Cylinder Works 270cc kit for YZ250F '20

fpandjic
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fpandjic
Edited Date/Time 3/20/2022 12:24pm
I have recently purchased this kit and the bike is currently in the building process. Does anyone have experience with it?

I tried contacting CW for a map, but they said they don't have one or should I say they had one, but that bike is no longer with them so. I assume it needs more fuel, but if anyone has some map for it and would share it, I would really appreciate that.
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SKIDLID
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SKIDLID 8/8/2020 3:23am
8/8/2020 3:23am
my past experience with a big bore kit on a carb yz290 it needed less fuel. I had to lean out the main at least 3 steps from the original jet. I also have a big bore scooter for my kids when they where younger and it required the same thing.
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DB505
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DB505 8/8/2020 6:27am
8/8/2020 6:27am
Keep us posted on the build
PTshox
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PTshox 8/8/2020 1:20pm
8/8/2020 1:20pm
Very interested in doing the same thing. Would like to see someone post a map.....

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byke
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byke 8/8/2020 1:32pm
8/8/2020 1:32pm
Momus wrote:
Sucks harder. Leaner.
^^^That.

An engine is an air pump. Increasing the volume of air that moves through the engine per cycle, like from increasing the displacement, would require more fuel to match the increased air flow. A carb or open loop fi system would not have the ability to compensate on its own.
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Gravel
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Gravel 8/8/2020 7:44pm
8/8/2020 7:44pm Edited Date/Time 8/8/2020 7:45pm
Carb experience doesn’t correlate with EFI. Big bore or more compression with a carb will absolutely pull more fuel, usually needing smaller jetting. You don’t pull fuel from an injector, it’s a pressurized delivery. It’ll probably need more fuel from the map.
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nascarnate326 8/9/2020 6:27am
8/9/2020 6:27am
I think these kits would be more popular with vet riders if CW offered the exact tune needed. I cant imagine doing a rebuild and not having a legit 100% tested tune from the manufacture.

Are there other companies like Tokyo Mods that have ready to go tunes?
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Moto520
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Moto520 8/9/2020 7:52am
8/9/2020 7:52am
I know TZR Motorsports did a 270 kit on a buddy’s yz250f. He did the remap as well so contact them!
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fpandjic
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fpandjic 8/9/2020 8:01am
8/9/2020 8:01am
nascarnate326 wrote:
I think these kits would be more popular with vet riders if CW offered the exact tune needed. I cant imagine doing a rebuild and not...
I think these kits would be more popular with vet riders if CW offered the exact tune needed. I cant imagine doing a rebuild and not having a legit 100% tested tune from the manufacture.

Are there other companies like Tokyo Mods that have ready to go tunes?
Exactly. How can a company be selling the kit and then not having the map for it... It's like they never tested it. Their answer was that the bike is no longer with them and therefore they don't have a map.
yz133rider
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yz133rider 8/9/2020 8:04am
8/9/2020 8:04am
nascarnate326 wrote:
I think these kits would be more popular with vet riders if CW offered the exact tune needed. I cant imagine doing a rebuild and not...
I think these kits would be more popular with vet riders if CW offered the exact tune needed. I cant imagine doing a rebuild and not having a legit 100% tested tune from the manufacture.

Are there other companies like Tokyo Mods that have ready to go tunes?
fpandjic wrote:
Exactly. How can a company be selling the kit and then not having the map for it... It's like they never tested it. Their answer was...
Exactly. How can a company be selling the kit and then not having the map for it... It's like they never tested it. Their answer was that the bike is no longer with them and therefore they don't have a map.
Tons of companies sell cams, pistons. exhausts and don’t have a suggested map for any of it.

Tons of products are marketed as lighter, faster, more power, the best! Etc

And have zero info on how much lighter, how much more power, zero details.

Our aftermarket industry in largely a joke in those details. There are exceptions of course but largely that’s how it is in Mx.
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Momus
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Momus 8/9/2020 10:20am
8/9/2020 10:20am Edited Date/Time 8/9/2020 10:26am
Momus wrote:
Sucks harder. Leaner.
byke wrote:
^^^That. An engine is an air pump. Increasing the volume of air that moves through the engine per cycle, like from increasing the displacement, would require...
^^^That.

An engine is an air pump. Increasing the volume of air that moves through the engine per cycle, like from increasing the displacement, would require more fuel to match the increased air flow. A carb or open loop fi system would not have the ability to compensate on its own.
Have you had any actual tuning experience on racing engines?

The bigger bore allows more air into the cylinder in the same amount of time as the smaller bore did.

