750 Engine Replacement - What would you use?

[Loud]

I'm looking for suggestions on how people would go about building a warm 750 engine.  It's for my '85 GSXR750.  It hasn't been well cared for and it has high mileage - the odometer has just gone around the clock and now reads 45km.  Rather than just blindly rebuild it I thought I'd ask the forum what they would do, were it them.

I know that a lot of people put Bandit engines in but that just doesn't seem for me.  My cars have always been rev-happy  twin-cams (Fiat, Renault Clio Sport, Peugeot 206 GTi 180)  and my bikes 2-stroke screamers, plus the say what now!? 600 I currently have.  The higher the revs, the happier I am - I love blipping the throttle and changing gears.

From what I've read, that seems to indicate that I should be looking for a Slingshot 750 motor which should bolt straight in.  That would also mean a cable-clutch, which I'm pretty used to.  But then there's part of me that wants to retain the original bottom end and build something a little special out of that.

The bike is going to be mostly show and only a little go, that's going to mean a Yoshi system and Keihin carbs.  More than that, I'd love to hear your thoughts.

Cheers for your time

[Captain Chaos]

What?

[vizman]

I like to take it to the dangerzone......re-build the 7fiddy six speeder!

[Captain Chaos]

or get a 600 engine, they rev even higher

[kokolis]

Just put a 1100f  engine, has 36 bhp more... haha

[Dr Jon]

+1 for thee 1127 motor. Not exactly a screamer tho but will do a good job of trying to pull your arms out of their sockets! 

[Loud]

5 hours ago, captain chaos said:

What?

Ha, I see what you did there   If it's of any consequence, the four year old water cooled Suzuki GSXR of six hundred ccs is for sale, to fund the slabbie.  So you won't hear any more talk about it from me!!

Guys, I realise that the 1100 is the popular choice.  Here in Australia the majority of people chug around on late model 1000s and drive automatic V8s, while I'm taking my bikes and cars through the gears and to the limiter and having a fun time of it.

Let's say that I kept the original bottom end that has been around the clock.  A rebuild is going to need new bearings, presumably still readily available.  Do the conrods fail around this time, or would they be right to go after a balance and shotpeen?  What about pistons, are they horrendously expensive (if the block needs more than just a hone)?  Or would a Katana 750 long block be an easier starting point - they come with the DOT heads, I think?  Then high comp pistons and new cams.

[zookrick]

If you want a real revvy top endy engine go for the 750 short stroke. I have a Teapot 750 with a header, GSXR cams, ported head and it screams, reminds me of my RM125 dirtbikes when I was a kid.

[Gammaboy]

If you want *really* revvy, chuck a gas turbine in it.

[Loud]

1 hour ago, Gammaboy said:

If you want *really* revvy, chuck a gas turbine in it.

Gas turbines are soooo sixteen years ago.

[Captain Chaos]

5 hours ago, Loud said:

Ha, I see what you did there 

no you didn't.

Stop talking gay car stuff on here, this is OSS.

PS: auto V8 >>>> high revving shitbox

[Loud]

27 minutes ago, captain chaos said:

no you didn't.

Stop talking gay car stuff on here, this is OSS.

PS: auto V8 >>>> high revving shitbox

Forum rules:

6. There is custom code built into the site that converts certain words typed into a different word or phrase. Do not adjust your television screens, these replacement words are for your own safety.

GSXR600. 

What.

And I've got no issue with auto V8s - Some guys just like to have a hand free when they're driving, no judgement here!

So, captain chaos, what's your best 750 combo idea?  I'm not looking to spend mega bucks, I just want to spend money on the right things.  If it's cheaper and easier to make a Slingshot/Katana/'85 GSXR750 go faster then I'm all ears.

But if you're keen to banter some more then I'm happy to see what you've got - time is on my side as of late and I could do with the laughs.

[vizman]

why not take some of time you have on your hands to read through the various projects and other threads on this site, I'm sure it will give you some ideas on the best way for you to make your slabby how you want it. depending on your budget, skillz, timescale etc, I'm sure you'll find some inspiration.

[Loud]

...Tough crowd.

