I recently obtained various bits and pieces as the bare bones of a KR250A project, frame No. KR250A-009209 and engine no. KR250AE-009255. As frame and crankcase set came from the same source (a breaker's in France) and the numbers are close it's safe to assume they belong together.
The intention is to build a track bike so originality is NOT the goal. Front forks will either be KR-1/KR-1S or RGV250 upside down fork assembly. As for the weird standard rear suspension, this will have to go. Nobody makes a replacement shock so an alternative setup will have to be designed, perhaps a copy of the 1982 GPz550 setup if there is enough room to squeeze that in. If not, a copy of the Yamaha monoshock setup.
Wheels- 17" front and rear. KR250 race fairing and seat, if I can find a source for them.
The frame has been taken apart and first step will be to weigh the bits.
KR250A track bike project.
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Gerrit
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KR250A track bike project.
"Mine is a long and sad tale", said the mouse.
"Indeed it is", said Alice, looking at the mouse's tail.
"Indeed it is", said Alice, looking at the mouse's tail.
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Gerrit
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Re: KR250A track bike project.
Weight of main frame: 6.16 kg.
Weight of rear subframe: 2.315 kg.
Weight of LH side plate: 1.33 kg.
Weight of RH side plate: 1.385 kg
Total weight of frame minus nuts and bolts is 11.19 kg.
Weight of rear subframe: 2.315 kg.
Weight of LH side plate: 1.33 kg.
Weight of RH side plate: 1.385 kg
Total weight of frame minus nuts and bolts is 11.19 kg.
"Mine is a long and sad tale", said the mouse.
"Indeed it is", said Alice, looking at the mouse's tail.
"Indeed it is", said Alice, looking at the mouse's tail.
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StrokerBoy
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Re: KR250A track bike project.
Sounds great ! Looking forward to seeing it progress.
Kawasaki KR250 Tandem Twin (x4) & KS-II 80,
Yamaha RD350LC,
Suzuki GSX-R750RK & RB50 Gag.
Yamaha RD350LC,
Suzuki GSX-R750RK & RB50 Gag.
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Gerrit
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Re: KR250A track bike project.
Surprisingly, the steering head of the KR250A is 5 mm longer than that of the KR-1(S), 195 vs 190 mm, which means the steering stem of the KR-1(S) lower fork yoke is 5 mm too short, requiring a longer stem to be made.
"Mine is a long and sad tale", said the mouse.
"Indeed it is", said Alice, looking at the mouse's tail.
"Indeed it is", said Alice, looking at the mouse's tail.
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Gerrit
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Re: KR250A track bike project.
First pics.
The side plates have been modified by cutting away the footrest brackets:
Tabs will be welded on for the rearsets.
The side plates have been modified by cutting away the footrest brackets:
Tabs will be welded on for the rearsets.
"Mine is a long and sad tale", said the mouse.
"Indeed it is", said Alice, looking at the mouse's tail.
"Indeed it is", said Alice, looking at the mouse's tail.
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Gerrit
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Re: KR250A track bike project.
As a full fairing will be fitted the four lugs for the belly pan aren't needed and were removed:
"Mine is a long and sad tale", said the mouse.
"Indeed it is", said Alice, looking at the mouse's tail.
"Indeed it is", said Alice, looking at the mouse's tail.
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Gerrit
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Re: KR250A track bike project.
First rough surgery on the rear subframe:
"Mine is a long and sad tale", said the mouse.
"Indeed it is", said Alice, looking at the mouse's tail.
"Indeed it is", said Alice, looking at the mouse's tail.
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Gerrit
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Re: KR250A track bike project.
Next step is to carefully remove these two weird brackets, one at a time, and replace by 20 x 3 mm round tubing:
I might need them later for an altered rear suspension setup.
I might need them later for an altered rear suspension setup.
"Mine is a long and sad tale", said the mouse.
"Indeed it is", said Alice, looking at the mouse's tail.
"Indeed it is", said Alice, looking at the mouse's tail.
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maccas
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Re: KR250A track bike project.
Fantastic! Keep the updates coming!
I'll be embarking on something similar in the future.
My plans were tz250 reverse cylinder forks , swingarm, shock and linkages with similar butchery to original frame. Here is q video of a bike that was modded in japan with tz rear shock and zxr400 swingarm, i think!
https://www.google.com/url?sa=t&source= ... 9GgKw7Lv43
I'm heavily basing mine on this video!
Dan
I'll be embarking on something similar in the future.
My plans were tz250 reverse cylinder forks , swingarm, shock and linkages with similar butchery to original frame. Here is q video of a bike that was modded in japan with tz rear shock and zxr400 swingarm, i think!
https://www.google.com/url?sa=t&source= ... 9GgKw7Lv43
I'm heavily basing mine on this video!
Dan
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maccas
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Re: KR250A track bike project.
Regarding the steering stem and head, be careful here as the rake is quite relaxed, so the yokes have quite a lot of offset built in to bring the trail back to a reasonable number. Make sure to check the offset on the forks you intend to fit so you don't make it super lazy steering!
Dan
Dan
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maccas
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Re: KR250A track bike project.
See pic from Tim's website of the same bike. Sorry attachment didn't work.
Dan
Dan