KX500 on a T4 bottom end

[David Roberts]

Thought I'd start a new topic instead of mixing it in too deep with the photos of everyones nice quads.
I've done an 86mm bore with a 75mm stroke which is a KX500 cylinder on a stroked Tecate 4 crank. It's 435cc on the first bore and 456cc at max bore. Requires a rebalance on the crank and extra weight on the counterbalancer but they run pretty good.
On the stock cylinder and crank we go up to 406cc but it gets a bit skimpy on transfer port area.
Magoo, if you can do the new cases, a crank, cylinder, piton kit and head for 2500.00, that would be a pretty good price.
I did a motor recently with billet cylinder and head on a T4 bottom end. It was an 81mm bore but the guy who builds the cyliders offers them up to 90mm bores. Be cool if there was enough crank case to support that big of a piston. It's got a 24mm piston pin!
But that top end is 1500.00 alone, plus all of the machine work.

[Magoo]

That would be a lot of work getting a kx500 on a tecate4 bottomend. I never was too excited about the kx500 in a tecate 4... Everyone I have seen was never that fast. Even Evans kx610 powered tecate wasnt as fast as my 300 tecate drag bike at the time. I have also had a kx500, with a ftz drag pipe, 44 alcohol lectron, and pvl ignition not really out preform anything else i had. The stock tecate cylinder has nearly the same intake and exhaust as the tecate but with smaller transfers and bore/stroke.
Here is a pic of the kx 610 powered tecate.

[Magoo]

Do you have any pics of these engines I would be interested in seeing the billet cylinder and the kx500 engines.

The biggest tecate engine I have ever done was a 450, it was a 85.5 bore with a 78mm stroker crank for a tecate. Here is a pic of the some cylinders, the 450 cylinder is the one on the far right with out the ports cut in it yet.

[Magoo]

here is a pic of the 8mm stroker tecate crank that I used. I had a problem with the engine though with water leaking in from beneath the sleeve so I trashed the cylinder and never rebuilt it. But I have figured out how to build it with out cuting into the water jacket. Just havent gotten around to doing it.

[Magoo]

sorry about the picture quality... these pictures were taken before there was digital cameras..hehe. I have made quite a few mistakes when building new engine kits, I have about 8 cylinders that are screwed up because I decided to weld a spacer plate to the top of the cylinder, or cut out the towers in the reed cage etc. My 400 kit is awesome though. I have finally figured out how to build a good 400 kit, I will get you some pictures of it when I am finished with the kit. I have some pics right now, but they are the before pics and I want everyone to see the before and after together....

[KingOfKawies]

Hummm............... Pics would be nice. Got any Pics Dave. Wouldn't Mind seeing some pics of the Billet topends and a KX500 topend on a T4 bottom end. I have came to the conclusion that it would just be easier to build new cases. Setting here looking at a T4 bottomend and topend to a KX500 and wondering how. Looks like the cases would have to be bored way past the safe level to even get the skirt to fit in the case but hay I have been wrong before and the deck height comes into question with the frame.

[David Roberts]

Not sure if I have pics of the KX 500 cylinder on the T4 case but I do have some of the billet top end.
I'm still in Taiwan but I'll get them off my other computer and post them after I get home in a couple weeks.
Because I use the T4 crank and only a 75mm stroke (never got anything longer to live much more than a weekend or two) I have to reduce the height of the 500 cylinder, making it just a touch taller that the KXF with a spacer plate. Attaching the cylinder does require a bit of welding and re-machining of the case but it does fit. Not a bolt-on by any means but it's not really too bad to fit it.
Been putting CR 500 jugs on TRX's for a long time too and it's pretty much the same amount of work.
A new case would be cool if it can be done reasonably for a limited quantity. Hardest thing that I can think of is the case web in between the crank and the transmission. If you use a larger gear on the crank to get the transmission farther back it changes the primary drive ratio a whole lot. Could possibly use a larger gear on the clutch baket or both the 500 crank gear and basket.
Last time I looked at doing a KX500 in a T4 I was planning on building a counter balancer to add on and just using the entire KX500 engine.

[Magoo]

your right about the case between the crank and the transmission. I was just going to move the crank about 5mm forward and machine a new gear on the crank. I figured it would gear up the bike by %10 or so... Another problem is the clutch cover wont fit and would have to be extended. Probably I would use a 6mm stroker or 8mm stroker on the stock crank, and I would just modifly the cylinder like you did. It wouldnt be as big as a stock kx but it would be easier.

[David Roberts]

10% increase on the input drive would be huge, especially considering that it is a bit tall now but the extra displacement might pull it OK.
I don't know what a KX500 is stock. The std crank gear might work. The distance on the 500 has to be longer than a T4.

[FTGRACING]

Hey, if you guys could make this happen I hope many of our T4 riders would jump on this. Even if it is $2500 for a good reliable 500 motor, I'll take it. Hell, the Banshee guys would spend that in a heartbeat to make there quad faster, have you saw the thousands they spend to trick out their quads.