KBL96251 trouble (24" 2x Motor bike build)

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j bjork   10 kW

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Re: Kelly KBL 96251 and QS V3 273 trouble

Post by j bjork » Jan 16 2021 4:51am

It was exactly that kind of break I mean. I dont think you will break the tubes.

I might add that I dont have any experiace with that kind of problem myself, but when I built a fast bike I used a dual crown fork even though it is only rear wheel drive..

It might not break right away, but with time when the metal flexes it wears out. Make sure to look closely for cracks often.

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Ronin   1 mW

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Re: Kelly KBL 96251 and QS V3 273 trouble

Post by Ronin » Jan 16 2021 6:45am

Thanks for your input, was thinking a lot about this, and even this fork seem to be built with bigger and stronger materials I got an idea instead of finding another fork... Cut up two stainless pipes that fit perfectly down the holes and attach somehow on the handlebar. Maybe weld it tight on top of the fork. I measured 32,5mm in the holes, and with 3-4mm thickness pipe material I think it could make the fork very much stronger. And maybe switch from aluminium to a strong steel handlebar. And about the frames forkhead (hole), that could be the weakest part too, so instead of welding more material around the neck, I could build a kind of steel banner to wrap around and mount 10cm below the head with strong screws. Just thinking loud... :)

Here are some more detailed pictures of the fork.
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Ronin   1 mW

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Re: Kelly KBL 96251 and QS V3 273 trouble

Post by Ronin » Jan 17 2021 7:36am

So I just found these 2 pipes of hard steel from a not working garage jack, not so very heavy but dont think I can bend them easily. They fit perfect into the holes in the fork. Have to hammer them down the last part. So how long down should I jack them down? All the way to bottom, 20cm? And some clammers or something to tight to the handlebar so they cant move without breaking it.

I renamed this thread to include building project of this bike, hope that is ok, or should I make a new thread with building project pictures?
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amberwolf   100 GW

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Re: Kelly KBL 96251 and QS V3 273 trouble

Post by amberwolf » Jan 17 2021 11:04pm

Looks like your crown is steel, so it's less likely to just break like mine did...but it could still bend/twist in the same manner, and become unusable. It's more likely that the steerer/crown joint would have a problem, but it depends on how they built it.

If it helps, the problem is more likley to be from braking forces with all the extra weight on it than the motor acceleration.

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Ronin   1 mW

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Re: KBL96251 trouble (24" 2x Motor bike build)

Post by Ronin » Jan 19 2021 4:30pm

Ok, so I have ordered a new fork I will try to fit.

https://www.ebay.com/itm/630MM-FRONT-FO ... 3378947569

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amberwolf   100 GW

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Re: KBL96251 trouble (24" 2x Motor bike build)

Post by amberwolf » Jan 20 2021 1:14am

That doesnt' say how big it's steerer tube is, or which kind. Did you already ask the seller to make sure it will fit your headtube?

There are several headtube sizes and styles for bicycles, and then there are motorcycles, pitbikes, etc etc. :( One article about bicycle types:
https://www.bikeradar.com/features/the- ... -headsets/
wiki page
https://en.wikipedia.org/wiki/Head_tube ... _diameters
sheldon brown (my usual go-to for bicycle info)
https://www.sheldonbrown.com/cribsheet-headsets.html

If it's for a motorcycle it probably won't fit your bicycle unless you cut off your headtube and weld on a new one, and get new bearing cups. ;)

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Ronin   1 mW

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Re: KBL96251 trouble (24" 2x Motor bike build)

Post by Ronin » Jan 20 2021 4:41pm

Thanks for links and info, the steerer tube is 41mm wide and 120mm high. not sure about the bearings, know there are many many many standards
Anyway, ready for a forkhead cut and replace tig opereation if necassary, I Think the operation to get the motor axle to hold torque and not slip will be the biggest operation. And have to make some solid special clamps for the extra brake caliper too. Joy project :D
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