Seized 660cc motor : what happened ?

[Bill Jurgenson]

The flywheel puller I found for $54 is for Raptor specifically.

no, it is a one-size-fits-all. You can see that it has slots for the three pullbolts so that it fits as many different radii as possible.


A dedicated tool is made for the specific purpose.
That said, for your presumable usage it will probably do.
Be aware that if the flywheel has never been removed, it will take considerable doing and patience. The best way is with an air impact wrench and even then, you probably just have to sit it out. Even over night. By hand, use a big hammer and a piece of lead between it and the centerbolt of the puller to coax "gently." Also remember to grease the threading of that center bolt generously with "Molykote®" or other graphite sulfide grease.
If you do not use such a protector, the end of the crank will be peened out, the threading ruined.
If you have an acetylene welder or propane torch, heat up the center of the flywheel carefully before starting. That does make it much easier but is not absolutely necessary. I don't even tho I have the welder in the shop. If you do not use such a protector, the end of the crank will be peened out, the threading ruined.

[keithcross]

I agree with Bill on this one, removing the flywheel on these engine is a B*******. I don't have the luxury of a one off tool, so used a car hub puller, which is similar to the one shown.
Must get round to re-building the engine one day, it only needs a selector drum and a few bearings as it used to run sweetly. No wear on the gears or big ends was apparent either.
As for welding the case, best of luck, but I am not convinced it will work for long and next time it might damage some more internal parts.

Keith

[hb7]

Friend of mine has a racer crankcase which was welded after the rod broke....
It's still running with a raptor crank....
The way I would do it is weld it on both sides and if possible hand fit the bearing into it's
slot using a dremel tool. I've been lucky before....

[Bill Jurgenson]

the crankcase of my Mondial is welded in a couple of places, including one important bearing seat which was milled after welding. It is holding up just fine.

[hb7]

Yes, I am planning on welding the case. I have to find somebody competent to mill the bearing seat.
I'll clean and cut the groove in the crack. Fortunately, MZ is my hobby....
The crack goes into the cylinder seat....

[Wonkmeister]

Bugger!

Bill your such a geek!LOL!

What happened?...now if only we had a £1 for every time that question was asked eh Bill!!!! Simply my answer is...your motor shat itself through lack of servicing or you had a "freak" fatality...

Remedy....FIX IT! Thrash it...break it again....fix it....thrash it.....sure you catch my drift!



I want pictures of the hardcore mash-up of your motor...love the carnage! Bad-ass......not so good on the old pocket though!

[hb7]

The END result of the monster burnout.....a bent balancer, broken crankcase, seized conrod.
INSTANT JUNK.

[Bill Jurgenson]

People, don't wait for it to happen - and it happens far too often, not just to Henri.

Till now, I have had 4 bikes with this engine, 3 Skorpions and the SZR. WIth the blue Tour, the same thing happened as to Henri. I didn't know better; it was my first xtz engine. The red Sport would have been victim if I hadn't checked early on. Yesterday, I checked the Yamaha because the metallic clicking - more like clanking - when starting and at idle worried me. It was high time! The gear package could be turned back and forth on the crank at least 1/8" before the nut was loosened. The woodruff key is indented 3/10mm for the balancer gear and 2/10mm for the primary gear. It wouldn't have taken too much longer to shear off the key entirely.
The package loosens because the two sheet steel retainers for the springs of the balancer gear compress just enuf to relieve the torque of the nut. Since the balancer gear has those springs as damper, the blow is actually increased. Once there is play, it increases rapidly. Then it is only a matter of time till you get what Henri and I got.

This not a quirk of fate. It happens far too often even if Yamaha and MZ are not ready to admit it. Of my 4, three were or would have been victim. The fourth, the racer, has no counter balancer. Add to those my freind Heinz' Sport, which was almost done when he broke the engine to replace the piston. Another I have seen myself, not just hersay.

So, I repeat, take the time, remove the right side cover and check the primary drive. Check the gear on the balancershaft as well. It took me 2 hours yesterday with cleaning up afterwards and I did have to remove the clutch since repair was absolutely necessary. You'll need the gasket in any event and if you do have to go at the primary drive, you'll have to ake off the clutch first. So you'll need the woodruff key for the crank and the "nutfixing washers" (sorry, forgot the name in English) for clutch and crank. These are all penny articles so get them first.
If you have to take the beast to the shop, stand behind the guy and hold a gun to his head to make sure he actually does what you demand. Chances are, he won't otherwise as I know from experience. he dare not take more tha the 2 hours I needed or he is a crook

[hb7]

Follow up report : the woodruff key was also sheared off on the rotor.

