85R FMF Fatty pipe question

[360X]

I put a FMF Fatty pipe and a new FMF turbine core silencer on my 85R a couple of months ago.

According to FMF's website, they say to leave the stock jetting in the carb and remove the airbox lid, which I did and I added an airbox lid outerwear/billet combo to it as well.

My R pulls really hard on the bottom and top end, and it idles fine. The problem I have is the mid-range is bogging somewhat and I moved the needle clip to the top slot to lean it out more. The factory needle position is in the 2nd slot from the top, but it ran worse when I had the needle in that position.

I was told by a fellow member of the forum here, that the Fatty pipe has an issue with the bogging in the mid-range. I just want to know if others have experienced this same issue.

Do I need to go to a different pipe like an ESR or something else?

I ride in the mountains and in the sand so I guess I'm going to need an all around style pipe.

Thanks.....:cool:

[NOS_350X]

The FMF pipe is avgerage at best. So another pipe will be much better. Fmf kinda just thows pipes out there without any research

Going from a stock pipe Even with it being an fmf you are defently going to need to jet it up, all the way around,

[360X]

Nick,

I did jet it up fatter, and that only made it worse. I rejetted the main jet with jets 1 and 2 steps bigger than stock, and then the top end was all blubbery and not clean. Then I moved my needle down from the 2nd slot(factory setting) to the 3rd slot down and it bogged and blubbered worse than it did in the 2nd slot on the needle. I threw in a fatter pilot jet as well, but it didn't make it any better.

I live at 2100' elevation and ride up to around 3500' elevation mostly.

This is FMF's statement regarding jetting;

"We know how difficult jetting can be sometimes, that's why when we test our exhausts we also adjust the jetting to see what works best. Sometimes stock jetting works fine, other times a slight adjustment is needed. Here is what we've come up for in our area and is a great starting point for you as well. There are way too many variables in jetting to give you a recommendation that works perfect. Use these specs for a reference to help aid you with your specific bike. We developed these specs with a 32:1 fuel to oil mixing ratio of a 50/50 mix of race fuel and super unleaded, 0 - 1500 ft altitude at 70 degrees outside temperature."



Your choice: HONDA --> 1985 --> ATC250R


Jetting Information

Main Jet: 145
Pilot Jet: N/A
Needle: STOCK
Needle Position: STOCK
Power Jet: N/A
Air Screw: 1.5
Fuel Screw: N/A
Comments: Remove airbox lid snorkel


I know Troll had to use stock jetting on his 85R, lean out his needle to the top slot, and modify his airbox lid because in our area where we live the R's just run too rich.

[NOS_350X]

Well about the ONLY truth teller, Whats a plug chop show with a new plug??

[Rex Karz]

My FMF Fatty/FMF Silencer equipped 85R runs quite well with a 135 main and 52 Pilot and no airbox lid at sea level - 1500'.

[360X]

Well I have to do that next, but if jetting it richer makes it worse, then obviously it needs to be leaned out some. I ran in the mid-range with it and pulled the choke on, and it really started to bog down hard then.....:chuckle:

I'm just wondering if my stock 85R Keihin PE carb has a worn jet needle because it did the same thing with the stock pipe and silencer on it come to think of it. It was on the top slot of the needle when I bought it, so the PO must've tried to lean it out as much as he could.

I just got an 86 R Keihin PJ carb and I had to order a jet needle for it since that was the only part missing from it. I'm hoping that it's 85R carb doing it and not the pipe causing the issue....

Any ideas as to what the best all-around pipe would be for my R?

An ESR ATC5 pipe maybe?

Rex, is that with the stock 85R Keihin PE round slide carb?



Thanks,
Doug

[Dammit!]

I was told by a fellow member of the forum here, that the Fatty pipe has an issue with the bogging in the mid-range.



Complete BS. I used to run a FMF and know several people that currently do and nobody had that problem once the machine was properly tuned.

People rag on FMF a lot and I don't know anything about their pipes for other machines but their R pipe really isn't bad. Are they as good as a Paul Turner? In my opinion, no, but they're better than people give them credit for. I had a distinct increase in power going from stock to the FMF. I had less of an impact going from the FMF to the Paul Turner High Rev (still a nice increase but not as dramatic). My trike still ripped with that FMF on it though. Hell it ripped with the stocker on it. :lmao: The PT has been the best for me so far. And it's not an "all top end" pipe at all. Don't let the name fool you.

I think you'd notice a bigger performance increase from getting a good PWK carb rather than getting a different pipe. The 86R carb is an improvement from the 85 (I think those are junk personally) but the PWK is a real nice carb. Easy to tune also.

