My exhaust port is enlarged since I noticed the pipe was smaller than the port now. Doas anyone make just an oversized headpipe for the Mojave? If not the IDS2 is too quiet for me and seems to choke off the machine too much. The Cobra is too cheep(you get what you pay for) so I won't buy one of them. My only other choice would be a supertrapp 4" race exhaust without the discs. I have seen many people run this exhaust at flat tracks and moto's with incredable power. People with the IDS usualy don't perform much better than stock and are too quiet. The big gun has the best sound (like a YZ400F) and I feel it performs best at high RPM. Before I got the pipe I didn't even know there was a rev limiter and now It hits the rev limiter constantly.

 

You can buy just the headpipe from Supertrapp. But if you want a really big head pipe call James
Lucky atv 1-800-233-2637. They are closeing out some of the old Coffman exhaust for Mojaves. If they have any left they are selling the whole system for 75 bucks. This setup has the largest headpipe you will find and loud open silencer, definantly a full race pipe. I dont like the bend in it just before the silencer however. You can see a picture of it on their web site but I can't remember the address. I doubt that any head pipe will work with your Big Gun silencer without modifications but that should be a simple task for a good automotive exhaust shop. You would want to connect the new head pipe to the Big Gun at a point where the big gun's pipe has become the same size as the head pipe you are using.

Keep in mind that as the head pipe gets larger and the system flows more freely the power band is moved up. Low end is sacraficed for top end. That is not always a good thing for scrambles and xc racing.

As for the idea of just changing to a supertrapp, the 4" racing series without disc is the best flowing. However the Ids2 is about the same if you run the racing series without the disc. And
without the disc it is about as loud as the 4".
I am always looking to reduce the noise on mine but you seem to want it loud as possible. Please don't give our sport a bad name by doing your recreational riding in an area where your loud pipe will annoy people. I have two Mojaves, one has a 4" supertrapp and the other has an IDS2. I have to run the discs because spark arrestors are required where I ride most. I really can not tell much difference between the two pipes. the IDS2 is on my more modded one with big cam, huge port job, highrev springs,no rev limiter,high compression piston, and a 38mm carb with a clamp on K&N. I had one of those all out racing Coffman pipes on and changed to the IDS2 to try and make it quieter. I was surprised that i picked up more bottom and mid and really dont notice any loss in top end power. I run 20 disc on it and i really like the pipe. The other mojave has a high compression piston, high rev springs, stock cam,no porting,stock carb and clamp on K&N. I run the 4" on it and it makes great power, but with 14 disc is one of the loudest things in the woods.

If you decide to buy a supertrapp you may notice that Rocky Mountain ATV has the lowest price but on the IDS2 they only carry the quiet series, not the racing series. Many people nave ordered this pipe without asking and think they are running the race pipe but have the quiet pipe. The quiet pipe will not make as good of power and it is most noticable on the top end. Make sure you get a race pipe if you buy a IDS2.

The DG and Cobra pipes are cheap made and lacking quality in my opinion. I have yet to buy anything from DG that fit. I even had to modify their nerfs and skid plate to get them on.

 

Thanks for the help mojaveaddict! I will probabely buy the Koffman and fit the head pipe up to my Big Gun. I have a mig welder and a torch to fit them together.

I am not only looking for a loud pipe but a good souding one. The big gun is only louder than the disk exhausts and is muck quieter than a 4" open supertrapp. I don't like the way disk systems make it sound "metalic" compared to the thumping of a silencer. I agree an open megaphone is too loud but better than discs. Also I mostly ride either at home or at the racetrack so I am not "recreational" riding with the Big Gun. A few times a year I go to the mountains and then I put the stocker back on.

As for the loss of low end for top end it is not a factor for me. I am never in the low end except when I put around. This is because I rev the guts out of it in every gear and if it is even close to the low end I slip the clutch. Even in the woods I never get into the low end. I always downshift as I am braking and always slip the clutch through the turn until I get straitened out.

One last thing is I see you have a 38mm PE carb. Did it help top end power? Did it help or hurt throttle response? I was going to get a 33mm Mikuni pumper but was also thinking about a PE.

 

My Big Gun sounds really good. A nice loud rumble.

 

My vote goes for the supertrapp a little louder than some. Great design, I like the intermediate pipe, good straight route.

 

How is the Cobra cheaply made?

 

Mojaveracer, The 38PE does make more power on top and throttle response is only slightly better.
This carb is really a little large for the mojave and I believe a 36PE would be much better. But even though they make this carb I could not find one anywhere. If you find somewhere to buy a 36PE let me know. I switched to the 38 because I could not get the stock carb to work right after I ported the head and installed the largest Web cam. You need these mods and the rev limiter removed to take advantage of the 38.

Couple of tips if you decide to use a 38pe.
Get a thumb throttle from a honda 250x or 300ex. The mojave thumb throttle requires a lot of modifying to add enough stroke to get WOT. The honda throttle is easily modified by just grinding off the stop inside. I bought a carb kit($169) for a 250x that came with the cable and used a honda throttle from a 250x that I bought for 10 bucks. You may run a twist throttle and eliminate the problem. I just hate twist throttles.
The carb comes jetted WAY to rich. Even with the coffman system, ported head, and clamp on K&N filter I had to jet down. Comes with 160 main- I now have a 150 with the needle dropped down one position. Comes with a 50 pilot- I have a 41 in.
You will also have to modify the top engine mount to gain a place for the cable to run. The mojave was not designed for a top pull carb.

I dont know anything about the Mikuni pumper as I have never tried one and dont know anyone that has. I have heard the Lectron and Quicksilver carbs work really well, but me and my buddies cant afford them so I'll probably never see first hand to find out for sure.

 

You are talking about all of these pipes, but what about an FMF? I know someone who has one on a Warrior. Don't they make one for the Mojave? Whick one wins the best for anywhere; the best on private land, public trails, or race that has a scilencer and/or spark arrestor? With that having the best over all performance and sound (at least for a stock Mojave).
Does anybody know if there is a battery kit avalible for constant power? I was also thinking that if I did have a battery, to put two lights on the supports for the front fenders to have better visability. Does this sound doable? Also if anyone has put on an actual neutral light. My cooling fan seems to never kick on, but it does rarely. Has anyone changed their thermostate/sensor for this?
What's the best High Pro. spark plug to use on 89 octane?

Hey, thanks