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6 speed transmission for YZ 250

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I have been making some inquires regarding the aforementioned to a reputable company out of the UK.

They are currently looking at some ratios to suit the 6 speed.

What I have suggested is pretty much the same 1st to 5th as the standard YZ with the 6th being a little taller than the WR 5th.

Basically an over drive on the current 5 speed but with out it being a big jump to 6th. A Close ratio 6 speed, so to speak.

They have assured me that they can do this, and looking at their product range I have no doubt they can supply.

Cost? Well that is a little prohibitive for a 0ne Off, around 4000 UK Pounds.

Yes that is a new bike.

However costs can be reduced significantly if there are enough orders.

They have estimated around 1700 quid (UK Pounds) if they produce around 65 sets.

Bear in mind that this is not just one additional gear but a full gearbox including shift barrel, forks, full gears and shafts with a polished finish, basically the complete package.

For that money I would buy a set. That would keep the KTM out odf my shed for a long time at a much cheaper price.

Matched up with a EG 300 kit would be pretty awesome.

Some how about some comments, feedback on ratios, hands up who may want one.

Anyone else out there have any other sources for this type of work?

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I would love to have one, but the cost would stop me. Not that it would not be amazing to have, because it would.

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wr1-5 is enoufgh for me. I like the long spead out gears of wr1-5. The olney place I tap out 5th all the time is when I ice race. In the summer im lucky to tap 4th out riding off road.

With the crapy reliability of shift forks, gears, and dogs in stock design theres no way id stress anyting more stuffing another gear in there. I just wouldnt feel comfortable going 20 miles into the woods. The stock box is already too flawed for me.

Might not be a bad mod for a stock bike but I bet even a stock bike would tare a 6 speed up.

The avalibility of parts would blow im shure too.

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Why the need ? I have run a Wr gearbox in a Yz 250 2t and its perfect, and I very rarely needed to go faster in 5th

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You're looking at it from the wrong direction.

It might be a whole lot less expensive to CNC or cast some new cases that accept all the existing YZ 250 parts 1999-2012, but use a 6 speed from another application like a Yamaha Raptor Quad.

Prototyping on a 3D printer would be efficient if you can find someone with that service. Machinist's Wax or Delrin would be a good prototyping material for development of the CNC program. The cost of the metal would probably be around $200-$500 per pair (large billets are not cheap).

I have the machinery to build cases, but I'm out of the USA until June.

I've considered a few other oddball custom case projects:

-CR500R or KX500 cases that directly bolt into a YZ frame.

-Using a cylinder from a Ski-Doo 800 E-TEC snowblower with a CR500 transmission that bolts up to a CR250R or YZ250 Chasis would be neat.

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Why the need ? I have run a Wr gearbox in a Yz 250 2t and its perfect, and I very rarely needed to go faster in 5th

Do you ride motocross or trails?

thanks in advance

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I agree the cost is prohibitive.

For those who think you don't need a 6 speed, go ride one of the new KTM EXC/XC with the 6 speed. It is Very impressive. Much better suited to the 2T than the WR gears which I have been running for many years.

The manufacturer ín the UK is NOVA Racing. Check them out. They do some good work.

I'm going to check another route also which should be cheaper.

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I run 14/47 gearing with WR gears on my YZ250. I would love to run a lower sprocket combo and still have that insane top speed, and perhaps less gap between the middle gears.

But not enough to spend $2k+ on it.

I will keep my eyes on this though.

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I run 14/47 gearing with WR gears on my YZ250. I would love to run a lower sprocket combo and still have that insane top speed, and perhaps less gap between the middle gears.

But not enough to spend $2k+ on it.

I will keep my eyes on this though.

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Basically an over drive on the current 5 speed but with out it being a big jump to 6th. A Close ratio 6 speed, so to speak.

This is exactly what Yamaha had in the 1980 YZ250G. Why they went to the 5 speed in 1981 and continue it to this day remains mystifying.

