MZ/MuZ Riders

Hi there

Just thought I would share this one. Don’t know if anyone else has had similar experience.

End of last winter I noticed two distinct things. The oil in my reservoir had started to turn milk white and my starter was making a grinding kind of noise. I put the oil issue down to possible shortness of journeys (never really burning moisture off) during the winter and the hydroscopic properties of the oil. So with this in mind I did an oil change ASAP and used fully synthetic (less hydroscopic I am led to believe).

Never thought the two could be related until I had stripped out the starter and gear mechanism with the intention of replacing the starter. I had purchased a genuine brand spanking new Yamaha Raptor starter from ebay USA for about £50. I was well chuffed with my purchase, especially after being quoted between £300-£500 for one over in the UK. Unfortunately the commutator shaft was different from mine, so I decided to swap the casing and brush set.



The starter had been turning slower recently or hitting what I thought was a dead spot. When the gear cover/mechanism was removed it was full of thick white goooo. And surprise, surprise, the bearing the starter mates with was rusty and seized solid. Hence slow noisy starting or just plain click from the solenoid. Looks like someone had the gear mechanism apart and put some kind of sealant around the existing gasket. Can only guess water must have seeped through the gear unit. I know the bike never lost coolant. Anyway will be dropping off the gear assembly to our local bike guru for bearing extraction / replacement next week. Pictured below the starter mechanism. Any comments greatly appreciated.



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No expert on these motors but is your water level dropping in the reserve bottle?I have been around engines enough to know that if water is in the oil there is nearly always a problem. Have you checked the head gasket?

SURE DOES NEED A GOOD LOOK AS PARTS FOR THESE BIKES ARE GOING TO GET HARD TO FIND
AND EXPENSIVE
DAVE

I did fear for the head gasket, but because the coolant level never went down, I kind of dismissed it. The oil in the tank has remained its natural colour since I changed it early this year.

just a thought,does this casing normaly have oil in it,never had mine apart,and if so what or how does the bearing get lubed or should it be a sealed/shielded one and if it does not have oil in it then maybe the gasket just let water through hence the extra sealant that was added to it.

This was the theory I was working on. Well hoping anyway. Maybe previous owner had issues with the gear unit at some time, and did a bodge instead of proper repair.

did a bodge

is what happens to often
dave

had water get into the engine cover on A R75 bmw where the points are
when the water became contaminated with aluminum particulates
the bike died took cover off and bunch of water ran out
cleaned points and road home
then fixed it so it could drain

one thing at a time:
Parts for the XT/XTZ engine are not going to get scarce any time in the near future - or more distant one for that matter.
You guys simply have to get the notion out of your heads that the engine has anything at all to do with MuZ; it has nothing whatever to do with MuZ.
It is Yamaha, plain and simple, one of the most common Yamaha engines there is in fact. Since Yamaha engines are built to a sort of "Erector Set" principle, they share as many parts are as possible: the clutch is used in a whole raft of different engines; the timing chain is used in all XT/XTZ/Raptors/Grizzlys but also e.g. in the R6. Just examples. You can stick this XT600 engine in the Skorpion without the slightest problems.

A friend of mine is riding a Skorpion with that engine.
Stop trying to get parts for the thing from so-called MuZ dealers. You don't take your washing machine to the radio shop to have it fixed.
You want Yamaha parts, you go to the Yamaha dealer.

That said, when the oil looks like that, there simply is water in it. It has become an water/oil emusion. Stop kidding yourself that there is nothing wrong. If fact, for that dimeadozen ball bearing to get like it is in the picture, there must be a lot of water in the oil.
There is or should be no oil anywhere in the crankcase: it is a dry sump engine. But there is oil mist everywhere, inculding up there in that far corner of the case and there should be. The starter gear and the timing chain both spray a lot of oil around that side cover - as they should. Ballbearings do not need more than a bit of oil at any time. Grease is not good - or rather at best good for your peace of mind. Even in packed bearings, the grease is forced out by the cages and the balls run only on the film. All the bearings in this engine run only on a film provided by the the oil mist the various moving parts create. The only force fed bearings are the conrod big end which is a needle bearing and the plain bearings of the camshaft.

It is easy enuf to replace that standard ballbear in the the small cover and you can get it at any jobber. No need to pay a premium price at the motorcycle shop. In fact there is almost never a need to get bearings or seals from the motorcycle shop. There no special bearings in the engine anywhere and precious few in the frame. Even in the frame where special bearings are used, e.g. Strut linkage, that part is OEM Yamaha, not MuZ. Checkout 1990 FZR600 to find the entire swingarm with linkage, lock-stock-and -barrel!
Here is one online source of information:
http://medias.ina.de/medias/en!hp.ec/1_R*0;bgTpg875FKt6
and another:
http://www.skf.com/portal/skf/home/products?newlink=1&lang=en
with which you have both principle manufacturers.
Here:
http://www.skf.com/skf/productcatalogue/jsp/viewers/productTableViewer.jsp?&lang=en&maincatalogue=1&tableName=1_1_1&presentationType=3&startnum=1
The left column is the shaft diameter (d), the next the OD (D), then the width (B) and the last at the right the number of the bearing with which to order or buy it.

