atc250sx/es 315cc big bore? Fourstroketech.

[nilesj]

Anyone have any experience with Fourstroketech's 315cc big bore kit for the es/sx?

[Ghostv2]

Pm Micky Dunlop, he should have some experience with them.

[Mickey Dunlap]

Anyone have any experience with Fourstroketech's 315cc big bore kit for the es/sx?

What do you want to know?

I have a Big Red myself and I'm building new kits for them. The first one is a 350cc big bore with sleeve piston and gaskets for $349, cams will be $225 exchange and the valve springs $95. The kit is made to run on pump gas.

[Jmoozy27]

What do you want to know?

I have a Big Red myself and I'm building new kits for them. The first one is a 350cc big bore with sleeve piston and gaskets for $349, cams will be $225 exchange and the valve springs $95. The kit is made to run on pump gas.

Mickey, could a 350x head be incorporated into this to increase performance? Just curious???

[TheRealFatShady]

I'd like to know if we can use a 350x head, maybe needing a new gasket and 350x studs. I've heard you can use a big red cam in a 350x head, though I'm not sure on that.

Would be great to be able to do this swap without having the chain tensioner on the wrong side, like it is if you were to try to build a big bore with a 350x jug

[Mickey Dunlap]

Mickey, could a 350x head be incorporated into this to increase performance? Just curious???

It could, how ever I would have to put 4 valve pockets in it, and it would be stock 350x compression flat to piston. So by the time you build a reverse grind cam I don't think you would have anymore HP then this kit with my cam. The 250x/300ex head is better and would have higher compression but still have the cost of doing the cam and 4 valve springs vs the 2 valve stock head, plud I can make the stock head flow as much as the 4 valve stock heads off the 250x/300ex. The only reason I would use that head is to go big valves and keep the small combustion chamber. over a 350x. The 350x head is also harder to build a head pipe the works.

[Mickey Dunlap]

I'm building the 350cc kit to give it good power with out a big cost. This isn't a race bike other wise I have a 420cc kit already that runs a big valve 300ex head and a big cam. I was going to build that for my self as a sleeper motor but for right now from a business stand point I should have a kit that is at a good cost for the power gain. I didn't get to go dyno my big red this week, but I think the kits going to give a good 60-70% hp gain.

[Jmoozy27]

Wow, so if I send you my top end you resleeve it and rework head or is it a straight up cylinder and head purchase?

[Mickey Dunlap]

Wow, so if I send you my top end you resleeve it and rework head or is it a straight up cylinder and head purchase?

I just put the parts prices up, no re-sleeving nor head porting. Most customers will just buy the parts and have a local machine shop do the work. Most won't port the head or go big valves, like I said these are not race bikes so most of the power will be in the 100cc bigger and the new cams.

[leevarnado]

sure wish i had a 350 bigred.maybe my next project.

[Mickey Dunlap]

sure wish i had a 350 bigred.maybe my next project.


I think this is something Honda would have came out with if...............

[86T3]

I kinda want to buy a big red just to buy this kit.

[Mickey Dunlap]

I kinda want to buy a big red just to buy this kit.

That's what I did.

I want to buy a 350x for the same reason, the kit I'm building for it and the rear fenders I'm making.

[86T3]

Do you play with 2 strokes at all Mickey? Or want to throw a leg over one for old times sakes? Sorry for the thread hijack niles

[Mickey Dunlap]

Do you play with 2 strokes at all Mickey? Or want to throw a leg over one for old times sakes? Sorry for the thread hijack niles

No the only 2 stroke I will build is a "true as can be 200r works bike". I have a line on the head and cylinder from one I can get, just don't have the time for another project.

[86T3]

How about throwing a leg over one?

[Mickey Dunlap]

I really don't like riding others bikes. I don't even know if I can ride. I know the more weight I lose the more my Carpal Tunnel acts up. When I broke my arm I asked the doctor if being fat was the ticket to not having Carpal Tunnel, he said yes. Last time I got down to the weight I should be I couldn't even drive a car without my arms going to sleep. I was training with a rider that moved back here and the same thing happen when riding bicycles. So my goal is to do a little riding my Team Honda 200x for some pics and bring it with me to Trike Fest and them putt around on my Big Red this year while I lose more weight, then get the Carpal Tunnel taken care of next fall sometime when engine building slows down.

[sledcrazyinCT]

What would you suggest for an exhaust?

[Mickey Dunlap]

What would you suggest for an exhaust?

I'm going to run stock at first, then try a Honda 450r stock muffler trying to get more power but not the noise. If not that I'll build my own or find a super trap,

[86T3]

I really don't like riding others bikes. I don't even know if I can ride. I know the more weight I lose the more my Carpal Tunnel acts up. When I broke my arm I asked the doctor if being fat was the ticket to not having Carpal Tunnel, he said yes. Last time I got down to the weight I should be I couldn't even drive a car without my arms going to sleep. I was training with a rider that moved back here and the same thing happen when riding bicycles. So my goal is to do a little riding my Team Honda 200x for some pics and bring it with me to Trike Fest and them putt around on my Big Red this year while I lose more weight, then get the Carpal Tunnel taken care of next fall sometime when engine building slows down.

I got a real fast tecate with a hydro clutch in need of an ass in the seat, if you think you want to take it for a spin at a race let me know and it will be there

[nilesj]

thanks for the info guys