GT500 Pistons

[oldjapanesebikes]

The new pistons I'm installing are the same as used in the GT750, but I see on the parts lists that on the T/GT500 the small end side shims/washers, as are used on the GT750, are not listed - and I don't see anything in any of the service bulletins saying they should be added. It looks as if there is room to fit the shims, and I can't think of a good reason not to - it actually looks like it might centre the small end bearing better than not having it.

Comments from anyone ?

[oldjapanesebikes]

Some additional data - I have an original, standard bore piston, and the small end gap minus the small end bearing width gives 1 mm bearing float side to side on the gudgeon pin. The GT750 piston's small end width is 26.7 mm which is 2 mm wider than the original piston small end width of 24.7 mm and so would give a possible side to side float of the small end bearing on the gudgeon pin of about 3 mm which just seems excessive. With the shims in, as used on the GT750 engine, the side to side float is the same 1 mm as the old piston having no shims however I suspect lubrication of the bearing might be an issue.

Anyway - I'll leave them out for now - need to move on to other things.

[titan performance]

Hi OJB.......no shims on the 500 !

[oldjapanesebikes]

Hi OJB.......no shims on the 500 !

Yes that was the original design - I mentioned so in my first two posts on this thread. While I freely admit that I'm not an expert, it just seems like an increase of potential side float of 2 mm from the original design is excessive, so I'm puzzled as to the 'why'. If no one has an answer, then that's OK too - but I would have expected that when the piston design was changed to match the GT750 that the con rod and spacers would have been changed to match. It almost looks like an engineering oversight on Suzuki's part.

Any way - the engine is back together, and without spacers.

[H2RICK]

Ian, if the Buffalo uses the pistons with spacers and gets adequate lubrication to the wrist pin bearing, why wouldn't the same logic apply to the Titan pistons and wrist pins ???

This whole dilemma of yours smacks of accountants reducing the parts inventory by subbing in parts that will fit and work "okay"....not necessarily properly and durably.........just "okay".
When will companies learn that accountants should be kept away from the engineering and purchasing departments ??
I'm all in favour of increasing efficiencies in a company where possible...but let's not throw out the baby with the bathwater.....which is exactly what happens a lot of the time when accountants get involved. Grrrrr......