GOL single ring pistons

Charles · Post by **Charles** » Sun Jul 03, 2011 2:14 pm

Hi,

has anyone ever used GOL pistons in their KR1S?

Bought a set of barrels on Ebay germany and they come with 5 brandnew GOL pistons. Found out GOL is a italian piston manufacturer, I had so far never heard of: http://www.pistonigol.com/

Charles

KR-1R · Post by **KR-1R** » Sun Jul 03, 2011 10:49 pm

1) The GOL piston is made of aluminium-silicon alloys 18% [AL.SI. 18%). These alloys have a limited
coefficient of thermal expansion able to optimize the assembling between the piston and cylinder to
get the best use at all the temperatures.
2) The pistons' skirt is finished with diamond tools, according to the original form and ovalisation.
3) The normal size indicated on the head of the pistons refers to cylinders with zero tolerance. The
arrow drowned on the piston head shows the way out of the discharged gazes.
4) The piston already has its negative tolerance, which is calculated on the basis of thermal expansion
of the material and in particular on the engine characteristics. During the assembling you should
control that the notch-rings are between the windows of the cylinder.
5) The GOL piston is supplied with normal or special rings, pins and circlips or seeger.
6) The piston pin must be mounted by using slight pressure on it or by heating the piston slightly. Do
not force piston pin entry with hammer or any other tool, since it could cause seizures in the pin hole
or a deformation of the piston.
7) The circlips or seeger must be mounted with special pliers. Be sure that they're perfectly locked in
their side.
8.) All the pistons are submitted to thermal stabilization treatment.

They dont seem to list any for the KR
most likely a Yamaha or Cagiva if 56mm
prices aren't especially cheap either

Luders · Post by **Luders** » Mon Jul 04, 2011 7:03 am

I've had a bit of a look around and found a TZ site that had written a bit about them.

They basically said they were slightly heavier than the standard piston, but this made them more robust.

If they are making racing pistons, I would be interested in knowing what kind you have there Charles and what they are off.

Charles · Post by **Charles** » Mon Jul 04, 2011 7:06 am

Hi Ben,

Luders wrote:I've had a bit of a look around and found a TZ site that had written a bit about them.

They basically said they were slightly heavier than the standard piston, but this made them more robust.

If they are making racing pistons, I would be interested in knowing what kind you have there Charles and what they are off.

I haven't received them yet, will post some pics as soon as they will have arrived here. Bought a set of mitakas from BDK too, so can compare them to those.

Charles

Charles · Post by **Charles** » Sun Jul 10, 2011 8:23 pm

Received the GOL pistons yesterday: they are single ring, otherwise they're identical to the used Mitaka one I got here (haven't received the new ones from BDK yet)

They weigh 164g (incl. ring) compared to 150g (incl rings) of my old mitaka.

Will post some pics tomorrow.

Charles

Luders · Post by **Luders** » Sun Jul 10, 2011 8:35 pm

That site was saying they were heavier, but that was a good thing in their opinion.

Charles · Post by **Charles** » Tue Jul 12, 2011 3:44 pm

here finally some pics:

What do you think? I think they could be used in the KR1S.

Charles

JanBros · Post by **JanBros** » Tue Jul 12, 2011 4:21 pm

Charles wrote:here finally some pics:

What do you think? I think they could be used in the KR1S.

Charles

probably yes, but one big problem : seems the deck height is about 1mm less ? so less compression and your squish totaly f*ucked up ...

only usable if with shorter barrels I recon (if you want good power).

Charles · Post by **Charles** » Tue Jul 12, 2011 4:24 pm

JanBros wrote: probably yes, but one big problem : seems the deck height is about 1mm less ? so less compression and your squish totaly f*ucked up ...

only usable if with shorter barrels I recon (if you want good power).

or a head with adapted inserts...

Charles

Charles · Post by **Charles** » Tue Jul 12, 2011 5:08 pm

Will measure the difference in deck height as soon as I'll have a new mitaka piston at hand.

Measuring with an old inprecise caliper gives a difference of approx 0-0.1mm.

Charles

JanBros · Post by **JanBros** » Tue Jul 12, 2011 5:30 pm

Charles wrote: Measuring with an old inprecise caliper gives a difference of approx 0-0.1mm.

Charles

looks more in the pic's. are the gedgeon-pins at the same height in the pics ?

Charles · Post by **Charles** » Tue Jul 12, 2011 5:35 pm

JanBros wrote:
Charles wrote: Measuring with an old inprecise caliper gives a difference of approx 0-0.1mm.

Charles
looks more in the pic's. are the gedgeon-pins at the same height in the pics ?

They are the same height. I measured from top of gudgeon pin hole to dome of the piston.

Charles

Luders · Post by **Luders** » Tue Jul 12, 2011 6:49 pm

what model are they? I'll try some with my next engine.

Charles · Post by **Charles** » Tue Jul 12, 2011 6:51 pm

Hi Ben,

Luders wrote:what model are they? I'll try some with my next engine.

On the box ist just says Kawasaki, no specific model.

If you want to buy a set of mine, you're welcome.

Charles

Luders · Post by **Luders** » Tue Jul 12, 2011 7:39 pm

okay Charles, I'll do that