Will i notice a difference?

[84_200x_49660]

When you bore out a cylinder do you notice a difference in power? My cylinder is stock bore right now and it needs to be bored out. What's the max you can bore a 200x cylinder? Do i have to change jets at all?

[Yamaha_Rules69]

Dont bore it out to the max, just enough to clean it up and install a new piston. Boring it out dosnt add much power, it just wastes cylinder space - unless you have a bolt on big bore kit that would greatly increase the cc's. If you want more power out of it, install a high compression piston, bigger carb, aftermarket cam, and performance pipe.

[RIDE-RED 250r]

No, as far as just going in the .010 overbore increments you will not notice any significant power gains. What little may be accomplished will mainly be from just getting the cylinder back in specs allowing the engine to make its normal power. As to jetting, you will likely not need to rejet just going up .010 on your bore from where it is now. Im not sure what the max bore is on the 200x, but im pretty sure there are more overbore sizes for the pre-'86 models vs the '86 and later models....

someone correct me if im wrong but is it the 86 and later 200x that you can only go as far as .030 over??

But whatever you do, dont jump from a stock bore thats out of spec right to the max overbore thats available. Only bore it as much as you need so you will still have boring available to you when the next rebuild comes around....if you are stock now, just go .010 (.25mm) over this time. Cuz when you run out of over bore, you need to replace the sleeve, which will run you about $200 or more...

I guess Yamaha_Rules69 and I were posting at the same time! LOL

[dksix]

Minimum bore is better, makes the cylinder last longer. Raising compression is what increases power but then you need other mods to get the most out of it. I just rebuilt the top end of my 84 200x but I stayed with stock compression and first bore (+.010"). Remember that the first gen X's had some kick starter problems. If you are one of the lucky ones that has had the upgraded springs put into it you may soon be looking at splitting the cases and replacing worn kick starter gears (I'm thinking you'll have to split the cases to do it, I may be wrong).

[Xpress]

Just put a later model 200X engine in it.

[atc350xer]

Just put a later model 200X engine in it.

Huh? :crazy:

[Xpress]

Huh? :crazy:

On second thought, nevermind... :crazy:

[Dirtcrasher]

You can probably bore more than .030 over, but then the wall thickness of the cylinder sleeve gets thinner; At which point they heat up fast and can crack.

Like all above said, get a good shop to measure up the piston and bore and just bore it as much as needed. Usually .010 cleans up most 4 strokes unless they have a ton of miles on them and ran low on oil. There is no reason to go 1 or 2MM's larger than the stock bore, it just doesn't add performance as much as people think.

Unfortunately, the best bang for your buck is expensive. It can be stroked (longer stroke), it can get a new cam and heavy duty valve springs with a 10.25/10.50:1 higher compression piston. That with a mid range cam give you nice gains in power. Removing the airbox lid and cutting large holes in it and then jetting the carb also help, especially if you have a different silencer that flows better. They allow the main jet to jump up a few sizes as well as raising the needle; but, every case is different as far as jetting goes.

Tired/hammered valves can also affect performance if they leak; And a light cleaning up and removal of rust casting helps fuel flow better through the head.

From what I've been told (as far as thumpers) the intake likes to be matched to the carb boot but left a bit rough, however, then exhaust can be ported and polished helping the spent fuel to get out of the head smother.

[Spaulding350X]

i went with a 10.25 compression piston (stock is 9.5) and a xr cam. i got a noticable power gain and can still run pump gas. i did have to re-jet though. what ever you do just bore the min amount that way the cylinder can be bored again in the future. there will be no real power gain in boring it to the max size as you will only gain a cc or 2. how ever they do make a 220 stroker kit for the 83-85 200x that will give you good power.