I want my 550/750 conversion to backflip. Help and give opinions

[kwakhead]

Felt like throwing that last pic in lol

 

[faceplant]

dude thats badass!!id say scrap that modded stock pipe for a factorypipe,a 650 one should fit,or if u can squeeze a 750 factory pipe in there,run 200 Plus psi and hold your nuts lol

 

[kwakhead]

Idk what you're smoking but it must be some strong sht, a 1100 outputs 120 hp, that's your engine with another cylinder. And a chamber that stock lets the engine breathe very well... I guess everyone can dream


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a factory pipe alone adds 25hp to a 750 sxi engine, making 75+25 HP = 100hp already, then I'll run 220lbs compression, lightweight flywheel, power reeds, already has ported cylinders, and can't forget brand new NGKs lol

 

[kwakhead]

dude thats badass!!id say scrap that modded stock pipe for a factorypipe,a 650 one should fit,or if u can squeeze a 750 factory pipe in there,run 200 Plus psi and hold your nuts lol

can't fit any other pipes sadly this stock pipe has worked perfect this far though, I'll open it up a ton for the next set of mods. Maybe a magnum pump and trim later if I get the $$$

 

[faceplant]

do it!! and take a good video of it!like to see this happen

 

[kwakhead]

Some am hulls backflip with limited nodded Sj engines. Why would this engine and hull with planned mods not be back flippable? I see it as already done

 

[kwakhead]

Take me another month or so to get to it, but I don't screw around, I finish things quick. I got to finish my superjet build, and the three other customer's 650s first

 

[kwakhead]

Busy garage lol

 

[faceplant]

i see!good stuff man


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[theVetteman3]

Kwak your ski would have so much more interest on pwctoday (seems like that's what you're looking to get)

Indeed it would... most of the conversion guys are over there.

Are we talking flat water flips? In my opinion, going on my third year with a 550/750, it'll take a lot more than simply 130hp to flip this thing. Find a good Kawasaki based parts set up which flips an aftermarket hull. A JS will be harder to flip than that hull. Quantify the differences between what you've got here and that hull, and figure out how to compensate. Does that make sense? On what hulls can a 130hp set up flip?

For example, if there's 30 lbs more weight, that is HUGE. How will you move weight around, or work to offset that increase in weight? Will you need to increase thrust? Also I'd go with the biggest mag pump which can fit. I'd be worried anything you put in a 140mm wont be steep enough. Again find someone with a hull that has all kawi parts can tell you what flips in their hull.

Also I think the JS would need so much reinforcement to make it strong enough that you'd end up adding weight instead of removing weight. The basic JS hull is heavy and weak.

If ever I was bored one day, I'd like to work with someone to make a carbon JS hull with an improved bottom taking cues from the sxi pro and sxr. A strong carbon or even fiberglass JS hull with a 140mm pump cavity would be amazing.

 

[theVetteman3]

Some am hulls backflip with limited nodded Sj engines. Why would this engine and hull with planned mods not be back flippable? I see it as already done

Because those a/m hulls are way more optimized for that task. All details even down to the pole and pump placement. Do those skis with limited engines have basic pumps? My gut is if only a pump swap and a limited 750 was required to do the job, it would have happened not too long after the 750 engines came out.

Oh and one more HUGE thing. You'll need a good pipe. When you figure out your hull mods, at a minimum you'll need the factory wet pipe. And even then, probably that wont be enough. you may need to figure out how to fit a sxr dry pipe on that 750 engine. That's about as good as Kawi pipe design gets currently.

Even for now, I would not at all run that 650 pipe on that 750 engine. It'll choke it like crazy. That pipe will not add hp to a 750 engine like putting the cheater pipe on the stock yamaha engines will. Yamahas come with mufflers, with no convergent or divergent cone sections. I think you very well could be down on power over a stock 750 with this set up. I'd say a PJS 650 pipe is the minimum you should have. I use that pipe because I like the linear power band. For max hp without modding the hull, the 650 factory pipe is your only option. Jetpro second. If you can get it to fit, the big Coffmans pipe would be third.

Seeing it as already done is sure as heck jinxing your chances.. lol. I think by the time you're done you will have spent more $$$ (materials, labor time) than what you could get an aftermarket flippable hull for. But prove me wrong, I want to see one of these flip!!!

 

[kwakhead]

A factory dry pipe sucks for bottom end. If I'm gonna get a pipe- its gonna be a b pipe. Even still I'm thinking dual sbn44's. And yes, I'm carbon reinforcing the hull. It may be heavy, but not as heavy as a normal Sj hull, and some can backflip a Sj hull with the right setup.

 

[theVetteman3]

No, an improperly set up dry pipe sucks with bottom end. Particularly without ECWI. Power Factor pipes are dry pipes. But I'll agree that the sxr pipe is extremely heavy. But a wet pipe wont make the same power, so you'll have to increase displacement or something to compensate.

I think you'll need more carb than dual 44s. Those will limit your power and throttle response too maybe a little. If you're going to spend all this effort too, if I was you I'd bore out the 750 cylinder as much as possible, to get the max hp boost (however small) from the bump in ccs. I think about every 50ccs or so is ~5hp, but its been a while since I asked an experienced friend.

If you want max power, as a guideline a perfect superstock sxr 800 engine makes ~160hp. Thats a superstock ported cylinder, factory pipe dry pipe, dual 48 Novis, Advent, ect.. all the goodies. The best racing wet pipe Kawasaki 750s from back in the day made ~120-125hp, or about what a perfect limited sxr does today with the factory dry pipe. So if you're going to just have a well set up B pipe engine with dual 44s and pump gas compression, that'll be probably just over 100 or so.

 

[kwakhead]

No racing fuel. Planning on 210 lbs compression. Didn't want to go much bigger on the carbs because I don't want to constantly replace my reeds. Another bore out and rebuild is out of question. I hate rebuilding good motors, I feel like I'm wasting parts and $$$ for just another 5 HP.

 

[kwakhead]

No, I am running racing fuel I meant.

 

[kwakhead]

I believe dual 44's will be sufficient. I believe my hull is more than capable, just need a proper engine, pump, and trim setup. Then I'll be back flipping a "550"

 

[MikeyB]

Sounds like you have all the answers you need, now go out and do it already!


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[kwakhead]

It'll take a while to clear out and start! Lol

 

[kwakhead]

I can't possibly fit a dry pipe in my ski. My stock pipe is modified to a dry pipe as of now.

 

[Quinc]

I am sure dual 38's would be enough or maybe even better for the low end snap you are looking for. Before you dump more money into it you might try practicing off boat wakes first, or if you have anyone in the area who has experience b/fliping a ski ask them to try it on yours.