Bike engine in 10ft jetboat

[TonyB]

Here's a weird one. A non-biker freind has just asked me to recommend a suitable bike engine for a jetboat. It needs to have a bit of power and be watercooled. Obviously that leaves plenty of candidates... I was thinking of a GSXR1100 or a Bandit 1200 motor, as there should be a few around and there's lots of knowledge about them. But they use a combination of water and oil cooling, don't they? He was hoping to pick up a road going bike cheap, ride it for a bit, then pull it to bits I can't see him picking up a water cooled 1100 or 1000 in road worthy condition very cheap though...

He has built another 10ft Jetboat using a turbo charged three cylinder Daihatsu engine, so he knows how to go about it. My concern with the bike engine is that the power is spread over a huge rev range: where a turbo car engine tends to make excellent torque and good power from 3k to maybe 6k revs, a bike engine will spread it's power over maybe 7 or 8K revs. Maybe that's not ideal- I don't know. Any suggestions?

[Devil]

Should be heaps of options. Yamaha's latest waverunner has the R1 engine in it, ive had a go on the previous model and it certainly gets up and fucks off.

Maybe find a pranged R1 or 'busa and scavenge.

[clint640]

Your common-or-garden single stage colorado jet unit runs best at around 4000rpm so ya want something with peak power about there, 100hp probably, basically ruling out most 4 cyl motorbike engines. How about a goldwing mill? they probably make good hp low down, one of the 6 cyl ones would be cool, but most likely rare & expensive.
If he's using a jetski unit however it will probably take higher revs & open up a few options.

Cheers
Clint

[**R1**]

Here's a weird one. A non-biker freind has just asked me to recommend a suitable bike engine for a jetboat. It needs to have a bit of power and be watercooled. Obviously that leaves plenty of candidates... I was thinking of a GSXR1100 or a Bandit 1200 motor, as there should be a few around and there's lots of knowledge about them. But they use a combination of water and oil cooling, don't they? He was hoping to pick up a road going bike cheap, ride it for a bit, then pull it to bits I can't see him picking up a water cooled 1100 or 1000 in road worthy condition very cheap though...

He has built another 10ft Jetboat using a turbo charged three cylinder Daihatsu engine, so he knows how to go about it. My concern with the bike engine is that the power is spread over a huge rev range: where a turbo car engine tends to make excellent torque and good power from 3k to maybe 6k revs, a bike engine will spread it's power over maybe 7 or 8K revs. Maybe that's not ideal- I don't know. Any suggestions?

Hey Tony, i have a mate whos got a GSXR1100 motor sitting in his shed, its a yoshi 1260, but its the old M model(oil cooled) let me know if your mate is keen? i will see if he wants to part with it.....sounds like fun tho

[TonyB]

Your common-or-garden single stage colorado jet unit runs best at around 4000rpm so ya want something with peak power about there, 100hp probably, basically ruling out most 4 cyl motorbike engines. How about a goldwing mill? they probably make good hp low down, one of the 6 cyl ones would be cool, but most likely rare & expensive.
If he's using a jetski unit however it will probably take higher revs & open up a few options.

He's looking at keeping the gearbox to keep it simple, so I guess it's a matter of selecting a gear that suits the jet unit?

Hey Tony, i have a mate whos got a GSXR1100 motor sitting in his shed, its a yoshi 1260, but its the old M model(oil cooled) let me know if your mate is keen? i will see if he wants to part with it.....sounds like fun tho

Not sure how that would work out, but can you ask your mate anyway? If my mate doesn't want it, I bet there's other KB'ers that would snap it up. I bet there's someone out there with an M, drooling at the thought of it right now...
Other options would be the original CBR1000 mill, as they are water cooled and have a faily flat torque curve. Were the old GPz's water cooled? He want's to keep it cheap.

[TonyB]

He's looking at keeping the gearbox to keep it simple, so I guess it's a matter of selecting a gear that suits the jet unit?

