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Danimal521

yz450 GYT-R Jetting Recomendations

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I have a 04 YZ450. It was bought from Canada so it is FIM regulated so it had that cone tail pipe, not the US model. I say that because I think the jetting is different. I have switched to a GYT-R muffler and am NOT running the spark arrester. I live in FL it is 90 degrees and 0 sea level. After I switched the muffler my head pipe will glow red right away in idle. I have not ridden it because this is BAD. I think the slow/pilot circuit is lean, but I cannot find any recommendations ANYWARE for this pipe. I am running the stock head pipe, if anyone has recommendations or a place to get them please let me know, thanks. Everything is stock, I have turned out the fuel screw to 3 turns.

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the yzf's we get in nz also have the 'cone' end cap (they look way better) there is no spark arrestor in the pipe so how does this change the specs. I wouldn't worry too much about your header pipe glowing just go up (richer)in pilot jet size. Stock pilot is a 42 try 45 or larger.

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Do you know any other differences between the FIM and the US model? Is the jetting the same? I have a few pilot jets at home and I have a 45 so that will be easy. I just wish Yamaha made it east to turn the carb to change this! And the fuel screw is really hard to get to as well. This is my first 4 stroke and I am used to just turning the carb, but on the 450 the 450 the head stay blocks because of the 2 throttal cables, ugh.... anyway I will start with a 45. It glows like a light bulb... I think it changes the specs because ther is more air flow now. That GYT-R end pipe is oval and wider at the end. So I think that the exaust can clear out with easy now. Also if you look at the Yahaha Site it shows a dyno and that end pipe only encreases the bottom end. So I would think to do that you need more gas, so somehow it makes it lean like you suggest. Anyway, really nice looking pipe and it sounds wonderful!

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You really shouldn't need to re-jet for the GYT exhaust pipe. Any jetting changes you need to make are more likely due to atmospheric conditions you encounter. :cry:

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the yzf's we get in nz also have the 'cone' end cap (they look way better) there is no spark arrestor in the pipe so how does this change the specs. I wouldn't worry too much about your header pipe glowing just go up (richer)in pilot jet size. Stock pilot is a 42 try 45 or larger.

Where in NZ are you, will i need to change my stock jetting (ive just picked up a new 04)

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