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Mean Green- ZXR750 H1 rebuild

65275 Views 138 Replies 33 Participants Last post by  Wurnman
my bike was sitting in my brothers garage for over 2 years, waiting for me to fix it. It just gave up on me one day and wouldnt start so i put it in his garage and slowly started to become one of those people who used to be a biker. Didnt like it that much. kept saying i would fix it, or get it fixed, but really didnt know what was wrong. I knew little about motors. but i had a manual and a socket set.

since i fixed it and got it back on the road, its been my pride and joy. seriously, i love it and ive done a ton of miles on it during the summer. (we actually had a decent summer in Ireland for once)

so im gonna put up some pics and describe what we did to fix the bitch. its been really enjoyable, and ive invested in some tools and even learned some stuff on the way. I also cursed a lot and threw some spanners around and lost some knuckle skin but thats a different story.

First off, we had to check the compression. It was brutal. Really low. but to get an accurate result, i needed the engine to be hot. the old girl had to be started for the first time in over 2 years. using jump leads and a can of easy start she fired up, after a lot of trying, and not before i managed to start a little fire. but it didnt damage anything and it looked quite nice, so that was okay. anyway, the compression was still really bad, as low as 30 psi on some of the cylinders. the manual says that the compression pressure should be between 139 to 213 psi. a squirt of engine oil into each of the bores brought it way up over 200, so at least we knew that the rings needed doing.

At this stage i hadnt even dreamed wed be capable of doing it ourselves, but after some astronomical quotes from mechanics, and during a night on the beer with my bro, we looked through the procedure in the haynes manual and decided "how hard can it be?"

D day arrived. bodywork off. rad off. exhaust off. chain off. all electrics disconnected. airbox and carbs off.

Engine out:

Awaiting molestation:

Dismantled the engine and sent the block and head off to an engine specialist. Cams, valve followers and pistons laid bare for your pleasure:
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I hooked it up too a car battery it spun over like fuck and fired right up! lol il check out the fan and i must remember to take more pics!!! hopefully have some pics of it fully built soon!! oh must get headlights!!!!
Right so, Im ressurecting this thread (again) cos I just had to rebuild the clutch on the fucker. I have now accepted that this project will never be finished and it will keep me occupied until well after I have grey pubes. And I shall annoy you all with every step along the way.

I was driving to work when I noticed that the clutch wasnt disengaging properly. Wasn't that far from home so I did a U-turn fairly sharpish and limped the bike back home.

(re: clutchless shifting, I know theres a lot of controversy out there about whether it makes you quicker or not, but it certainly gives you practice for when you have to drive a bike without a clutch. Just dont fucking stop. Ever.)

I had fitted a Hel clutch line not too long ago, so my first thought was that there was air in the system, not allowing the the slave cylinder to push the push rod far enough to disenage the clutch.

Bled the FUCK out of it, still no joy. Then, not one to be hasty at all, I decided that the master cylinder was at fault, so ordered a rebuild kit. Still no good. At least I knew it couldnt be the slave cylinder seal, cos I had replaced this not too long ago. But I still opened up the cylinder to see what was going on. Gave it a good clean and put it back on the bike.

Still no good.

For some reason I then had the mad idea that the push rod was too short (I dunno, maybe the evil kwacker pixies had come in the night with a junior hacksaw and cut off a couple of mm from the pushrod). Maybe.

So I used a couple of different things as shims to make the pushrod a bit longer. Did it work?

Did it fuck.

Thanks to a suggestion from a member on here (thanks vitamine27) I had the fantastic idea of opening the oil filler cap to see if I could actually see the plates moving when I pulled the clutch in. They were moving as they should. So why the fuck wasnt it working?

Right. Time to open the fucker up.

I didnt bother draining the oil. Instead I put a couple of planks of timber under the wheels, so the bike was leaning over further on the sidestand. Took the clutch cover off and not so much as a drop of lost oil.

And there it was

With the cover off, I could see that when I pulled the lever, the pressure plate wasnt coming out square from the bike, what was happening was that while one side was pushing out properly, the other side wasnt coming out at all, leaving the plates still engaged. Time for further investigation.

This is with the pressure plate off, and the clutch plates removed:

I have a spare engine, so in order to avoid going further than I had to, I swapped out everything Id taken off so far with parts from the spare engine: plates, pressure plate, springs etc. But the problem persisted. I had to go further. But this fucker was spoiling all my plans:

Yes, the dreaded clutch hub nut.

I went for the one on the spare engine first. I already have the head and block off so it was easy enough to lock the engine by putting an extension bar through the small ends of all the con rods.

To lock the clutch I decided to sacrifice some of the clutch plates to do this:

This wasnt my idea, it was suggested in the haynes manual if you dont have te correct 'clutch holding tool'. (Who does..?)

I then strapped the engine to a plank to stop it rolling around the floor. After this I thought it would just be a matter of buying the right sized socket, slipping it on and bobs yer uncle.

