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HIGHFLYER419
07-06-2004, 02:17 PM
What is the difference in an 86 trx 250r engine and an 89 250r engine if any?

wilkin250r
07-06-2004, 03:48 PM
There are a few differences in the ports and such, but the cylinders are completely swappable, you can put an 86 cylinder on an 89 engine and it will run just fine, so those differences are rather minor.

One of the major differences are the connecting crankshaft, specifically the rod length and piston. Starting in 1987, Honda used a longer rod and a shorter piston. (the piston isn't actually shorter, but the rod is mounted higher inside the piston, so the distance between the pin and dome is shorter, but the piston skirt is the same length). This is referred to as the "long rod" crank. You can use an 86 rod with an 86 piston in any motor, or an 87-89 rod and 87-89 piston in any motor, but you can't use an 87-89 rod and an 86 piston without adding a spacer plate.

The upper gears are a little higher on the 86.

The 89 had a slightly different (and better) clutch design, but there are kits to upgrade the 86-88 clutch to the 89 style.

The motors are basically identical on the outside, and you can mount an 86 motor into an 89 frame (and vice-versa) without any modifications.

dawnchris
07-06-2004, 03:54 PM
Where you at in Nevada Wilkin? You race dez?

HIGHFLYER419
07-06-2004, 04:36 PM
THANKS FOR THE INFO -I DIDNT KNOW IF ANYONE WOULD REPLY
YOU GUYS ARE GREAT THANKS AGAIN

wilkin250r
07-06-2004, 05:06 PM
Originally posted by dawnchris
Where you at in Nevada Wilkin? You race dez?

Desert racing in Nevada is big, but alas, I don't race the desert races. I don't have quite the experience and stamina to comptete in the big-time races like the Best in the Desert Vegas to Reno race, those things are brutal. And all of the smaller desert races I possibly COULD compete in are all down in Vegas, which is about a 7 hr drive for me, and I simply don't feel like driving that far.

I do a little flattrack racing in a local circuit, but that's about it for racing. Most of my riding is recreational around my house, or out at Sand Mountain.