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Bought a 24 Husky factory edish and it comes with FMF slip on and it has a spark arrestor. Just racing mx so i would think it would be ok to remove, but i had some friends remove there's and said they had issues with there bike cutting out and stalling time to time. Put the arrestor back in and the issue went away.
What have you guys tried?
I'm not an expert. My experience. I have a stock YZ250f - with PC pipe and stock engine the bike ran better with the arrester in there. I put a Vortex and dual injection....bike work better with it removed.
Its probably adding some back pressure.
I’d just leave it in. Save your ears a little.
I’d leave it.
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I took mine out because my wash plug won't fit otherwise, and they get gunked up and you''ll need to maintain it. I noticed no difference on how it rides with it in vs with it out on my kx250.
250 or 450?
A number of the GNCC Pro class riders simply cut the screen off but keep the insert.
250
The bike will run a bit lean without the spark arrestor. You may need a remap of the ecu. You’ll probably hear lean pops and have flame outs from time to time.
On a 250, you can take it out and pick up a little throttle response but lose a little mid/top pull but it's definitely a very subtle difference. I have tested it both ways on my 350, which is similar power curve to the 250, and on a 450. I prefer the insert in.
You've seen them get gunked up even on a 4 stroke?
Well, to be honest the manual for the FMF pipe I had said to take it out and clean it every-so-often. Admittedly, I just took it out lol I could imagine they would though. I never ride trails so it seemed like a good idea to take another maintenance item out of the equation.
I’ve seen them get ashy but not to where it effects flow. Just burn it off with a torch for a few seconds and put it back in.
New England Pro Keith Johnson ( the one that runs Southwick now) . Found out that his bike ran better with one years ago when he raced some GNCC's , and he ended up running it in MX too. If You are just on a closed course , I would give it a try . Remove it and ride it, put it back in. See if You can feel any changes.
Its totally different, but funny thing on one of my UTV's removing the spark arrestor added almost as much HP as a full system would add. Just .3 HP less than the claimed HP when tested on a Dyno . On another SXS it adds the same power , but keeps it less loud. I have only run them removed while on my own property effectively being on a closed course. The bikes that I have personally removed them from have not been EFI . So the SXS's are my only experience with removing one from a bike that did not need to be jetted.
I have never run one on any of my MX bikes. Just leave them out or uninstall before putting the pipe on.
My 04 yz450 seemed to pick up some power and response after I removed it.
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