My ZXR750M Engine Build / Tune

Barry_M2 · World Chat Champion Joined: 09 Sep 2004 Karma :

So, it all started around this time last year, I'd swapped my L model ZXR750 for a M (RR) model, but it had a small problem!!! (See first picture) Laughing

After initially sourcing an old J engine, pulling the pistons head and barrels from it and rebuilding the M engine, I got bored of it and decided to strip it down and do the job again, but with a few performance parts.

My shopping list was:

Wiseco 73mm (+2mm on standard) High Compression Pistons (now up to 793cc)
Barrels bored out to match pistons
Race Kit Ti flat face valves
Race kit valve springs
Ti spring retainers & seats
Full Factory Race Cams (these are items used in Aaron Slight's ex WSB bike in 1994)

The above items I had to get shipped over mainly from the US, but the cams came from Australia.

The pictures below show some of the progress of the job.

It's taken this long mainly because of house hunting in my spare time, and I dont like working in a cold garage!!! Laughing

So, I finally got the engine back in the chassis last week and after fitting a new battery, got her fired up for the first time in over a year, and she sounds lovely!!! Very Happy

While letting the engine idle up to normal operating temp, I noticed a small water leak, which on further inspection turned out to be a split O ring.

So, I hope you like the 'few' pics I took while doing the rebuild. Thumbs Up

PS: I did clean the head and crank cases up, but dont have any pics of that yet! Wink

____________________
ZXR750R (M2) - For the road.
CBR1000 RR4 - For the track.
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Odie · World Chat Champion Joined: 24 Jul 2004 Karma :

Why go to so much expense and not clean the engine?
Just an observation, was always told and have stuck by the fact that your work + surface must be clean when working on an engine, clean enough to eat off.
Stops bits of crud getting into your nice re-built engine and buggering it.
other than that looks a good job.
Odie
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You are so ugly when you were born the doctor said "I?m gonna drop it, if it falls is a rat, if it flies is a bat."

Barry_M2 · World Chat Champion Joined: 09 Sep 2004 Karma :

All metal surfaces were clean when I assembled it.

I have an engine stand (floor standing) I use when I rebuild my engines that holds them around chest height. The engine is on this in the last picture, but you cant see it.

The head was assembled in my living room as you can see from the pics. The barrels and pistons put on with the crank cases on the engine stand, I only moved it to the floor to change the mounting brackets I was using. And get an 'above view' picture. Wink

It's only the outside of the cases that were a little grubby, but they are now all clean.
____________________
ZXR750R (M2) - For the road.
CBR1000 RR4 - For the track.
https://www.bikechatforums.com/profile.php?mode=viewprofile&u=4332

quacker_boy · Cuddle Bitch Joined: 06 Sep 2005 Karma :

Are the flat face valves presumably to bump up the compression ratio are they? What's the ratio going to end up being with the pistons and valves then?

And what'd you mean by lapping in? Is that what i understand to be grinding in to get the valve seat flush with the head with a paste with an abrasive in or is it something differet all together?

I'll shut up now, think i've asked enough questions for the time being Razz

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wizzzard wrote: Imagine God just stopping by, tidying your front room up and then quietly letting himself out again. Statisticly more likely to happen than Korn being on here.

Barry_M2 · World Chat Champion Joined: 09 Sep 2004 Karma :

400bandit · World Chat Champion Joined: 21 Dec 2005 Karma :

That's pretty sweet. I kinda have a thing for them bikes and I'm not even a sports bike person tbh. How many ponies did it/will it make?

Top stuff

Joe
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Current Bikes 650 Honda Bros, VTR1000 Firestorm // Past Bikes: Sachs Madass 50/110cc - Bandit 400 - FZR750
(+ a XS650 in lots of pieces in my garage and other places...)

Barry_M2 · World Chat Champion Joined: 09 Sep 2004 Karma :

Not sure on power, I do need to get it on a dyno to get the fueling done. I'll be happy with around 130 at the wheel, any more a bonus.

I'm more hoping the torque is alot better than stock, which it hopefully will be with the bigger pistons.
____________________
ZXR750R (M2) - For the road.
CBR1000 RR4 - For the track.
https://www.bikechatforums.com/profile.php?mode=viewprofile&u=4332

Deano · World Chat Champion Joined: 17 Feb 2003 Karma :

when I bored my 400 to 433 the difference in torque was very noticablle, absolutely lovely.

Top job for doin it yourself, you dont see many peeps try these things themselves these days as peeps seem to be scaremongered into thinking that its Mission Impossible and so technically advanced that it puts them off.

my workbench when building my nc30 wasnt a clean room from independance day and it doesnt need to be as some may be lead to thinking. though I did keep it clean but before putting anything in the engine I just went over it carefully and cleaned again before installing. Also covered the engine with a dust sheet when not working on it to stop dust build etc.

top job are you gonna try and set up the fuelling/carbs yourself?

Barry_M2 · World Chat Champion Joined: 09 Sep 2004 Karma :

I've got quite alot of tools now, collected over the past few years. I ballanced the carbs myself, they are spot on, but the fueling can only be done on a dyno really, if you want it spot on. And I'd rather spend £50-60 whatever it is and have it right rather than guess. I think the fueling is pretty much there, but I'd prefer to be safe than sorry and have to pull it apart again.

I do all work myself, cars and bikes. There are very few people I'd trust with my engines etc.. I just cant justify paying someone £50 an hour for something I'm quite capable of doing myself, and not have to worry about quick turn round and risking a botched job!

Thumbs Up

____________________
ZXR750R (M2) - For the road.
CBR1000 RR4 - For the track.
https://www.bikechatforums.com/profile.php?mode=viewprofile&u=4332