Bottom line, the FMF isn't the weak link here. Your R isn't tuned right. That 85 carb isn't doing you any favors. Get a good carb and spend some quality time experimenting with your tuning and you'll be in good shape.

By the way, that altitude change is big enough to cause issues. Jet it where you ride it. You might even be able to get away with tuning it up high at your normal riding spot and throwing a stock airbox lid on at the lower altitude. If it ends up being too rich with the stocker you can vent the lid a little bit at a time until it's right. That's the easiest way to jet it for two locations. If the difference in altitude was more extreme I'd recommend swapping carbs that are tuned for each place.

[wild200x]

i just recently put a fmf fatty one the My R. i ride at 4500 feet in elevation. i also run a 39 mm pwk carb. before the fmf i was stock on the pipe. i went up 5 count them FIVE sizes on the jet to get a good plug chop. the diference in performance is incredable. the fmf pipe is the best mod so far for power that i have doen to my trike. its iritating to see the pipe slamed just because the p.t. or the esr may be slightly more power. the diferance is not worth the price diferance (double). unless you are realy a seriouse racer, you dont need to spend 400 bucks for a pipe. i think you got other carb issues if your having that much trouble.

[wild200x]

Fmf kinda just thows pipes out there without any research

,this statment is crap!

[NOS_350X]

this statment is crap!


Obviously you havent worked with different bikes and fmf pipes. They are a very generic pipe builder and they base there building off of fit, not dyno time. There 4 stroke pipes are even worse. Dg is probably the only other pipe that will consistently under-perform VS a FMF. (not counting 4 stroke pipes)

[Rex Karz]

Rex, is that with the stock 85R Keihin PE round slide carb?


I believe it is the stock carb, yes.

[Rustytinhorn]

Installing a longer needle will lean out the lower midrange (approx 1/4-1/2 throttle) Basically when you lengthen the needle, it is like adding more clip positions to the top of your needle.
Also decreasing the needle taper will lean out the upper midrange (approx 1/2-3/4)

[wild200x]

Obviously you havent worked with different bikes and fmf pipes. They are a very generic pipe builder and they base there building off of fit, not dyno time. There 4 stroke pipes are even worse. Dg is probably the only other pipe that will consistently under-perform VS a FMF. (not counting 4 stroke pipes)you act as though the 250R pipe they make is crap. all i can say is that they are not. they are quite a nice ad-on! you could argue some more or you could just admit i am right. unless you havent replaced a stock pipe on a R w/one, you dont know. and if you have, then you do know. the p.t. is worth the money only if you are serious about raceing. if you just ride and dune, the fmf is a great way to go, just because there are some that perform slightly better, dont meen this one is bad. dollar for dollar, it is the best mod you can do for performance. they may make some crapy pipes, idk, but the R one is a good performing pipe!!

[jenndnn3]

I agree with CARB being the issue.. if stock try a 36 or 38.. Someone mentioned better mod, I agree.

Lets just say for a minute NOS is right, even with a crappy exhaust IT still is pulling MORE air that your carb is restricted to by its size,,, ADDING bigger jets just keeps adding more fuel. Remember FMF recomendation remove air box lid (IE push more air through) even doing that helps but WILL always be limited to the size of the CARB.


NOS you are a lone ranger in the fmf is just crap..Perhaps Tonto will help you soon?

[scrambler250R]

Hey, guys this might be a dumb question but where do you even get those other pipes at?:doh: Because the only pipes in the big mail order books is FMF,and only DG for older 250Rs.I don't own an R yet, but it would be nice to know where to the good stuff when I do,thanks guys.

[wild200x]

i think d.g. is the only pipe ya can get for the 82-84 Rs. do a search for Paul Turner. you will find a p.t. for a bit over 400 bucks new. but oly for the 85 and 86 R.someone else may have the websites saved but i do not. if anyone does, post a link if ya would.

[NOS_350X]

http://www.eddie-sanders-racing.com/oscmax/
http://ctracing.com/
http://duncanracing.com/

direct is about the only way or a local shop.
There are the 3 big ones

[NOS_350X]

NOS you are a lone ranger in the fmf is just crap..Perhaps Tonto will help you soon?


Im not saying its not an alright pipe. It works and makes many people happy. I wasnt blaming the problem on the pipe.:chuckle: You can put a straight pipe on and it run, even run good. But comapred to what you can get, it isnt up to par. Badchevelleman has an old signature series FMF pipe, that one is alright, but its night and day diffrence from a regular FMF>

I do feel once it is jetted properly it will be alright, even with the 85 carb. Althoguh pj carbs or pwk are much better.

