Fitting an old m900 into an old m750

[fasterdammit]

I've got a '97 m750, with a custom-fit Sil Moto exhaust (custom, because that was the only way to make it fit), & a stage 2 DJ kit in its original carbs.  58k hard-earned miles on the engine and a dead clutch.  I have a line on a similar vintage m900 motor with its 6spd transmission - motor runs but has a dead cylinder - for a handful of magic beans.  I also have the hair-brained idea of buying this motor, replacing the bad cylinder and dropping in a pair of hi-comp pistons, and stuffing the whole assembly into the m750.  A couple reasons: I've always wanted to hop up an engine; it would be nice to have another gear and more power; because the bike is already non-stock (courtesy of an absent-minded Hyundai driver), and ... because, why not?

Presumably, at the very least, I will need shorter intakes and taller exhaust header pipes.  Possibly more appropriate ignition coils?  I don't recall if my '97 have Mikuni 36s or 38s, so a pair of carbs might be required as well.  What else am I not thinking of? 

Yes, I know, they make new/better bikes all the time - but I love my '97. I like the idea of hot-rodding it.  Making it a bit of a sleeper.  It'll take convincing me of my sheer & utterly complete lunacy to get this idea out of my head - but I'm willing to listen if somebody can convince me that it's a truly stupid idea.  Will it take effort, time & money?  Yes, I understand that.  Can I do most of it myself?  Probably (except modifying the exhaust, but I have a welding buddy who can handle that).  But if you say I'm going turn my frame into a pretzel, that could deter me.  (Although, I've already cross-braced the front engine mounts)

So there's my questions to you, dear readers:

1. Is this a worthwhile undertaking?  Or am I just a dumbass for trying.
2. Barring being a dumbass, what do I need to think about if I do this?

Thanks in advance for your input.  y'all rock.

[koko64]

Go for it. Although M900s are around with all the work done.

That's what Rudemouthsky is doing. He's going the Full Monty with it though, so I suggest don't go full Rudemouthsky, only partial Rudemouthsky Unless you want to and we will enable.

Here's a basic DIY recipe'.
JE high comp pistons
Ignitech Ignition
Exactfit coils
Light flywheel.
Jet kit and open airbox with K&N filter.

Optional, but awesome and $$$.
944 kit
FCR carbs*
Porting
Cams
Bigger inlet valve.
There is nothing stopping you giving the ports and intake manifolds a clean up if you are conservative and careful.

* Besides porting, with this mod you will feel a significant improvement in engine response.

[ducpainter]

The frames are the same, and if you get a 900 of the same vintage the mount bolts should be the same too.

Lots of info on Brad Black's site about carbs   bikeboy.org. I think they're basically the same. Koko's suggestion about FCRs is good, but be aware they're very different than the Mikunis and require a different start up procedure and a bunch of tweaking to get right.

I say go for it. You'll love the 900.

[MonsterMadMarty]

Go for it

I think the only major different between the M750 & M900 outside of the engine is the M900 has dual front brakes.  Depending on the $$$ you have just start by fitting the standard 900 motor. I believe the carburettor and ignition are the same so upgrading them can come later!

Nick at nick@angladaoriginals.com often has complete low k 900's for sale (pre 97 Monster 900's have the bigger valves in 97 the M900 got the smaller 750 heads with smaller valve for better low end torque)

[Duck-Stew]

(pre 97 Monster 900's have the bigger valves in 97 the M900 got the smaller 750 heads with smaller valve for better low end torque)

Big valves & cams have a 'V' stamped into the head.
Small valves & cams have a 'W'...

[koko64]

+ 1 there. Get the V head for sure.

[MotoPsycho]

Just a silly question. Would dual discs matter ? For me, I'm not going to go any faster with a 900 motor. I'm just going to get to the same speed faster. For my dollar, I'd leave the single disc and save a couple of pounds with better brake pads.

[Nibor]

Sounds great, but most importantly, what's happening with your old 750 engine? 

Partway through doing similar to my 750, but just upgrading the 750 engine itself with pistons/FCRs etc, not dropping in a 900.

[fasterdammit]

I love you people.  You're my new favorite crack.  Enable! Enable! Enable!

@Nibor - not entirely sure what to do with the 750 lump.  It began feeling a little tired, so I was already considering a refresh around 75k.  I'd like to think I'd rebuild it on the bench, then maybe find a frame to tuck it into.  Although, I've often daydreamed about adding a turbo or supercharger to a Ducati lump ...

Otherwise, the 944 kit was on my list at first too, but I thought I might get more-for-less out of a pair hi-comps.  Plus the over-bore would be more one thing I couldn't do myself.

Ok, you've made me feel less like a lunatic.  Or maybe more of a lunatic who has good company, which is even better.  Many thanks!  I'll be sure to detail things here if/when I take the plunge!

[MotoPsycho]

We're all lunatics in good company. When I was looking to do my 750 hot rod stuff I found out either the 786cc kit or a hi-comp kit was the same price, fcr's were double that. Add the 2 up and can still get a 900 for almost the same money and makes more power stock.

[SpikeC]

 You'll shoot yer eye out!