MZ trackbike engine rebuild.

[Gazdaman]

Ok, story begins as of Easter sunday 2006.

https://www.gaz-racing.co.uk/images/Silverstone/Full/Mz-fresh-orange-cropped.jpg

I was happily hooning around Silverstone when I seized.
To cut a long story short Dad took it apart and found the big end had gone. So Dad bought a crank and con-rod off eBay for £16. Bargain.

Now the task of splitting the cases to fit it!

Just take it as read that we split the cases. (Dad actually split them because with my rash decision-ness I left 3 bolts in and just kept hitting it harder and gave up).

So we'll start the story from the re-assembly.

https://72.9.145.220/~bristolb/images/MZEngine/IMG_9348%20(Small).JPG
New main bearings and crank oil seals. We also built it into a set of new eBay crank cases which cost £9

https://72.9.145.220/~bristolb/images/MZEngine/IMG_9356%20(Small).JPG
I swapped over all the bearings from the old crank cases with the aid of a blowtorch and a 'drift'. (Read big 'ammer). I greased up all the bearings thoroughly before putting them in the new cases and placed the gearbox in.

On my first go of slotting the gearbox in I got it all in upside down, and wondered why I could only get two gears!

In this picture the main bearing and oil seal are already in the casing. The crank is then placed into the main bearing. (By placed, I mean 'ammered).

https://72.9.145.220/~bristolb/images/MZEngine/IMG_9384%20(Small).JPG
With the con rod held by 2 extension bars and 2 bits of wood I could press the clutch onto the crank. The primary and secondary drive gears have already been put on in this picture.

You need a shim to fit over the crank but press against the clutch, then tighten down the nut to press it onto the crank.

Instead I used 2 15mm spanners. Did the trick.

https://72.9.145.220/~bristolb/images/MZEngine/IMG_9386%20(Small).JPG
Clutch cover back on, I fabricated a blanking plate out of aluminium to block the hole where the old oil pump was. Otherwise gearbox oil pisses out.

https://72.9.145.220/~bristolb/images/MZEngine/IMG_9390%20(Small).JPG
Front sprocket on, minus 3 teeth.

https://72.9.145.220/~bristolb/images/MZEngine/IMG_9393%20(Small).JPG
Tarty stator and generator (electronic ignition system) pressed onto the crank, barrel studs in, and piston replaced.

The piston has lost a piston ring because it was broken. They have 3 anyway as standard, so I'm just going with 2.

New base gasket too.

https://72.9.145.220/~bristolb/images/MZEngine/IMG_9394%20(Small).JPG
Empty shell of a bike looking sorry for itself.

https://72.9.145.220/~bristolb/images/MZEngine/IMG_9395%20(Small).JPG
Right crank case on, barrel on.

https://72.9.145.220/~bristolb/images/MZEngine/IMG_9409%20(Small).JPG
Engine back in. And it runs! I can even select all the gears. I havn't had a chance to test it properly. So Llandow in June will be its first proper test.

https://72.9.145.220/~bristolb/images/MZEngine/IMG_9415%20(Small).JPG
Took a trip to a local racer's house today, came home £50 lighter, but with 2 spare engines.

The MZ will live another day!

Gaz

[Mr.Everready]

And again

https://www.bylow.dk/Nonsec/webselv/bylowweb/img/20/Redex_logo_lille_150dpi.jpg
____________________
the undemocratically unelected mod of the Scottish section

[Gazdaman]

Works for me, and others..

That domain name seems to have problems for some people. For the majority it seems fine though.

Gaz

[Mr.Everready]

It's working now, you change anything ?
____________________
the undemocratically unelected mod of the Scottish section

[pwntifex]

Legendary.
____________________
the warped one: This is a follow up from the thread 'my willy hurts'

[Gazdaman]

[2Smoke]

Gaz, you are lucky!! Good cheap bikes to rebuild those MZ's! An rgv will cost a fortune to do, plated bores, expensive cranks!

I'm suprised you didnt have any tuning work done whilst it was apart?

Also, this:
https://72.9.145.220/~bristolb/images/MZEngine/IMG_9384%20(Small).JPG

Is not good practice, it can sometimes elongate the small end scrapping the conrod!

Paul
____________________
Currently in the stable.. '89 TDR250, 86 NSR250 '79 350LC, '79 DT175MX, 82, Pasola, '98 R1, '95 Speed Triple.. all of them total sheds..

[Gazdaman]

Seems the fairly widely accepted method of arresting the engine...

I wasn't putting a huge amount of pressure on it but I see your point.

I was tempted with some tuning, but tuning on these things involves mainly barrel and head work, with a yamaha con-rod. The yam con-rod obviously involves getting the crank pressed apart, new big end bearing etc and the cost goes up.

I just needed a working reliable engine for trackdays. But now I have the spare engines, I can use one on track whilst I tune up the other.

They also modify 5th gear aswell, to change the ratio I assume, but I couldn't really be arsed with that. So I did put plenty of thought into tuning it whilst it was apart but decided this was the best course of action.

Gaz

[MarJay]

[Gazdaman]

The MZ engine is as simple as an engine can get really. And I found it quite difficult and I was very worried about getting something in slightly wrong.

