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2000ex
08-03-2001, 08:19 AM
I am awaiting my shiny new stock bore JE 10.5:1 piston as well as an XR400 cam. Does anyone run this particular setup?

I was going to go the 416 route, but thought the 16 cc would not make that much difference. (all in the compression ratio). I currently running a White Bros E Series, modded airbox, choke removed and a 165 main. I am having high hopes for some new found HP.

08-03-2001, 09:27 AM
I'm thinking of running the same exact setup so I'd be VERY interested also.....or any imput at all would be great,,,:D

2000ex
08-03-2001, 10:41 AM
Rico,

I asked the guy at JE if there was any choice in comp ratios for the stock bore and he said, no. I really dont think I will be compromising much HP with the 10.5 vs the 10.8, and the motor should run cooler than the 87mm as well.

I was hoping for the 10.8:1 but that was only available for the overbore.

Come on, I am sure there are others here running a high comp stock bore.

400exRacerX
08-03-2001, 10:48 AM
i want to run a high comp stock bore. b/c i dont want to run into all the problems of boring and honing the cylinder and worring about having engine problems with sleeves cracking,seizing bearings etc.... with stock bore high comp you will gain some more heat but not as much as a overbore, the power gains will be nice too with a cam. but the problem is right now i dont have the money for this mod because i just cracked my swingarm 550$ need new a arms, brake lines, and shocks.:grr :mad:

08-03-2001, 12:01 PM
2000ex,

I recently installed a .020 Wiseco 10:1 piston in a friends machine with the stock cam and a White Bros. box. There is definately a noticable difference in power. Before, our quads were always about dead even. Now he consistently beats me. :mad: As well, from a "seat of the pants" feel, you can definately tell a difference.

Given that you're going to 10.5:1 and adding the XR cam, you'll have to notice impressive gains. Please post results when you are done as I've been planning to do a similar mod. I have a friend who has a Superflow dyno on order, and I'm waiting to get a run on it with my current setup as a baseline so I can say for sure what the difference is with the mods.

Did you call JE directly for your piston?

Dana

2000ex
08-03-2001, 12:42 PM
Bumpy,

Thanks for your response. I have been a member of this site and Gabes list since pretty much their inception, but rarely if ever post.

Seeing and reading my fair share of posts, I think this combo should yield great results. I love the reliability of the machine, and really didn't want to tear it down and bore it, etc unless it was necessary.

Yes I called JE directly, they were very friendly and helpful. I cannot wait to have that little shiny new slug at my door.

:D

NVR2L8
08-03-2001, 12:44 PM
2000ex: I used to ride with someone that ran the same set up that you're considering. The stock bore high-compression JE piston and XR400 cam made a significant difference in power--up throughout the rev band. What really woke up his engine after these mods though, was when he added a 39mm FCR carb. After bolting on the carb the engine just seemed quite a bit more powerful everywhere, as well as extremely responsive.

2000ex
08-03-2001, 12:49 PM
I have heard nothing but great things about the FCR. I think I am leaning towards running some triple rate Elka's before I spend more $$ on go fast parts.

Shocks are perhaps the best investment in being able to go fast and pummeling those pesky Raptors through the woods.

:grr

inacoma91
08-03-2001, 01:26 PM
This sounds interesting. I was planning on doing the 416 kit in the future .........but if you get pretty good gains from this then i might consider doing this instead guys!!!!:D So how much is going to cost to get the JE piston and a XR cam??

2000ex
08-03-2001, 02:11 PM
The cam from service Honda was $120, top end gasket kit $26. I believe the piston was $136 plus shipping. Total of $282.

I am hoping for more HP for my dollar than the pipe I am running which was around $220. From what I have read over the past year I doubt I will be disappointed. I will keep you posted on the results once I get her set up and dialed in.