Worked it out for my FZR, which is the only bike I have info for gearing at the drive sprocket. If you want the jet unit to be doing around 4Krpm at the engines peak power the gearbox should be in first. If you want the jet unit to be doing around 4Krpm at the engines torque peak the gearbox needs to be in second. Works out just about spot on for the FZR engine, but he'll have a hard time finding one of THOSE, and he sure as hell isn't having mine!

[750Y]

i have a few ideas for engines that would make a good anchor for that boat...

[inlinefour]

i have a few ideas for engines that would make a good anchor for that boat...

Yea, but not many would do the job at sea. I spent a decade working as a deck hand and spent alot of time with jet boats. I'd suspect that a 10ft unit with a bike engine would be gutless and would not even pull one skier. I've seen 10ft boats with 350 chevs in them as a good unit...

[flipper]

Hmm I know a guy with a running ZZR1100 motor sitting on a shelf he definitely wants to sell, will be a couple of grand though but includes everything to make it go, ie loom, cdi, carbs, blah blah blah. Came of a bike that a mate put through some armco. They have a reputation for being a very reliable and physically strong motor. Better torque low down than R1's etc and a mechanically stronger motor overall (less stressed).

Cheaper than a Blackbird/Hyabusa motor.

Kawasaki claimed > 140HP stock at the crank and they were the fastest road bike of the early nineties (The Hyabusa of their day). Not sure how you get more power out of em but this guy will know if thats required as he as a ZZR1100 for his road bike as well.

PM me if interested

Cheers

[Coldkiwi]

ZZR1100's not a bad idea. Its got plenty more to give under tuning too I would think.

Funnily enough, I was actually chatting to a friend of my wifes on Sunday who races F3 jet boats and he told me about a boat that had used a bike engine, complete with gears but it didn't last too long. From what I learned, the drivers generally throttle the engine up to around 7-8000rpm (on f3's anyway, F1's might run a little lower) and leave it there. Taking corners apparently consists of leaving the throttle wide open, trimming the front of the boat down so it grabs the water, creating a huge drag to slow the boat, hoofing it round the corner and then lifting the nose out again! (and i thought braking for puke's hairpin was freaky!)

[TonyB]

Yea, but not many would do the job at sea. I spent a decade working as a deck hand and spent alot of time with jet boats. I'd suspect that a 10ft unit with a bike engine would be gutless and would not even pull one skier. I've seen 10ft boats with 350 chevs in them as a good unit...

I have wondered about that. Whats the approx output of a 350 in standard tune? I guess the bike engine would have the advantage of being significantly lighter.
ZZR engine could be pretty cool- maybe he could rig up a blower to pressurize the airbox, as they are set up for ram air.

[clint640]

A stock 350 is about 200hp.
A light 10' boat with 100hp wouldn't pull a single skier but would probably go alright, our 110hp (heavy ford V6) 12' tinny does 33mph & pulls a wakeboard or 2 skis no problem.

There would certainly be humour value in ripping past someone on the river & hooking another gear

Cheers
Clint

[marty]

this is a hell machine that runs 2 R1 engines thru jet units. it goes like stink - test drove it a month ago.

[Devil]

A stock 350 is about 200hp.
A light 10' boat with 100hp wouldn't pull a single skier but would probably go alright, our 110hp (heavy ford V6) 12' tinny does 33mph & pulls a wakeboard or 2 skis no problem.

There would certainly be humour value in ripping past someone on the river & hooking another gear

Cheers
Clint

??
We had a fibreglass Buccaneer 510 Cabin(16') with 90hp on the back and it'd do 60km/h easy. What makes you guys think a 10' boat with 100hp couldnt handle the jandle?

[marty]

i guess if it is propped/jetted for speed, then it would be difficult (look at ski race boats - their holeshot is crap, but they'll do 100mph). simply prop/jet it for holeshot. my bayliner did 80kmh with a 14 1/2 x 21 prop, but struggled to pull me out in double bindings, changed it to a 17 1/2 x 17, and it still does 70k, but has a totally different holeshot, and doesn't drag my fat arse for miles any more