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RCannon

Eric Gorr yz 300...info finally!

187 posts in this topic

I know we have been talkign a "bit" about this and been interested. I contacted Eric and he sent me an e mail talking about the status of this project. I found the ideas behind it fascinating. Its not sales smack, as I asked him about the project. Even if it were, hes basically giving us a better product for 1000.00 less..WITHOUT OPTIONS as compared to anyone else. Now, the rest of the post is what ric gave me permission to post. I dont thank that needed to be said as I am Clown Shoes compared to Erics writing skills.

So, here it is!:

The development of a 295cc 2-stroke is more complicated than just boring and plating a cylinder and shoving a bigger piston in it. Although a 2-stroke engine is a uncomplicated mechanism, it is a complicated unsteady gas dynamics mechanism. Anyone who has bought a Max Power 285 and experienced pinging, bogging, spooging, and erratic power knows what I mean. Big bores are very dependent on the proper porting and cylinder head shape but there are several companies that just bore and plate and shove bigger pistons in 2-stroke cylinders without paying attention to the details.

People argue that you can't make a 250T competitive with a 450F. But what are they really talking about? They're talking about power delivery to the rear wheel , and quite frankly the Japanese manufacturers don't know how to build a 250T, they're still copying a basic engine design from Eyvind Boyesen dating from 1979. Engineering knowlege has leaped forward quite a bit since the 70s! Engineers are trying to make 2-strokes produce power characteristics like 4-strokes (traction and acceleration), and make 4-stroke crankshafts have gyroscopic characteristics of a 2-stroke (rolling the bike over in a turn). The 4-stroke gyro solution involves the use of a lightweight connecting rod made of MMC and changing the balance factor of the crankshaft. But this costs a minimum of $2,000 and only lasts 50 engine hours. Thats OK for F-1 teams with hundred million dollar budgets, but not for dirt bikers!

AJ Waggoner from Service Motorsports heads the development of the successfull CR500AF product line. We've worked together for years and produced a 500cc 2-stroke with a very likeable powerband. Now that Greg Foster, the owner of the business has bought all the other motorcycle franchises, we want to roll into the 250T market. For enduro riding the KTM300 is a great bike, but with a high price tag and impending hgih import tarrifs, that model might disappear quickly. Besdies there are a lot of YZ250s out there that handle a heck of a lot better and are lighter. AJ suggested that we build two models, a 58hp MX3 version and a dual-sport model with power delivery like a water faucet.

For the development of this engine I used a design program sold by the SAE and written by Professor Gordon Blair. It is an unsteady gas dynamics prediction model that helped me come up with some parameters for porting, head shapes, case volume, and how everything works together with available exhaust systems.

I've also come up with a way to machine the cylinder in order to reduce the cost of a kit and keep it a top end only mod so people could avoid the expense of busting open the bottom end. AJ is looking into a custom ignition system with the proper flywheel mass as a deluxe option. I've looked a couple of different piston designs and its going to be priced the same as a standard 250 piston, not the typical Max Power/RPM high priced custom piston. Ideally I'd like this kit to sell for between $600-700 which is still far less than the average top-end maintenance cost of a 250F.

Right now I'm testing kits for these model year 250Ts; Suzuki RM250 2003-08 and Yamaha YZ250 1999-2009 These engines are so close in dimensional design that they can use the same head gasket and detonation ring, piston kit, and porting configuration. Plus the cylinders have a sturdy casting, flexible powervalve designs, ample intake systems, crankshafts with balance factors on the high side, heavy-duty transmissions designed for 450Fs, and open crankcases that are ideal for boosting the engine displacement.

I hope to be marketing a 295 kit for the Suzuki and Yamaha by mid-February and I will be advertising it on Thumper Talk first.

Best regards, Eric Gorr, Forward Motion

Back to Roland....Thats all the info I have. Sounds like I need to save about 200.00 per month to be set up by April!

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Sign me up!!!

Oh, I did. I had him charge you for two kits. Oddly enough, one gets shipped to salt lake City........

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I already have the max power 285 kit,but looks like I'll be sending my spare cylinder to Eric Gorr.Erics right about some companies just boring the cylinder out and shoving in a bigger piston,I guarantee that Max power did not do anything but bore the cylinder,machine the head,and modify the power valve,they didnt touch the ports.As for the jetting on my 285,I have it pretty close right now,but its still not perfect,the jetting been a pain in my arse.I cant wait for Eric to have this 295 kit ready,it sounds awesome!!!!!!:thumbsup:

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Sounds good, at least we have something new to talk about regarding the YZ.

It sounds as if Service Honda , or should I say Service Motorsport? might provide 2 versions, did EG give a clue as to which he would make available, MX3,dualsport or something in between? Hopefully they will remain on par with the 250 in terms of reliability and won't have the jetting or overheating issues so commonly found with the KTM. I'm wondering though what the following statement means?

Now that Greg Foster, the owner of the business has bought all the other motorcycle franchises.

Does it provide us with some insight to the question, When will Yamaha discontinue the YZ???

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Yea, I just filled my airbox with sand in hopes mine blows soon.

Damn, what a cool development. Me needs a trashed cylinder as I believe I have a head to spare...well, and powervalves.

I cannot wait for a sample of this 300.

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Every year is the last year Yamaha will stop making 2 strokes. That is always said.

This is a sweet kit. I cant wait to give my EC250 a 275 kit. Sounds like quality work for sure.

