Pistons/rings

The place to talk about your Tandem!
StrokerBoy
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Post by StrokerBoy »

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> 8) :D
Kawasaki KR250 Tandem Twin (x4) & KS-II 80,
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WIGARUS
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Post by WIGARUS »

Image
KR on the right
Image
KR on the left
Image
KR on the left

hope this helps some of you lads :)

KMX125 +2.00mm oversize.
Last edited by WIGARUS on Mon Jun 29, 2009 2:54 pm, edited 1 time in total.
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ScottaKR
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Post by ScottaKR »

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

:oops: 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. 8)
KR250 Tandem Twin (Naked) :mrgreen:
KR1 Red/White
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WIGARUS
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Post by WIGARUS »

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 :P
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ScottaKR
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Post by ScottaKR »

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<
KR250 Tandem Twin (Naked) :mrgreen:
KR1 Red/White
KR1S Track Bike (has been put on hold for now)
ZXR750 H1 (Winter project)
StrokerBoy
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Post by StrokerBoy »

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 ?
Kawasaki KR250 Tandem Twin (x4) & KS-II 80,
Yamaha RD350LC,
Suzuki GSX-R750RK & RB50 Gag.
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ScottaKR
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Post by ScottaKR »

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.
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Mustang
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KR250 Pistons

Post by Mustang »

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!
KR250 under construction and one for spares or future project!
StrokerBoy
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Post by StrokerBoy »

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.

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Post by nigb »

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.
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Post by Mustang »

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.
KR250 under construction and one for spares or future project!
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Post by nigb »

No problems Mustang I'll detail what I actually do to the piston
StrokerBoy
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Post by StrokerBoy »

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... :?

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Post by nigb »

post deleted (wrong info)
Last edited by nigb on Wed Nov 25, 2009 11:31 am, edited 1 time in total.
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Tambo
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Post by Tambo »

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

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. :cry:

But, he kindly sent them to me to have a look at for the ol' tandem-twin. 8)

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 ! :lol:
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 ?
Kr1s c3, vfr750fg, Dnepr MT11, Pegaso 650
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