Burnt up the piston and cylinder

[Nick24]

Hi, i just recently took my motor apart and found out that the piston and cylinder are shot. So, i want a cheap easy fix cuz i will more than likely sell the EX next spring.

I found a remaned cylinder with a 1mm over bore and 11:1 piston with gaskets for $350 on ebay which seemed like an alright deal. I am concerned about the compression though. Will i be able to run it on pump gas if i do that?

I plan on getting the HD studs cuz my head bolts keep coming loose. So, I am not worried about the higher comp piston pulling the studs since i plan on installing hd studs.

Also, what would be a good cam to go with because that is ruined also.

Thanks, Nick

[dxcody]

You can still run Unleaded fine on an 11:1.

That is a pretty good deal. You have to watch those though, because alot of times on ebay just because it says it has a cylinder, most of the time you have to send in your cylinder and then they resleave it, bore it, and hone it.

I have a stage 1 hotcam, and i kinda wish i would have gotten a stage 2.

Its up to you, but if you are into kinda fast paced riding then stage 2, or if you just putt around, go stage 1. Neither will make a outragous difference.

I have rode my buddys with a stage 2 and liked it way more, but there isnt really enough to tell with a high comp piston.

Your choice, but IMO go stage 2 with that set up.

[Nick24]

So, will 87 octane be ok? I keep that in a tank at my house or would I have to go get like 90 or 92 octane gas at the gas station. Also, can i use the stock valve springs with the stage 2 cam?

Just out of curiostity, what do you think it will be worth when i am done fixing it. It's a 2001, yellow, good plastics, nice shape overall.

- HMF comp series exhaust
- New front tires
- Moose air filter
- Recently changed axle bearings
- Good rear tires
- Front end widening kit
- Alba Pro Armor nerf bars

Possibly after fixing it...
- 11:1 wiseco 1mm ovr bore
- Stg 1 or 2 Hotcam

[dxcody]

Yes you can run regular gas. You wont get 100% full potential but it will work. I mean if you can run a higher octane then do it but its not a must do. I ran regular octane every once in a while in mine when my wallet was sore.

You can use stock springs and everything with a hotcam as far as i know. I am running stock springs and valves on my 400ex.

I would say you could get 2000-2500 easy.

I sold my 2000 416ex for 1600 and it had that set up and it needed a new exhaust and a few other things and i only had mine up for sale for like 3 days.

Be careful though because i truely do regret selling my 416ex. it was my best quad i have ever owned.

[Nick24]

Alright sounds good.

I know it is kinda a tuff decision if i would sell it or not. The only quad i would sell it for is a 450r or yfz450. But who knows, if i get the higher comp piston and cam, I may be plenty happy with it.

The neighbor kid is out growing his dirt bike and really likes my quad so, I would prolly sell it to the neighbors just so i could get him on a quad, but not sure if i would be ready to sell it to someone else ya know.

[inv3ctiv3]

Originally posted by Nick24
. So, i want a cheap easy fix cuz i will more than likely sell the EX next spring.



This is what is wrong with people today and why I almost never buy used ****.

[CJM]

Ill say this only once: You buy once and cry once. Otherwise if you dont spend the coin now you can spend it later when it blows again or something goes wrong. NEVER cheap out on something like an engine-it will bite you in the arse later.

Price list:
-135-150 bucks for a wiseco piston, 85.5mm, 86mm should be fine or an 87mm, (thats 402, 406 or 416cc)
-30 bucks for gaskets (cometic MLS OEM is actually more)
-50-75 bucks to bore your stock cylinder oversize at a local machine shop or send it somewhere.
-10 bucks for jets.

Thats like 250, an easy 100 bucks less than the ebay setup-which you dont know wtf your truly getting even if new..

I cant understand your logic when this is way cheaper and you know its done right and no one comes back to you after you sell it.

btw with 11:1 compression, dont even try and run regular in it-you need 93. 11:1 is the threshold of where in some cases depending on mods you may need 100+ octane. Most get away with 93. You want to run 87-buy a 9:1 piston-stock compression.

[dxcody]

i thought you could run regular octane with an 11:1 but no higher comp then that.

Huh shows what i know lol

But yea CJM is right, you fix it right the first time and you wont be hurting later.

You try to put paint over rust, and that paint makes it look good, until the paint starts flaking. Then you are back to square 1.

[Nick24]

Yeah, I completely understand. So, i should get the piston i want and then take my cylinder to a machine shop and have it bored to that piston?

As I think about it more and more, I think i will just build it the way I want and keep the thing for awhile.

So, with that said, here is what im thinking...

- 87mm (416cc) piston 11:1. Could I do 12:1 running 92-93??
- Stage 2 hotcam
- Bore my cylinder
- GT Thunder HD Studs

What's already done...

- HMF S/O
- Open airbox
- Moose foam filter
- Right now my jetting is 170 main and 42 pilot at about 900ft elev. Will i need to change that??

Also, would a SPAL fan be necessary with this setup? If so, where should I get one and is there a thread somewhere that is like a how to, if I do need it.

