Squish band design

maccas · Post by **maccas** » Thu May 24, 2012 10:36 am

Hi guys,

Not far off re-doing the squish on the head of my KR and I have a couple of questions.

Is it best to cut a curved squish that matches the dome radius of the piston perfectly? This would mean that the squish clearance is constant at all points on the squish band. I know that this is more difficult to do than cutting a simple angled squish band but I have the equipment available to me to do it.

Or shall I stick with a plain angled squish?

1. If the latter is the case then should I cut the squish angle such that the middle of the squish band is closest to the piston?

OR

2. Cut it such that the outer edge (next to the cylinder wall) is closest to the piston?

OR

3. Cut it such that the inner edge (closest to the spark plug) is closest to the piston.

At the moment my head is cut like in case 2 so the squish at the edge of the bore is about 0.75mm and then it goes upto 0.95 at the point closest to the spark plug. I don't think this is the best way.

Any experience on this to help me would be fantastic!

Cheers,

Dan

TwoStroke Institute · Thu May 24, 2012 11:56 am

Plan B

1. Will deto to pieces
2.Correct
3. Will deto to pieces.
Take a 0.5mm swipe off the head face and your in business 0.7 to 0.9 will work perfectly.

maccas · Post by **maccas** » Thu May 24, 2012 12:19 pm

Hi Lozza,

So you are saying the pic below is the way to go:

(apologies for how crude it is)

Won't this lower the squish velocity compared to a squish band that is designed to be more symmetrical in regard to squish clearance?

Dan

scooble · Post by **scooble** » Thu May 24, 2012 1:01 pm

I was under the impression that the squish band should force the last remaining gas from the outer to the inner and push it all up towards the sparkplug, so that the sqush band acts like squeezing a bar of soap

TwoStroke Institute · Post by **TwoStroke Institute** » Thu May 24, 2012 1:59 pm

Yes will lower msv but you don't want higher msv, you looking for the missing 1000 rpm on top.

Luders · Post by **Luders** » Thu May 24, 2012 3:08 pm

That makes sense now, as originally I thought it would have best been even.

KR-1R · Post by **KR-1R** » Thu May 24, 2012 9:13 pm

somewhere, sometime, somebody will try out something new

Post by **500bernie** » Thu May 24, 2012 9:36 pm

Would attempting to swirl aid combustion?

TwoStroke Institute · Post by **TwoStroke Institute** » Fri May 25, 2012 4:38 am

500bernie wrote:Would attempting to swirl aid combustion?

swirls your wallet to aid their bank balance

maccas · Post by **maccas** » Fri May 25, 2012 8:23 am

Thanks guys,

Will report back here when done

Dan