[CeaserTheThird]

FMF Old Signature Series pipe & FMF new Gold Series Pipe are the SAME (aka FATTY ) ! ! !

Had them Side by Side and Ran them both :burnout:


Same Pipe , New Updated Name :loser:

[NOS_350X]

FMF Old Signature Series pipe & FMF new Gold Series Pipe are the SAME (aka FATTY ) ! ! !

Had them Side by Side and Ran them both :burnout:


Same Pipe , New Updated Name :loser:


Ur funny,

There are 3 diffrent pipes, The old FMF, (Gold series) The signature series cant think of the name on the signature right now, and the new FMF Gold Series FATTY.

[badchevelleman66]

Im not saying its not an alright pipe. It works and makes many people happy. I wasnt blaming the problem on the pipe.:chuckle: You can put a straight pipe on and it run, even run good. But comapred to what you can get, it isnt up to par. Badchevelleman has an old signature series FMF pipe, that one is alright, but its night and day diffrence from a regular FMF>

I do feel once it is jetted properly it will be alright, even with the 85 carb. Althoguh pj carbs or pwk are much better.


and that bike almost put you on your ass lol i dont think its a standard fmf it has a name ingraved into it
fmf is not a bad pipe just not that tuned into performance like the other big 3

[wild200x]

you are talking drag race perfomance though. most are needing just a good upgrade for dunning.
also, i cant believe for 1 minute that fmf dont use a dyno at all. they just made i pipe that looks good on the trike and it just happened to perform great???? i dont think so. and my fatty does perform very well thank you. to say anything different is to call me a lier. a lier i am not! it sounds like some of you are baseing your opinion on an old pipe laying around. feel free to send it to me if it is junk....

[Dammit!]

Just FYI, a modern FMF Fatty is almost identical to a Paul Turner Type 6 pipe. Size and shape are just about spot on.

The Paul Turner I compared the FMF to was a very old one. Didn't actually say Type 6 on it but after talking to Duncan Racing about it I'm 99% certain that's what it was. The high rev is very obviously different. I should have taken a pic with all three lined up.

[CeaserTheThird]

:slap: NOS 350X - I really don't feel like proving you wrong :duck:

I'll post some pictures of all 3 i had Sold them to the Board member's - I think Wild 200x bought 1 ? ? ?

[wild200x]

yes, yes i did! and i love it! thanx again!

[Blown 331]

I swapped from FMF to ESR on my 85 and wow that was an insane difference. Money well spent. This was a few years back and I bought 2 pipes from ESR at one time so they sold them at $210 each and I got like $70 for my FMF on ebay so it wasn't all that much money I had to put out there and it was totally worth it.
My bike has a 36mm flat slide, Rad valve, fresh wiseco and I'm running just one layer of the head gaskety for compression. With these mods FMF to ESR was insane.
I guess you can just take this as my opinion but I love my ESR.

[jenndnn3]

I have the type 6 and the fmf,, I dont think they are the same????

[Dammit!]

That type 6 is the one I sold you isn't it? I compared it to a FMF pipe I had at the time and the shape and deminsions were extremely similar. The PT was just a slight bit bigger in overall diameter and the largest section of the pipe was located in the same spot on both pipes (high up on the pipe compared to the low bulge of a HR).

I should have taken pics. I'd be real curious to see if that fmf I no longer have is identical to this old one I have right now.

[NOS_350X]

On a 2 stroke pipe the slightest diffrence can make huge diffrences in power.

Ive herd of oldschool MX racers trying to Mimic dents a pipe might get to copy performance changes one might cause. That Slight size diffrence could lead to huge power diffrences.

[jenndnn3]

I think so, Dammit, but we had all pipes side by side. I was actually comparing the sectional I have. Wanted to make sure what it was, a lowend sectional. It is like the type 6's (I have 2 now) The FMF I have is definatly different. More slim at the stinger way fatter in the belly. plus the reach around was a different. And it produced way better then the type 6 on my machine (that is important because most forget in pipes and 2strokes and how your machine is setup will effect which pipe performs best). I can take picts in the near future probably when I pull the pipes off. I am very curious now on that esr pipe myself. But that will wait till one falls in my lap.

It was really nice to get the FMF against the others, because it really showed the difference between the 3 I have.

[Dammit!]

Yeah Jenn, post pics whenever you can. I'd like to see it. If I get a chance before I sell this old FMF I'll take pics next to a HR.

[jenndnn3]

Oh yeah I forgot I have the pt high rev to. It is more like the fmf, if I recall correctly. Hard to compare it at the reach around because it was kinda munched into the frame. We are not sure we can save it. I really like your post on the pipe question by the way as far as bubble, nice and simple!