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Discussion Starter #1
So I was browsing around and notice that all the jet kits I find for the TRX300 are for 92 up. None say they are for 91 and older. Is there a difference? I assumed they were all the same. Where do you get your jets? Is it better to buy a kit?
 

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You can actually go to the dealer and buy individual jets for about 8 bucks each I wouldn't be afraid to say that the 91 carb is the same as the 92-up ? some one wih a little more utility knowledge will be able to answer this for you.
 

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Discussion Starter #3
Oh sweet! That would be easier just to go to the Dealer and get a couple. I'm wanting to do an air filter and exhaust sometime since my muffler is about rusted out.
 

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I believe the carbs are the same, but the jets could be a different size, because the earlier models had that pipe that had the big drop down curl where it came out of the head and the 92-up had the pipe that just curled out of the head and went straight back. The mufflers are a little different, too. The first picture is the 88-91 pipe and the second picture is the 92-2000 pipe.


 

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Discussion Starter #5 (Edited)
Oh wow thats interesting. Looks like the later year exhaust would be better I would assume you could use the later style exhaust on the older bike. If the jets are different then that would almost make sense that the newer exhaust flows better.

Just looked it up on BB and yeah the carb looks the same but the main jet on mine is a 120 and in 92 its a 125.
 

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Yeah, I don't know for sure if the jets are a different size or not. I just thought they might be, because the pipes are different. I have seen people interchange the pipes, but if I remember correctly, the mounting brackets are just a little off and won't line up. You might have to do a little fab work. I would say that the jets in the '88 model are definitely different, because the '88 model came out with a bigger cam, than the '89-'2000. I figured that might be why they used the different pipe, but if it is they didn't change the pipe until '92. That would make me think that the '88-'91 pipes would flow better, because it's the same pipe they used with the bigger '88 cam, but I could be wrong. Because of the cam, the '88s ran a little better.
 

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Discussion Starter #7
AHH yet more information I didn't know LOL. So yeah the pipe could be different because of the cam and tuning. Thats really interesting about the cam, I wonder why they would in essence "detune" the newer models? Emissions maybe?
 

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By the way, have you took your pipe off and looked back in the exhaust hole coming out of the head? The 300 head is restricted bad by the way it's made. I always wondered if they would run any better by grinding that restriction out.
 

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AHH yet more information I didn't know LOL. So yeah the pipe could be different because of the cam and tuning. Thats really interesting about the cam, I wonder why they would in essence "detune" the newer models? Emissions maybe?
The '88 is the first year that they made the 300. I heard that a lot of people was wrecking them and getting hurt and they were afraid they would end up like the 3-wheeler, so they put a milder cam in the '89-up to slow them down a little bit. The '88s were the fastest 300's that they made.
 

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Discussion Starter #10
no I haven't I literally haven't had to do anything to it except maintenance since I've owned it. But it wouldn't surprise me if there is a big road block inside there. If I ever take the head off I may see what a die grinder or dremel can do with it.
 

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Discussion Starter #11
AHH yet more information I didn't know LOL. So yeah the pipe could be different because of the cam and tuning. Thats really interesting about the cam, I wonder why they would in essence "detune" the newer models? Emissions maybe?
The '88 is the first year that they made the 300. I heard that a lot of people was wrecking them and getting hurt and they were afraid they would end up like the 3-wheeler, so they put a milder cam in the '89-up to slow them down a little bit. The '88s were the fastest 300's that they made.
LOL Thats just crazy. I guess I always though it ran great and had plenty of power for as old and small as it its.. but I didn't know they choked it after that year.
 

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Moose where you buying jets.Mine at the dealer were only like $4 a piece.
 

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Porting is fun! just don't polish the intake side you want it a little rough to create a vortex in the passages but definitely polish the exhaust side and the piston indention so carbon will not stick.
 

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I just got my 142 for $2.50. Moose ur gettin ripped on ur jets man.
 
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