FMF Fatty vs. SST

[Studboy]

Marcus,

I am measuring the power difference by the speed (Gear that I can pull and RPMs) that I can pull up the racing hills at the sand dunes, which is a notable increase with the doma. The bike is harder to ride with the doma pipe in the dirt, quicker revs and less lowend, but the pipe does have more hit and overrev than the stock pipe.

I just don't get how the doma can make less power EVERYWHERE compared to the stock pipe and run faster up sand mountain.

Again I'll ask, do you think that the altitude has anything to do with it?

And, when you dyno all of those different pipes, do you really spend the time to get the tuning right for the pipe or do you just run them with the same jets?

 

[marcusgunby]

Well i did use the same jetting for all 3 pipes but it was jetted nice and crisp before any pipe was tried.I think thats why the rm didnt do well in the dyno shootouts , they used std jetting and suzuki are easily the richest out the box.

Jetting each one is very hard to do perfect but no jetting would stop the mid range dip on the hgs IMO.i havnt myself found many pipes need major changes to jetting.Other have.I was once helping a rider and we were given a doma system for a cr125-told to run a 460 main by the importer (std was 380) i wasnt going to do that and i put in a 420-i fouled the plug mid practice-my rider wasnt impressed.

Only pipe i have found needed silly jetting was a sst due to detonation.The stingers are too small id and they cause detonation, this is a problem for all late model rms upto 04 so i would actually fit one(SST) to a 02 unless i had very good fuel.

We used race fuel(euro 110octane) and it still detonated on a cr with a sst.

cant help on altitiude-i would think it has a effect but it maybe the same for all pipes? RR should know hes clever LOL.

Maybe the hard hit in the power pulls it up out the sand better or into the power harder?I have never ridden dunes but it sounds fun :thumb:

 

[MX-727]

Hey Marcus, missed this a few months ago. I'm pretty sure I had the first generation silencer as I purchased it in December of '02. I'll double check this weekend. Time for a repack anyway.