I removed the rotor using three long 8mm bolts threaded through the rotor/ flywheel and pressing against the gear, using an airwrench to sequentially tighten each bolt. Comes off beautiful with NO damage to the crank threads.
( In my case the crank was damaged from the sheared off woodruff key.)
This was after breaking 3 different gear pullers.....(Calvan, Harbor freight, Snap on)
I stopped before the Snap On would be damaged....

[Bill Jurgenson]

almost exactly two years ago, I checked the balancer gear and key in the crankshaft of the Yamaha and it was high time. I cleaned up and replaced the key and tightened down.
Now I had the bike in the shop for other service and the clacking was more than disturbing, so I chose not to drive it at all until I could finally replace that gear with the solid one from Slipstream I favor.
It arrived yesterday and I did the repair. It was even more high time than 2 years ago.



that would not have lasted much longer!!


BTW: it is not necesssary to drain the water when a job behind the right side cover must be done that can be done in the bike:
clutch or things like the above
Remove the water pump as a whole by withdrawing only the three long M6 bolts that secure the entire pump but leaving the 2 short ones that hold the cover and the hoses, pulling it off and tying it to the right with cable binders.

The engine is so smooth and quite it is uncanny!!

Do not take clacking noises from down there lightly. they can be very expensive and potentially dangerous if the lockup occurs at speed.

[djsbriscoe]

Hi,
Could someone please post a drawing from the XTZ660 manual or a copy of an engine microfiche to illustrate the suspect parts in this discussion. I'm preparing myself mentally for having to do this work myself at some stage so I'd like to see what were talking about. I don't want to partially strip the engine just to have a look. This is obviously a job that's best done asap.
Bill, do you have a photo (or link) of the slipstream gear you mentioned?
Thanks.

David.


P.S A lot of the links to photographs in this post are no longer working. Maybe the photo's could be posted in the gallery instead.

[samandkimberly]

I'm glad this post popped up in front again - I've been listening to a clunking noise on my Skorpion and I'm betting this is it. When I tear mine apart I'll take pics and post.

Getting the gasket, woodruff key and tab lock washers in advance is a very smart idea. Unfortunately I can't just order SXR660 parts in the US. Does anyone know id these particular parts would be the same as SRX/TT 600 parts? They sure look the same.

Thanks,

Sam

[hb7]

Don't need a gasket, I use silicone form a gasket...no issues.
Locktab,re use old one for spacer function, blue or red loctite
never been wild about hammering these tabs down on ball bearing axles.
Key and locktab is the same as 1995 xt600 in the USA.
Use www.partshark.com....

best,
Henri B
http://moto-science.com/

[hb7]

My question to you Bill....

What are you doing about the slight side to side slop on the balancer gear ?
Are you going to shim it up some ?

best,
henri

[samandkimberly]

I'm not a big fan of silicon gasket - it's messy. There's also the fact that it changes clearances removing the gasket. I don't think this is an issue with this particular cover, but on some covers with bearings in them you have to be careful and make sure you don't create a binding issue by removing the gasket. What I usually do is glue the gasket to the cover and then put a thin layer of grease on the other side - this gives you an oil tight seal and it can then be removed/reinstalled many times w/o damaging the gasket. When I do decide to eliminate a gasket I use Loctite 518 - an anerobc gasket maker. It only hardens under the gasket surfaces so you can wipe the rest away - no long strands of silicone goop inside or outside your engine. Great stuff.

As far as the lock tab washers I like them because I'm a space case and when I use them I can tell if I finished the job correctly at a glance. I'll use loctite too on this one.

I wouldn't hesitate to do the job exactly as you suggest, but I have time on my side so I might as well do the job right.

Sam

Don't need a gasket, I use silicone form a gasket...no issues.
Locktab,re use old one for spacer function, blue or red loctite
never been wild about hammering these tabs down on ball bearing axles.
Key and locktab is the same as 1995 xt600 in the USA.
Use http://www.partshark.com....

best,
Henri B
http://moto-science.com/