KR-1S.co.uk Forum

Posted: **Wed Sep 19, 2007 4:15 pm**

ScottaKR wrote:Once they're finished and I have them back, I'll measure the hole size and post up all the details along with pics of the modified pistons.

=D>

Posted: **Sun Jun 28, 2009 12:28 pm**

KR on the right

KR on the left

KR on the left

hope this helps some of you lads

KMX125 +2.00mm oversize.

Posted: **Mon Jun 29, 2009 8:25 am**

Nice work there Wigarus. =D> =D>
Have you already fitted these to a bike yet?
Did you use the KMX bearings as well?

I'd kinda forgotten about this thread since I picked up a motor that had been barely run in before being stored to fit to my bike.

Just found this guy on Ebay who has the 2mm o/s kits.

Posted: **Mon Jun 29, 2009 2:54 pm**

http://www.perthstreetbikes.com/forum/f ... tzr-79220/

I've been a little busy with my other bikes

Fitting a 421cc banshee engine into my TZR

I will be doing this though in the future, the pistons are so close its not funny as you can see by the photos...

I've also edited my above post as there were three of the same pictures

Posted: **Sat Jul 11, 2009 3:48 pm**

Well, I bit the bullet this morning and ordered a pair of 2mm O/S piston kits and bearings on Evilbay.
Now I've just got to wait for them to arrive from the UK. [-o<

Posted: **Wed Sep 30, 2009 9:39 am**

I've been contacted by another KR owner needing pistons/rings which has got me wondering where we're up to with finding a suitable alternative.

I've been distracted with other stuff so have made no progress, has anyone else got anywhere or even tried something out ? Should we look at getting some made ?

Posted: **Wed Sep 30, 2009 1:55 pm**

Well, I got the pair of the 2mm o/s KMX pistons, and they look like they'd go straight in except that they way what feels like twice as much (havn't got scales to weigh them properly), so I'm not exactly keen on fitting them as the engine would be massively out of balance. You could possibly fit them if desperate (not that I'd recomend doing so), but you wouldn't want to take it anywhere near redline.
I'm starting to think it's either a case of get some made to order like you say, or maybe find a piston & rod combination for a conversion. I'd lean toward the later myself as it's always good to be able to get new pistons of the shelf if one nips up.
I havn't got any further with the 300cc conversion either, as buying a house has left little funds left over for spending on bikes.

Posted: **Fri Oct 02, 2009 4:31 am**

Hi I am urgently looking for pistons for my bike, does'nt seem I can find any. I am following this posts about the KMX pistons, but can not seem to make my mind up yet to buy a couple or to continue looking!

Posted: **Fri Oct 09, 2009 7:25 pm**

Brand-new genuine KR250A piston is 134 grams (no rings, no gudgeon pin, no circlips) if that helps anyone. I don't have a KMX one to compare it with, sorry.

Posted: **Mon Nov 23, 2009 1:12 pm**

I have bought some KMX pistons to try. Bare weight (no rings, no gudgeon pin, no circlips) is 157grams - 23 grams more than KR piston. I will machine the holes & the flats on side of piston & re-weigh. 1st time I have posted on this site. KR is great bike & I have just ridden it from Sydney to Melbourne & back to attend VJMC rally.
Nigel

Posted: **Mon Nov 23, 2009 3:51 pm**

Hi there, be sure to submit these hole measurements that is going to be machined in the KMX pistons,. I still have mine to go and drill and I do not have a old piston to measure it from.

Posted: **Mon Nov 23, 2009 9:37 pm**

No problems Mustang I'll detail what I actually do to the piston

Posted: **Tue Nov 24, 2009 10:15 am**

Moriwaki Man pointed me at someone on Yahoo Auctions Japan who appears to have had a batch of KR250 rings made. No pistons though sadly.

I've ordered a couple of ring sets to see if they're any good. Will report back on here when they arrive. Not even sure what they've cost me yet...

Posted: **Tue Nov 24, 2009 11:59 am**

post deleted (wrong info)

Posted: **Tue Nov 24, 2009 3:22 pm**

StrokerBoy wrote:I haven't found a source of new KR250 piston rings I'm afraid. But have I found a compatible alternative ?...

Tambo was after a cheaper alternative to KR1 rings and took a risk on some for a KMX125 (but +2mm oversize to give a 56mm bore). No good - they're completely different to the KR1 rings in everything except bore size.

But, he kindly sent them to me to have a look at for the ol' tandem-twin.

Looks promising so far. The shape of the ring ends is the same, the depth and thickness looks the same, and there's one flat and one tapered ring (top one) as per the KR. I've not done any measuring yet and I'm slightly worried that the KMX rings have a bigger ring gap, but I'll try them on a spare KR piston/barrel and do a bit of measuring at the weekend.

If this does work out to be good news, the icing on the cake is that you can pick up new pattern KMX rings for about 3p a dozen !

It's so long ago, I can't remember costs, but they were certainly cheap (maybe £2 - £3 a set), and certainly available on their own.

Has anybody run them ?

KR-1S.co.uk Forum

Pistons/rings

KR250 Pistons