93 Exciter SX performance mods

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ace16a

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I'm wanting to get some more performance out of my Exciter SX and don't know what works and what doesn't. I have PSI twin pipes, stock carbs, stock clutchs, no airbox (just filters on carbs), and lowered track 2". Everything else is stock. I'm guessing that doing some clutch work would be the easiest and cheapest way to get some more speed and acceleration, but what can I do to the engine and carbs? Should I put V-max 600 top end on? Bore stock cylinders out? I know this sled could be a lot more, I just don't know what to do. I've read that the PSI twins jump the hp from 85 to 103 with 270 jets. Also that 95+ V-max clutch works good,too. Thanks for any input.
 

you should probably jet up a couple sizes with those pipes. in all honesty i would put the airbox back on too, not too much to be gained by taking it off and you are more likely to go lean without it. the 570 is not a reed motor, its more sensitive to lean conditions.
 
I heard that about the air box, but it was removed before I bought it. Does a standard exciter box work?
 
In addition to the above recommendation of re-installing the air box, I'd recommend finding a cold air intake - best to have the engine getting cold air instead of hot, under-hood air.

The SX engine was around 92-94 hp stock - DynoTech says SX w/ PSI twins was 104 hp - CAI adds 2 or 3 hp for estimated 106-107 total.

DynoTech tested '94 VX 600 - 98 hp stock, 107 hp w/ PSI twins.

I'm not entirely sure how much can be gained through clutching but I'd suspect that, like all others from this period, there was a bunch left on the table there.

If it were me, I'd leave the SX as is - twin pipes & CAI. There isn't much more to be gained from porting and/or boring, and it would hurt the sled's desirability as a collector's sled down the road - and this one will be a collector's sled! If you need more power, I'd suggest you look for another sled, and leave this beauty alone!
 
I agree. I don't want to hack this sled up, that's why like to look into putting a different clutch on or adjusting the stock clutch instead of changing the motor. Last spring I had the cylinders honed and was told that the center of the cylinders are wider than the top and bottom. So I'm going to be resleeving anyhow and that's where I was going with the over boring questions. Is there any significant gains or am I better off going with stock sleeves. I'm also looking at getting another SX without a top end so I was thinking about using the vmax 600 top end, if buy it.
 
The SX cylinder is basically a standard exciter cylinder that has been ported, and as far as my understanding its ported about as far as it can go, so there is nothing to be gained by attemting to port it.

Any Exciter II airbox will work. they are the same.

With clutching you won't really gain any power, it really just controls how its put to the ground. I have a 89 exciter and i found that stock it engaged a little to low for my likings, i am running a comet clutch with a stiffer spring and heavier arms so it opens later in the rpm band and it opens a little faster and more aggessive. I'm running a stock secondary with a new SX secondary spring. I also have flat slides tuned to SX specs and a PSI single. 8 tooth drivers up front gave me a slight amount of bottom end but to be honest I didnt really notice. i did drop from about 90mph top speed to around 85 on the railroad grade. i'm going to be gearing to SX specs to add even more low end as well.
 
Is the comet clutch a good one to use or is a newer stock clutch going to be better? I've noticed a lot of aftermarket upgrades for the newer stock units. Do all of the newer ones fit?
 
Find a PSI 650 Genesis kit. Good for 118-120HP with your PSI twins and 44mm carbs.

Mark
1973 GP643 for sale
 
I ran 44's on my exciter with a psi pipe, awsome. You will have to port out the intake to except the larger flange. I believe the bolt hook up was the same. I ran prefilters on the spigots only. `108 comet cant remember the weights, I just know very heavy and knotched. somewhere around 4500 rpm engagment.
 
44mm carbs that are aftermarket or did you bore out the 38mm stock ones? Also, do both vmax clutches fit or just the primary?
 
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My sled started has a 1987 107HP Bender Terminator/Exciter. The original owner upgraded to a 650 PSI Genesis kit in 1989/90. 10 port/reed valve cylinders,Genesis head and IRS(or 44mm carbs)48mm Fuel injection. Made 119.1HP on C&H's dyno. Uses Yamaha Watercraft 650 pistons. These kits show up on Ebay every once in a while.

Mark


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You have to replace the original 38's if you bore, you can only safely go 40mm the round slide is only 44, this only give 2mm on each side for stoping air bypass. You can now find many 44mm round slides on ebay.
 
I saw a 1989 exciter last year with that kit on in but a piston was bad and I didn't think I could get the parts so I passed on it. If I had known that it was a genesis 650 motor I would have bought it. The guy only wanted a couple hundred for it with an extra pair on cylinders. Now I'm looking for one and can't find it. Anyone have one or know where to get one?

As for the clutches, will a srx or viper one fit?
 
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the sx cylinders intake are 2mm closer then other exciters i had good luck with a bender pipe upgrade to a newer clutch take my word on this the buttons<plastic >are differant on the next year.ive spent many hours on mine and had to upgrade and use cat weights with a pin kit to get it to work they way it should.
 
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