Kx500 into Tecate 3

[BigGreenMachine]

Could I just switch my 250 topend and head for a kx500 tpend and head or do I have to swap the entire engine? How much frame modification am I looking at here?

Thanks!

[200x Basket]

too much work on a 85, it is simple on a 86

[BigGreenMachine]

Do u mean switching the topend is too much or changing the entire motor? Why?

[Curtis-Tecate3]

You would have to swap the entire motor. The top end will not simply bolt on for many, many reasons. As far as swapping the entire motor the 86/87 will accomodate the motor far easier than the 84/85 due to the front frame downtube. The 84/85 250 motors had a side or angled exhaust port which used a single downtube frame. The 86/87 use a center port exhaust with a "Y" or split downtube frame. The KX500 Motors have the center exhaust port requiring a split downtube frame. To install a 500 on an 84/85 Tecate you would need to replace the downtube to accomodate the exhaust. Oh, and then you would have to figure out how to route the right side exiting 500 expansion chamber to work on the 84/85 designed for a left side pipe...

Curtis.

[BigGreenMachine]

Sorry to hear that, I'm gonna make an educated guess and say it would be the same deal for the new generation 250's also. Oh well, with my new CT Racing sleeve I can still go with a biger bore, then those Raptors will pay.

Thanks for the info you two. :-P

[SteveATC24]

Damn Curtis, that about covers it.....

[sportvette]

has anyone ever made a thread with pictures on replacing the kxt 250 engine with the kx 500 engine?

[Curtis-Tecate3]

Sportvette, I have asked several people about publishing the details but it seems that no one is willing to share the info so far. I have had conflicting reports as to the ease of the install on the 86/87. Some guys have said no frame mods at all and others have said different.

I for one am curious. Does anyone want to share the details???

Curtis.

[Jeb]

I've heard the rear of the motor bolts up with the swingarm and frame fine. then, the underneath motor mount lines up with the extra holes in the frame brackets.

Next, i've heard that you have to make custom front mounts, head stay (or not run a head stay) and cut a half-circle out of the crossmember in the frame above the head to clear the spark plug on the taller 500 motor.

This is all Hear-Say. I've never seen one.

If you want to do an 84/85 open class motor Tecate, look into the KX420. It was aircooled. Or maybe an aircooled KX500. These engines may have had the side exit exhaust port. I think they made an aircooled 500 for one year model, 83/84 time frame.

Do the research and see. :-D

[BigGreenMachine]

Thanks for all the info you guys. I'm definately going to try this in the next year or two. Hey Jeb, are the bikes in your avitar your own. The yellow tri-z looks sweet. Do you mind if I ask you to post a bigger pick?

[Jeb]

.... Hey Jeb, are the bikes in your avitar your own ????


Yes.

I also have an 82 ATC70 that I have had since new. It was my first ride. I also had a red 84 KXT for years but decided to part it out.

The Tri-Z only needs an extended axle to be mod'd to the hilt.

I'll get a bigger pic. :-D