08-03-2001, 02:30 PM
Definitely keep us posted cause I'm bangin my head on the wall tryin to decide on what to do with my motor....I can get it pissed off to the max but I don't wanna risk reliablity,,,,but it sounds like we might be able to do these simple mods and be happy with our decisions,,,plus a carb down the road,,,anxiuos to here what your outcome is....:D

2000ex
08-03-2001, 02:36 PM
I hope to have the parts at my door on Monday at the latest. Hopefully barring any issues at work, I should have everything ready to go by next weekend.

I had been banging my head for a while as well. Basically I said screw it I am just going to order the damn stock bore. As you said, simple and reliable....no need for any shop time, etc. Just pull apart, and put together. Should be a fairly easy and painless process.

I still cannot believe NOBODY here is running this setup with their machine yet :huh

I am sure it will be so close to the 416 that it is not worth all the head banging....

08-03-2001, 02:52 PM
Well the 416 bike that I've rode is a rocket ship but he's also got an electron carb,,had headwork done by TC racing plus every other bell and whistle added to it so I know it won't be that fast but I think she'll have some stump pullin torque,,which is what I want,,,, I guess you'll be the guinea pig for this small process..:D

tinner
08-03-2001, 05:25 PM
Well,I kept my stock bore but my mods are a little different than what you guys are talking about.I have the JE 10.5:1 piston,GT Thunder cam and "race porting",FMF MegaMax & HiFlo pipe,and both K&N &UNI filters.This is really impressive even with the stock bore!Even before the new head pipe it ripped pretty good.It is still plenty torquey too even with the cam I have...sure a little more low end would be nice,but it's real easy too pick the front end up if you're not careful.:D I'm not at all dissapointed that I didn't bore it out.The biggest pain for me was getting it jetted because my motor was demanding more air,I still want to work on that more,but that's after the frame replacement and chassis mods.:D :D Oh yeah....you can still run 93 octane too(if it's good gas).You won't be disappointed!!Jim

quadfamily
08-03-2001, 09:11 PM
OK, so who can post the phone number for JE? I want to see if they have a piston like that for my 300EX. Thanks!

08-04-2001, 07:22 AM
I`m waiting for a dyno sheet on a 11:1 Wiseco drop in,479 grind Web Cam,my head work,stock carb,W/B E-Series pipe.The dude told me it made 36.5 HP,38.5 with FCR carb.I what to see the sheet!!!:rolleyes:

2000ex
08-04-2001, 07:58 AM
JE can be contacted directly at (714)898-9763.

Check out their site at http://www.jepistons.com

2000ex
08-07-2001, 03:07 PM
Well, since the parts have yet to arrive at my house as of yesterday I figured I would start the teardown process.

Very simple and straightforward, I have tore down my fair share of 2 strokes but never a 4 besides a car or truck motor. It was a breeze and everything looks to be still in great shape.

I just got off the phone with Walter at JE and he said the piston was shipped on 7/31 so I am keeping my fingers crossed that it is at my door when I get home. I may have some results for all interested earlier then the weekend!

Wheelie
08-07-2001, 11:29 PM
Are you doing any porting etc......? I have been thinking about that exact setup, 10.5 JE Piston with an xr400 cam. Are there any valve spring mods or head work required to make the xr400 cam work, or is it all just a "bolt in" mod? I want to know how it works out for you..
Later

2000ex
08-08-2001, 06:36 AM
No work necessary such as valve spring mods or hardfacing the rockers. The xr400 is a factory Honda part and drops right in.

I am doing some minor port work such as port matching the exhaust ports and polishing them. Very minor intake work, mainly scuffing the ports for better fuel atomization. I started this work list night and should be finishing the porting and reassembling the head tonight.

86atc250r
08-08-2001, 09:23 AM
I think you'll be happy with the stock bore setup...

Keep in mind that the JE piston compression ratios are quoted for the XR - so that means take .2 off what they show, for use in the 400EX unless you use the XR top end gasket set.

A stock bore JE then becomes a 10.3:1 and the 87mm becomes a 10.6:1.

