TT/ XR

[Expat]

Which 500 4 stroke engine is the most viable base to build a strong racer.
Performance parts availability, durability, performance etc

TT or XR??

Just engines.

[mick25]

I have played around with the TT500s and XT500s for the past 20 years they are strong as,they are reliable strong gear box .And have a big cult following as well.THey go great and parts are still easy to sourse ,The skys the limit with after market goddies..CAMS ,HIGH COMP PISTONS...etc etc

The early model XR XL 500 dont run cam bearings in the head so some motors can chew heads and cams up its some thing to keep an eye on, but they go
 great...


The later model XR500 1983,84 ran cam bearings but had cracking head probs but a mate of mine had his spark plug size reduced in the head to take a
smaller dia spark plug so there was more meat between the valve and spark plug hole this is where the cracking happens and its works fine (ballards can get this done)   But i have never owned a XR OR XL500 before so thats all my info some might have some more tips on the XR500

[Marc.com]

the Xr motor is like the next generation on 4 stroke, more compact .... another weak point of the first XR is the clutch basket, banding it was mandatory.

[evo550]

Expat,
I ran a later 550/600 yamaha motor in a race bike for about three years without so much as a backfire. Only maintinance it got was oil and air filter every race. Couldn't kill it with a stick and a ton of grunt. Down side is twin carb setup.

[Marc.com]

Expat,
I ran a later 550/600 yamaha motor in a race bike for about three years without so much as a backfire. Only maintinance it got was oil and air filter every race. Couldn't kill it with a stick and a ton of grunt. Down side is twin carb setup.

TT600 engine is next generation and technology is same as XR500...... awesome motor I have drum braked TT600 in barn fresh condition.....motor is much better than suspension at the moment.