OKOs For Yamahas
Kits for TY 175
We have a few different kits for the TY175.  For mostly stock engines we use the 21mm carburetor.  It gives the best overall performance.  The kit may be purchased by itself or with a Venhill universal throttle cable.  We offer the cable since the stock throttle cable does not have enough free length inner cable for the OKO.  For TY 175s that have the WES or other free-flowing exhaust, we use the 26mm carburetor.  If the stock airbox is used, since it is fairly restrictive, the 24mm may be the better choice.  Carburetor size is directly related to flow through the engine, so the better the flow, the larger the carburetor that will work.  You can choose the size you want below and whether or not you want a cable.   We also offer clear float bowls and UNI two-stage filters.  Eliminating the airbox and using the UNI filter will greatly improve air flow.  One note:  The air boot at the carburetor intake will need to be heated and stretched a bit to fit the OKO.  We immerse the boot in boiling water for a couple of minutes to soften it so it will stretch over the OKO intake.  Also, these kits are designed to work with the Autolube disabled.  If you use the Autolube you will need to insert a nipple into the side of the carburetor as it was on the stock carb.
Clear Bowl Options
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Cable Options
UNI Filter Options
Kits for TY 250
Kit for TY 350
Kit for IT 200
Kit for WR 200
Ty 250s have jetted practically identical for all.  Best results have come from use of the 26mm.  The kit for these is just the carburetor, jetted for the TY250 and it comes with extra jets, just in case.  The OKO intake is larger than the stock carburetor's, but we heat the rubber air boot in hot or boiling water for a minute and then it stretches over the end of the OKO.  If your air boot is too stiff after heating to stretch, we can provide a sleeve for it.  You may need to cut the end of the air boot back a bit.  Your throttle cable should work.   This kit is available in Metallic or Black.
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The kit for the Yamaha TY 350 uses a 28mm K-103 OKO (Curved top).  It is markedly better than the stock carburetor and made fourth gear wheelies a breeze.  Our test bike had Boyesen reeds, and we recommend these as well.  Though we heat and stretch the airbox hoses for the TY 175 and 250, our air box hose did not want to soften up and stretch, so we added a sleeve for it and include that in the kit.  Others may be able to stretch theirs for a more stock look.  We used the stock cable, but needed to modify it and use the adjuster at the carburetor end.  If needed, a cable for the 350 can be ordered above.  We offer a discounted price when the cable is purchased with a carburetor kit.
The kit for the Yamaha IT 200 consists of a 36 or 34mm OKO K-104 carburetor.  Our test bike had a 36mm Keihin, so we used the 36mm and got excellent results with improved power and throttle response.  We believe the 34mm will also work well since the IT came with a 34mm carburetor.  If your focus is more on low to mid-range power you may want to use the 34mm.  Inserting the carburetor into the manifold was a tight fit, as was the air boot, but both stretched a little, easily to accommodate the OKO.  Our throttle cable worked and we "assume" it was stock.  Cables are available to order above if you need one.
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We developed a kit for the WR200 with the help of our customers off site.  The kit used the 30mm OKO D slide with the curved top.  It comes jetted for the WR and includes extra jets for fine tuning and elevation differences.  Our customers tell us it eliminates the midrange "blubber" and increases both power and throttle response.  There is no need to modify your manifold or air boot, but you may need a throttle cable which can be ordered above.  The 30mm OKO is available in metallic or black.
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