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Discussion Starter · #1 · (Edited)
I got lucky and picked up a used 2021 KLX300SM with 325 miles. So far so good with about 1400 miles now but I have been pushing it harder and revving it higher and noticed between 7 and 8k RPMs usually in 3rd theres a noticeable dip in power. My KLX is bone stock with stock air and exhaust so I buy a Dynojet PCFC and try it out. I got a discount on black friday and pulled the trigger. Installed it and I have my list of pros and cons. Main thing is it did smooth out the dip in power and that is the reason why I bought it. Staying with the stock exhaust for now but I may try drilling a hold in it some day if I get really bored with it. Or go with a delkevic or yosh midpipe and then try some of the cheap exhausts on ebay.
Cons;
1. Power commander, why must I start the bike before the fuel pump shuts off or it will not start? Almost as soon as you turn the key you must hit the starter. Otherwise it will just crank and crank and the orange idiot light comes on. Annoying. I found this out on one of the FAQ's after buying it or I would have been calling and asking why wont it start?????????
2. It comes with 2 maps one for KLX300SM and one for KLX300 and they are both exactly the same for stock air and exhaust. I guess the bike is too new to have just one after market exhaust map? Dynojet please get on it. We need one aftermarket exhaust map to work with here.
3. Postitap connector to connect a wire from the PCFC to the throttle position sensor is kind of lame. They should have made an inline connector. For $250 yeah they could have done that instead of poking a hole with this positap thing into my harness but I did it anyway. It does work but I am not a fan.
4. I was hoping for some nice stickers to put on the bike and I am not a fan of the dynojet stickers they provide. Not that important but I want quality stickers when I buy something.
Pros
1. It does make the bike run better. Especially in the 7-8k rpm range with no power dip so that's a plus and one of the main reasons for my purchase.
2. Install was fairly easy. I did not have to completely remove the tank and was able to leave the hoses attached. Nice to have paper instructions included but color would be nicer than black and white. I put the PCFC on top of the battery cover instead of on the battery as instructed but be aware you should trim down the cover or it will crease the sticker on the power commander. Not a big deal and I trimmed it after I made this discovery.
3. I got mine on sale on black friday at 10% off retail.
4. PC software - nice to be able to see what's programmed and that's when I found there were only 2 maps and there are no others on their site at this time of 12/2021. Come on dynojet. if there is someone in Vegas with a KLX300 and an aftermarket pipe please bring that puppy over to them asap.
 

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I got lucky and picked up a used 2021 KLX300SM with 325 miles. So far so good that about 1400 miles now but I have been pushing it harder and revving it higher and noticed between 7 and 8k RPMs usually in 3rd theres a noticeable dip in power. My KLX is bone stock with stock air and exhaust so buy a Dynojet PCFC and try it out. I got a discount on black friday and pulled the trigger. Installed it and I have my list of pros and cons. Main this is it did smooth out the dip in power and that is the reason why I bought it. Staying with the stock exhaust for now but I may try drilling a hold in it some day if I get really bored with it. Or go with a delkevic or yosh midpipe and then try some of the cheap exhausts on ebay.
Cons;
1. Power commander why must start the bike before the fuel pump shuts off or it will not start. As soon as you turn the key you must hit the starter. Otherwise it will just crank and crank and the orange idiot light comes on. Annoying. I found this out on one of the FAQ's after buying it or I would have been calling and asking why it wont start?????????
2. It comes with 2 maps one for KLX300SM and one for KLX300 and they are both exactly the same for stock air and exhaust. I guess the bike is too new to have just one after market exhaust map? Dynojet please get on it. We need one aftermarket exhaust map to work with here.
3. Postitap connector to connect a wire from the PCFC to the throttle position sensor is kind of lame. They should have made an inline connector. For $250 yeah they could have done that instead of poking a hole with this positap thing into my harness but I did it anyway. It does work but I am not a fan.
4. I was hoping for some nice stickers to put on the bike and I am not a fan of the dynojet stickers they provide. Not that important but I want quality stickers when I buy something.
Pros
1. It does make the bike run better. Especially in the 7-8k rpm range with no power dip so that's a plus and one of the main reasons for my purchase.
2. Install was fairly easy. I did not have to completely remove the tank and was able to leave the hoses attached. Nice to have paper instructions included but color would be nicer than black and white. I put the PCFC on top of the battery cover instead of on the battery as instructed but be aware you should trim down the cover or it will crease the sticker on the power commander. Not a big deal and I trimmed it after I made this discovery.
3. I got mine on sale on black friday at 10% off retail.
4. PC software - nice to be able to see what's programmed and that's when I found there were only 2 maps and there are no others on their site at this time of 12/2021. Come on dynojet. if there is someone in Vegas with a KLX300 and an aftermarket pipe please bring that puppy over to them asap.
Hi, I currently own a 2021 KLX300 and bought the PCFC for the euro KLX250s, was wondering if you could share the MAP that came with yours? Thanks.
 

