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ross.crymble 01-07-2012 09:06 AM

Oil way hole TZ v RD crankcases?
Hi guys, just got a recon set of R5/RD crankcases for my 350G. Centre main half clip grooves have been cut but the oil way below the selector barrel is drilled. Question is should I blank it off like stock TZ cases? I canít think of a reason why its not drilled in a TZ but is in RD cases.


M.du Maine 01-07-2012 11:00 AM

Hi Ross

The Yam RD roadbike had a oil-bath clutch where it's wishfull to
get then and when some fresh oil in, and it was good for durability.
A TZ had a dry clutch and was a competition engine.
The oil in the primary drive was only for some gear lubrication, all the extra
was only drag + loss off power and extra heat to the cranc case.
I that way it's better to close that hole, also the one where the
kickstarter shaft went through the casing at the gearbox side.
Then most of the oil is 'pumped' to the gearbox.
The reason to put in that middle circlips you must tell me, except
you are using roller bearings on the outer cranc side.


ross.crymble 01-07-2012 12:05 PM

Thanks Michel
I hadn't thought of the drag on the primary gears, I have the kick start blank fitted but I will block off the oil passage as well. I think I will use silicone or rubber as I don't fancy a metal plug dropping out inside the gearbox :(

I am using roller main bearings on the outers.

Thanks again

M.du Maine 01-07-2012 12:21 PM

Yes Ross, you can put in anything, as there is no force on it.
I have put Epoxy in, but also some piece of left over rubber or silicone adterwards.
You also can cut off that 'kickstarter spring holder' from thre casing
and leave that metal plate on top of the clutch axle bearing if that was on.
Somehow that RD/TZ casings were 'over-engineered' and a lot off parts
are outdated or un-necessary.
It's actualy funny that a TZ engine with a straigt cut primary gear have four clips on the cranc, where a RD has only one, does that make sense ??


Bud 01-08-2012 08:59 AM

I have been wondering why all the extra circlips in a TZ crankcase. Do you really need the extra circlips?

I am going to build an engine using RD cases, and I was unsure if I had to do the circlip mods.

At the Aussie Championships, my TZ350E crank was floating sideways by 3mm. We pulled it down, found it had the single circlip. So, not having any other option at the time, we loctited the bearings in a position which restricted the side movement.

The bike ran perfectly for the next 6 days of practice and racing at the Aussie and Tassie championships.

Twinshock750 01-08-2012 09:38 AM


Were all 4 bearings moving in the cases? WE had one once where the crank was floating inside a main bearing as a press fit at the centre had moved a little! Kerry was doing 2-01's at PI with it all weekend!

M.du Maine 01-08-2012 06:57 PM TZ350E crank was floating sideways by 3mm........
How is that possible, as if you have the clip on the primary side, it's
allmost 'locked' in place.
That bearing is 'bolted' on the cranc.


Bud 01-09-2012 04:32 PM

The bearing wasn't moving, but the crank was!

gintim 07-08-2019 06:10 PM

Hi, what are people using to block the kick starter hole in the crank case?
Regards , Tim

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