RD350 YPVS 1983 Cafe

The deeper i look, the more money it takes :
Crank is out of specs on all points but runout which i cant get to measure before i buy an impact wrench for the flywheel. Also there is severe galling in the bottom crankcase so i will do a full engine rebuild, anything less would be foolish by now.

8000kms with no mercy, high revs and a lot of very quick warmups before wot. So its no surprise, really two strokes are like models to me, they are high maintenance but fun to ride
It was running a little hot, there was some burnt oil on the underside of the piston crown

Galling and visible wear/axial play/ bearing play

If the axial play is way too much like mine, you will be able to diagnose it just by moving the rod through the intake while the engine is still in the bike, i already knew this some time ago:/
Also notice the crappy prep job on the side case lol, i dont have enough patience

Ahh finally some progress, got the flywheel off without the impact wrench and the engine cases are separated. Gearbox looks ok by first glance, no bad galling or wear. Those yamaha gearboxes sure can take a beating lol.

Below are pics where i left it today, minus the crank which is stored safely and not on the edge of a stool now.
Maybe i will get it rebuilt if it can pay off, i found a replacement crank for it, stock rd but within specs, didnt have the funds for a stroker athena and cylinder kit this season, oh well maybe next year
Now i need to order some lower end rebuild seals and gaskets, and whatever else is worn beyond specifications.

I am going to remove the rev counter drive completely, i dont use it anyway. And if i change my mind, it would be a nice excuse for me to upgrade the ignition and pv controller. Still undecided if i should get it ported or not, maybe i will just clean the intake and transfer up a little including a base gasket match.


The galling feels much less than it looked, i think i can buff it out a little and call it a day

Got it running again, almost there now

Loving the green paint. Looks like a blast!

That mess in the crankcase is from metal dragged around in a prior engine disaster. If the big ends of the rods are not showing signs of rubbing, all you need to do is to clean it up a little. The only way the rods could be rubbing and galling would be if the big ends had failed badly. Crank rebuilds are not too expensive as a rule but check out VITO's and see what they have to an RZ - for future reference.

Teazer is right, that galling is from pieces of piston ring by the look of it. I love RZ's (or RD350LC as I know them ). Nice bike

Wow. Bike looks rad. Love the green. Nice job.


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teazer said:

That mess in the crankcase is from metal dragged around in a prior engine disaster. If the big ends of the rods are not showing signs of rubbing, all you need to do is to clean it up a little. The only way the rods could be rubbing and galling would be if the big ends had failed badly. Crank rebuilds are not too expensive as a rule but check out VITO's and see what they have to an RZ - for future reference.

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Makes perfect sense, the PO said he did some engine work on it. The crank is good though apart from too much lateral play at the big end bearings. It was running smooth when i tore it down. Got a replacement crank for it which had less bearing play. Anyway i need to split the cases again because i am a fool. Did not seal properly so it ran for a short while before filling the crank with gearbox oil and spoiling the plugs. Or, thats what i think happened. I had to leave the bike out of frustration. On the bright side, i still had all the parts organized so nothing was missing upon reassembly.