The XR cam provides excellent throttle response, good bottom thru top and a very smooth, usuable powerband. The GT Thunder cam (and other performance cams) have a hit in the mid, but not nearly the bottom or throttle response of the XR cam. Depends on what you're doing, which one is right for you.
I'd love to have a dyno compaison of the two engines we've built using each cam.

Unless your cam chain is really worn out (like mine was), get the XR gasket set for increased compression with your stock bore piston.

Keep us (here and on the list) informed on your results....

08-08-2001, 09:32 AM
I've heard that there are 3 head gaskets for the 400ex and that to get more compression to only use 1,,I don't know never taken the head off of one...So Gabe do you suggest using the XR gasket instead of the other with this stock bore and xr cam setup...I'm going to be doing the same exact thing so your imput would be greatly appreciated..??:D

2000ex
08-08-2001, 09:46 AM
Thanks Gabe for the reply, I never thought about the difference in quoted compressions between the XR and the EX due to the thinner gasket. Well, I already have the cam and gasket kit from Service Honda and the gasket kit is for the EX. I am really not going to lose sleep over the .2 difference in compression.

Any updates on those Elka's? I am looking at getting a front pair, but may wait until they get their valving dialed in. I have heard nothing but great things about them with the exception of their initial tuning from the factory.

86atc250r
08-08-2001, 10:34 AM
You've got it - The hardware's great, the tuning's marginal.

I'm thinking about sending mine off to GT Thunder, PEP, or some other suspension tuner to get it right.

Although - I hear their tuning is getting better by the day.

Also, the newer shocks have a new shock head that allows for more travel, there is also now the availability to have high and low speed compression adjustments.

I'm halfway considering selling my set and getting a newer set.

Rico - Yes, the 400EX's head gasket is made of 3 metal plates. The XR is made up of 2. I can't remember the exact construction to be able to tell you if you could simply remove plates for increased compression.

The thing to keep in mine is that if your cam chain is worn, a thinner head gasket will somewhat worsen the problem by a small amount. I've already been thru 1 cam chain on my 2000 model - they seem weak. I replaced it with a Sparks HD chain - seemed to be the same manufacturer, just thicker link plates.

400exRacerX
08-08-2001, 11:17 AM
is this a commen thing on a 400ex to be snapping cam chains??

86atc250r
08-08-2001, 11:26 AM
Not snapping them, wearing them out (stretching). If you let it go to the point of breaking, you'll spend a whole lot more money.

When the chain stretches it retards the cam timing, which shifts power into the upper RPMs and adds slop to the system. My eventually stretched to the point where it was making noises. Ran great though.

When I put the new chain in, it was so much of a difference that I had to step down a few jet sizes.

400exRacerX
08-08-2001, 11:34 AM
what is it like a slapping sound?

86atc250r
08-08-2001, 11:38 AM
More of a light, random "clanking" at constant RPMs. It will be coming from the right hand side of the engine. Usually heard just above idle or in the mid at light cruise.

quadfamily
08-08-2001, 09:04 PM
In case anybody want's to know, I called JE and they don't make any pistons for a 300EX at all.

Leo
08-09-2001, 05:41 AM
I've had this stock bore JE piston sitting here on my desk for MONTHS...

I really should get going and put it in ;)

Leo

2000ex
08-09-2001, 06:55 AM
Leo,

MONTHS!!! How can you resist? Well actually it is quite a beautiful piece I bet it makes a great decoration :p . But I bet it would make your 400 happier then sitting on your desk as a decoration.

08-09-2001, 07:11 AM
Quadfamily,I know we are taking JE but Wiseco makes 11:1 for a 300ex,std to 80 over.

08-09-2001, 07:56 PM
Leo,

I've got some free time coming up this week... since you're in no hurry to try out that JE, send it on over to me, and I'll give you a full report with pics for the site... Tear down, installation, and seat of the pants feel!!!! :D :D :D :)

2000ex
08-10-2001, 09:54 AM
Gabe, Rico, et al.

