MZ/MuZ Riders

In answer to my own question, I would not recommend trying a top end rebuild with the engine still in the frame. If you have a ramp to lift the engine to working height it might be o.k. but grubbing around on the floor with the forks/wheel in the way is not recommended. I got to the point where I just had the bottom bolt left and realised (after discussion with Tigcraft, who very kindly came over to help) that it would be much easier to remove the engine. I built an engine stand and worked on the engine on my workbench.Glad that I did because I managed to drop one of the decompressor cover plates into the crankcase. After cursing and berating myself for a while managed to recover the bracket with a home made magnet tool. Amazingly the bracket managed to bounce across the crankcase and into the hole by the gearbox. Discovered some light scoring to the front and back of the cylinder and the piston. Decided I might as well rebore and replace piston. Wiseco 10:1 piston on way. Anybody have any thoughts on gasket sets? Seen some adverse comments on Athena elsewhere but they are by far the easiest to get. Genuine Yamaha are very expensive and they don't seem to do a set. Used Partsharkworld to get Yamaha number for top end set but it isn't recognised by my local dealer. May try and get Cometic set from USA. Any advice gratefully received.
Justin

Can't go wrong with Cometic if you can get them.

I'll offer to re-ship the Partshark gaskets etc. to you in the UK.
I'm in Los Angeles and ship to UK / EU all the time. I know the lowest cost ways to do it......

hb7777@gmail.com


All the best,
Henri Baccouche
http://moto-science.com/
323-933-1366
skype shb777

pod35 wrote:Glad that I did because I managed to drop one of the decompressor cover plates into the crankcase. After cursing and berating myself for a while managed to recover the bracket with a home made magnet tool. Amazingly the bracket managed to bounce across the crankcase and into the hole by the gearbox.

It's amazing where parts will find to hide themselves. Was rebuilding a Goldwing engine many years ago and had just bolted the heads back on ( in frame) and my (now ex) wife was helping me by picking up odd nuts and washers I had dropped. Which she put on the tank. One of which rolled off the tank and with perfect aim dropped down the hole in the top of the head for where the coolant tube bolted on! Oh how we laughed............... much much later!

friend of mine had kids playing in the shop one night
they were launching small items across the shop (nuts and bolts) with a small trebuchet
he removed a spark plug on a BMW and stepped to the work bench
and a small nut made a perfect hit on the open hole
at least some one saw where it landed and it was recovered
dave

pod35 wrote:Just had my MOT and the tester told me that the bike was burning oil and was right on the limit for an emissions fail, so I'm going to rebuild the top end. Bike has 99500+ km so it's lasted pretty well. Here's my question; is it possible to get the barrel off the engine without removing the engine? If not has anyone built an engine stand or is it easy to work on without one?
Ta

Justin

Burning oil-like a 2-stroke?

Imagine trying to get an old Jawa through an emissions test?That`s probably why there isn`t one for bikes

Finally spoke to the MoT tester this morning. He said that there is no formal emissions test but he does check for visible emissions and can fail a motorcycle on those grounds. There's no doubt there was a fair bit of blue smoke. I always use this guy because he has a reputation for being strict - just what I want from an MoT.
Top end is off now and I have found scoring to the little end bearing, so the crank is coming out. Spoke to SEP in Kegworth who will bore and sleeve the little end and inspect big end. Will get them to do rebore and regrind valves while they are at it. Have also bought solid balancer gear.

Justin

A new con rod is only ~68 USD.
If you are going to split the crank......

pod35 wrote:Finally spoke to the MoT tester this morning. He said that there is no formal emissions test but he does check for visible emissions and can fail a motorcycle on those grounds.

Ask him to show you where it says that in the testers manual. I think you'll find it isn't there.

I'm all in favour of having a strict MOT, but I'd be sorely annoyed for failing on items that only exist in the testers imagination. (Although in your case, it does sound like it was time to sort the engine out anyway).

The examiner can refuse to test if

"The vehicle emits substantial quantities of avoidable smoke"

but it does sound like matey is being a bit of a jobsworth. Anyway here's hoping the rebuild goes OK

Thanks for finding that, therealche.

We seem to have veered off from the OP a bit, but that refers to the examiner being able to refuse to test the vehicle in the first place (and so can't charge you a test fee). However, that's meant to cover instances when you can't see what's going on in the workshop while the test is being carried out, rather than a bit of visible smoke.

However, you can't *fail* the MOT test because of smoke emissions on a motorcycle. There's no box for it on the DVLA computer to record that as a failure reason.

Back on topic, yeah, good luck with the rebuild.

Been a while but I've been busy.........too busy. What started out as a simple top end rebuild has got way out of hand. When I took the barrel off I found a lot of scratches down the bore and on the piston but no other damage, in fact without the scratches the bore would have been ok. Removing the piston showed damage to the little end, again lots of scratches and evidence of the pin siezing on the right hand side. There was too much damage to leave it so the con rod had to be replaced. Crank was duly removed (oh what fun we had removing the rotor/flywheel - many thanks to my friends at Motorworks) and taken to SEP at Kegworth for the crank rebuild and rebore. Incidentally the infamous balance shaft drive wheel keyway showed no signs of damage at all. Have obtained the solid drive wheel so will fit it anyway. I then set about cleaning the cases and gear shafts. Cases were fine apart from some paint bubbling on the bottom - undecided whether to repaint cases, but the gear shafts were in a bad way. The fifth wheel gear and the fourth sprocket gear were badly pitted (interestingly only half way round each gear and only on one face). Could this have been the source of whatever left score marks on the barrel,piston and little end? So now I need to replace the shafts/gears too. Happy days. Don't suppose anyone has a SZR660 cluster going begging? Enjoying the rebuild but not the cost, but hopefully there is nothing else needing work in the engine. Did notice a fair bit of play in the rear suspension when the engine was removed, knowing my luck there's scope for lots more money to be spent there.
Justin

A'up Justin.
I recently pulled the the rotor from a skorp fairly easily.
Remove the alen bolts that hold the rotor to the starter sprag then spin the sprag so the threads in the rotor don't line up with the threads in the sprag,
then screw in evenly 3 m8 bolts and gently tighten as evenly as possible till the rotor pops off the crank. It's a method used for removing brake drums. Too late now I know
I'm sure I still have a Baghira cluster, if it's any good to you send me a p.m.
Chalks.

Thanks Chalks. Sent a p.m.

Justin

Hey Justin,

What gaskets did you end up using, and where did you source them?