Ex Compression??

[QuadJunkies]

Can someone tell me what the Comp. should be at for my 426ex??? We are going to do a reading tomorrow but didint know what it should be..... Looks like we will be tearing into a few other things besides just the Comp. Im leaking oil as of today :(

[stupid driver]

i have an 11:1 Je piston on my 426ex, and i absolutely love it. I could not be happier with the setup. the torque that the added compression gives is amazing. I changed the piston/compression after i had gotten used to the power, and i never thought the gain would be as noticeable as it was. I might add, i did also put in heavy duty head studs when i bumped the compression. Just my .02

[QuadJunkies]

Originally posted by stupid driver
i have an 11:1 Je piston on my 426ex, and i absolutely love it. I could not be happier with the setup. the torque that the added compression gives is amazing. I changed the piston/compression after i had gotten used to the power, and i never thought the gain would be as noticeable as it was. I might add, i did also put in heavy duty head studs when i bumped the compression. Just my .02 thats cool that you love yours. I love mine too!!! Soooo......................... Do you know what the Compression reading should be?? I have a Ross 11:1 in mine ;) and other mods in my sig..
What I was referring to was, I wanted to check the compression inside the motor not the piston. sorry I should have made that more clear. ;):o

[stupid driver]

sry about that, i guess i could have used my head a little bit on that one, i kinda wondered why youd be putting diff comp. in your motor(from what i hear that thing runs like a bat outa hell as it is:D )

[stupid driver]

as far as motor compression, i am sorry, i cant help you on that. Im sure somebody will know though.

[Steve-o 400EX]

what type of gaskets do you use, your compression is not really 11:1 if your run stock gaskets, to get the true compression you run no base gasket and one thickness of the head gasket. that should get you to the correct compression. If ur running an XR setup which is a little higher compression than stock 400ex compression. I have a 10.8:1 JE piston with the XR setup and it is at about 10.5 or 10.6:1. So if you do a compression test and it shows up a little low, your motor is still ok and its where it should be.

[QuadJunkies]

Originally posted by Steve-o 400EX
what type of gaskets do you use, your compression is not really 11:1 if your run stock gaskets, to get the true compression you run no base gasket and one thickness of the head gasket. that should get you to the correct compression. If ur running an XR setup which is a little higher compression than stock 400ex compression. I have a 10.8:1 JE piston with the XR setup and it is at about 10.5 or 10.6:1. So if you do a compression test and it shows up a little low, your motor is still ok and its where it should be. I think you are not understadning what Im asking. For instance....... My kids mini quads with ther mods a good compression reading should be in the ball pakr of a 165ish. When I ask for a compression reading Iwhat I ams referring to is when you put a compression tester in the spark plug whoel and trun it over,this will give you a internal compression reading of the motor.. This is what I need to know.... What is the low side number reading?>? high side reading??? I have a basic Hetricks 426 kit

[Steve-o 400EX]

alright, i got ya, i dont really know a whole lot about, internal compression readings, i guess i just missunderstood what you were askin.

[quadmxracer]

Im going with anywhere from 120-140 for good range and any thing under 120-100 is time for a rebuild.

[mojoe2878]

the stock 9.1:1 puts the compression in the 120's, with a 11:1 it should be in the 140's or so. maybe a little lower if the engine needs new rings.

[QuadJunkies]

Originally posted by mojoe2878
the stock 9.1:1 puts the compression in the 120's, with a 11:1 it should be in the 140's or so. maybe a little lower if the engine needs new rings. thats what I was looking for. ;)We was going to do a redaing this wk end then I found out Im leaking oil, not sure why it is doing this,its been about 8 months since I had my 426 done and its ran perfect since the day it was done. It stills feels strong, I just noticed the last two rides that it smelled hot yet it wasnt,then Troy noticed oil around the middle( mid gasket /bottom of jug maybe)

[Rider#11]

i just did a compression check on mine today and it was 205lbs. stock is 100-120 it says in book..i run about 11:1 compression...205 is after a years worth or racing. its stroked though so might make a difference nad the piston size is 426.

[QuadJunkies]

Originally posted by Rider#11
i just did a compression check on mine today and it was 205lbs. stock is 100-120 it says in book..i run about 11:1 compression...205 is after a years worth or racing. its stroked though so might make a difference nad the piston size is 426. thanks for the scoop!!! so, is it normal to have an oil leak after only having the 426 done after 8 months??Ive raced prol. 30 races between Troy and I and a duning trip this summer on it...Just wondering if its wear and tear maybe or what else might be causing the oil leak....:confused:

[Flynbryan19]

Wheres your oil leak coming from Tina?

[QuadJunkies]

the middle mid gasket /bottom of jug maybe???

[cals400ex]

Originally posted by QuadJunkies
the middle mid gasket /bottom of jug maybe???


when you say middle gasket, i think your referring to the head gasket. but, the bottom is the base gasket. is it where the cylinder connects to the case? or where the head connects to the cylinder?

[QuadJunkies]

Originally posted by cals400ex
when you say middle gasket, i think your referring to the head gasket. but, the bottom is the base gasket. is it where the cylinder connects to the case? or where the head connects to the cylinder? Its showing oil in this area,thats why I said maybe a Mid...Its not up high or real low both leaks are showing oil in thie area

[cals400ex]

right in the middle there??

well that is definately above the base gasket. that also seems to be above the head gasket. at the very top of that pic you can see the gasket that is between the head cover and the head. that doesn't leak much there usually.

[seven]

You could have blown a head gasket. You said there wasnt a lot of oil just a little right? I would say put new gaskets in it and call it good. Pat Gill ran his 440 for 4 years and going. You shouldnt have to rebuild a 4 stroke every year!

[QuadJunkies]

Originally posted by seven
You could have blown a head gasket. You said there wasnt a lot of oil just a little right? I would say put new gaskets in it and call it good. Pat Gill ran his 440 for 4 years and going. You shouldnt have to rebuild a 4 stroke every year! yeah, its only a little not much.Troy said it should be fine, Im just paraniod and dont want to mess anything up!!:p It still runs like always, just never changed this stuff before in mine:huh

[cals400ex]

maybe i am confusing you or your confusing me but the headgasket will be between the 6th and 7th horizontal fin from the top. if that is where you see oil, it is more than likely the head gasket. you may just want to clean it off and ride it more and see if the spot comes back.

[seven]

Maybe you are getting the stretched studs on your jug. Its mostly comon in the 13to1 pistons though.

[94snake300ex]

On my motor I have some leakage at the head cover because it doesnt require a gasket but you have to put sealant on it if you didnt that is what might be leaking.

[UglyMotha™]

Originally posted by 94snake300ex
On my motor I have some leakage at the head cover because it doesnt require a gasket but you have to put sealant on it if you didnt that is what might be leaking.


the 4hundy's use a gasket http://www.exriders.com/vbb/images/icons/icon14.gif


never could figure out why they didnt use one on the 300