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Discussion Starter · #3 ·
Hi, I currently own a 2021 KLX300 and bought the PCFC for the euro KLX250s, was wondering if you could share the MAP that came with yours? Thanks.
Hi I will see about downloading and attaching it to this message.
 

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Discussion Starter · #7 ·
Yoshimura exhaust - Last one left - if you are in the market for a high quality exhaust buy this one now on sale for 299.99. Note it does not come with a bung for the O2 sensor. You would need the midpipe for the $539 exhaust which is available for $165. Thats $465 total for the same system for $539. Or go with an O2 delete which may work better. I can tell you that this exhaust looks and sounds great. For now I will have to ride it more to determine if its any stronger than before.
KAWASAKI KLX250S/SF 2009-14 RACE RS-2 SO SS-AL-SS
SKU: 143002C350
 

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Yoshimura exhaust - Last one left - if you are in the market for a high quality exhaust buy this one now on sale for 299.99. Note it does not come with a bung for the O2 sensor. You would need the midpipe for the $539 exhaust which is available for $165. Thats $465 total for the same system for $539. Or go with an O2 delete which may work better. I can tell you that this exhaust looks and sounds great. For now I will have to ride it more to determine if its any stronger than before.
KAWASAKI KLX250S/SF 2009-14 RACE RS-2 SO SS-AL-SS
SKU: 143002C350
You don't want an O2 bung anyway, because the Powercommander needs an O2 eliminator to work properly.
If you run the O2 sensor, the ecu will constantly try to correct to 14.7:1, and go by the O2 reading.

Dynojet used to include an O2 plug with their fuel controller, but it had the fragile resistors outside the connector, protected in heatshrink, and have a high failure rate.

I solved this by hollowing out the connector, and soldering the 2 - 330 Ohm resistors to the terminals, and then filling it with molten plastic, so they can't be damaged by vibration.

These plugs actually work without the Powercommander, and get the air fuel ratio down to 13.5:1.

Plastic Magenta Rectangle Composite material Cylinder
 

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Discussion Starter · #9 ·
Good to know. I know the EJK comes with one and was wondering about the PC and the O2 sensor. I am going to have to try to get my hands on one of these. Dang I could of saved buying that midpipe.
 

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Good to know. I know the EJK comes with one and was wondering about the PC and the O2 sensor. I am going to have to try to get my hands on one of these. Dang I could of saved buying that midpipe.
EJK also stopped including it, but it's the cheap $15 type...

Mine is $25 shipped in the US, with a lifetime warranty, that you'll never need.

Arrow has a really nice exhaust for the KLX, 2 actually, one is stainless, and one is titanium. On ebay...
 

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Discussion Starter · #12 ·
Good to know. I know the EJK comes with one and was wondering about the PC and the O2 sensor. I am going to have to try to get my hands on one of these. Dang I could of saved buying that midpipe.
Kawasakibrad.com sells them for a good price and they look high quality.
 

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Make sure to remove the secondary ECU controlled throttle plate inside the throttlebody.
It's responsible for the sluggish throttle response, and it also starts to close off at higher RPMs.

You remove the rubber duct that connects the throttlebody to the airbox.
Once removed, you'll see the venturi plate, and you just remove the JIS screw, that looks like a small philips, P0, and save them in a ziploc bag, so you can reverse the procedure.

I also make a PAIR delete, an adjustable plug n play IAT, that modifies the intake air sensor signal, and I make DFI couplers without wires sticking out, for KX's.

Here's my PAIR delete kit...
Green Product Rectangle Material property Plastic
 

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Discussion Starter · #16 ·
Make sure to remove the secondary ECU controlled throttle plate inside the throttlebody.
It's responsible for the sluggish throttle response, and it also starts to close off at higher RPMs.

You remove the rubber duct that connects the throttlebody to the airbox.
Once removed, you'll see the venturi plate, and you just remove the JIS screw, that looks like a small philips, P0, and save them in a ziploc bag, so you can reverse the procedure.

I also make a PAIR delete, an adjustable plug n play IAT, that modifies the intake air sensor signal, and I make DFI couplers without wires sticking out, for KX's.

Here's my PAIR delete kit... View attachment 140026
I may give the removal of the secondary ECU controlled throttle plate inside the throttlebody a try. Thanks.
 

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Removing the secondary throttle will require significant fueling changes especially between 5000 to 8000 rpm.
Will be tough to do without a WBO2 or a dyno. The secondary throttle is just over half open all the way to 7k RPM then opens at a linear rate to 9k RPM.
 

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That reads the narrow band O2, not very useful for the kind of tuning required.
A WBO2 is going to run $100 to $120 minimum, and would be temporary for tuning. I personally would not do a permanent install of a WBO2 on a bike that is going to be used off road. 18mm bung installed or bung adaptor needed.
 
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