The resulting increased speed of the air lowers the depression over the carburettor's main nozzle and with the difference between atmospheric pressure acting on the fuel in the float bowl and the low pressure in the venturi now slightly greater, more fuel is drawn in.

Also, the higher air speed may also improve the mixture quality with better atomisation and less wall wetting, which may also contribute to a leaner setting- or the original jet being retained; which is the same thing.

*An engine pumps air- and so do you. That cliche you used is superficial.

An engine is more a high temperature, high speed and high force chemical reaction chamber.
mxrose3
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mxrose3 8/9/2020 10:35am
8/9/2020 10:35am
I just did a 270 kit on my 17' YZ250F. it definitely needed more fuel up top. Pretty close to stock on bottom rev range though.. Plug was black before the kit, and then after doing the 270 it was really light colored. I'll try to get the map I'm using on my 17 posted here, but it will prob be different on the 20' - and I'm still playing with it. But at least you can get a ballpark idea.
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byke
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byke 8/9/2020 10:46am
8/9/2020 10:46am
Momus wrote:
Sucks harder. Leaner.
byke wrote:
^^^That. An engine is an air pump. Increasing the volume of air that moves through the engine per cycle, like from increasing the displacement, would require...
^^^That.

An engine is an air pump. Increasing the volume of air that moves through the engine per cycle, like from increasing the displacement, would require more fuel to match the increased air flow. A carb or open loop fi system would not have the ability to compensate on its own.
Momus wrote:
Have you had any actual tuning experience on racing engines? The bigger bore allows more air into the cylinder in the same amount of time as...
Have you had any actual tuning experience on racing engines?

The bigger bore allows more air into the cylinder in the same amount of time as the smaller bore did.

The resulting increased speed of the air lowers the depression over the carburettor's main nozzle and with the difference between atmospheric pressure acting on the fuel in the float bowl and the low pressure in the venturi now slightly greater, more fuel is drawn in.

Also, the higher air speed may also improve the mixture quality with better atomisation and less wall wetting, which may also contribute to a leaner setting- or the original jet being retained; which is the same thing.

*An engine pumps air- and so do you. That cliche you used is superficial.

An engine is more a high temperature, high speed and high force chemical reaction chamber.
What's a depression? Is that where we put Prozac tablets in our gas tanks?

It's amazing they even make different jet sizes the way you're talking. I guess the engine just takes whatever it needs and the orifices are meaningless.

Hahaha, no, it's just an air pump. Pumping more air volume means you need more fuel to maintain the same air:fuel ratio. You can make it sound like a fission reactor if you want, but I'm afraid it's just not as complicated as you want it to be.
yzf162
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yzf162 8/9/2020 11:04am
8/9/2020 11:04am
byke wrote:
What's a depression? Is that where we put Prozac tablets in our gas tanks? It's amazing they even make different jet sizes the way you're talking...
What's a depression? Is that where we put Prozac tablets in our gas tanks?

It's amazing they even make different jet sizes the way you're talking. I guess the engine just takes whatever it needs and the orifices are meaningless.

