KR-1S.co.uk Forum

Use a piston with a lower comp height The link where to buy the filler in the UK has been posted on Pit Lane. A gusset only need be tacked in 2 spots on each corner, to minimise distortion the cylinder should be bolted to a plate, pre heated , welded then covered in heat blankets/sand to cool slowly. Basic welding stuff.
Look at the Aprilia dyno curve, Aprilia had a staff of 100 working 8 hours a day 5 days a week, 2 dynos runing 3-4 cylinders a day, under the watchful eye of the historys most winning two stroke tuner, who developed the most powerful and winning two stroke engine of all time at a WORLD CHAMPIONSHIP level. Why wouldn't anyone believe Jan Thiel.

*filler was used to test duct angles and directions

Reference to "Stucco Verde"
on Page 16, 28, and 30 of part 2 of the thread

I don't know of a suitable piston with a Crown height 1mm lower. TZ pistons I know are either the same or 2mm lower.

Great thread but I couldn't see any manufacturers information for the "stucco verde" ..perhaps I missed something ? To be fair on the ipad it looked like some pictures or links may have been missing?

After doing a bit of research (which isn't easy as stucco verde just means green resin) two products seem to stand out

Belzona 1111 from the USA and ..
Loctite Hysol 3475 A & B. .. Which is reputed to be resistant up to 190 degrees whilst offering good resistance characteristics on to aluminium

Are these the infamous "stucco verde"...? Seems like I would have more luck trying to find lord Lucan ?

On page 28 there were 2 links

http://www.steelmodels.com/resine-stucc ... -1.uw.aspx

and

http://www.cecchi.it/italiano/htm/resine.html

It appears the upper one is the stuff Jan Thiel used. I haven't investigated as I have no need to use the stuff at the moment but reference is stored.

Thanks MJ

The Army Models Stucco Verde is a bargain at that price (€ 8 )
I don't need any at the minute either but I may just get some to try out instead of using rock steel / JB

mj43 wrote: I don't know of a suitable piston with a Crown height 1mm lower. TZ pistons I know are either the same or 2mm lower.

according to woessner compression height of KR piston is 29.50, according to Mitaka it is 30 (sorry, too laisy/too cold to crawl on my attic to measure one ).

YZ 125 '89 compression height according to Woesner is 28, Mitaka says 28.5 and I believe the Wiseco's I have are 28.50.

said it before and say it again : I believe this is by far the best option as a replacemant piston, and it will be produced for a long time by a lot of different manufacturers.

Jan

by 28mm I take it that is from the centre of the gudgeon pin hole to the top edge of the piston - which is 20mm in my books which is what the 3TC/3AK/4DP pistons are. I believe the '89 YZ125 are the same.

26J/59W and stock KR are 22mm or 30mm in your terminology (give or take 0.5mm )

It seems to be available under the Trade Name "Kneadatite" and is refered to as Blue/Yellow, Due to the color of the two parts, it is called "Green" as that is the color of the mixed putty.

mj43 wrote:Jan

by 28mm I take it that is from the centre of the gudgeon pin hole to the top edge of the piston - which is 20mm in my books which is what the 3TC/3AK/4DP pistons are. I believe the '89 YZ125 are the same.

26J/59W and stock KR are 22mm or 30mm in your terminology (give or take 0.5mm )

yes, my numbers are compression height, as oposed to crown height

just remembered my engine is open , Wiseco YZ125 89 crown height is 20mm, KR1 (first, with the bad pins) is 21.5 mm.

Mark, I thought you were looking for a lower piston compared to an original

Jan

I use 3TC which are the same as the YZ125. However as they are ~2mm shorter I have been shortening the barrel which makes an already weak barrel weaker. My new solution is to run a longer rod (KDX200/220) which is 109mm rather than 106mm which means I can raise a barrel by 1mm.

Mark,

Have you considered the conrod from a 3xv? Its the same rod thats used in the 3yl/4dp/4tw tz so is more than capable of taking the grunt. Its a 110mm centre to centre. The small end eye is the same fitment as the kr, would have to measure a big end eye for you when i go to pick up my crank i'm getting rebuilt.

Dan

500bernie wrote:It seems to be available under the Trade Name "Kneadatite" and is refered to as Blue/Yellow, Due to the color of the two parts, it is called "Green" as that is the color of the mixed putty.

Cheers $12.50 for 36" that is cheap. 1 year shelf life not sure I would use 36" in a year....

mj43 wrote:Jan

I use 3TC which are the same as the YZ125. However as they are ~2mm shorter I have been shortening the barrel which makes an already weak barrel weaker. My new solution is to run a longer rod (KDX200/220) which is 109mm rather than 106mm which means I can raise a barrel by 1mm.

Why don't you take it of the top of the cylindre ? I did :
- barrel stays as strong as it is
- exhaust port lines up nicer with the piston top
- lowering transfers is easier and less chance of not getting the direction of the flow right (presuming the original is good).
- exhaust port raised, what we all do eventualy
- transfers raised a bit (more time-area) but keeping the blowdown time

maccas wrote:Mark,

Have you considered the conrod from a 3xv? Its the same rod thats used in the 3yl/4dp/4tw tz so is more than capable of taking the grunt. Its a 110mm centre to centre. The small end eye is the same fitment as the kr, would have to measure a big end eye for you when i go to pick up my crank i'm getting rebuilt.

Dan

Interesting Dan, let us know when you get yours back.

Well looks like I have some answers much quicker than expected.

http://www.ns400r.co.uk/forum/viewtopic ... ght=conrod

All the 3xv conrod dimensions are in that ever so helpful post.

I love google.

Dan