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The development of a 295cc 2-stroke is more complicated than just boring and plating a cylinder and shoving a bigger piston in it. Although a 2-stroke engine is a uncomplicated mechanism, it is a complicated unsteady gas dynamics mechanism. Anyone who has bought a Max Power 285 and experienced pinging, bogging, spooging, and erratic power knows what I mean. Big bores are very dependent on the proper porting and cylinder head shape but there are several companies that just bore and plate and shove bigger pistons in 2-stroke cylinders without paying attention to the details.

People argue that you can't make a 250T competitive with a 450F. But what are they really talking about? They're talking about power delivery to the rear wheel , and quite frankly the Japanese manufacturers don't know how to build a 250T, they're still copying a basic engine design from Eyvind Boyesen dating from 1979. Engineering knowlege has leaped forward quite a bit since the 70s! Engineers are trying to make 2-strokes produce power characteristics like 4-strokes (traction and acceleration), and make 4-stroke crankshafts have gyroscopic characteristics of a 2-stroke (rolling the bike over in a turn). The 4-stroke gyro solution involves the use of a lightweight connecting rod made of MMC and changing the balance factor of the crankshaft. But this costs a minimum of $2,000 and only lasts 50 engine hours. Thats OK for F-1 teams with hundred million dollar budgets, but not for dirt bikers!

AJ Waggoner from Service Motorsports heads the development of the successfull CR500AF product line. We've worked together for years and produced a 500cc 2-stroke with a very likeable powerband. Now that Greg Foster, the owner of the business has bought all the other motorcycle franchises, we want to roll into the 250T market. For enduro riding the KTM300 is a great bike, but with a high price tag and impending hgih import tarrifs, that model might disappear quickly. Besdies there are a lot of YZ250s out there that handle a heck of a lot better and are lighter. AJ suggested that we build two models, a 58hp MX3 version and a dual-sport model with power delivery like a water faucet.

For the development of this engine I used a design program sold by the SAE and written by Professor Gordon Blair. It is an unsteady gas dynamics prediction model that helped me come up with some parameters for porting, head shapes, case volume, and how everything works together with available exhaust systems.

I've also come up with a way to machine the cylinder in order to reduce the cost of a kit and keep it a top end only mod so people could avoid the expense of busting open the bottom end. AJ is looking into a custom ignition system with the proper flywheel mass as a deluxe option. I've looked a couple of different piston designs and its going to be priced the same as a standard 250 piston, not the typical Max Power/RPM high priced custom piston. Ideally I'd like this kit to sell for between $600-700 which is still far less than the average top-end maintenance cost of a 250F.

Right now I'm testing kits for these model year 250Ts; Suzuki RM250 2003-08 and Yamaha YZ250 1999-2009 These engines are so close in dimensional design that they can use the same head gasket and detonation ring, piston kit, and porting configuration. Plus the cylinders have a sturdy casting, flexible powervalve designs, ample intake systems, crankshafts with balance factors on the high side, heavy-duty transmissions designed for 450Fs, and open crankcases that are ideal for boosting the engine displacement.

I hope to be marketing a 295 kit for the Suzuki and Yamaha by mid-February and I will be advertising it on Thumper Talk first.

Best regards, Eric Gorr, Forward Motion

Back to Roland....Thats all the info I have. Sounds like I need to save about 200.00 per month to be set up by April!

Is the max RPM going to change with the kit? How much of the strong "250 2 stroke hit" is going to be stiffled?

I find my GG300 has noticably more TQ but the fun of the hit is sacrificed due to the linear power band.

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Crap I just did the top end including jug too.

I may be on a search for a plated YZ 250

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I may be on a search for a plated YZ 250

Those same thoughts entered my mind.....:thumbsup: I'm pouncing on one if I ever see one for sale.

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Those same thoughts entered my mind.....:thumbsup: I'm pouncing on one if I ever see one for sale.

I came across a 4G one....

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sounds like the 450 buster i have been looking for! Hopefully a complete bike wont bust my bank! I am really curious to how the rm3000af would be...the best handling frame coupled to a snappy engine that has been smoothed and strengthened. sounds good to me :thumbsup:

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I the engine performs like the ktm300, then I'm all over this...

I hope that he can really tame the hit out of it. I ride enduros and would like something steady and predictable with lots of low end torque that doesn't spin the wheel too much.

I am not sure its completely legal to run a 300 jug on a yz250 is the district 37 races. We'll have to see about that...

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Wow, this is promising. Now why in the hell did a I do some preventative maintenance on my YZ last weekend? I went and put in an OEM top end kit. :thumbsup:

Oh well, I'm actually quite happy with everything power/torque wise now that I have a Rekluse on board. However, this is the next big mod for sure. One can always use more torque, right?? :smirk:

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I sure hope that Service Motorsports has "YZ300" stickers available for the rear fenders so all will know.

Now if I can just nurse my top end for a few more months

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Wow, this is promising. Now why in the hell did a I do some preventative maintenance on my YZ last weekend? I went and put in an OEM top end kit. :thumbsup:

Oh well, I'm actually quite happy with everything power/torque wise now that I have a Rekluse on board. However, this is the next big mod for sure. One can always use more torque, right?? :smirk:

I have an extra scoop of sand, so no problems! We'll fill your airbox too.

"Someone " also told me the piston weighs less than a Wiseco Pro Lite.

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