View Full Version : Je Piston Install?
Waynes400ex
10-12-2003, 01:50 PM
I just recenlty have done a 440 kit in my ex. I was wondering which way to put the piston facing? It does not have any marks on it that I know of!
L.Vegas400
10-12-2003, 02:26 PM
there should be an arrow on the top of the piston, it faces the front of the engine(exhaust side). if there is the letters IN it faces the intake or rear of the engine. if there are no markings i would guess it is made to go either way, but dont quote me on that.
Glamis400ex
10-12-2003, 06:17 PM
if it doesn't have any markings, I would place the larger cut outs on the top of the piston, to the exhaut side.
Glamis
L.Vegas400
10-12-2003, 07:24 PM
Originally posted by Glamis400ex
if it doesn't have any markings, I would place the larger cut outs on the top of the piston, to the exhaut side.
Glamis
exactly i forgot about that. the exhaust valves are larger hince needing the larger indention.
Interesting..... I didn't know that the exhaust valves were bigger than the intake. Anyone know why? When I was messing around with car motors years ago the intake were larger.
Just curious, Joe
Waynes400ex
10-12-2003, 09:51 PM
Not to be a jerk but the intake are bigger. I was thinking the same also the piston should be placed with the bigger cutout lined up with the intake valves!
Colby@C&DRacing
10-12-2003, 11:22 PM
The JE pistons have no markings on them line the larger cutouts up with the larger valves. For some reason Ross puts arrows on their pistons but JE doesn't:rolleyes:
Originally posted by Colby@C&DRacing
The JE pistons have no markings on them line the larger cutouts up with the larger valves. For some reason Ross puts arrows on their pistons but JE doesn't:rolleyes:
Just to clear things up...
Which are bigger, intake or exhaust?
Joe
Waynes400ex
10-13-2003, 01:09 AM
I'm in the process of putting mine back together the intake are bigger valves
Glamis400ex
10-13-2003, 05:58 AM
Wayne400ex,
my apologies...the intake are larger...not the exhaust. Long day yesterday. sorry:huh
Glamis
Waynes400ex
10-13-2003, 09:22 AM
No Problem!!
L.Vegas400
10-13-2003, 01:03 PM
that makes two with bad info, the intake are bigger, BUT if you have a manual take a peak at page 100 figure 90. in the pic you can see the larger indention is on the exhaust side of the piston. if you have your old piston around or a new one you havent installed yet take a look at them.
Waynes400ex
10-13-2003, 01:24 PM
So the manual is wrong?
Waynes400ex
10-13-2003, 01:27 PM
So which way do i install the piston?
Originally posted by L.Vegas400
that makes two with bad info, the intake are bigger, BUT if you have a manual take a peak at page 100 figure 90. in the pic you can see the larger indention is on the exhaust side of the piston. if you have your old piston around or a new one you havent installed yet take a look at them.
Interesting..... Could it be because of valve lift, duration or timing? Meaning the exahust valves are open later during the exhaust stroke.
The intake valves are closed for the most part during the compression stroke, right? So intake valve/piston clearence shouldn't be an issue.
Am I anywhere near correct or am I talking a bunch of chit?:p
Joe
L.Vegas400
10-13-2003, 04:47 PM
Originally posted by Waynes400ex
So the manual is wrong?
no, its a photograph of the piston installed. look at the picture or an uninstalled piston. i went out in the garage and looked at my piston and the larger indention go toward the exhaust valves. i went through this same thing when i put mine in, except i quit goat thinkin and put the arrow,(pointing toward the larger indentions) facing the intake and had to turn it around.
Originally posted by JOEX
Interesting..... Could it be because of valve lift, duration or timing? Meaning the exahust valves are open later during the exhaust stroke.
Joe
i am thinking this exact thing, i just couldnt put it into words in my last post.
the larger dents are for the exhaust valves and face the front of the engine.
Waynes400ex
10-13-2003, 05:11 PM
Ok so the larger marks on the piston go lined up with the intake our exhuast ?
adeptex
10-13-2003, 09:32 PM
The larger diameter cuts in the piston are for the intake. JE does mark the piston with an arrow but it is laser engraved and is not very deep. It most likely will not be seen if the piston is not new.
i was about to say...i had an arrow on my JE piston lol :eek2: :huh
Glamis400ex
10-13-2003, 10:02 PM
this is not a good thread at all. too many folks saying to many different things, I spoke before I actually went out and looked since mine is apart at the monent. On my head, the intake valves are larger, and my piston doesn't bang on them
Glamis
Waynes400ex
10-14-2003, 01:01 AM
My JE is brand new and has no arrow!
L.Vegas400
10-14-2003, 01:27 AM
if you have it apart, look at the indentations in the piston it's self. even on the STOCK piston, the exhaust valve indentations are larger. i still have my stock piston, i just checked it for the 3rd time, the exhaust valves side have a bigger spot on the piston.
will someone with a new piston(c&d racing for sure) take a look at a piston with an identifing mark(arrow or something), and see that the exhaust has a bigger indentation.
those in doubt take a look at page 100 figure 90 of thier manual it is clear that the exhaust has a bigger one.