As for bodging the job on the small cover, hardly possible. There is a gasket for it, included in any gasket set for the XT600/XTZ660/Raptor660 gasket set.
and of course it can be ordered individually at your friendly Yamaha dealer.
Yamaha US provides the microfiches for all maschines sold in the US:
http://www.yamaha-motor.com/sport/parts/home.aspx
so, for instance, knowing that the aircooled XT600 is virtually identical to the XTZ660 which was not sold in the US, you select at the top;
motorcycle,
1990
XT600
and there in this case, you select "crankcase cover" on the left and get this page:

there you can easily see the gasket, Nº.33, and in the scrollable list at the bottom under that reference, the part number:3TB-15455-00-00 GASKET
also telling you what it is called.
I use Loctite 5926 for this and all other mating surfaces in the engine myself. The only gasket I routinely use that of the chain tensioner: 4X7-12213-00-00 GASKET, TENSIONER CASE
Click camshaft chain on that Yamaha link above and there you have it, complete with part number.
The bottom end of the XT600 is identical to the XTZ660 but it is a 4-valve engine. For cylinder and 5 valve cylinder head, you have to select:
ATV part;
2002;
YMF 660RP Raptor


But be aware, that the bottom end of the Raptor 660 is not the same as the XTZ and the Raptor 700 is no help at all.

Here is that swingarm mentioned above:

Look up what you need and take them to you friendly Yamaha dealer. Don't scare him with tales of an MZ! Just tell him you need OEM Yamaha parts. The same part numbers work in Europe as well; I use this site all the time to find the part numbers to order here in Germany. Yamaha is Yamaha.

now back to the frothy engine. Don't delude yourself that there is nothing serious amiss. There must be.
For a starter, take off the left sidecover entirely and checkout what sort of residue is at the bottom of the crankcase where the oil is scavanged. When you order that small gasket, you can also order the large one:
34K-15462-00-00 GASKET, CRANKCASE COVER
Just for kicks, you can crosscheck with the Raptor to see if that might be the same part. It is not, but the small gasket for the starter cover is.
I hope you find that the starter freewheel is spinning freely and the crankcase doesn't have an inch deep sludge layer at the bottom.

Thanks for the input guys. I have already rectified one or two other bodges on the bike, so not much would surprise me.

I am definately looking to replace the starter cover gasket, but never thought about the crankcase, so will inspect inside and replace this also. We have a main Yamaha dealership in Bristol, which isnt too far from where I live. I try to source generic parts from them and the more skorpin specific parts from Grahams in Taunton.

If the crankcase has residue at the bottom, is it just a case of cleaning it out, or would there be more involved than this. Would it be a good idea to flush the oil system through a couple of times ??

Took Bills suggestion and ordered crankcase cover gasket and starter motor gear cover gasket. Had the faulty bearing replaced earlier this week with a nice free running shiny new one. Those links to the Yamaha parts are brilliant Bill. Once identifying the part numbers I just go to my local dealer with the list and hey presto.

With all my new gaskets and after treating myself to a few new tools (any excuse to buy more tools) I went about removing the crankcase cover. This is all new territory for me. I bought the Skorp to use as a general commuter, have some fun on it and generally try learn to do much of my maintenance. Any way drained the contaminated oil out of from the drain plug and oil pipe. Removed crankcase cover to find bits of sealant. Not lots but looks like someone has been in there using it at sometime. The gasket was slightly perished in places. But when I inspected the case more carefully , had noticed water droplets around the generator area and a thick dense cream deposit in the plastic removable cover for adjusting the crank when setting valves. After cleaning this gunk off thought it kind of strange there was no rubber O ring or gasket on the it. Looked on the Yamaha parts site and there it was. One missing O-ring.

I cleaned all the surfaces my new gaskets would mate with, all inside the covers and flushed some clean oil through. Unfortunately the crankcase cover gasket was the wrong one. I had ordered the second crankcase gasket and not the immediate cover gasket. Anyway will be going to Yamaha dealer first thing Monday with a list for gaskets, O rings and of course and nice new Oil filter

Finally got all me bits back together on the bike. Filled it with some nice fresh oil and replaced the filter. Tested the starter before fitting and it worked nicely. Finally cranked it over. What a difference. No more grinding, slow laboured turning. With the beefy replacement battery I installed a couple of months back it spins over three times faster than I have experienced since purchasing the bike two and a half years ago. Cant wait to crank it on the below zero mornings now.

below zero c or below zero F i go for the F
coldest i ever started one was 27 below F and it was the only thing in miles that started that morning
and road it 3 miles to work

now days if its that cold i will just pile on more covers and go back to bed

Bill

Being a bit dumb on occasions, the pictures you show of the swinging arm, does this fit the Scorpion or Baghira/mastiff models?

Keith

my turn to be dumb:
what swing arm? what pictures?

If you mean pictures on my blog or home page, then it is the standard Skorpion swingarm, i.e. original Yamaha FZR600.
I have played around with various other arms, but never actually mounted one finished.
Over at the Yahoo MZOG, you can find info and pics of how to adapt a R6 swing arm to the Skorpion.
http://groups.yahoo.com/group/MZOG/photos/album/894002077/pic/list
tho it probably won't work, cause you have to register to get into that group.

happy New Year.

Sorry Bill, but I thought it was obvious that I was refering to the pictures you posted earlier in the thread. Just me being dumb again I suppose.

Keith