probably be easy to correct with cold weather jetting, but I don't really ride when it's that cold anyhow, so I don't generally bother.

As Mike said, the throttle response with the FCR is unreal - I've actually geared my quad up to tone down the response for cross country racing since it was causing steering problems coming out of corners & if you accidentially bump the throttle a little when going thru a rough section, you get a serious unexpected surge of power...

Expect some tuning time, but once you get it dialed in, it's a great carb.

[86atc250r]

Yep, I've still got some fine tuning to do on mine as well... But it runs well enough that it's not really a priority at this time. Just a couple little weird areas that could use a little time spent on them.

[86atc250r]

Still waiting on my PEP shocks.... I've got the dual row carrier info written down, I'll try to find it tonight, hope I haven't lost it.