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This is exactly what Yamaha had in the 1980 YZ250G. Why they went to the 5 speed in 1981 and continue it to this day remains mystifying.

Well there is a question,

Can those gears be made to fit. It may only require some shafts made???

Do you have the ratios for the YZ 250 G?

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My GasGas had a 6 speed. I would love to have 6th for the transfer sections in Enduros. I got vibrated to death in 5th on a 5 mile long pavement transfer section at Caney Creek a few weeks ago. But maybe in the range of $500-900 US.

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I have been making some inquires regarding the aforementioned to a reputable company out of the UK.

They are currently looking at some ratios to suit the 6 speed.

What I have suggested is pretty much the same 1st to 5th as the standard YZ with the 6th being a little taller than the WR 5th.

Basically an over drive on the current 5 speed but with out it being a big jump to 6th. A Close ratio 6 speed, so to speak.

They have assured me that they can do this, and looking at their product range I have no doubt they can supply.

Cost? Well that is a little prohibitive for a 0ne Off, around 4000 UK Pounds.

Yes that is a new bike.

However costs can be reduced significantly if there are enough orders.

They have estimated around 1700 quid (UK Pounds) if they produce around 65 sets.

Bear in mind that this is not just one additional gear but a full gearbox including shift barrel, forks, full gears and shafts with a polished finish, basically the complete package.

For that money I would buy a set. That would keep the KTM out odf my shed for a long time at a much cheaper price.

Matched up with a EG 300 kit would be pretty awesome.

Some how about some comments, feedback on ratios, hands up who may want one.

Anyone else out there have any other sources for this type of work?

I would absolutely love to have one of these in my bike especially since I have a lot of time at wide open blasts in the desert and dunes. The issue is its way too expensive for me. You do get a lot for the kit and Im sure its well put together but all my money is going into my truck now.

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Thats a major eng'ing job to fit that (6 gears) into the case.

If your off road only just put the wr gear set into it ,,job done, esp. if it's a 300

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It could be done. But more than likely the gears would get narower. Ive already seen countless gears break teeth in stock 250's. There are enoufgh forks a proper drum would need to be made. The yz transmission seems like such a poor design to me. I dont know how adding another gear would be making the bike any better durability wise. I ride 250 2 strokes because there simple and dont brake if you know what to check/fix. To bring the $ down why dont you design just the gears and drum new. Then just recut the stock shafts for the new circlip slots. Redoing the main shafts wont get you any more room in the case.

yz295 + wr1-5 and a rekluse is pure love my 05 has 0ver 600 hours on it

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Not to be rude but a lot of people here are suggesting the wr gear set swap - while that may more than suffice for many people the OP has clearly considered this option and is interested in seeing what other alternatives exist, be it custom gears made or otherwise.

As the OP said the new KTMs have a 6speed and he is interested in seeing if something similar can be made for our beloved yz's rather than investing in a whole new bike

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This is exactly what Yamaha had in the 1980 YZ250G. Why they went to the 5 speed in 1981 and continue it to this day remains mystifying.

I installed the '81 IT250H six-speed transmission gears in my '81 YZ250H, (which I recently bought back, and awaits refurbishing.)

It was perfect for me, and plenty reliable, as the next two owners attested.

New custom-manufactured 6-speed gears would not likely have the same flaws that Yamaha's mass-produced 5-speed gears do, despite perhaps being a bit narrower, imho.:ride:

I hope a 6-speed wide-ratio transmission can be found for my '06 YZ250's, one day!👍

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just put a whole ktm 300 6 speed motor into a yz frame.probably the cheapest most reliable way to go.

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just put a whole ktm 300 6 speed motor into a yz frame.probably the cheapest most reliable way to go.

You are probably right. That would give electric start also.

The new 300 6 speed is an awesome combo, except the chassis, which I personnaly don't gell with.

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