Riding withYamaha GYT quiet insert.

Installed my insert on a very strong running 00 WR400 this past Friday. Next morning rode at one of my favorite desert/mountain areas located between Mojave and Tehachapi California that requires lots of power.

Well yhat insert really made my ride quiet but it lost at least 25% of its power. Turned it into a real pile.

Any similar stories out there? I figure I can rejet leaner but doubt if I'll see acceptable results.

Any suggestions?


If you were running wide open on the exhaust, try like you said and go leaner. See how it runs that way. You'll surely lose power going to the insert though. I just got mine and put the insert in and pulled the stock insert. Never rode it stock but mine has a lot of power this way. It's running way too lean though. I need to rejet before my next ride.

I'm trying to find a balance between the two also. I am lean with out and rich with it in. I think as the Temps warm up it will start to come in.

I put in the GYT-R insert last week to quiet down my 426. While the reduced noise is nice, I thought my screaming 426 had turned into a weak 250! I expected a loss of power at high rpm, but found reduced power from top to bottom.

The power loss from just off idle though the midrange was the most notable and disturbing for me. I realize some rejetting may help, but don't know if I can stand all the weakness. :D

Has anyone with both the GYT-R and the Pro Moto Billet ridden both and compared?

I'm considering either modifying the GYT-R or building my own insert. What do you all think would result from drilling some holes in the tubes on the GRT-R? I'm thinking maybe a series of 1/4 or 3/8" holes on the tubes. :) Would that improve flow or interfere with the existing flow?

What jetting changes has everyone been making when they go from uncorked to the insert?


I'd say to cut the ends off of the tubes. The PMB looks a lot shorter, and the sound is the same as GYT-R. The longer tubes would seem to create more back pressure and slow the flow of the exhaust. I think cutting the ends would also be easier than drilling holes IMO.


I run a Baja Vortip in my WR426. I think the GYT insert will perform the same. I run stock jets with the needle on clip 5 and the bike rips. Open pipes like E taper needles, baffled pipes may not. I would try the stock D taper and raise the needle one clip. I did the James Now mod. and went in approx. 1/2 turn on the fuel screw from stock. Starts great, hot or cold and from the bottom to WOT it jumps.

I too run the GYT-R muffler insert and haven't found that there was a great loss of power or even a loss of any kind. I may be an old fart but that bike has more power than I can use any way, so why should I need more. The absolute best part of the insert is that it makes the bike QUIET.


Yamaha needs to hire the dude that designed the DRZ400 exhaust. Seems to flow good and it's quiet. What a concept. :D

All the aftermarket inserts will reduce horsepower. But, if it keeps the EnviroDemies off our backs, then I say it's a fair tradeoff. :)

When I was running the stock WR pipe I used a vortip. I did end up cutting the tubing shorter for more power (very noticeable increase) - but you have to be careful not to cut too much or you will exceed the 96 db limit. Also check for welding globs in the tubes that restrict it even further. I ended up buying a used YZ pipe and putting on a PMB spark arrestor end cap - then installed a custom vortip - resulting in a huge overall power improvement over the WR pipe with a vortip.

And yes, my YZ250f almost felt as powerful overall as the stock 02 WR426 pipe with stock vortip. :)

I am currently using the PMB insert. I had been using the GYT-R but had an opportunity to get the PMB and I like it better. I noticed with both inserts that jetting had to be leaned up considerably to get most of the performance back. I would estimate that I am probably taking about a 5%-10% power hit but no more than that. Leaning it with the inserts made a big difference.

Stock jetting was 42pj, 4th position needle and 150m.

Uncorked: 48pj, 5th position needle and 158 main.

PMB/GYT-R: 45pj, 4th position needle and 158 main.

I'm at 2700ft. elevation. I'm currently at two turns out (on the pas) and I think the bike runs very well considering. It's warming up more and more so this will need to be tweaked a bit...but overall I'm satisfied with it. :)


The WR450 service manual lists the stock US pilot jet as a 45 but you listed your stock pilot as a 42. Did you pull out a 42 when you started your jetting adventure?

FYI – your feedback reads well and sounds creditable. That is something I find refreshing. Thanks

I am still waiting for mine…..

Woops...that's a typo. :D Sorry about that. Overall I know we're taking a performance hit (minimal at that) using these inserts but the lower noise levels will be beneficial for all of us in the long run. I'd rather ride with a little less performance than not ride at all. :)

I can also ride it in my subdivision without the neighbors hearing it from a mile away. :D

Hey ddialogue,

Are you running stock needle? I've got a YZ needle I'm about to install. Just added the Baja baffle and having a bit of low-end stalling right now. Riding about the same elevation as you but probably a little warmer (N. Ga). My plan is to richen up fuel mixture screw, 155 main, stock pilot, YZ needle on 4th click.

Yes, I'm still using the stock needle. I'm interested to hear how the YZ needle works for you. I don't have any hesitation off the bottom on my bike unless I quickly blip the throttle off idle while in neutral...which doesn't happen while riding.

I'm running the insert as well. I had my bike to rrp cycle last week for the flywheel work (they are not a yamaha dealer so it cost me $45, but worth it because they have top shelf mechanics - www.rrpcycle.com ) While they had it, i had one of the race mechanics have a thrash on it to evaluate performace. He said that the power was strong, and the jetting seemed crisp. He mentioned that for a woods bike its got alot of grunt. He was a little pissed at me though because now he wants one for his woods days.

Its possible to get good throttle response with the insert, just keep tuning till you get it.




What up with you !!!! All the trouble of getting my GYT-R insert and now you are saying the PMB is better? That sucks! I think I am gonna save some ka-ching for a new pipe.


Mine seems to run great from about 1/4 throttle up. Riding this weekend, the only problems were in tight stuff like rock or log crossings. Bike would stall when blipping throttle at a large log approach when I was trying to lift the front wheel in 1st gear. It's definitely not as strong as it is uncorked, but it's way too loud for the area I ride in without the insert. I agree with the other guy whe said better to loose a few horses than loose access to the land. I've been encourging my buddies to quiet down their bikes as well.

Now I feel bad!! :) Honestly, I think performance between the two is very close. Sound reduction is the same. The PMB is much better looking and only weighs 4oz. I haven't weighed the GYT-R but it's gotta weigh somewhere around 2 lbs. :D Save your money for some new riding gear or something! :D

BTW, I'm having way too much fun with these new graemlins! :D :D :D

I canceled my order for the Gyt insert. :jawdrop:The baja designs is real close to uncorked and i've been happy with it. :D Next time we hook up we'll have to switch inserts to see the difference. :)

Sounds good Bill,

We will have to get together here in the next 2 - 3 weeks.


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