Big Gun SDS

I have a big gun sds with the quite core spark arrestor on the way and was wondering if anybody has any experience with it. I'm not expecting any more power, but it will be nice to change the oil filter and I needed a spark arrestor. Why not buy the good stuff for such a great bike. They also assured me it will be around 96 decibal and for 14$ I can get an even quiter core later that will be around 93 decibal. They seem to be a great company. I will let you know how it works when I get it. Great Forum. 99' YZ400

ETS! PLEASE PLEASE PLEASE tell me all about this exhaust system when you try it out. I assume you are getting the entire system?

I have yet to find anyone that has tried one and can tell me how well it works.

I talked with Mike from Big Gun and he said one of the mags said it was like a 'tractor' on the low end meaning it added tons of torque which is just what I'm looking for.

I can't WAIT to hear your response. Can you do us a favor? Before you install it, ride the bike around with the system you have now, make the swap, and immediately ride it again. This is how I can tell performace gains. I have to ride before and after a modification.


I'd love to hear the results too! Has anyone seen a shootout or dyno results on ANY aftermarket pipes for the 400? Alex

[This message has been edited by alexjoz (edited 04-16-2000).]

I put the Big Gun SDS system on my 426 Monday and the one major problem so far is the clearance between the head pipe and the fuel petcock on the IMS tank. They don't touch but it's REALLY close, so I slapped the stock tank on for now. I ripped up and down the street a few times and found it did very controlled wheelies REALLY well, awsome low-end power! Sorry, no high speed testing in the 'hood. Following one of the tuning tips that came with the pipe I raised the needle one clip position. BTW, it's also REALLY loud! I'll be riding the trail from hell (really tight, technical, big hill stuff) this Sunday and if I survive I'll report back.


'00 YZ426

No Alex, everyone is still awaiting the release of the FMF IV2SA. Supposedly it just got released for the YZ and is about 1 week away for the WR.


I will bring the new pipe to my local track and trail and ride it stock and then install the sds system. I have a 50 pilot, 180 main, and stock clip position and they told me I should be spot on for jetting. I studied all the aftermarket pipes before I bought this one and narrowed it down to the stroker set-u p and this one. Stroker was not very friendly with their tech dept. They told me I couldn't talk to anyone because they were preparing for a race the next weekend. It was a tuesday afternoon and I wanted to talk to a real person not e-mail like they wanted. I figured they are in business to sell parts, which makes more money than racing so I said "piss on em." I wanted their big bore kit this winter, but plenty of other places sell them. I've been waiting about two weeks for it so I will let you know when it comes in. I'm still not expecting any power gains so I will be honest on what it does. I know a guy with a new 250 with a pro-circuit pipe that said it ran so much better and then he crashed and put a huge dent in the pipe and all of the sudden it ran so much stronger on top. Yeah Right! Some people think they are getting more power because it is louder or has a name on it. It might move the powerband around a little, but I will tell it like it is. 500 dollars is a lot of money to spend on a pipe so I will be honest and admit if I get screwed. At least if it don't do anything I have a cool looking spark arrestor.

I read a short report in one of the mags that said they had to trim the front fender because it hit the SDS headpipe. Did any of you have to do this?

Yeah, trimmed about 1/8 inch off, no big deal, compared to those cheap plastic radiator air flow things that explode when a rock comes within a foot of them. :) Which mag did you see the report in?


'00 YZ426

[This message has been edited by YZFWrench (edited 04-16-2000).]

The guy at Big Gun told me the proto-type head pipes some the of the magazines got were to tall and would bother some of the aftermarked tanks, but he said they have a new design that gives plenty of clearance. Still waiting for mine, getting antsy!

The SDS system makes quite a noticeable improvement in the low to midrange power, once I changed back to stock jetting (I was running a 48 pilot & 165 main but fouled the plug). It starts really easy, even without the hot start pulled, and overall power is much crisper, the way it should have come from the factory. There's enough low-end grut to be able to launch off short run hills just by rolling on the throttle, and while top-end power wasn't as drastically improved I felt I got to top speed quicker without revving the engine too high. At both low and high speeds I was able to lift the front wheel over rocks & roots with an easy twist of the throttle. I can also pull a higher gear going up hills and can really lug the engine and find plenty of power. Basically all the strong points of a 4-stroke engine are really enhanced by this Exhaust system. Even though the IMS fuel petcock and tank are close to the headpipe(s) they didn't heat-up any worse than sitting in the sun.