Hahaha, no, it's just an air pump. Pumping more air volume means you need more fuel to maintain the same air:fuel ratio. You can make it sound like a fission reactor if you want, but I'm afraid it's just not as complicated as you want it to be.
Please don't give bad advice if you don't. Know how carbs work or have engine building and tuning experience. When it comes to carbed bikes, a big bore will increase fuel flow through the added suction that the larger piston produces. In the simplest of explanation. Most big bores depending on the amount of work done to the motor will run fine with stock jetting or run slightly rich. Most often you need to go down 1 size in the main.
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byke
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byke 8/9/2020 11:13am
8/9/2020 11:13am
What magic happens that causes it to suck at an increased ratio? Because what you're saying is that 10% more air pulls 15% more fuel through the same size orifice. What is the other force involved that causes the relationship to change exponentially for the fuel?
Gravel
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Gravel 8/9/2020 11:16am
8/9/2020 11:16am Edited Date/Time 8/9/2020 11:17am
Why are people arguing about carburetors? The question is about EFI bikes..
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Momus
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Momus 8/9/2020 11:43am
8/9/2020 11:43am
mxrose3 wrote:
I just did a 270 kit on my 17' YZ250F. it definitely needed more fuel up top. Pretty close to stock on bottom rev range though...
I just did a 270 kit on my 17' YZ250F. it definitely needed more fuel up top. Pretty close to stock on bottom rev range though.. Plug was black before the kit, and then after doing the 270 it was really light colored. I'll try to get the map I'm using on my 17 posted here, but it will prob be different on the 20' - and I'm still playing with it. But at least you can get a ballpark idea.
Carburetor fitted?
Momus
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Momus 8/9/2020 11:49am
8/9/2020 11:49am
byke wrote:
What magic happens that causes it to suck at an increased ratio? Because what you're saying is that 10% more air pulls 15% more fuel through...
What magic happens that causes it to suck at an increased ratio? Because what you're saying is that 10% more air pulls 15% more fuel through the same size orifice. What is the other force involved that causes the relationship to change exponentially for the fuel?
Google up on Bernoulli love.
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Momus
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Momus 8/9/2020 11:52am
8/9/2020 11:52am
Gravel wrote:
Why are people arguing about carburetors? The question is about EFI bikes..
Following up Skidlids carby observation. Yes EFI is different.
resetjet
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resetjet 8/9/2020 12:49pm
8/9/2020 12:49pm
Honestly its only the map keeping me from buying this kit. So if you get a good map, please post.
Schlava
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Schlava 8/9/2020 5:16pm
8/9/2020 5:16pm
270’s work really well with mapping for stock bore. Builders I talked to said you really didn’t need much change till you went to the 276 kit
mxrose3
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mxrose3 8/9/2020 9:50pm
8/9/2020 9:50pm
mxrose3 wrote:
I just did a 270 kit on my 17' YZ250F. it definitely needed more fuel up top. Pretty close to stock on bottom rev range though...
I just did a 270 kit on my 17' YZ250F. it definitely needed more fuel up top. Pretty close to stock on bottom rev range though.. Plug was black before the kit, and then after doing the 270 it was really light colored. I'll try to get the map I'm using on my 17 posted here, but it will prob be different on the 20' - and I'm still playing with it. But at least you can get a ballpark idea.
Momus wrote:
Carburetor fitted?
Hell no!
dantking
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dantking 8/9/2020 11:01pm
8/9/2020 11:01pm
byke wrote:
What magic happens that causes it to suck at an increased ratio? Because what you're saying is that 10% more air pulls 15% more fuel through...
What magic happens that causes it to suck at an increased ratio? Because what you're saying is that 10% more air pulls 15% more fuel through the same size orifice. What is the other force involved that causes the relationship to change exponentially for the fuel?
Vacuum! There For the carb bike will run rich. But the fi bike will inject the same amount off fuel there for it will run lean
tobz
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tobz 8/9/2020 11:13pm
8/9/2020 11:13pm
Shocked that a 2020 model needs a 270 kit Blink
fpandjic
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fpandjic 8/25/2020 3:53am
8/25/2020 3:53am
tobz wrote:
Shocked that a 2020 model needs a 270 kit Blink
Then why we have 450 models? Smile

Unfortunately still nothing, no one has the map...
zman721
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zman721 8/25/2020 5:36am
8/25/2020 5:36am
I had one on the previous generation YZ and it ran ok, but lean with stock map. I ended up with it gradually getting richer as both RPM and throttle opening increased. Highest number in the top right and working way down to 0 in bottom left. I later bought an aftermarket ECU from a well known tuner, and he gave me his map for that kit and the stock ECU and it matched mine exactly haha.

Short of a dyno.. seat in the pants, looking at a spark plugs if you want, and following the same logic I think could get you pretty close. Either way you shouldn't be blowing shit up.
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Yama310
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Yama310 8/25/2020 5:42am
8/25/2020 5:42am
I just put this 270 kit in my 2019 that has a GYTR head on it. Bike absolutely rips now. It definitely needs more fuel as the original maps I had were spitting and popping. I still need to do more tweaking but this map smoothed it out.



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fpandjic
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fpandjic 8/25/2020 6:23am
8/25/2020 6:23am
Yama310 wrote:
I just put this 270 kit in my 2019 that has a GYTR head on it. Bike absolutely rips now. It definitely needs more fuel as...
I just put this 270 kit in my 2019 that has a GYTR head on it. Bike absolutely rips now. It definitely needs more fuel as the original maps I had were spitting and popping. I still need to do more tweaking but this map smoothed it out.



Thank you so much! If you come up with improved map, please let me know! Wink
Bruce372
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Bruce372 8/25/2020 6:42am
8/25/2020 6:42am
Compression can change on a big bore also, so all bets are off predicting fueling IMO.
GetItOnLikeTron 7/30/2021 4:56pm
7/30/2021 4:56pm
yz250f all have weak cam chains. Even with stock parts the chains have been know to fail will relatively low hours. try and keep the bike off the limiter that is when the chains see the most stress.
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