If it was a liquid cooled twin with powervalves and other assorted gubbins I wouldn't want to go anywhere near it!

On the other hand, if you take it slowly, take lots of pictures as you disassemble it's just big lego.

And those pics make it look like less than a days work, which it probably could be if I was more confident. In reality, it took the best part of a week.

Gaz

[MarJay]

[Gazdaman]

Getting the old crank out was not pleasant. It involved hitting it /hard/.

We knew it was scrap though. I suppose if you don't try it you'll never know if you can do it.

It's when the cases do finally split and an entire gearbox falls on the floor and you think "where the fuck does all this go?"

Gaz

[Wave2k]

All this talk of blowing up big ends and small ends and whatnot, ahhh dont you just love 2-strokes.............not.

Exellent job though gaz that bike is a true legend.
____________________
Ducati 1299 Panigale
2009 Corvette C6 z51
RS125->CBR400->RXS100->GSXR750K2->Ducati749S->CBR600RR5->TL1000R->DRz400->RSVR1000->Honda VTR SP1->CBR400->GSXR1000K6->Honda H100->CBR600RR3->Ducati1299

[Vin]

Interesting stuff.
To hijack the thread again.
1. What bike is the seat unit from?
2. I'd be really interested to see a photo of the rear brake linkage/rear set.
Cheers.

[DOS]

I don't think I would have beleaved it with out the pictures.
Good work Gaz.

Paddy.

[Gazdaman]

Seat unit is from a TZ 250.

And the rear brake set up is a full on bodge up job. There are closer pics of it at www.gaz-racing.co.uk under 'race bike project'.

Thanks for the comments

Gaz

[Vin]

Thanks
Off to look now

[Gazdaman]

Well, llandow was yesterday and the MZ went really fucking well if I'm honest.

https://www.motographs.co.uk/images/010607-Llandow-SWB/All-pictures//Small/IMG_9724.JPG

The volume of smoke was pretty much comical.

https://www.motographs.co.uk/images/010607-Llandow-SWB/All-pictures//Small/IMG_9736.JPG

But yeah, it handled really well, brakes were pretty damn good, all the gears worked, so I think it can be deemed a success..

I felt it starting to tighten up towards the end of the session so I came in. Don't know if it was nipping up or if it was a fuelling issue, but either way it was brilliant.

Only did 1 session on it though, first session I went out and forgot to turn the petrol tap on, so I managed to get it as far as the first marshal post, about 100yds onto the track.

After I turned the tap on it didn't want to bump start, so back I came on the recovery truck.

Then I borrowed a GS500 from the organiser, he's a cab driver and some drunk bloke couldn't pay so he gave him this bike that had been sitting in his garden.

I was second person out behind the instructor (the owner of my ride), after the two laps of no overtaking I tried to outbrake him into the bus stop only to lock the front wheel and fly past him in a puff of smoke and squeeling. Dodgy.

Then I took a mates SRAD out.

So 3.1 sessions, 3 bikes, knee down on all of them. And a well behaved MZ.

Love it.

Gaz

[DynaMight]

It was very smokey!! I was out the same session as you yesterday (Black 03 636 with Red/White roof helmet) Heres a pic my mate got of you

https://i118.photobucket.com/albums/o114/DynaMight/SWB%20Trackday%202007/th_DSC_0651.jpg
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My bikes are at https://www.bikepics.com/members/dynamight/

[paulodd]

the beast did run well. only managed to get a couple of pics....

https://i22.photobucket.com/albums/b336/coventrybikers/DSC01080-1.jpg

https://i22.photobucket.com/albums/b336/coventrybikers/DSC01086-1.jpg

https://i22.photobucket.com/albums/b336/coventrybikers/DSC01090-1.jpg

https://i22.photobucket.com/albums/b336/coventrybikers/DSC01091-1.jpg




Then gaz arseing about

https://i22.photobucket.com/albums/b336/coventrybikers/DSC01083-1.jpg

https://i22.photobucket.com/albums/b336/coventrybikers/DSC01081-1.jpg




Was a good day out!
____________________
Paul
1999 Yamaha R6
www.coventrybikers.co.uk / www.norfolkriders.co.uk

[Luke_Retrofly]

So when you racing with BMZRC then gaz

Luke
____________________
Flounced - Long overdue
Fuck you bitch I'm in the top 10 list I can do the what the fuck I want!

[Gazdaman]

As soon as I can afford it! I think that bike's up to it tbh. I'm aiming for when I come out of uni. Still gives me time to sort out engine tuning and 17" wheels.

Nice pic Dynamight. Did I pass you? Akrapovic can?

Gaz

[DynaMight]

[Gazdaman]

Ah, I think I was just snapping at your heels for a while.

Nice pics, was hoping there'd be some decent pics of the MZ since it rarely gets an outting.

When's the DVDs gonna be ready to go out?

Gaz

[Luke_Retrofly]

Hi
I reckon you would do well on your stock MZ, you seem like a proper MZ racers, a proper loon, the only way to race em I guess.

What do you need those brakes for anyway .

Luke
____________________
Flounced - Long overdue
Fuck you bitch I'm in the top 10 list I can do the what the fuck I want!