Information kindly supplied by Ito Hiroki
piccys of the KR-1R/KR-1S
brochures on Ito Hiroki's site http://www2s.biglobe.ne.jp/~hoti/kr1sr.html
| Bike | Kawasaki KR-1R D1/D2 |
| Wheels | Same as KR-1S |
| Carbs | Kehin 35 PWK (KR-1S has 28 PWK) |
| Motor | Gear ratio for KR-1R from first gear to 6th gear are 2.357,
1.700, 1.409, 1.208, 1.120, 1.043 Gear ratio for KR-1S are 2.533, 1.727, 1.315, 1.086, 0.962, 0.862 first reduction ratio / second reduction ratio for KR-1R are 2.541 (61/24) / 2.666 (40/15) first reduction ratio / second reduction ratio for KR-1S are 2.541 (61/24) / 2.928 (41/14) Also, KR-1R has stronger springs for clutch than KR-1S. |
Atsushi Yamaguchi has modified his KR-1R (thats his bike pre mod above) by fitting the front end of a ZXR 250
It is a straight swop. KR-1S front wheel is a bit wider than a ZXR250 but still fits ok. See his site
http://member.nifty.ne.jp/computerature/bike/bike.html
To read info of Japanese sites use the translation engine on the altavista site http://uk.altavista.com/trns
Carb bits can be found on this site http://www.hase.gr.jp/~extreme/archives/sources/genuine/
A bit about the KR-1R from Peter Lodge - 'I rode against a KR-1R a few years ago (more than a few years actually). Ridden by Rob Frost, it was originally prepared by Jack Machin for Paul Brown. I remember it being a fraction faster than mine & his gearchange points were totally different. He definitely had the big carbs on as I caught him with the tank off after the race! Don't know what happened to the bike, but it went down the road a few times that I know of, taking me out once. Rob went on to 125 & 250 Supercup & briefly rode a Superbike. Think he rides an R6 now at national level & tests for Fast Bikes magazine.' (26 July 2001)
Continuing the story of Rob Frost's KR-1R - a snippet from Tim
Pritchard "... found a picture of Frosty's old KR1-R. Pete Lodge was
right,it was imported by Jack Machin for Paul Brown to race, and when they
got hold of it, XX paintwork resprayed a KR1-S logo over the original
KR1-R one that first adorned the bike.. to be honest though, the damn
thing never ran right and the photo that I have included in this email was
at Donington, where he pulled out of both races due to it running so shite
and not due to the fact that he had forgotten to put the front wheel in! I
hope you can use the pic, sorry about the quality, but to be honest it was
a miserable day at Donington..." (16 Nov 2002)
"Having owned a KR-1 since February 1989(!) when I saw the british MCN article I had to have one (R). Incidently Simon Crafar (one time Red Bull 500cc GP winner) raced a KR-1 in 250cc sports product here '88/'89. Shortly after the S was released here due to overwhelming sales of RGVs it started getting its arse kicked. What could be done? Kawasaki NZ asked dealers what was needed; dry clutches? race igitions (3 ignition curves switchable) or race chambers or carbs? And so the KR-1S C3A variant was born - an S model factory fitted with the 35mm carbs from the R model. KR-1SP was distinguished by yellow Sports Production stickers under Kawasaki along the side of the belly pan. Anyway my story is ... I found in '91/92 what is believed to be the only R model in NZ (frame number 25!) at an importers (200 miles away) and for only NZ$3200 (1000 quid). Whether this had been proddy raced in Japan (remnants of Team Green stickers on tail section) is uncertain. Doubtful as was still wearing factory OEM tires front and rear. Two of my friends have each owned KR-1S and KR-1SP so it was fitting that I own both a KR-1 and KR-1R. Parts of this bike have visited your shores - barrels replated by APTEC Coatings. Whats required - 35mm KR conversion: Modify standard Reed block inserts (white part) to transition of larger bore of 35mm rubbers. Inlet tract rubbers (engine side) 2 x PWK35 carbs Air box rubbers/trumpets for above. If non OEM source of carbs unavailable try Sudco in USA - they have ultra-spec'd Quad Air Screw species (!) - Trick but expensive although can be ordered jetted to suit at US$230 each. Or contact local motocross breakers/wreckers and obtain 1990 KX125 H1 carbs (PWK35 will require rejetting - needles, pilot jets and mains). NZ$100 (30 quid) second hand. Beware of abrassive wear from dirt and sand to the throttle slides as new replacement slides will cost more than second hand carbs. 