Good 680 Ultra Mods?

[arcticcatwill]

A friend just got a 97 680 rmk, bone stock fresh rebuilt for $650 with a brand new 144'', the bad is the seat and hood, sat outside for a while.
PSI or SLP pipes?
Do the make a boost bottle?
Are air pods a must have.
What id the best bang for the buck?

Will

 

[pura vida]

had a 96 ultra in a wedge chassis. is the 97 in the evolved? pipes make a HUGE difference on that sled. depending on your elevation you might try a different head and plenty of room for porting improvements with that motor, iirc. but i had a hell of a time keeping the thing from bogging out in any kind of powder after i put the pipes on. seemed that as soon as one of the pipes got an snow on it, it would cool off and fall on its face. never did get it to run great in deep snow but i really didn't know much about jetting/clutching/general setup then. probably the fastest sled across a lake i've ever had and it wasn't even geared for speed. not sure if that helps much but good luck and enjoy.

pv

 

[powdercraver]

The ultras are very front heavy. Go with a set of slp triples, youll reduce 35 pounds up front and your sled will rip and be a lot more manageable and floatier on the snow.

Good Luck

 

[modded93xlt]

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[miketolle]

SLP pipes will be your best bet. they get tricky to find and needles are a problem. SLP doesn't make them anymore, but you can get the diagram from them if you want to try to machine your own... SPX needles work with them too.. However they are harder to tune... I have heard alot of people haveing problems getting them set up with clutching and jetting to make them really shine.

what are the jetting specs for them?

 

[modded93xlt]

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[modded93xlt]

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[Neckbone_509]

slp pipes

I have the pipes,can, 2 sets of slp needles, one set of stock carbs and one set of board carbs (40mm) to match the pipes. I also have the mounting bracket for the can. I will sell as a set carbs and all for 300.00 very nice pipes!

 

[509kid]

psi mod blaster pipes, hands down my sled rips and im not too far behind the watercraft sleds when it comes to drag racin, hell i even beat em ah couple times.

 

[X2Freeride]

http://www.startinglineproducts.com/instsheets/09-680.pdf

there is the link to the instructions for the pipes, but just so you know jetting and clutching on these engines with SLP pipes seem to vary alot from engine to engine. Even SLP says to use thier guide as a baseline to tune from. I run 380 380 370 but know of a guy that runs the same set up with 420 420 410. I know mine runs ritch, but I wanted to stay on the ritch side to be safe, I am ok with any power loss i have from it.( better then having to buy a new engine)

Ah yes, there is nothing like the sound of a piped Ultra screaming down the ditch, field, or up the mountain. Ultra's can be tricky to pipe and your 100 percent correct in saying that they are tough to get set up just right. One thing about the Ultra if your tune on your pipes isnt right on 90 percent of the time the sled is actually slower than it was stock in good tune with spot on clutching, gearing, and jetting. Your right in running somewhat rich though as the Ultra's really tending to lean out on Long pulls on the center cylinder. I think if I remember right we ran 3 different jets in ours with the middle being the richest for that reason.

It takes time to test stuff to see exactly what you can safely jet to by piston wash and plug readings, to me thats half the fun. Nothing better than getting a sled tuned just right then gain 5-7 MPH on top with a simple gearing or helix change. The ultra is a little heavy but it can be a sick sled when it works right.

While I will agree that each sled is somewhat different run ability wise the large jetting differences your seeing was more than likely due to the fact that he was running different needles than you. Jetting and clutching are things that have no set order of operation you can get the similar results with very different setups.
But with the same needles if he was at similar elevations he had to be STUPID rich provided you both run the stock air box.

Back in the day HOT TO GO did some big things with the Ultra I think they made both a 800 and a 900 Kit for them. those were SUPER potent. The 900 made 180 Plus HP in pump gas forum. That would definitely offset any extra front end weight.

 

[X2Freeride]

A friend just got a 97 680 rmk, bone stock fresh rebuilt for $650 with a brand new 144'', the bad is the seat and hood, sat outside for a while.
PSI or SLP pipes?
Do the make a boost bottle?
Are air pods a must have.
What id the best bang for the buck?

Will

PSI's seemed to be more consistent and better running pipes for these sleds. SLP had a few issues with their pipes for these when they first came out first. We were one first people to try the SLP's they blew up the sled twice because the specs were so far off. SLP was great to work with though and made it right. After lots of testing and tuning we got it going good.

I cant recall that I have ever seen a boost bottle for a Ultra, Nor have i ever seen anyone run one.

If your going to ride the sled in any kind of powder you going to want to say away from pod filters, Also with pipes an air box makes tuning 100 times easier as pod filters just bull hot air from under the hood and hurt performance.

Pipes are by far the best bang for the buck along with spot on jetting clutching and gearing. Really wakes the sled up. Reeds IMO helped the sled out too. We also had a SLP airbox on ours as well... I dont know that youd be able to find one now days though they are pretty scarce.

 

[modded93xlt]

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[X2Freeride]

I have to say I really like you're imput on this. I have to rebuild my engine this summer, I am not sure what happened but it kinda blew up. I was leaking coolant into the engine. I went for broke to get back to the trailer rather then be pulled and ran it flat out for 15 miles. It smoked like mad! but made it back and I shut it down(didnt' die) pulled the engine apart and all the pistons and cases looked ok. So I am not sure why it leaked the coolant into the motor.

Anyhow, point is, I think it always had a small coolant leak, which I think is why I could never figure out how to tune it and am going to keep in mind youre thoughts when I rebuild it!

Thanks GREAT POST!

No problem thanks for the props. Any idea what base gaskets were used in the engine? some of the aftermarket ones were prone to leaking. You almost have to either use OEM gaskets or the aftermarket ones that are the metal laminate ones. You will get her running again.

 

[modded93xlt]

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[Snowlover]

Make absolute sure you check each cylinder degree timing to make sure you have not twisted a crank. The stock cranks would twist, letting one cylinder be out of time. It would still seem to run fine, but trust me, the cylinder will burn down again.

I will never tell you why I know this.

ModBlasters were awesome but terribly loud.

 

[X2Freeride]

I am not sure, the guy I bought the engine from said it was rebuilt at 2k and I have another 1500-2000 on it since I've had it. So i'm not sure, none of the gaskets looked torn but then again none of them looked to be in as good of shape as I would of liked to see. Thanks for the vote of confidence!

No problem, sometimes all it takes is someone else to be interested in your build to get your motivation going again. Its hard to say what exactly happened, the guy could have even put the base gaskets in wrong.... I've had Ultra base gaskets fail before a few times. So I went to metal laminate ones.

Too bad you couldnt find a HTG 800 or 900 kit. I know where there is a HTG 900 ultra based engine for sale.... cheap too!