250-500cc WR300 engine conversion kit?

Anyone know where I can get a good deal on the 250 to 300 conversion kit?
I found one here, but my god, $1500??: http://www.ktm-parts.com/8000H0915.html
I don't even need the pipe as I plan to run my Gnarly.

1500, lol...would be better to find a 360 bike, steal the engine, and refresh it..
then you would have a 6 speed and big trail torque

I was just looking at the parts catalog. Looks to me like all the parts are common between the two top-ends except the obvious:
Head
Cylinder
Piston/Rings
Power valve (not all the parts, just the valve itself)
Booster valve which is part of the power valve assembly
Gaskets

Even just buying those parts separate will be over a $1k. So I guess I'll go back to my original plan and get an Forward Motion 295cc kit.

Pm rancher 1 he might have a kit for sale. Also check the classifieds.

I wouldn't mind trying the 250! Potential swap? Pm me if an option you wanna consider mate

I thought the 300 kit was $1,000 new from the dealer. When I bought my 250 I thought I would go to a 300 when I wore out my 250. 2 problems with that; (1) I like my 250 better than any 300 I've ridden and (2) it looks like it will never wear out.

What is it about the 250 that you like better than a 300? What type of riding are you doing?

I like that it revs out higher and quicker, all the 300s I've ridden pull in the middle like a 450 4t and then go flat on top. The 300 does pull harder in the mid but since putting a Lectron and a Gnarly on my 250 it's like a tractor with over rev. I use 13:49 gearing and 1st is just a bail out gear + with the higher revving 250 my speedo (when it worked) read 80mph topped out.

I should add that stock the 250 has 205 psi cranking compression and if you want that much static compression on a 300 you need to buy a race head or mod the stock one.

Very nice. I do have a lektron en-route. I was planning to do the top-end, and I cannot decide what to do about upgrade or keep stock. I think I'll try the lektron for a while. Maybe just do the rings on the 250 for now. I use this bike exclusively for technical single track so I'm not too concerned with high speed riding. I almost never get beyond 3rd gear .

Well, as is proven by the wb165, CCs do make a difference. I think you could setup a 250 to be almost as good as a 300 though. Lectron will help, maybe race head/hi comp mod, others say that adds a lot of grunt. G2 throttle with the Lectron and cable made a significant improvement in throttle control and response Gotta say, biggest game changer to me is the Rekluse and in combo with the above it's truly a different machine. I can come to almost a complete stop in the worst spot, then just feed it a little juice and off she goes, super smooth and sweet when it's all tuned right. Also, lose it, throw it away, tumble down the hill or toss in the ditch, stuck on a rock or log and it just sets there idling, waiting for me to get it together

yep, the lectron is sweet regardless of cc.

I guess I didn't explain why the over rev is important to me, it's not so much for the high speed although it's fun to have it when I get the rare chance to use it. I also ride single track most of the time and having more over rev allows me to get more out of my 250 by making it pull a gear longer. For example I can rev it really high in 2nd or 3rd when approaching a hill allowing me more speed in the same gear without shifting. It's kind of like having the fun of a ripping 125 but with an extremely meaty mid range that bails me out if I screw up.

I have a YZ125 that's really fun to ride but overall I know I'm faster on my 250. I've been curious to try a Lectron on my yz but since it's a second bike and rarely gets ridden I haven't got $400 curious yet.

Thanks. I can picture that exact scenario in my head, so that makes good sense to me.

I had my Mikuni as perfect as I think it could have been, it wasn't even sensitive to weather changes like others complain about. The Lectron makes it much easier to ride since there is no transitions from one circuit to another only the addition of the powerjet at WFO. The selling point for me was an additional 20 miles per tank of fuel when riding singletrack which for me meant that I didn't need an oversize tank and I'd also save on race fuel in the long run. The mileage isn't a factor in sand or wide open riding but it really saves fuel in the tight stuff. Along with that same low speed efficiency is that it never loads up and needs cleaning out once you get in the open also it starts and re-starts easier, I never put it in neutral on restarts and usually leave it in 2nd or 3rd and off I go. I have ridden it from 1,500 ft air to over 10k ft without touching the adjustment screws or jetting... if you were picky then once you get to about 9k ft you can give the idle screw a half turn with your fingers and you're good to go.

If I rode my YZ more I'd spend the money

Man oh man did the lectron transform this bike! I'm definitely keeping it a 250. Thanks Kelly! And thanks to all the peeps who responded on this thread.

Usually the power jet is too rich. I had mine set at a 1/2 turn out from full closed. The rod is usually a 1/4 to 1/2 turn to rich.

Since starting this thread, I've sent my cylinder to Millennium Technologies for their over bore kit. $750 (including shipping) later, and I now have a paper weight and they aren't returning my calls. So if anyone has a complete top end I would love to work something out. I'll try rancher 1, as 454x mentioned, if I can figure out how to pm him.

Wow, that bears some explaining. I thought MT had a good rep

As I understand it, there are two or more divisions or departments (business units) at Millennium Tech. One does the plating and honing of cylinders and has been highly recommended to me by other people. That's why I went with them in the first place. Then there is the side of the business that does the over bore and porting. That was started by Eric Gorr who is apparently not a part of Millennium anymore. But it seems like his crappy work ethic has remained.

The problem with my cylinder:
I sent it to them on 2/24/16 for a "big bore 295 kit" they sent it back with a hole in the exhaust port which caused coolant to flood the cylinder. I sent it back to them and they welded it up and were supposed to replate and rebore due to warping caused by welding. As soon as I got the motor back together and started the break-in I heard metal-on-metal contact. This is 20 minutes into break in mind you. So I've now pulled it and discovered scoring on the cylinder and piston. It's going to grenade if I try to run it. They told me squish is supposed to be .050", but it measures over .077". I can only assume they sent the cylinder back warped, or perhaps the welding they did plugged up the coolant path on one side causing uneven expansion. I haven't got a way to measure accurately enough to tell.

I'm now two months into this without a running bike, so I guess I'm going to have to try to piece together some OEM parts and try to fight them for a refund. There's no freeking way I'd send it back to them a third time for more "repairs". And it doesn't seem like that's an option anyway, since they won't return my emails.