1991 KX125H2... models on (motors became 54mm x 54mm bore/stroke) went to larger 38mm carbs - although cool on paper I believe is overkill for KR and inlet tracts to suit would be a pain. When I can (locate) I will send full jetting spec for the SP. If I can locate the photocopies of Kawasaki part sheets for all things KR-1SP and R (most of my stuff is now in longterm storage), I will forward them onto you. All parts are available here (ex Japan - around 1 week) at last pricing new OEM 35mm carbs had risen from NZ$330 (100pound) to over $450 each. "
and there is more
"...Part sheets for KR250C3A Sport Production variant of KR-1S (identical carbs to KR-1R (D1)). The TIF images should be printer friendly at 600 dpi resolution (airbox pwk35a pwk35b reeds). The sheet referring to KX jetting is from 1990 H1 models - KX125 of this year has same PWK35s as KR-1R but with different jetting (compare this sheet to parts list of C3A models to see jetting required). I also have a sheet with all model variants including engine and chassis batch numbers and colour schemes - but it is in storage with my workshop manual at moment. The models imported here came with 14/41 sprockets which gave slightly less top speed but greater acceleration."
three more fiches with C3A specific parts throttle cable, tank and barrels.
| Part | Number | Price |
| Air Box rubber | 14073-1394 | NA |
| Carbs | 15001-1647/8 | NA |
| Throttle Cable | 16065-1196 | £19.55 |
| Reed Block assy with reeds |
12021-1084 | £85.18 |
| Fuel Tap | 51023-1168 | £35.26 |
| SP Barrels | 11005-1596/7 A | NA |
Prices from Cradley Heath Kawasaki add Vat and P&P
.'As I remember the KR 250 C3A was a coming together of the standard C model and the Japanese domestic D. The D was the base model that they used in Japan for their race class that had to be based on a "road legal" bike, they had 35mm carbs, programmable igniter box, close ratio gear box and different port timing. Also available were another set of cylinders for "racing use only" that New Zealand used for our limited numbers of C3A. The difference between a "NZ" C2/C3 KRI-S and a C3A KR1-SP is ; cylinder port timing'
| Model -> | C3 | C3A | D2 |
| exhaust close degrees ABDC (only the top of the exhaust need to be raised) |
94 | 96 | 94 |
| scavenging degrees ABDC | 63 | 63 | 63 |
| cylinder head (the higher compression ratio of the C3A gave more mid-range grunt but was prone to detonate on fuel of less than 100 octane we were meant to run 96 at "production" race meets) | 7.4 | 8.1 | 7.4 |
| Part | No |
| carbs l/h | 15001-1647 |
| r/h | 15001-1648 |
| main jet #145 | 92063-1362 |
| needle jet R1372J | 16009-1567 |
| pilot jet #40 | 92064-1140 |
| slide 6.0 cut away | 16025-1161 |
| throttle cable (fits standard handle bar controls / twist grip) |
54012-1383 |
| choke/starter cable (fits std h/bar controls) |
54017-1120 |
| carb holder | 16065-1196 |
| carb holder clamp | 92037-1326 |
| reed block assy (same reed petals but has a different "stuffer" in mouth of reed block) |
12021-1084 |
| duct carb to air box | 14073-1394 |
| duct carb to air box clamp | 92027-171 |
| fuel tap (can use std C tap it little less flow and must be run on "prime" as big carbs have no fittings for diaphragm connection) | 51023-1168 |
| fuel tap 0-ring (use this if you use big tap) |
43049-1066 |
Return to KR1-S FORUM Return to Main Index
This document WAS maintained by Mark Jordan.