I've had the bike for about two weeks and can't count how many hours I've spent researching my project - on this forum and others..  Truth is that it was mostly on another as I didn't come across this site until it was suggested to me.  Anyhow, so far this devoted search has lead me to purchase:

• CBR929 triple clamps for the added rake they'll allow (I learned that the hard way - I bought '93 GSXR triple clamps first)
• TL1000S forks (again the hard way, see above)
• KTM SuperDuke 990 wheels with 320mm discs front (reason for the TL1000S forks!)
• A GSXR1100 link to raise the rear - also a reason for (eventually) choosing the CBR929/TL1000S combo over the shorter  Hayabusa and TL1000R forks, to help me correct the rake
• '86 GSXR750 swing arm, due to it being 25mm longer like the '85 Yoshi race bikes
• CBR900 swing arm, to rob of its brace and TIG to the '86 unit
• Nissin calipers from a Bandit 1200S, as I didn't think the 6 pots really suited the look I'm after

There's a specific Airtech fairing kit and a Yoshi exhaust on the near-future list, I even have the general plan for the colour scheme. 

It's not like I'm wasting people's time, I've built bikes.  Here's a 2-stroker I finished recently (forum rules say this is cool to post) and it additionally has a Suzuki engine (although not the Suzuki badging required, but, again, it's a 2 stroker and the rules seem to indicate it's okay to post), just in case you missed it in my first post on the forum:


You might catch it in Fast Bikes magazine soon.  I tend to commend sources of help (when I receive it) as I recently did when it won Best European at Perth's Motorcycle and Scooter Show (before you ask it was entered as a motorcycle, not a scooter )

So, in summary, in the many, many hours that I've spent looking around, I've seen a million threads about 7/11s and only a small number on 750s - these were being rebuilt to factory spec. 

If you feel like sharing your forum knowledge and pointing me in the direction of some memorable 750 engine builds, that'd be ace - I'll happily read over them from there

Thanks for any help you might be able to provide.

Edited January 7, 2016 by vizman
Clarification [and a picture of a guzzi and an aprillia]

[KATANAMANGLER]

My advice on which engine to put into a 750 is invariably an 1100. Bandit 1200 engines are plentiful enough. If you fit a set of RS 36 carbs and dial in the cam timing to close the lobe centres it will move the power delivery further up the rev range. The accelerator pumps on the RS carbs can be timed to give a 2 stroke like kick in the pants. At. 130 BHP you can still wring its neck without  requiring Rossi like skills to hold it together. The idea that a lighter 750 Slabby frame with a 1200 cc engine would be anything other than a thoroughly engaging sensory experience would be misjudged. 

There is no replacement for displacement ...full stop,

look at the vault and read the article on the first 7/11. Conceptually, It's the very antithesis of the properties you describe and one of the original corner stones upon which OSS was founded.

So in conclusion, put an 1100 engine in it.

[vizman]

I was always looking for that extra gear after swopping my 750 for the 11....

[Captain Chaos]

8 hours ago, Loud said:

So, captain chaos, what's your best 750 combo idea? 

an 1100 engine of course.

[banoffee]

I'm happy with the mildly modified 750 engine in mine, plenty fast enough. Until I go for a ride with @Thestig and he's on his 1100 that is

[markfoggy]

Well if you really wanna be different about it, fit a watermelon engine from '94 or so. That's how Hammamatsu sought to keep things interesting as the years crept by. 

Now they really are cheap and have a higher rev ceiling than any of the Oil boilers. Conventional tuning on one of those (cams valves, flow etc) would keep you happy enough I'm sure.

[vizman]

 never go full retard

[markfoggy]

There are times when you just get so rude and obnoxious. 

Man wants a screaming 750 and he can bugger off to the Watercooled section if he ends up going that way.  I'll buy a B12 at some point, rip its guts out in search of glory and you can drag Cup-Cake across here.

Fair exchange.

[Gammaboy]

Wonder how much work is in putting a w/c in an oil cooled frame?

[markfoggy]

Engine will probably just bolt in, it's the plumbing that would be a nightmare.

Finding a rad solution that would give you front wheel clearance would be a major issue. Lot's of lateral thinking required.

[vizman]

cosmo had a 1100wc in a slabby 11

[Gammaboy]

37 minutes ago, markfoggy said:

Engine will probably just bolt in, it's the plumbing that would be a nightmare.

Finding a rad solution that would give you front wheel clearance would be a major issue. Lot's of lateral thinking required.

RGV 250 rad mounted high (where original oil cooler was), second rad under seat like an oil boiler race kit?

Split rads like a SP1/SP2 race kit?

Edited January 7, 2016 by Gammaboy