Hey Gabe, I took a 1.5" holesaw (w/ 1/4 drill bit center style) and cut out the middle of my silencer cap. It wasn't louder at all at idle and it seems to be barely louder under power. I decided that drilling the 3/8" holes was too difficult. P.S. You all know how I feel about noise (hate it) Anyway, I was wondering why you are bothering since GT Thunder shows no real advantage in no end cap at all. I know that your engine is modded though. I have a question, why bother with the xr250 box? It seems to be of no real advantage if power starts to drop off after the rev limit anyway. Also, when are you going to post some times or dyno reports, better throttle response just doesn't cut it for me since winter is coming soon and the annual tear down begins shortly thereafter. I want to see your bike some time, Do you ride in Northern MO ever? I would go to St Joe on a Sat. if I knew you were going to be there.

 

Not interested in modifying the end cap at this time, but the main silencer body itself. There are some very serious restrictions in the construction of the chambers themselves that I have never heard of anyone playing with...

The XR250 rev box was also an experiment. My theory was that when stock, the power pulled to very near the revlimit. With more compression, a lightened piston, a ported head, and a more agressive cam - I thought it might be a good idea to try it out. My engine pulls substantially higher in the RPM band than it used to. Have I tried the stock CDI box since the mods? No. But it certainly does seem that I would be hitting the stock rev limiter in the first 2 gears provided it were there. If I did not race I probably wouldn't run the XR250 box, but in some of the events I do, hitting the revlimiter can cost you a race.

Would you like an acceleration run sound file? I let it pull 'till the power stopped in 1st and 2nd so I could listen to the engine (not necessarily the fastest thing to do). But you do get to hear where the power ends currently thru the stock carb and exhaust. I really wish I had done this when stock so I could compare the two side by side.

I have posted a couple of timed drags back in TRX400EX right after break-in. I don't feel that timed drags do the engine justice as the top end is stronger, but the mid range (during typical riding) is MUCH improved. Don't get me wrong though, it will outrun a stock bike as well as any "piped only" bikes I have run it against. I did my first woods riding since the upgrades last weekend and was very happy with the very noticible improvements. Also got to ride a Raptor around a little. My engine feels like a 2 stroke compared to the Raptor's power... Very, very different power. As far as Dyno runs go, I don't know anyone, anywhere nearby with an ATV/MC dyno. I do have some friends with an automotive dyno capable of up to 500 HP, but I don't think it would work well for an ATV & haven't talked to them in a while. I'd hate for them to think that the reason I called was to try to bum a free dyno run from them when it probably wouldn't work anyway.

I feel that the FCR would be the next substantial improvement to this combo, even with the stock exhaust from the "almost" WOT testing (I can elaborate if you like, just take a lot of typing) I have done while out riding. I think an FCR would also make a big difference when drag racing.

I race in NE-MO sometimes. Next season there will probably be a National HS in Kahoka, as well as the ST Joe benefit race. I will probably attend those. I would also like to get up to ST Joe to just ride sometime as I have never been there - same for Finger lakes. I do ride Deepwater every now and then, but that's quite a ways for you to travel. Can't go to St Joe this weekend, gotta race in Bolivar.

If you want anymore info about anything I have discussed - shoot me an e-mail...