Just wanted to let you know that you can definitely spilt the gasket into 2 layers just as the XR gasket. It did take a bit of careful pulling, but I did it. Now I can realize that extra .2 compression, YAY. No, all kidding aside I should have everything buttoned up tonight and start the break in process. I will have a full report once I get everything dialed in.

08-10-2001, 10:00 AM
Well I"m eagerly awaiting your report,,,just remember to get the work done before the beer drinking takes place...:D

400exRacerX
08-10-2001, 11:09 AM
whats the compression on that piston leo?

2000ex
08-11-2001, 11:05 AM
UPDATE:

I have everything back together and am going out now for a break in ride. From the sounds of things it does have a noticeable deeper thump than the stock machine. I will post an update later this afternoon after I get back.

It is going to be difficult not to really hammer on it, but I am sure I can give a pretty idea as to the increase in HP across the powerband.

08-15-2001, 05:22 PM
Hey 2000ex,

What happened on the ride? You seem too have dissappeared for the last couple days since you said you were going riding.
I have been real interested to find out how everything worked.
Hope nothing bad happened. Let us know whats up.

thanks.

Craig

2000ex
08-15-2001, 07:18 PM
Sorry for my lousy followup

Yeah, all is well with the new setup. I took it for 2 break in runs on Saturday and rode her all night for 3-4 hours. I really tried to ensure that I varied the revs and really only hammered on it briefly. I think I will need to make some jetting adjustments, but I am pleased thus far.

There is really no change in the bottom (good thing) as it still can pull wheelies from a virtual stop with no clutch. The real improvements are definitely in the midrange, and hopefully in the top end. From what I can tell, it pulls much harder in the midrange, but more seat time is needed for me to really give a good read on it. Definitely worth the $280 for everything. More bang for the buck than the White Bros pipe I am currently running.

Leo
08-15-2001, 07:43 PM
Originally posted by 400exRacerX
whats the compression on that piston leo?

The stock bores JE I have is 10.5 to 1, but thats in an XR400..

I think in an EX it works out to about 10.3 to 1..

Leo

MARCUMS ATV
08-16-2001, 08:00 PM
Guys I dont want to get too much free advertising here and I will be sponsoring a link very shortly but check out my site. I guarantee the lowest prices and have cams and pistons in stock.

Thanks
Terry

08-17-2001, 08:26 AM
Terry,Thats a little high for a valve job,that includes new valves right?It would for fine for a 5 angle,5 valves.I charge per valve not per cyl. A lot of differince between a 2 valve Warrior & a 5 valve Raptor!!! You should go back and ck your prices on the site,they don`t all seem right,misprints.Just my 5 cents,inflation LOL

08-20-2001, 11:13 PM
I see that Weisco makes an 11 to 1 stock bore piston for the 400ex. Any thoughts on how this might compare to the JE 10.5 to 1? Would I be able to run pump gas at 11 to 1? Thanks for your input.

skemp
08-21-2001, 12:12 AM
You should be able to squeek by on really good 93 octane Premium, but there might be some problems with pinging/detonation, and you don't want that. Talk to some people that have 11:1 and run or have tried running pump gas. You never know I guess. I think 11:1 is the max comp. for pump though.

08-21-2001, 06:52 AM
The JE piston is lighter than a wiseco that's the main reason I think most people including myself use and buy the JE. And I'll be going with the 10:8.1 piston in mine and with the XR gaskit,,and probably be OK with pump gas,,,I've just read to many times that the 11.1 piston pings on 93 octane gas.

tinner
08-21-2001, 03:32 PM
I have the JE 10.5:1 and the only problems I've had was the quality of premium fuels.When I first put it back together it pre-detonated...but the gas was kind of old.Then I used the same gas (newer) and it was pinging a little.After this I use only Amoco and I havent had any problems since...just a bad gas station nearby.In the GT Thunder website they say you're safe until going higher than 11.0:1 compression.I was leary and went with the lesser compression to be safe.Man...what a massive difference in power!:D :D Jim

08-21-2001, 03:42 PM
how much power differance would there be with a 10.5:1 on pump gas compared to a 11:1 running race gas?