Post by: Twostrokepower!!! on May 17, 2012, 05:43:25 PM
My choices are;
Vertex
Pro X
Wiseco
Oem
Out of all these which one will give me the longest life and engine performance? Also my cylinderr is brand new, do i neeed to increase from the standard bore? Or will it be fine as the same size?
And for the reeds, i am thinking of getting the boysen pro series reeds. They are supposedly the best... Any opinions on these parts for a nasty small bore 2stoker?
Post by: arnego2 on May 17, 2012, 07:14:22 PM
I do 40 hours on my YZ250.
Post by: MetalMike1982 on May 17, 2012, 07:24:16 PM
Post by: cnrcpla on May 17, 2012, 11:00:29 PM
Post by: scotty dog on May 18, 2012, 12:29:30 AM
Post by: Twostrokepower!!! on May 18, 2012, 05:47:13 AM
Post by: arnego2 on May 18, 2012, 11:42:07 AM
Have a look http://wossneronline.com/forged_pistons/index.php?main_page=product_info&cPath=50_64_97&products_id=835
Post by: Twostrokepower!!! on May 18, 2012, 09:03:09 PM
Post by: riffraff on May 19, 2012, 06:17:11 AM
Post by: arnego2 on May 19, 2012, 02:11:59 PM
Post by: juliend on May 19, 2012, 04:40:23 PM
There is 48.5 which is standard, and then 49.0mm, 49.50mm,50mm,and 50.50mm. Should i keep the stock bore or go alittle over because of the used cylinder?
You would not go to a larger size piston just because it's a used cylinder. If you do have to go up a size, you would do so because the cylinder is damaged and has to be bored and re-plated or sleeved. If the plating is in good condition, a stock cylinder is your best option. If the cylinder is out of spec, a simple strip and re-plate and again the STD piston would be the next option. If there is actual damage to the cylinder that requires welding or boring, then you would be looking for a larger piston.
Of course, this assumes the kx85 is plated? I believe it is....
Post by: teampryor on May 19, 2012, 06:31:03 PM
Keeping it stock also helps with resale.
You can strip and replate at stock bore size with better plating for around $200 but if you bore you can add a $100 to the price. Big bore pistons are more expensive too.
In small bore applications cast pistons work quite well cast pistons retain there size under heat better than forged pistons.
Wiseco makes forged pistons
Wossner makes forged pistons
Pro X makes cast and forged pistons
Vertex makes cast and forged pistons
OEM is cast.
I would reccomend the cast vertex piston. In motocross application by an aggressive rider ring at 10hrs and replace top end including wrist pin bearing at 20hrs. And yes get an Hour meter.
Thats our schedule on our yz 125s For trail riding play riding intervals are much longer.
Post by: VintageBlueSmoke on May 24, 2012, 01:02:56 PM
OEM pistons are more durable (last longer) than forged and are usually cheaper but don't usually have the wide range of sizes and performance improvements often required for modified cylinders and heads.
If you are not racing, don't bother with a bore unless the cylinger is damaged. If you are not racing, you'll probably out grow the bike and get on a 125 before you'll need (or afford) the miniscule addition of power.
If you are racing, check your rules very carefully. As stated, Supermini is a misnomer for the class. It should be called the SUPEREXPENSIVE class. I know guys that have over $10k in there Cobras! Just think how crazy they'll get on shifter bikes!
Post by: ACMX on May 27, 2012, 07:13:09 AM