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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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Good stuff Ronski !!

Cant wait to see more pics
Ok ive this internet thing sussed now... more pics

got the engine block and head back from the shop. He honed the bores for me, pressure tested the cylinder head, gave it a light skim, took out all the valves, put in new valve seals, recut the valve seats, lapped em all back in.

garage needs a tidy:

freshly skimmed:

nicely honed:

now to rebuild the fucker:

seriously, this is like porn to me:

Pistons in. nice new rings. Circlips are cunts, arent they? PING

Cylinder block on. That wasnt easy.

head on. finally got to use my shiny new torque wrench

cams and followers in. slathered in oil. good word, slather.

just had to put the rocker cover on, and it was ready to go back in the bike! over a couple of evenings we got the motor back in, rad and exhaust back on, fluids topped up etc.

while the engine was out, i sent the oil cooler and rad off to a radiator place where they cleaned out all the fins properly and pressure tested them. Whatever they soak the rads in to clean them must strip off the coating too, cos they came back to me freshly painted too.

While i had access to parts such as the steel fan housing, oil cooler mounting bracket, rad guards etc i got all the rust off with a wire brush and gave them a proper painting with red primer and black hammerite. they wont rust again in a hurry!

so this is how she looked for the first test ride:

is that oil leaking on that nice clean forecourt? FUCK!!

turned out thet the oil was from the various banjo bolts in the plumbing around the oil cooler, despite using new copper washers. had to coat each washer with silicone and reassemble it all. it did the trick.

what was another problem was that the engine seemed to be overheating like a bastard. even though the gauge wasnt budging at all. Turned out i needed a new fan switch, new sending unit for the temp gauge, and when i opened the thermostat housing to check it, it wasnt there! some twat of a previous owner had obviously taken it out when it wasnt opening.

and that, kiddies, is where i leave the story for now, cos im off to bed :rolleyes:
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That's super cool, I want to try rebuilding a motor some day, for the mechanically minded is it that hard? enjoyable or a massive pain in the arse?
The only thing I found with rebuilding an engine is the pistons are a bit fiddly and if you arent 100% sure what to do, it can be difficult "guessing" cause no one wants to guess wehn you have an engine in pieces!
yeah, u just have to take your time and be sure of what youre doing. Haynes manuals are the business. Its actually really enjoyable if youre into that kind of stuff, so Mitch, id say go for it. The sense of satisfaction from riding something you stripped and rebuilt yourself is fantastic. youll know every nut and bolt on your bike, and that has to be a good thing.
oh, and when you get the motor back together, no matter how careful you were doing the timing, make sure you crank it over a few times by hand before starting it up, just to be sure
Great work there Ronski

That's exactly where I'll be in the near future although I'll be rebuilding the head myself. I'll get the seats re-cut (or replaced if necessary) and the head skimmed but I bought myself a lapping tool and a valve spring compressor to do it myself. I have an original Kawasaki workshop manual so as long as I follow the instructions I feel I'll be OK.

I reckon my main blessing is that a.) It's only an 8 valve motor and b.) it's air cooled.

Looking forward to seeing it with the rest of it's clothes on too mate.

Merudo said:
how was the condition of the camshafts?
they were good, no pitting whatsoever. at least the previous owner had the good sense to do oil changes so he wasnt a total twat
good stuff mate. I asked mostly out of curiosity really due to the fact that I'd heard these were susceptible to damaged camshafts if owners weren't up to date with their oil changes or ran them low

Looks like it's going to be a cracker when it's done!
Its like Easter for the bike !!!
ok where was I?

oil leak sorted, bike overheating like mad. ordered the following parts:

and fitted em:

dont new shiny parts just look so fuckin lovely?!
but fuck how they look, the main thing is that they work properly. Temp gauge now reading, and the fan was coming on properly. no more overheating!

time to put her clothes back on![hr]
K916 said:
Its like Easter for the bike !!!
and gettin this thing back on the road was like christmas for me!
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so, i finally got to put the fairings back on:

And she was good to go!

since then ive had the carbs out for a proper strip and clean. ive had a dynojet lying round since forever, but wanted to get the thing running properly before i fit it. she was still running a bit rough, wouldnt tickover, would hesitate when given full throttle etc etc. no amount of fiddling with the pilot screws would fix it. so i decided to fit a spare set of carbs i had aquired a long time ago, just to see if it was any better. Stripped these to clean them, and fuck me if they didnt have a dynojet kit already fitted..

put the new carbs in, holy fuck she was sweet. pulling like a train. so i fitted a K&N filter and it only got better.

next installment: the breakdowns, the alternator issue, and just what the hell is a Gunson Colourtune anyway?!
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H1 are a great bike sold my one some years back, had only 18k kms from new. Rock hard rear suspension, hitting a bad bump was like getting kicked in the arse.
Green sex!
Wish I had the time for a project, everyone seems to be working on something as the weather is getting warmer :(
All funds are currently being channeled into useless yet necessary shit
puddener said:
Rock hard rear suspension, hitting a bad bump was like getting kicked in the arse.
yup, that ohlins sticker is there for a reason
best thread ever ronski!

very interested in who did the head work and rad/oil cooler. were the prices reasonable? i have my ever looming zx7/9r project all around me and as i have the 9r lump out, may aswell do some head work so i'd be interested to know.
Orange, youre in cork right? I left the head, block and pistons into cawleys on forge hill. He charged me 500 euro. Hes out of business now, and i feel he overcharged me anyway. I asked him to polish the inlet ports, and when i got the head back it looked like someone had just stuck a dremel into them and waggled it around a bit. As far as i know, he outsourced most of the work to murphys engine reconditioning. He got the piston rings for me and fitted them, but im sure i could have managed that myself..

dont have a number for murphys but everyone knows them i think. Cork engine centre in little island will do that kinda stuff too, i got my valve shims machined in there and they were good to deal with, none of this 'im better than you' crap.

got the rad and the oil cooler done in lee radiator services in the marina business park. that was kinda pricey too, over 80 euro i think. But the guy there knocked a bit off the price when i moaned a little. And when u think about it, theres a fair bit of work in sitting down and straightening out every little fucking fin. And i was really happy with the result. Even tacked on a homemade 'fender extender' onto the front mudguard cos i couldnt bear seeing that lovely oil filter getting all clogged again...

your project sounds very interesting.. will the 900 engine go in alright?
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Yep, in cork alright, for once i know of all those places!
Great stuff, funnily enough i was looking at cork engine centres business card the other day and was contemplating giving them a buzz. Good to know bike stuff isn't beneath them.

Cawleys went out of business alright. I used the dyno a fair few times with different bikes, he was decent in that regard. I remember doing 3 or 4 runs in 1 day with the Tuono - I came back with different mods each time to see the improvements - I think he only charged me for 1 run, which was sound. But yeah, can't say much about his other services as i never had the occasion.

The 9r engine from the b1/2 model fits pretty easily - some small brackets are required - thankfully I have a BRG fitting kit, so no messing about.

For some reason I thought you were in Galway? Did you move to Cork recently?
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