Bump....
It seems that there isn't a clear answer yet. No disrespect to those who have given an answer, there just isin't enough of a tilt for me to be comfortable. I'd like to eventually rebuild the motor so i'm looking for accurate info in the mean time.
Joe
adeptex
10-14-2003, 08:36 PM
OK, the cuts in the piston dome are there to prevent the piston from hitting the valves as it approches and passes TDC. Those cuts are not big at all on a stock piston because of the lower compression. The space between the piston dome and the head is greater on a stock piston so the cuts are less. When you raise the compression with a performance piston, this gap decreases because the dome on the piston is higher. Therefore more is cut to clear the valves. So........back to the arrow. If you dont have a mark and you can clearly tell that the cuts are larger in diameter, then you can tell which way to install the piston. The exhaust valves are smaller(look at your cyl head) so they must be matched to the smaller cuts on the piston. If you still are not sure call JE pistons at (714) 898-9763
Waynes400ex
10-14-2003, 09:08 PM
I was thiniking the same thing also. Can anyone else confirm this?
Originally posted by adeptex
OK, the cuts in the piston dome are there to prevent the piston from hitting the valves as it approches and passes TDC. Those cuts are not big at all on a stock piston because of the lower compression. The space between the piston dome and the head is greater on a stock piston so the cuts are less. When you raise the compression with a performance piston, this gap decreases because the dome on the piston is higher. Therefore more is cut to clear the valves. So........back to the arrow. If you dont have a mark and you can clearly tell that the cuts are larger in diameter, then you can tell which way to install the piston. The exhaust valves are smaller(look at your cyl head) so they must be matched to the smaller cuts on the piston. If you still are not sure call JE pistons at (714) 898-9763
I understand and agree with what you posted for the most part. Just some details i'm not convinced on yet.
I understand higher compression/domed pistons equals less valve/piston clearance hence the larger indents on the piston.
But, (there's always a but!:p ) what about my other post about the cycles of the four stroke motor......
Interesting..... Could it be because of valve lift, duration or timing? Meaning the exahust valves are open later during the exhaust stroke.
The intake valves are closed for the most part during the compression stroke, right? So intake valve/piston clearence shouldn't be an issue.
Am I anywhere near correct or am I talking a bunch of chit?
Joe
I should have added comprression in there too but didn't.
In the picture in the Clymer manual that was referenced the indents don't neccessarly look bigger to me, just deeper.
I want more info!:D Maybe more than needed?
Joe
cals400ex
10-15-2003, 08:36 AM
the arrow on a piston will face the exhaust ports (the front of the engine). you can simply compare your stock piston to the aftermarket one if you don't have an arrow on your aftermarket one. just remember, your stock piston doesn't have an arrow either. your stock piston has an IN on it. this indicates intake. so, the IN mark should face your intake ports (rear or back of engine). so now that you can see what way your stock piston goes in, compare your two pistons. where you have larger/longer indents on your stock piston, you will have larger indents on your aftermarket piston. i can't remember which one has the larger indents and i am not at home right now so i can't check. sorry joe, i didn't answer your question since i didn't know the answer.
Waynes400ex
10-15-2003, 09:24 AM
I called Je today and talked to there tech guy Brian he said the larger cutouts are for the intake!
L.Vegas400
10-15-2003, 03:54 PM
i dont know if it makes a difference but when i said larger i mean deeper. but who knows, maybe im a freaking idiot and dont know my *** from a hole in the ground. just so everyone sees what i see, look at page 100 fig 90 and post what you see.
Silverfox@C&DRacing
10-15-2003, 04:04 PM
After you called today I asked Colby about the piston and he showed me yep the intake is larger lengthwise not depth as what I was trying to measure:rolleyes: oops someday I will learn
L.Vegas400
10-15-2003, 05:21 PM
Originally posted by Silverfox@C&DRacing
yep the intake is larger lengthwise not depth
so what is the comparison on depth?
Doibugu2
01-16-2004, 08:25 AM
So I did a search like a good exrider. And was hoping for a easy answer.
I have an arrow on mine. Should it point towards the front or the back?
it points toward your exhaust. It indicates the air flow..
Doibugu2
01-16-2004, 08:44 AM
Originally posted by Rico
it points toward your exhaust. It indicates the air flow..
Thanks, now if I can just get Jeff to get my cam ready, I'll be good to go.
foleyit
01-16-2004, 08:46 AM
I installed my JE piston a while back and it didn't have an arrow either. I called JE as well, and I was instructed to put the larger cuts on the intake side. 6 mos and no problems!
Originally posted by Doibugu2
Thanks, now if I can just get Jeff to get my cam ready, I'll be good to go.
What kinda cam you gettin sucka:confused:
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