Scooterotica

how well do these work for a round-towner?

or to rephrase my question; of the pistons that SR offer which would be the pick for a round-towner?

there was some talk a while back of the SR piston having an incorrect taper which lead to a lot of piston slap on tickover.

I've had two setups (both SR185's) which indeed did rattle a tad on tickover- having said that they never nipped up and didn't rattle above tickover speeds.

I'm presently using an SR185 barrel bored to 66mm with a Mahle piston at 3 thou clearance- no rattle at all and no nip ups (despite reving the nuts off it!!)

Chris

So a Mahle piston is quite ok?

absolutely no problems with mine. Got it from Scooter restorations around £30.

Chris

I'm still using the standard SR piston, TBH i don't notice the tick over rattle anymore and the rings and construction of the piston are quality. I bought the kit from SR when they were £100 and it has been giving good value for the money ever since.

johnd wrote:I'm still using the standard SR piston, TBH i don't notice the tick over rattle anymore and the rings and construction of the piston are quality. I bought the kit from SR when they were £100 and it has been giving good value for the money ever since.

totally agree- the SR kit was very good value for money. Some rattled, some didn't and I'm sure it improves as its run in (either that or I'm getting deaf....)

Chris

red ghost wrote:how well do these work for a round-towner?

or to rephrase my question; of the pistons that SR offer which would be the pick for a round-towner?

I'm doing the same, just in the process of assembling a 185 SR engine for my London based scoot (Shocky's Jet). I bought a barrel from SR for £30 a couple of years ago (one of the last I think) and then bought a cheapo ebay piston for £19. I just had a look at it and it doesn't have ANY maunufacturer name on it at all Jut STD and an i in a circle.

As it's unlikely to be subjected to prolonged bouts of thrashing I'm hoping it will cope

one thing I've tried with the SR steel linered type barrels, is that because they're mainly alloy, the piston to bore tolerances can be reduced significantly.

My first one had 4 thou and rattled; the second 3.5 thou and still rattled (but not as much. The current one is 3 thou and there is not a hint of any slap or rattle. I'm tempted to build up another at 2.5 thou to see if that copes..........

Chris

if you start to reduce your clearance then you will encounter heat seizures,it will only rattle at tick over and cold ,
regards
joe