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does anyone run double base gaskets on there yz250

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while my suspension is away getting revalved im refreshing the motor im using my bike 05 yz250 for enduro and x country events, im trying to mellow the hit of the bike i have so far added a steahly 13oz fww fmf sst pipe (already on the bike when purchaced) with a long fmf standard q silencer, now im doing the piston i'm wondering if its worth adding an extra base gasket would it bennefit me ?? has anyone else done it thanks

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ditch the sst and get a gnarley. The bike will be more low end grunty and not on the pipe power like the sst.

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asked this question to steve plain-told me not to bother as it effects port timing and way to go was to machine the head to lower compression , done it on my 09 yz 250 , mellowed out the power and was real smooth , also get rid of the sst as they recommend :ride:what gearing do you have ?

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I actually just did this so it would be easier to kickstart. I wouldn't recommend it, it does NOT soften the hit.

It does make it physically easier to kick but takes away power from the bottom thus making the hit stronger- and it seems I have to kick it more often before it starts.

BTW I have a 13oz Steahly and the Gnarly.

Have you read the timing sticky?

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What do you have against the SST? I got one and so far so good. I'm happy with it.

opinion on these boards just seems to be its hard to jet for and until you get the jetting right it can cause detonation and melts pistons.

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sst is not really an enduro pipe imo, dont need much in the way of overrev in enduro riding,especially in the uk . who have you sent suspension off to mate?

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opinion on these boards just seems to be its hard to jet for and until you get the jetting right it can cause detonation and melts pistons.

I agree but IMO not many people look up their plugs after new top ends, new pipes, new whatever. In my case I always wanted to see a brown plug and the SST gave it to me. But I ride mostly on the pipe. Strictly enduro although we have open roads, hills and only a few small trails.

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sst sounds like it suits your area well , i wish we had more wide open where we live ,everywhere is real tight and technical!

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sst is not really an enduro pipe imo, dont need much in the way of overrev in enduro riding,especially in the uk . who have you sent suspension off to mate?

thanks for the reply's everyone i'll stick to the one gasket, hi aled my suspension is going to gibbs performance local chap with excellent reputation :busted: aled what gearing are you running mate i have only just got this bike so trying to do it all while i can machining the head sounds like a good move thanks

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arnego2 , that is quite cool! 13,50 gearing ,but i run a wr gearbox in mine ,best thing i done to it ,really good! just sent mine off to chris hockey (dr shox) for revalving , i have heavy flywheel custom made through dylan jones (yamaha off road experience) , 2 carb spacers , fmf gnarly ,18'' wheel ,hydraulic clutch its quite a weapon! i had all this on my 2010 . got an 11 now so need to transfer bits over to that one and selling the '10 as standard .

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does indeed sound like a weapon you got everything im planning,brought the wr gearbox last week aint sure weather to go the full slog 1-5 or 3-5 99 percent 1-5 though.and dr shox is spot on from what ive read one of the best

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If you like the area here is a folder with photos a zip folder 43mb

arnego can i come and live in your back garden mate lol that looks like a dream place to have to ride :busted: and yea 3-5 is easier but can you feel the gap ?

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Well the garden is more an area where we culture some stuff for the future, Avocado tress, Lemon trees and small peppers to fill the gaps so tends are not really fitting in there. :busted:

The 3 to 5 are perfect, no gap at all. The gears are in the engine I put into the RM250 frame.

The pics are only a 20 min ride of the entire area we have here to ride. The whole area holds around 90 of riding, sure you got to repeat some of it.

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What do you have against the SST? I got one and so far so good. I'm happy with it.

Steve explians it much better than I can.

Originally written by Moto814

The FMF SST pipe is an amazing pipe.

Why is it amazing? Because in just about every case, it will work WORSE than the stock pipe that came on the bike.

The SST uses a restrictive reverse cone and pressure bleed to intensify the return wave and lower the initial flow out the stinger section of the pipe. What that in turn does is increase piston crown temperatures and make jetting difficult at best.

Now increased piston crown temperatures can be compensated for to some extent with richer jetting. But, by doing that you are defeating the purpose of the pipe, and negating any power gain you may have gotten from the pipe in the first place. Why are increased piston crown temperatures bad? Well, in some cases they are not. You see most bikes are jetted horribly rich from the factory, and raising the piston crown temps in this case will "fool" the engine into thinking it is jetted leaner than it is. Which will in some cases improve power. But in most cases, it will just cause slightly better throttle response and an increase in the spooge out the back of the pipe.

After all that you may be thinking: "well this doesn't sound so bad, why are they saying this pipe is no good?" Good question. Here's the answer. Because of the restrictive nature of the pressure bleed from the pipe, it does not evacuate as efficiently as it needs to. This combined with the piston crown temperature increase yeilds jetting that is too rich. So now you have a pipe that "fools" the engine into thinking it is leaner than it really is, but also makes it much richer than it was previously. Here in lies the second problem. It makes jetting a nightmare. If you jet it by feel, you will be jetting richer, and compounding the too rich condition even more, making the bike run like a slug. If you jet it leaner, you will be increasing piston crown temperatures even more resulting in an engine siezure. Catch-22 anyone?

If you are buying a pipe for your bike, get ANY other pipe. Or better yet, keep the stock pipe. Most late model pipes are pretty good stock. If you want more over-rev, go with a Pro-Circuit Works or Platinum pipe. If you want more low end go with an FMF Gnarly, or Pro-Circuit Platinum2.

I have personally experienced these jetting dilemmas with friends' bikes and the SST. I would never run one.

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IMO every one of us has its own taste, so worse or best is the opinion of each person.

Some people like the SST and some people do not, no problem for me anyway. If you like lugging you don't like the pipe and if you ride on the pipe you could like it. :busted:

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