Big Gun SDS system (Cheated I don't know???)

Okay, put my system on tonight. Finally received the spark arrestor and super quiet core. Couple of things. Sounds louder than my E series with Quiet core insert at this point. Is this in my head???? Don't know but sure sounds fat. Easy to install. B.S. Nothing lined up correctly but got it installed. Problem #1. I have the IMS tank/seat combo. Big Gun stated that the head pipe would not interfere with my "pet cock" (is that what you call it/ it is late at this posting) B.S. again. Can't turn the valve to the on position. Question. Will I be okay running this on the "reserve position"??? IF not I am screwed. Queston #2??? This head pipe runs awfully close to the gas line from the pet cock. Will this be a problem???? seemed awfully hot down in that area. If a problem what would you experts suggest. I am riding Sunday to try this system out and do not want to be left hanging. Anyone running this system that can offer advice, please let me know. This Brand new system may be for sale very quickly.

Cheated???? Dont know yet, it may be a few to many beers and the late night.




With aftermarket parts one often feels chaeted.

The BigGun SDS runs very close to the tank. I trimmed my petcock handle to avoid hitting the pipe. I also made a heat shield which I later replaced with an automotive engine hi-temp heat-insulating blanket

I recently installed the Quiet core spark arrestor in my BigGun system. I experienced installation frustrations. I had to remove the BigGun nameplate to install the spark arrestor. It took lots of persuasion with a hammer to get it to fit. I left the nameplate off. Overall, it is somewhat quieter than stock, but not real quiet. No dB measurement.

My biggest issue with the system is bumping my riding pants on the header pipe when I pick the blue beast up after a fall. I ruined an old pair of pants. Time for new pants :) Unfortunately, my new pants now have minor damage as well :D. I invested in some automotive engine hi-temp heat-insulating blanket to avoid this in the future. I ma not sure how well it will work. Pant melting/toasting may be an issue with other aftermarket pipes as well. However, it may be just an issue with me taking too many spills where I get my leg up against the header pipe near the radiator.

In spite of all the headaches, the system performs very well. Great pull from the bottom on up with a much more tractable power delivery. For more details look at my post “BigGun SDS = Less shifting and a much lighter front end.”

Eric in WA


’99 WR400, YZ timing, BigGun SDS exhaust, Jetting: 48 Pilot, screw 2.25 turns out, DVP needle clip # 4, 180 main (500 ft alt). Air box lid on without the snorkel, IMS Tank, YZ Seat, Acerbis Handguards, Scotts Steering Damper, Renthal Bars, Devol Rad Guards, Dunlop 756 Tires (fantastic)

’99 Polaris 400 Scrambler –“Trail Couch, Toolbox and Lunchwagon”, ’99 Honda Z50R, ’97 Honda XR70R, Kubota L275DT and an assortment of farm equipment.


where did you install the heat shield? What is it attached to??? (pipe, Pet cock) where did you trip the value? Questions questions questions. I did not ride with it on this weekend because of these problems.

thank you for the info



The original aluminum heat shield had durability problems, so I went with the Starter Heat Shield blanket purchased from an auto parts store. Check it out at:

The insulating blanket is loosely wrapped around the pipe and secured directly around the pipe with lightweight stainless steel straps supplied with the insulating blanket. Don't go too tight! The straps are like hose clamps only much lighter and semi-permanent.

Note that this blanket is not a perfect fit. There is an open gap which I put inside toward the engine. You could buy a larger sheet for a better fit, but it is real spendy.

The blanket discolors somewhat due to the high heat, but it works reasonably well.

I am not sure what you meant by "where did you trip the value?"

I hope this helps. Let me know if you have any more questions.

Eric in WA

I also ruined my paints on the header pipe. I used automotive header wrap that comes in aroll 2 or 3 inches wide I wraped my header from the head to where it goes under the frame and used a hose clamp on each end. I replace it about every 4 months. Steel headers need to be cleaned and resprayed with header paint between wraps. No more burned legs or pants when the bike pins you

Thanks guys but I have opted out. Sending it back and moving on. Don't want the headaches or burns.



I assume you have the BigGun SDS. Is that correct? If not, what brand do you have?

What brand of header wrap do you use? Why do you have to replace it every 4 months?


Eric in WA

now, this may just show my ignorance of the WR series, but back in my 2-stroke crashing days, we reversed the petcock (put rotating section to inside of bike) to keep it from being damaged during the various slide events. can you do this? It was a pain in the butt to chnge to reserve, but at least I could :)


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