Will i need a different size gasket kit if i go with the 416?

Thank you guys :)

[dxcody]

From what CJM said, sounds like if you go any higher than 11:1 you better run the highest octane you can.

I would listen to him. I have had alot of problems and he has never steered me wrong. :devil:

I will say tho a 416, stage 2 hotcam and 11:1 is a amazing combo. There is quite a few riders that use that combo and i have never really heard any complaints about it.

I know alot about your basic stock 400ex motor, but i still have alot ot learn with the aftermarket stuff.

[400ex drifter]

Nick 24, your jetting should be fine the way it is.

I have a 416ex with 11:1 piston, stage 2 hotcam, and LRD slip-on exhaust and I use that same jetting. You may have to do some small adjustments to your needle position, but thats about it.

[Nick24]

Yup, I'm with ya on that one DX. :)

Sounds great Drifter. What do you run with your pilot screw? Or where do you suggest I start?

Also, do i need to get the cometic big bore gasket kit that is good for up to 89mm?

You guys have been great!!

Thanks so much for your help and input so far!!

[CJM]

No, just the cometic gasket set for a regular old stock size. It doesnt matter unless you had a 440-the piston never comes to the top of the cylinder. You need to make sure the set you buy is a multi-layered steel viton coated type. They also have a fiber/paper setup thats junk. You can easily see the right one on ebay-picture should show a rubbery looking black metal gasket set. Or you can order directly from cometic.

11:1 is the highest you can go with regular old gas at a station (93), anything higher in compression means you need 100+ octane due to detonation.

the 416 or 406, 11:1 and stage 2 hotcam is a very solid combo. Its no 450 but it can sure keep up with them.

Your jettings fine, same main and pilot I use.

[Nick24]

Sweet sounds good.

I picked up a 416 11:1 piston for 125 and a stage 2 cam for 125 and the local machine shop said 40-50 bucks for the boring also got the gt thunder studs comin so i think im doing pretty good so far. Sounds like I'll have a pretty fun ride after I'm done!!

Thanks for your help man. :)

[dxcody]

see what i mean!

CJM knows his shi*

~Cody~

[CJM]

Your welcome :D

[Nick24]

Hey, do you guys think a spal fan would be necessary?

Also, do you guys think the valve seals should be replaced?

Thanks.

[CJM]

Originally posted by Nick24
Hey, do you guys think a spal fan would be necessary?

Necessary? No, but its nice to have.


Originally posted by Nick24


Also, do you guys think the valve seals should be replaced?

Thanks.

If your gonna be in there you might as well replace them and lap the valves. Need a valve spring compressor tho and rocky mtn atv sells a good one for about 30 bucks.

[Nick24]

Hey, I have noticed after doing all of these mods my clutch is slipping.

Not sure if it is because of the added power and need a different HP clutch or if its because of the oil i am using or what.

The clutch is fine until about half throttle in gears 2-5.

I am just using some 10w-40 Pennzoil.http://www.pennzoil.com/#/motor-oil/pennzoil-conventional

Thats the oil I am using. Its just conventional 10w-40 motor oil. Not sure if that is what is causing the slipping issue or not.

Thanks for any replies, Nick

[CJM]

Cant tell from the site, but if it says anything about "energy conserving" on a little label on the back-yep the oils no good for a wet clutch like the EX.

Course you clutch could be going anyways, tusk makes an excellent cheaper replacement.

[DnB_racing]

Originally posted by Nick24
will i need a different size gasket kit if i go with the 416?
on air cooled cylinders, its not quit as critical as a water jacketed, on the water jacket cylinders the compression can actually cause the motor to over heat by pressurizing the cooling system, cometec recommends actually trimming the gasket for overbore on water cooled, and its a pain to do but it takes time and can be done,

it wouldn't hurt on a air cooled to trim it if possible, especially if your going high compression

it does add a chance of head gasket failure if not sized properly, but many have had no issues with the slight size difference, that's your call on how you want to do it....

I always size them, but im extremely anal, and dont want someone coming back on my work

[Nick24]

Originally posted by CJM
Cant tell from the site, but if it says anything about "energy conserving" on a little label on the back-yep the oils no good for a wet clutch like the EX.

Course you clutch could be going anyways, tusk makes an excellent cheaper replacement.

Yup. I drained the oil and put the Honda oil in there... helped a little, but I am thinking for 50 bucks I am going to get the Tusk kit.

[lilholt7]

Originally posted by Nick24
Alright sounds good.

I know it is kinda a tuff decision if i would sell it or not. The only quad i would sell it for is a 450r or yfz450. But who knows, if i get the higher comp piston and cam, I may be plenty happy with it.

The neighbor kid is out growing his dirt bike and really likes my quad so, I would prolly sell it to the neighbors just so i could get him on a quad, but not sure if i would be ready to sell it to someone else ya know.

450r is a great quad, for racing. but it is no where close to being as reliable as the 400ex for everyday riding or hard trail riding or even every once in a while racing.