Yoshimura Mechanical EX → Fire Spec treatment
Wow, this polishing is quite demanding, isn’t it? I wonder if it’s all done by hand?
It’s used, but it looks brand new. If you don’t remember removing the exhaust pipe, it’s risky, so please don’t request this service.
The chain is the trusted DID ZVM-X. Check the countershaft before replacement.
In harsh conditions, clean the threads and treat the chain with care. Match the chain plate press-fit width and install it properly.
I’ll skip ahead.
We found a slight seep from the clutch release, so let’s replace it with our standard remedy.
The top is used and the bottom is new. The lip section is about 1.5 mm smaller in diameter.
The clutch grips harder than expected.
Light polishing for reuse. Over-polishing the plating invites rust, so for reuse, moderate polishing is fine. Replace if there’s severe pitting.
I think moderate polishing inside the cylinder is good. Aluminum castings are very soft, so we don’t polish more than necessary unless the pitting is severe.
If you want it shiny and are seeking performance, surface treatment is the better approach.
It’s not leaking, but we’ll replace the shift seal too. Applying rust inhibitor to the shaft is even better.
These two jobs offset the rear caliper cost.
With a Nissin 4P and rear routing, the ST-FIT offers simpler plumbing than a 20-degree BJ.
Currently, without routing slightly outward, it contacts the upper caliper mounting point, compromising serviceability and appearance. So we added a spacer and fixed it with W-BJB for parallel alignment—unconventional but it works.
The caliper bolts are the usual Yamaha spec.
We’ll source pads and other parts next, so we’re putting this on hold for now.