But no. Fuck me, that thing is on there tight. I eventually got the leverage I needed by robbing a five foot length of steel pipe from the neighbours barn. Even though I had the levrage, the main problem now was getting the socket to STAY ON THE FUCKING NUT. The clutch nut was so fucking shallow, it was hard to keep the socket from slipping off, and trying to chew the nut up in the process. I was eventually successful. Ill tell ya, the feeling of satisfaction was fucking immense.

Bent the extension bar that was locking the pistons together. Its now only useful if I want to go for a wobbly 'comedy effect' when im loosening a bolt. Im usually on my own doing this type of thing, so itll probably stay on the shelf.

Right then. I then turned my attention to the hub nut on the bike. "ha ha", I thought, "Ive already done this once, so this will be a piece of piss". I thought that I could put the bike in gear, jam a bar through the spokes of the back wheel, and use the drilled clutch plates again to lock the clutch. Combined with my five foot long breaker bar, it should be easy enough to get the nut off.

Not so.

Even with all that leverage, because the engine was not directly locked up by the pistons, there was a massive amount of 'spring'. I still dont know where this freeplay was coming from, so if anyone has any suggestions, let me know. Even with back wheel and clutch locked up, I could turn the breaker bar about 180 degrees, without any thing happening to the nut (with a five foot bar, this is no mean feat) Even after buying a three quarter inch drive socket and breaker bar, and enlisting the help of my brother and his mate (affectionately known as 'Mr Persuasion'), we had no joy. Even with a lump hammer.

I needed a rattle gun.

I went online to see what I could get. And there it was: A 240 volt half inch drive electric rattle gun with 450nm of torque. Thatll do. Ordered that fucker and an impact socket set. Then I saw the shipping time.

"Please allow ten working days for delivery"

Two fucking WEEKS?! From the same fucking COUNTRY?! Apparently, yes.

Eventually, about five hundred years later, a courier came to me with this

Oh yes...

Oh sweet baby Jesus, yes.

My brother was still expecting an epic battle. It was about as much of a battle as the yanks dropping the bomb on Hiroshima. Game over.

Not so tough now, YOU LITTLE CUNT

So then, this is the reverse torque limiter spring (An early attempt at a slipper clutch) Notice how some of the tangs are broken off. Thatll be replaced so.

It was all so easy from here:

Look closely at this picture. See those rivet heads?

That shouldnt be like that:

Or that:

It should be like this:

I thought i could hear somethng moving around when I turned the clutch. Luckily they werent able to get out and wreak havoc in the engine.

So know i knew what was stopping the clutch from disengaging properly. The strip down should have stopped there, however, I now needed to replace the clutch basket cos a piece had been broken off in an early attempt to lock the clutch using an old alternator belt from a hearse, a footpeg, and a pair of vice grips. Dont ask.

The clutch basket wont slide straight out, that centre bearing has to be pulled out first:

See those two holes?

See these?

See this?

For once, something easy! Thank you, Mr Kawasaki!

Heres the clutch housing, minus the clutch:

So here is the clutch assembly, laid bare for your pleasure:

Heres the clutch off the spare engine, all cleaned up and ready to go in

Torque limiter springs:

Original springs Vs heavy duty springs. Heavy ones were in there but the clutch was a right pain in traffic, so im gonna put the original ones in, if theres any problems with slipping or anything, itll be easy enough to put the heavy duty ones back in.

Clutch all back together and functioning correctly:

Now kiddies, its time to make a gasket:

Take a cotton bud, bend like so:

And give that oil level window a good ole clean.

Time for a beer :D

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Sat here pissing myself laughing :) ""Not so tough now, YOU LITTLE CUNT!"" that spare engine of yours is gonna end up as a spare piston ring when you've finished robbin the fuck out of it :)
^^^ So did I! I'm guessing this was written up some time after "Time for a beer". And Ronski, "And I shall annoy you all with every step along the way." Oh no you won't.

Great write up and I like how you explain the process of elimination in order to fix the problems you face along the way.

I wish I was this mechanically minded or at least had the balls to open my bike up like this. I have a tendancy to fuck shit up with stripping a bolt/thread or something similiar - always something very slight but enough to put a stop to all work :(

Quo Vadas said:
I wish I was this mechanically minded or at least had the balls to open my bike up like this. I have a tendancy to fuck shit up with stripping a bolt/thread or something similiar - always something very slight but enough to put a stop to all work :(

Oh the irony... The reason Im not driving my bike today is because I stripped a thread in the head when putting the camshaft bearing caps back on. All I wanted to do was adjust the valve clearances. So maybe, just maybe, youre saving yourself a whole ton of grief by not opening it up!

Me and my brother do all of the work on our cars and bikes to "save money", but in reality we usually break more along the way, or find out we need a tool or something at 5.30 on a Saturday. Now im sitting here, bikeless, cos I have to wait till tomorrow to get a helicoil kit.

Still, its all a learning experience.