'00 YZ426

[This message has been edited by YZFWrench (edited 04-17-2000).]

It's a little louder than stock when you really wrap the throttle but I thought it was quieter when the engine made it's best power. BTW, I don't have the spark arrester installed (yet).


How about sound levels compared to the stock pipe? Louder? Quieter? Same?

They told me all their inserts are quiter than stock, but it could be sales talk. I'm still waiting, my buddy ordered the exact same set up for his 98' yz. We will be getting sometime this week I hope. We ordered the quite core spark arrestor tip, but there is a super quite core that was a few decibles quiter, I believe he told me 93' and the one I got was 96 decibles. I read somewhere that the stock yz is around 104. The guy I talked to said they are constantly working on the noise issue and possible quiter parts will be available in the future. Each new tip is around 14$ which isn't bad. Can't take the money with you anyway! Might as well spend it on cool stuff.

Well, by friend and I just got our sds headpipe and muffler monday. I installed the headpipe and tail pipe, but left the spark arrestor out for now. I haven't had a chance to ride it, but it seems to be a little louder when I started it. I didn't rev it out so I don't know if it is louder on top. I hope I can get to the track this weekend and bring the stock,big gun, and quite core sparkarrestor, and run them back to back. THey recommended 180 main and 50 pilot, which is where I'm at now. My friend has 175 and 45 and installed his pipe and told me he rode yesterday and said what I thought it would do. Hardely anything. He said the midrange seem to pull a little harder and that is all he noticed. He said it looks cool and was worth it because he can get at the oil filter. It is definetly a piece of good work. His jets are stock so maybe with the richer #'s he will notice a little more. He did say he wheelie walk like never before, but said he practiced a couple hours doing it, so it might be smoother. I will let you know how it turns out.

I rode my bike thursday for the first time with the big gun sds system and came away quit impressed. I haven't ran them back to back yet, but the bike seemed to pull stronger through the entire rpm range. The pipe was about as loud as stock without the spark arrestor in place. This was with 180,50pilot and 2.5 turns on the screw. Friday I tried to install the spark arrestor, so I removed the stock baffle and core and insterted the new quite core and packing. Then I tried to slop the sparkarrested baffle in place and it wouldn't fit very good. I took a rubber mallet and gently tapped it until it quite moving and the oval shape in the can didn't match up with the oval shape of the sparkarrestor. Now I couldn't pull the spart arrestor back out so I gently peened the the sides of the sparkarrestor until I could finally tap it in place. There are four screws that hold it in place and two of them lined up and two don't. I started to die grind the can so the holes line up and thought that was BS so Im gonna call them today. It is gonna be premanant and that is to much money to have to hack stuff. From now on I will have to pull the front of the silencer apart to change cores or repack. I hope they have a good answer. I was extremely carefull, but there are some marks on the end of the silencer before the sparkarrestor went into place. I did have it 3/4's together and it was quiter, but not a whole lot. I don't thinks it's like their claims. I was very happy until all this happened.

On a related note, MXA magazine just tested the White Bros. e-series carbon fiber and the GYT-R carbon fiber systems. They said the e-series was good throughout the range, improved over stock. And they said the GYT-R improved midrange only. Both pipes burned their legs though, along with their leathers, and both are over $600.

I called big gun and they confirmed my problems about the sparkarrestor as soon as I mentioned it. He was helpful, I just didn't like grinding on my new pipe to align the two holes. He also said I wouldn't lose any noticable power, but I haven't ridden it yet with the sparkarrestor. This pipe and head did just what I was thinking it would do. It did a little throughout the powerband, but if you got five hundred in your pocket and looking for a lot more power, go big bore. Iam happy with the noise level with the quite core in place and I have a cool looking pipe and silencer. It doesn't look cheesy like the fmf stuff or a bunch of tunable dics that I don't want to fuss with. Good stuff for a lot of money, but the looks are more impressive than the power. In the near future I will bring both stock and biggun to the track and evaluate. I would buy one again If I had to.

Did Big Gun say if the alignment is going to be fixed on future spark arrestors or will they just throw in a piece of paper telling you to grind away?


'00 YZ426

yzfwrench, they just told me that they are getting better since the first one, but the tolerances are so tight that it is hard to hold them. I wish I would have known about grinding on the end before I had it half way stuck in there. Anybody could have ground away on it, but I didn't think it was right if I had to do it to the new stuff so I didn't.

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