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[Dritto]

As I cannot bore my cylinder to 87mm (416cc), which I would like to, but not able to. Then I was considering about taking my cylinder sometime with me to UK to get it bored.
But really, how much of a difference will 19cc make? Will it be an immense difference? Why is it so popular to do this?
I'm gonna put a 11:1 piston with stock bore in it.
What mods are equally good?

Thanks :)

[2001400exrida]

the main question is how does your cylinder look now? is it grooved? if it's still in great condition you might as well just drop a high comp piston in there and call it good. Since boring is not readily available to you it would be much easier. You won't get much from the 16cc. The reason it is so popular is because when a stock bore cylinder starts to get worn out, it's best to just move up to the next bore and start with a fresh bore.

[Dritto]

the main question is how does your cylinder look now? is it grooved? if it's still in great condition you might as well just drop a high comp piston in there and call it good. Since boring is not readily available to you it would be much easier. You won't get much from the 16cc. The reason it is so popular is because when a stock bore cylinder starts to get worn out, it's best to just move up to the next bore and start with a fresh bore.

I have around 100hours on it. Do you think I'll be okay?
Btw, what does it mean when you hone a cylinder?

[cheater13]

When it gets honed, they're just smoothing the imperfections out of it pretty much. If it gets scuffed or scratched somehow that's normally what people get done before putting a new piston in.

If I'm wrong, someone will correct me but that's my $0.02.

[ben300]

When it gets honed, they're just smoothing the imperfections out of it pretty much. If it gets scuffed or scratched somehow that's normally what people get done before putting a new piston in.

If I'm wrong, someone will correct me but that's my $0.02.

theres more than just that. a cylinder needs to be honed in order to remove the shiney glaze that forms on the cylinder walls. by doing this, you allow the rings to seat properly during break in.

[2001400exrida]

that's assuming a glaze has formed. Typically a glaze will form due to blow by, or temperature issues. My 450r has zero glaze, while i did a slight hone with scotch brite i was not able to see any laquer type of glaze in my cross hatching. the main reason to hone is to improve the surface texture. that doesn't always mean smooth it out, in fact i could mean just the opossite if your'e trying to bring back the cross hatching

[CJM]

Overtime even oil lubricated metal to metal will wear. Eventually your cylinder will be ever so egged shaped, thats why people bore them. That or to remove imperfections caused by pistons/piston rings scraping the cylinder wall for whatever reason. The real way to measure it is to measure the bore using a bore gauge set. This way you can check the bore over and make sure it is round-not egg shaped.

You could always buy a sleeve, heat the cylinder up and the old sleeve pops out and new one can go in. Then you put a new piston in and your done. Or you could buy a stock setup cylinder and buy the piston of your choice to fit it.

LA sleeve in the US would be the one to contact for sleeves. Its not hard to change, you can seriously do it with an oven or a grill outside.

[atvrider13]

that's assuming a glaze has formed. Typically a glaze will form due to blow by, or temperature issues. My 450r has zero glaze, while i did a slight hone with scotch brite i was not able to see any laquer type of glaze in my cross hatching. the main reason to hone is to improve the surface texture. that doesn't always mean smooth it out, in fact i could mean just the opossite if your'e trying to bring back the cross hatching

Just wanted to point out that 450r cylinders are nikasiled, alot more durable and wear resistant than a steel sleeve. Always thought about nikasiling a ex cylinder if it wasnt so expensive!

[Dritto]

Why do small cylinders like ATV have so poor durability, compared to cars who can go thousands of miles?

[Drifterboy3]

atv and dirtbike engines are run so much harder than a car when is the last time you ran your car at 9000 rpms or bounced it off the rev limiter?

cjm what about decking the top of the cylinder?

[KKiowaTJ]

Poor mans way of checking cylinder bore, Get the piston you want and install a ring and use the piston to push it through, Checking the gaps in the ring. Use a feeler gage when you get the ring in and centered so you know where you stand. If you have some imperfections, You can sometimes hone it out and use oversize rings. Anything is possible, Have any pic's of the cylinder?

[CJM]

Decking it is only cutting away the top of the mating surfaces to raise compression using a standard piston. Has nothing to do with bore. You usually deck the head, not the cylinder.

[atvrider13]

If you have some imperfections, You can sometimes hone it out and use oversize rings. Anything is possible, Have any pic's of the cylinder?
I think you mean replacement rings?

[2001400exrida]

On the 400ex decking the cylinder is common, more common than decking the head. People do mill the head a bit, i've seen that quite a bit on this forum back in the day actually. That or use an XR gasket. It will make a tighter squish between head and piston

[KKiowaTJ]

I think you mean replacement rings?


Same thing, They are a bit bigger to account for seating and or if you had a build gone bad and you scored the cylinder wall, Fresh hone and rings can fix it sometimes. Just all depends on how the cylinder looks and tolerances.

[MtnEX]

Overtime even oil lubricated metal to metal will wear. Eventually your cylinder will be ever so egged shaped, thats why people bore them. That or to remove imperfections caused by pistons/piston rings scraping the cylinder wall for whatever reason. The real way to measure it is to measure the bore using a bore gauge set. This way you can check the bore over and make sure it is round-not egg shaped.

You could always buy a sleeve, heat the cylinder up and the old sleeve pops out and new one can go in. Then you put a new piston in and your done. Or you could buy a stock setup cylinder and buy the piston of your choice to fit it.

LA sleeve in the US would be the one to contact for sleeves. Its not hard to change, you can seriously do it with an oven or a grill outside.

No kidding?

Heck I always thought they had to be pressed out/in

[CJM]

Nope, buddy of mine did one for a friend with nothing more than a oxy/acetylene torch. Even better was we used the snow outside to cool the one we were gonna put in then cure it as well once it was done. Heated it up, old one popped out, put new one in and into the snow. Took all of 20 mins.

[2001400exrida]

You could always buy a sleeve, heat the cylinder up and the old sleeve pops out and new one can go in. Then you put a new piston in and your done.
There's more to it than just re sleeving and dropping a new piston in. Any machine shop will use a press as well, so they are in fact pressed in when done professionally. You will want to have that new sleeve bored to your piston. If the old sleeve isn't shot i would just have it bored. Most of the time there is machining work involved when you install a new sleeve, you don't just shove it in there and go with it, usually have to deck a bit becaue the cleeve and cylinder aren't always perfect. In this thread i'm linking you will see that we agree on this, regardless of what you've stated in this thread.

http://www.atvriders.com/vbb/showthread.php?440189-diy-sleeve




cjm what about decking the top of the cylinder?

this is much more common, not many guys deck the head on the 400's, it usually the cylinder when they're looking for tighter squish.

dritto if i was you i'd look for a good condition 400ex cylinder, you can sometimes get cylinder piston gets for only a few hundred dollars.