Killed the Bee - Best place for RZ engine rebuild?

[Skut]

Nipped up at speed on a country straight, partial seizure - much like standing on the rear brake (although far more deceleration until I clutched it). Trailered her home. Will kick and turn (not start), but a push start sounds nasty.

In other words, no idea of internal damage, or the cause (leaning out, pump failure....?) So question is, best place to take her for surgery? Gavin at GD?

Cheers, and sorry to trash such a gem , but coulda been worse I guess...)

[Desmo]

Good to save it and that it didn't totally lock up.
I've had it happen once and I still ride with my fingers covering the clutch even now, it scared me shitless
Absolutely Gav could do the work for you if you aren't up to it yourself.
Perhaps some internal mods whilst you are at it?

[Skut]

Cheers, can I have his full username (memory is shite) so I can PM?

Internals apparently already done - I have just undone them

[ninjaa]

Ah bummer unlucky mate. Took the head off yet to see anything?
Reminds me...really need to get my shit together & rebuild mine

[Desmo]

Cheers, can I have his full username (memory is shite) so I can PM?

Trying to find him, it's something like Gav(G.D.Engineering) or GD Engineering (Gav)

[Lefty]

I think this is his phone number:

0409 104 370

[Skut]

Thanks guys!

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[Slug_BM]

Those motors are notorious for losing the gudgeon pin circlips. It's probably made it's way to the top of the head. Best bet is to pull the head off and check the squish band for loads of dents and the bore for scores. The top end is pretty easy to rebuild.

[Loud]

Bugger, I know the feeling - took me ages to trust the bike again, particularly as the ride home from the mechanic resulted in an even worse feeling...

So is it worth Skut having the gearbox gears Magnafluxed to check for cracks from the stresses placed on the gears from the decelleration?

Reminds me...really need to get my shit together & rebuild mine

Geez, how have you not done this yet mate? Give me a call, I'll show you how to do it.

[g0zer]

sweet

its about time that bike got an athena 392cc top end

[yamasukiman]

can you recommend the 392cc Athena kit?
We have been looking at them as a cheaper way of bringing an rz250 to 350cc or so.
With having to buy reed valves and manifolds,power valves and seals and bushes, pistons etc the Athena kit looks to be good value but you lose the power valve.(We have a set of rz350 barrels that need a bore job).
These things always sound good(Athena kit) when you read the blurb but it's nice to know what people think that buy the kits.
Now's not a bad time with the Aussie dollar............

[g0zer]

it depends what you want from the bike.

imho a good YPVS motor with stock airbox pipes and carbs is an ideal street commuter bike configuration, economical off-pipe (for a 2T) and reliable. if you want a bike with a heavy duty clutch, vicious powerband, raucous two stroke howl and dont care how much petrol you burn build a 392cc with a nice set of aftermarket pipes.

RZ/RD 350 & Misc. 2-Stroke Tech BBS :: View topic - NEW!!! WICKED MOTORSPORTS RZ 350-421CC PIPES! DYNO CHARTS!

^note the spigot adapters, the athena barrels are banshee castings and use spigot for exhaust connection not bolted flange like a stock rz350.

dont forget to change the 250 oil pump out for a 350 pump.

[dplb]

carbs and plugs for bottom of waterjackets, banshee cases must have extra locating pins rz dont,will make sealing base gaskets very difficult without. Ive done the athena swap for same reasons u state. Its a brilliant thing most of the time but if fuel consumption is an issue then buy a small car, cause mine probly goes close to chewing as much as my fullsize 6 cyl car......my car doesnt sound nearly as cool thou. the kits dont rev like a z but they make easy as much power

[Skut]

Pulling out the engine today. Anyone have a manual handy?
Actually getting the lump out is going pretty smoothly (just photographing as I go). Best bit was when I came to the front sprocket and saw the big, burred nut. "That is going to be a bastard! Look at the battle scars! And have nothing to fit..." So I decided to go and buy a big arse spanner to fit - when I get back home, my six year old boy runs up and says "You didn't need to get that, I got it off!" Somehow he got it off with a stumpy toy shifting spanner he found with jaws just wide enough to fit.

I either need to hire him out to a mechanic, or hand in my man card!

After dropping the pipes I can already see that the left hand barrel is showing signs of a serious lean out; pipe at the manifold is white as is the port itself. Looking in with a torch I can see some scoring on the barrel and on the lower part of the piston skirt. Once I get it out I will pull the head off and see how horrible it all is....

[Skut]

P1010104.jpgP1010097.jpgP1010095.jpgP1010108.jpgP1010100.jpg

Now there's yer problem....

Ouch, and look at the extra port work now gone to waste. As to the cause? I guess the carb will need checking as that looks like a massive lean out

[Sean'o]

I have a manual if you want to borrow it Skut. They are a pretty simple engine to do the work yourself. New crank, gasket kit and seal kit from the Two Stroke Shop, barrels to Ray Eason for bore and a new set of prox pistons, assemble fit and ride in 3 hours You will need to split the cases, so will need a rattle gun for the clutch basket.
What were you doing when it siezed, full throttle for a while, or holding a constant throttle, like about half, at a reasonably high rev 8k or so?

[g0zer]

do both pistons so signs of melting skut?

eheh normally loosen the flywheel and sprcket nuts with the engine still in the bike and hooken up to the chain so you can lock the rear wheel

[Sean'o]

do both pistons so signs of melting skut?

eheh normally loosen the flywheel and sprcket nuts with the engine still in the bike and hooken up to the chain so you can lock the rear wheel

Looks like its too late for that, next time eh lol

[Skut]

Other barrel and piston are fine, and the plug is a nice dark tan. Yeah, full throttle for a few minutes in top...

edit: putting the pipes away, I tipped out many remains of melted piston (so glad I was going in a straight line at the time!)

BTW, I drifted out the gudgeon pin and freed the piston; in what form does a new piston present? Do I need to keep the roller bearing, clips and gudgeon or does it come together? I have not done this before. I hope to leave splitting the case to an expert as I have neither the time nor expertise (or even tools and clean workspace) - tough bolts I should leave to my son it seems

Only one port is a little munted (the piston rings seemed to have behaved otherwise) so I hope a rebore will sort it without too much drama.

The fact that one barrel looks perfectly healthy, and knowing the history of the bike, I am suspecting a clogged jet or something to blame for the lean-out. The bike runs pods (oiled foam) and has been ridden far harder prior to me and so I think it is the carb, yeah?
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[ritza]

ray easson did the last rebore and supplied the pro x pistons rings etc. small end bearing, i used gen yamaha, i will have a hunt to see if i have any gaskets left.