Thanks for the positive comments lads.
Andydd7 said:
that spare engine of yours is gonna end up as a spare piston ring when you've finished robbin the fuck out of it :)
youre right andy, theres not a whole lot left, but still, Id say its paid for itself a few times over by now
ronski said:
Even with all that leverage, because the engine was not directly locked up by the pistons, there was a massive amount of 'spring'. I still dont know where this freeplay was coming from, so if anyone has any suggestions, let me know.
id say all the backlash in the gears between the motor itself and the gearbox, the gears in the gearbox itself, and the chain and sprockets. all adds up

i found that a 3/4 inch rattle gun gets clutch nuts off without even noticing that its even on a nut :lol:
Great write up. It almost makes me want to quit the rat race and work on my bike for a few weeks instead.... :p
good stuff mate. yeah rattle gun is always the go. the 240V ones are pretty decent these days too, and some of the rechargables ones are not bad either. obviously air powered is the best but it's a big hassle to buy compressor, air line, gun etc just for the odd home project.
lol @ the incredible gasket screw driver
Humbug said:
lol @ the incredible gasket screw driver
"The Incredible Gasket Scraper"
Lump of sharpened copper, cable tied to end of a flat blade screwdriver.
Patent pending[hr]
Epic stuff Ronski haha.
That clutch never stood a chance, rommel himself never had such determination!
Yeah its nice to get it back on the road alright. But not before I had to change the feckin cam chain too. And I stripped some of the camshaft cap threads, so had to get intimate with a helicoil kit for the first time. Hours of fun! Took loads of pics as usual so Ill do a write up here when I get a chance. But the weather is too good lately to waste time in front of a computer!

Plus, I just noticed I have a fork seal to replace now. Jeeeeesus...

The joys of it!
oo helicoil in the head... that sounds like a headache I don't want lol.
Right. Been a while since I updated this, and Ive done a fair bit to the bike since then. Namely:
New camchain.
Fitted Scottoiler
Brought the cunt to France
Had camera fall off back of bike at 220kph
Of course, this means I lost most of my pics too, so ill just post up what I happened to save to disc beforehand. Its a pity really, cos putting in the camchain was quite interesting, but all I have of that is this:

The reason I replaced this was because, after doing the valve shims, I noticed that with the tensioner removed the chain looked very slack. Also, when i installed the tensioner it looked to be near the end of its travel. So I said fuck it, may as well do it now. I thought my chain riveter would be suitable for joining the camchain, but it turned out that the split link that comes with the chain doesnt have hollow point pins. That meant that the riveter wouldnt work.

One trip to the toolshop later, and I was the proud owner of a shiney new ball peen hammer. Just so you know, if youre doing this, you pretty much defitinely need a second pair of hands. If you have a third pair of hands also, these can be put to good use by making coffee and rolling cigarettes. Thanks, Nick.

Basicially, you have to put the rivet pins through the joining link, put a block hammer behind it (to act as an anvil), and gently peen the rivet over with the ballend of the hammer. Its actually easier than it sounds, but its a bit tricky. Oh, and DONT drop the split link down into the engine. Thats a good tip. Thank God for magnets.

Its I pity I dont have pics of all this.

When all was done, I realised that the chain was too long. Like WAAAY too long. Rang the bike shop. He said yeah thats normal, just take out a coupla links. Fuck sake. Took out about ten links and started the process again. At this stage I was shitting it that id take out too many links or get the timing wrong but it all went back together ok. I was nervous that the rivets wouldnt hold, this being my first time doing it and all. But its been up to 12,000 rpm countless times since then so I guess all is ok.

Putting back the camshaft bearing caps should have been a piece of piss. But one of the bolts just kept on turning. Took it out to see the delicate aluminium thread still wrapped round the bolt. My thoughts went something like this: "FAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAARRRRRRRRKKKKK"

First thought was to tap out the hole to the next size and use an oversized bolt.

But no. There was no way it was gonna be that easy. The bolt has to go through a little locating dowel and an oversized bolt was too fat for this. So it was helicoil time

This is probably one of the cutest things ive ever seen

Drilling always makes me nervous

Stuffed loads of rags around the area to avoid getting swarf down into the head


Always lube up before you start, kids

No room for the tap handle, so this had to do

Tap that bitch

Putting in the new thread

That little tab just had to be broken off

Then these were ready to go back...

in here

The new thread worked great. However, I had another moment of disbelief when i stripped another thread. And another when the bolt snapped in the hole. Each time, the cams had to be taken back out and the timing needed to be done again. Fuckin hell, Im not looking forward to doing the valve clearances next time. And receding valves is a known problem on these engines. Great.

Right, Im bored. Thatll do for now
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the gasket screw driver is an awesome idea! Im guessing it's just to clean the leftover gasket without damaging surface.
Humbug said:
Use a torque wrench mate!
Fuckin did. U gotta be careful with older bikes, you dont know how much the threads have been weakened over time. So the others i just did by feel
nappa4eva said:
the gasket screw driver is an awesome idea! Im guessing it's just to clean the leftover gasket without damaging surface.
Yeah, its a bit of copper.. softer than aluminium so doesnt do as much damage as a screwdriver or stanley blade
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