Fitting a FMF Fat boy to a RM 250

[cheese]

Hi Guys

Not too sure about this but I got a FMF fatboy expansion chamber and muffler. Is it safe to just throw on or should I wait till I recon the bike?? I'm going to get my cyclinder replated when I do it unless total moto x come up with a shit hot price on a new one.

Also would I need to rejet the bike with the new pipe, some say no bolt on and use, others say new pipe - more power - but to get more power, got to use more gas. Is this right????

Cheers

Stephen
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[scott411]

what jetting do you have know? is it standard, typically pipes do not need big jetting standard, and pipes are not normally just bolt on horsepower, they tend to shift it more than make more, FMF fat boy tend to be more bottom end power

[cheese]

yeah that is what I want anyway. I'll just chuck her on and go for it. I think I need the exhaust packing done, but that can wait

[Danger]

Do us all a favour and replace the packing before you fit it. You will get better power out of it that way as well. And don't race around the car park or up and down the road at Woodhill eh? Your jetting should not need changing.

[cheese]

I might drop it into the shop and get it done instead of covering myself with that itchy shit!

I don't race up and down the car park! What you talking about Willis?

[Brian d marge]

The packing I use is a pre cut roll, you just cut it to length and wire it in, I put some pink batts or wool round the outside ,,not needed .but does cut the sound a little more

Its very cheap

Also yes the FMF Fatty does produce a differing power out put ,,The cr125 I bought from scott I put a fatty on that with out any jetting changes, I could feel the pipe kick in ...THOUGH it wasnt as low down as I would have like ...with a bit of fiddling with the pilot /leedle I could have droppedthe rpm a bit

What was happening , it would hit the poer band and lose traction

Stephen

[cheese]

What do you guys use to clean all the old shit out of it too? my old one was caked with shit!

[zarinat]

the FMF website has jetting specs for your combo- to make the best of the pipe, best to start there. If in doubt go fat, especially in the sand -but i guess you know this...
Heat gets the spooge out.

[cheese]

What do you mean by go fat?

[Danger]

He means that if you are going to make jetting changes and are unsure where you should be, run your jetting richer rather than leaner because sand can be hard on an engine (you know, full throttle up those sand climbs). Running lean on the AS tends to rob a little midrange torque I've noticed which is noticeable in sand. Bordering on rich seems to produce the best midrange torque out of corners, just short of blubbery when idling along the rode seems to be best.

[zarinat]

yeah, sorry - rich rather than lean- we're talking main jet here...remember WOT & then shutting off at warp speed (as when drag racing along beach) is probably the best way to keep wiseco & ProX in business ! I can guarantee a sucessfull seize every time if you do this. Also, use engine ice- it definitely helps cooling- If you must ride in the sand - these little things will definitley help keep your engine living a little longer