T3 big bore ?'s

[danimal95]

what all is needed to do a big bore on a 86-7 T3?is it similar to the R's meaning will i need a new crank and rod to withstand the added weight and power?or is it more of a bolt on and go?also will a jug from T4 fit on the T3 with out and modification?

[honda250sx]

Contact Corey Sprock. He will give you a lowdown. He's built a few.

[MIK6]

I won't even do new piston / rings in a motor on a 20 year old rod. I have seen rods break almost as often as I've seen them hold together. For the extra $150 its worth doing the rod at least every few years, depending on how you ride it. I know its easier to get a rod pressed in and put new crank bearings and seals than it is to find a new case or cylinder and head. especially after spending the cash on a big bore. A lot if the newer KX rods fit 86/87 KXT motors, usually lighter and stronger w/ same stroke and bearing size.

I agree w/ honda250sx, sprock is the man w/ the big bores. i run his 300 kit in my 87. Its a bolt on kit, if you get his billet cool head you need to mod the motor mounts and the top radiator hose. make sure you put the 90degree fitting in before you put head on cylinder or it gets to be a pain.

T4s use different powervalve set up. You can use a T4 cylinder on a 87 KX motor (i think thats the year lol) and have a non counterbalanced T4 motor in a T3.

MIK6 / Mike

[Tecate250]

What?? Is that true Mike? I have an almost complete t4 engine. Plus I have my 84 frame back now. Did you ever use a Big Bore on your 1st gen tecates Mike? Any mods you would recomend for them? Still have not found an 86/87 but I will some day.

[nd4speed]

Here's a big bore kit for you: KX500 motor

http://www.3wheelerworldforums.com/showthread.php?t=66754&highlight=kx500+tecate

[nd4speed]

BIG BORE T4's sometimes use 99 KX250 Top, crank, and even trans gears.

http://www.kawieriders.com/forums/index.php?showtopic=33448&hl=

So if T4 top fits T3 then 99 KX250 fits too?

[cr480r]

So if T4 top fits T3 then 99 KX250 fits too?

T4 and T3 cylinders do not interchange... The stud pattern is different.. and the powervalves are actuated differently... The T4 shares the same stud pattern as the '87-'04 KX's.. The newer top-ends are nearly a bolt on with the right combination of parts.