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Discussion Starter · #1 ·
Hey all. Im new to this forum and am still learning my way around. I have a 1986 Fourtrax 250 that i aquired a little over a year ago. I tore the engine down about 6 month ago and wound up only honing it and replacing rings because it was in such good shape on the bottom half of the topend. On the cyl head, well i just cant leave well enough alone. I work in a machine shop in the racing engine business. To make a long story short i had the head on the flow bench and done a valvejob and some port work. I wound up gaining 20 CFM on Int and 14 on Exh. Theres a little overview of wear im at with it. Now i have a couple of questions about some parts. Im looking at the Cobra Megaphone exhaust mainly because i have 13.50 Super Swampers on the rear and they rub the stock muffler, and the cobra system looks smaller. Are they any good? Another piece i run across was the ricks motorsports hot shot CDI box. Says it has advanced ign curves and raises the rev limiter. Is there anything to this CDI box?. Sorry this was so long. Thanx for any input.
 

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Welcome to the forums. I always keep mine stock, so I can't really answer any of your questions, but everyone tells me that the Cobra pipes will just make your ATV louder and aren't any good for any performance gains.
 

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Agreed^^^^ Cobra ranks right up there with DG which stands for Don't Get!. Try HMF they make a topknotch system with proven gains on the sport tracks I see alot of utility quads with them too. The have a very nice deep throaty sound too.
 

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Discussion Starter · #5 ·
Welcome, keep it stock, less head ache and more enjoyable rides.
I would just as soon keep the stock exh, but my rear tires and the stock muffler arent getting along to well. Im really just interested in a smaller muffler to clear my tires. Not really looking for a huge performance gain, but i dont want it loud either.
 

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Sounds like a cool project man.I'd make your own muffler.I make mine and I have perfromance gains.If you workin a machine shop you could make real nice end caps and brackets.Let us know how it turns out and a video of it running with the ported head.
 

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I looked into replacing the cdi on my 300ex. After some research I came to the conclusion that unless the engine has had some work done the gain in performance would be minimal.
 

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Discussion Starter · #9 ·
Sounds like a cool project man.I'd make your own muffler.I make mine and I have perfromance gains.If you workin a machine shop you could make real nice end caps and brackets.Let us know how it turns out and a video of it running with the ported head.
I have thought about making my own to, but i figured it was just as cost effective to just buy one.
 

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Stay away from the Cobra exhaust they are junk, rust away in no time, go HMF, FMF, Sparks get a good name brand and good luck with the project. Welcome to the forums!
 

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Sounds like a cool project man.I'd make your own muffler.I make mine and I have perfromance gains.If you workin a machine shop you could make real nice end caps and brackets.Let us know how it turns out and a video of it running with the ported head.
I have thought about making my own to, but i figured it was just as cost effective to just buy one.
If you know where to go to get your steel and or aluminum you can have as little as $50 in a exhaust.
 

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Discussion Starter · #12 ·
Sounds like a cool project man.I'd make your own muffler.I make mine and I have perfromance gains.If you workin a machine shop you could make real nice end caps and brackets.Let us know how it turns out and a video of it running with the ported head.
I have thought about making my own to, but i figured it was just as cost effective to just buy one.
If you know where to go to get your steel and or aluminum you can have as little as $50 in a exhaust.
Thats prolly what i will have to end up doing since the onley exh for my 4 wheeler that i can find is cobra.
 
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