What do I need to do guys?

[Ameritude]

Hey Guys, this is my first post on the sight, so if I ask questions that have already been answered just let me know. Anyways, about 3 months ago I bought a 440 invader which i think is a 78, the mfg number says 77 but I didn't think they were produced then. The sled runs pretty decent, it had been sitting for about 9 years under a tarp for about 5 of them, after about 5 hours of just replacing fuel lines and semi cleaning the carbs, it started on the second pull and has started first pull every time since. Its got a horrible clutch chatter and a bit of low end bog. It also floods out when you just let it idle right after starting the sled, to me this feels like carb stuff or crank seal leaks (yes I've heard to replace the crank seals). Here's my plan, i bought the sled for racing (I actually bought two, but the other one was pretty torn up so its just a parts sled) after reading how much people suggest replacing crank seals, I've decided its probably in my best interest to do so, I've also decided to do an entire top end rebuild since I'm going to be taking the engine out anyways. I'm going to be putting a comet 102c clutch on it, (I've had great luck with it in the past with my other race sled) and lots of woody's traction goodies on it. My question's to you guys are as follows: 1. best seal rebuild kit and piston choices. 2. comet clutch cam arms and spring, any suggestions here are greatly accepted, I'm looking for about 4900 rpm engagement, I know that's quite high, but it makes for a very good launch. (if you disagree, please let me know what you would suggest otherwise and why) 3. ski spreaders, I want the stance a little wider and was wondering what a good spreader size was, I don't love the idea of ski-spreaders due to stress on the spindles, but its the only way to widen the stance while staying within the class that I want to for racing. 4. Oil feed... I don't know what to think about oil injection. I have all the parts for it, but I've never trusted the thought of relying on a mechanical pump to feed my engine the only source of lube  its going to get, ever since I got it running I had removed the oil injection and run premix instead, but what I'm concerned about is that I read somewhere on this forum that the oil injection also feeds the mid seal, the one between the cylinders and I don't know if that's true or not. let me know what you know about it, I would prefer to run without it because it saves weight and is one less thing to worry about failing. The final thing is me just asking you guys for any tricks that you have found or know that could give me an edge on the competition, remember, I'm racing in the 440 liquid stock, so nothing too extreme. Thanks in advance guys -Ameritude

[Interceptor398]

Welcome to the site!!  That is a lot to digest in 1 answer so--keep the oil injection.  On these sleds are are near bullet proof.  I get some of my sled stuff here  https://www.mfgsupply.com/garage/vehicleparts/parts/snowmobile/kawasaki/1979/invader+440/.  Others will chime in and help!

[gixxer6]

The only failure with the oil injection that I have ever experienced is the shaft seal starts to leak oil into the belly pan.  The pump system is solid, and still functioned 100% despite the leaking seal.  I run the stock injection system on my 9000+ RPM highly modified drag race Invader (Intimidator) with zero issues.  Way too many positives to even consider deleting it. 

The comet app chart shows B-1 weights with a purple spring.  I'm not sure what that makes for engagement rpm, but it's likely close to stock.  I set up a comet with B weights and a red spring that I was going to run on the Intimidator, but switched to polaris clutches before trying it.  I don't recall what engagement was supposed to be, but I was shooting for around 5000RPM. 

I don't recommend the stock Kaw clutches for anything other than very lightly modified.  If your class allows it, switching to polaris clutches is a huge improvement.  From everyone that I have talked to, the comet clutches are very limited and most don't have great results on the Invader/Liquifires. 

As far as pistons, I always liked SPI or OEM.  Winderosa or Cometic both make good gasket kits, but I always recomment trying to find NOS 4/6 LTD two piece head gaskets as they are far superior.  https://newbreedparts.com/ is a great source for Kaw parts. 

Welcome to the site and good luck! 

[Ameritude]

So if i was to use a Polaris clutch instead, what would you suggest? I know nothing about Polaris clutches.. also what tuning bits should i put in it

[mswyka]

Ditto on the oil injection.  I had one failed pump - the result was that it pumped too much oil.  Our other dozen or so pumps are still reliable after 40 years.

[Ameritude]

Anybody ever put electronic monitoring on a sled? like EGT's and stuff? if so, how affective is it for tuning?

[Ameritude]

also, if i was to buy brand new vm 36mm carbs for the sled, what would I have to do to get them back to "stock like" jetting, or even better what should i do to get them to race like jetting...

[gixxer6]

I had a modified 4/6 LTD a few years ago that had Aaen Pipes and dual EGTs.  It was an ok tool for tuning, but for what I was doing with the sled it was unnecessary. 

I rely heavily on my wideband O2 sensor for tuning my car.  Actually, without the wideband, it would be impossible to tune effectively.  I've thought about installing one on the Intimidator, but I haven't got that far yet.  I was planning to do some research on the effectiveness of using a wideband on a two stroke motor.  Until then, I will continue to check the plugs. 

[gixxer6]

also, if i was to buy brand new vm 36mm carbs for the sled, what would I have to do to get them back to "stock like" jetting, or even better what should i do to get them to race like jetting...

If converting from the stock power jet style carbs to standard vm 36s, I believe you add the number of the PJ to the number of the main to get your new main jet size.  But I think a better question is; Why buy new carbs?  The stock PJ's work great unless removing the airbox (which I don't recommend). 

IMO there is no "race jetting".  There is only the proper air-fuel ratio.  Which is more or a range...As it will vary depending on air temperatures. 

[Interceptor398]

Stock carbs work very well if they are clean and have good gas.  Like gixxer6 says, they are meant to have the air box on.

[Ameritude]

If you don't mind me asking, what does the airbox do exactly? Im willing to give it all a try, I just want the best performance I guess. Is there a rebuild kit out there for the carbs or a gasket/o ring kit, ide prefer to have as many new things as possible, just to eliminate them from defects if I can.

[gixxer6]

The airbox does several things.  It creates a vacuum that allows for the proper operation of the power jets, it quiets the carb noise down (it's louder than you'd think without it), and it pulls cool clean air from up by the vents in the hood. 

No one really makes a "carb kit" for these...Contact https://newbreedparts.com/ and tell them what you are doing, they are familiar with Kawasakis and can help you with what you need. 

[Ameritude]

so if I didn't want to run an airbox (for easy maintenance at the track) I would have to run new carbs?

[gixxer6]

You can still run the PJ carbs, but you’d need to re-jet it. 

[Ameritude]

Gothca, have any suggestions for amount of spikes in the rear track? Im oval racing it and want enough traction but not enough to push me through the corners with 10 inch carbides