Anyone know how to modify a 1976/77 STX340 (exciter340)??

MountainMax

MountainMax

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May 19, 2003
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hey guys, I have an old STX340-canada version of the exciter 340 same year, It's a fan cooled single carb,single exhaust sled. I want to get some more HP out of here, anyone have any ideas? do anyone make a tuned pipe for these old sleds? What if I shaved the cylinder heads?? bigger carb?? and what about clutching? should I try to find a newer primary and secondary clutch for it or will the vintage one be ok???Also I want it to hook up, and the largest track I can find is a .75" because it's so short 114" only, .



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hey that sure looks real close to the motor I just rebuilt in a 1989 Ovation, all though the suspension is different in my sled, and the carb. I don't know of much after market stuff for a 340cc fan cooled twin. Im one of those happy with a stock setup, so I can't say I have even really looked. Those motors are very reliable. with the way that sled of yours is setup with an older suspension, it may not be worth the hassle...but fun if you like to tinker...good luck, that sled looks great for its age.
 
the motor looks similar to the ovation, they make a tuned pipe for your sled, the engine is totally different the yours though, I have one out of my 83 enticer and compared them, blocks, heads and carb all different, only the shape is partly similar, It's a rare sled and I have just stripped it down to the bare frame to do a total restore, and wanted to improve a few things.
 
I know the handlebars back are the same as a gpx 338 but arent they free air cooled? I dont think they will allow dual pipes because mine is fan cooled, just wondering, I found a gpx racing site where I can get the cylinders ported........
 
I would do basic stuff, mill the head or peel the head gasket, polish the ports, jetting and airbox mods. Looks like a cool project, hope you post pictures when it is completed!
 
I will post pics up on my website, I have the sled completely stripped to the tunnel/bulkhead now, and am starting from there, I don't want a full out race sled, just a bit more Power, I did cut the heads on my old enticer 340's and gutted their airboxes, jetted her up to get more HP.............
 
You might be able to adapt a pipe from an SS440. It might be worth a couple of HP, then again it might not. It would be a cheap mod if it worked.

How about posting some progress pictures?
 
Thanks for the info, I will be posting pics soon, on my website also, but im waiting on my new Digicam to arrive, I have it stripped down to the bare tunnel/bulkhead and won't do anything till I get some pics of it, so I have somewhere to start, there is a hole in the bellypan and multiple cracks in the frame/bulkhead, lots of repairs to start here with first, it's gonna be a long project im afraid.....But it's the only sled I have left to work on, my other 5 are all done now.....
 
good info :)
I've got a 71' Yamaha 340 fancooled single carb out of a Snojet that I'm using for a go-kart, The orginal manual says its a 24hp engine (which I believe since the Sno-jet is was in hauled ass until the track fell off)
 
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