FCR 39 or 41
Moderators: trixynut, Mincehead, dicky, phuk72, Jak, Kevtrx849
- Wombat
- Forum Marsupial
- Posts: 1092
- Joined: Fri Jan 07, 2005 10:50 am
- Location: Carlingford, Sydney, Australia
Re: FCR 39 or 41
And wouldn't 39's solve that problem with enlarging the inlet rubbers that you have to do with 41's?
Seriously considering looking at 39's now
Bob
Seriously considering looking at 39's now
Bob
"The fire is almost out......and there's nothing left to burn!"
- steve speed
- Site Sponsor
- Posts: 1780
- Joined: Sun Jan 14, 2007 9:11 pm
- Location: rochdale England
Re: FCR 39 or 41
the problem you disscribe took me about 10 mins to sort ,,but getting the jets somewhere near has taken a lot longer ,,both 39s & 41s are a shed more power than the 38 miksWombat wrote:And wouldn't 39's solve that problem with enlarging the inlet rubbers that you have to do with 41's?
Seriously considering looking at 39's now
Bob
TRX850 ,The thinking mans R1
- Wombat
- Forum Marsupial
- Posts: 1092
- Joined: Fri Jan 07, 2005 10:50 am
- Location: Carlingford, Sydney, Australia
Re: FCR 39 or 41
There's a set of 39's on EvilBay right now with about 5 days to go. Trouble is that they're for a Ducati 900SS, and therefore no TPS. Would I be right? What's the mod to disable the TPS anyway.
What's the Mikuni flatslide equivalent?
Bob
What's the Mikuni flatslide equivalent?
Bob
"The fire is almost out......and there's nothing left to burn!"
- Tarwetijger
- TRX-Enthusiast
- Posts: 1524
- Joined: Tue May 15, 2007 9:31 am
- Location: Netherlands, Assen
- Contact:
Re: FCR 39 or 41
Don't know about the Duc thing but Mikuni flatslides are TDMR, 40mm, available at KEDO and TÜV geprüft!Wombat wrote:There's a set of 39's on EvilBay right now with about 5 days to go. Trouble is that they're for a Ducati 900SS, and therefore no TPS. Would I be right? What's the mod to disable the TPS anyway.
What's the Mikuni flatslide equivalent?
Bob
-
dirty trix
Re: FCR 39 or 41
What about the Keihin FCR40mm common on the MX bikes with the accelerator pump? Sure you would need to get two....
- steve speed
- Site Sponsor
- Posts: 1780
- Joined: Sun Jan 14, 2007 9:11 pm
- Location: rochdale England
- Kayla
- Site Sponsor
- Posts: 1670
- Joined: Fri Jul 04, 2008 7:49 am
- Location: County Durham
Re: FCR 39 or 41
I looked into doing it 'on the cheap' but the FCR-MX carbs are sidedraft and the TRX head is downdraft, plus you'd have to arrange some way of ganging the carbs together*.dirty trix wrote:What about the Keihin FCR40mm common on the MX bikes with the accelerator pump? Sure you would need to get two....
*I reserve the right to be wrong.
-
dirty trix
Re: FCR 39 or 41
Good point......
Cant see any 39's or 41's or even the Mikuni TDMR's at present, so was just fishing.
Have to see what 39's go for.....
Hmmm just posturing... much as I love my TRX if I did half the stuff I want to it it would cost me more than buying a 904ie monster and still only have a 5 speed box.....
Cant see any 39's or 41's or even the Mikuni TDMR's at present, so was just fishing.
Have to see what 39's go for.....
Hmmm just posturing... much as I love my TRX if I did half the stuff I want to it it would cost me more than buying a 904ie monster and still only have a 5 speed box.....
- idl1975
- TRX-Enthusiast
- Posts: 749
- Joined: Wed Feb 21, 2007 9:19 am
- Location: Surrey
Re: FCR 39 or 41
My bike, with non-expert dynojetted for K&N + micron slip ons made 79 bhp on Specials of Glasgow's dyno back in the day - if you already have cans on the bike, the extra £300-400 would seem to get you 6-10hp without head work or the 878 kit. Yours isn't on stock exhausts, is it?Kayla wrote:That's answered one of my questions, thanksGreg wrote:From the perspective of a 39 owner...
...bags more grunt all over, instant throttle response and of course 15 extra horses.I'd have expected better response and a bit more power and torque but that's a huge increase for a relatively small cost.
Not that I'm saying FCRs aren't da sh** though, 'cos of course they ARE.
-----
'04 Aprilia Tuono Fighter
'00 Scooby Sport Wagon
'76 TY250.
'04 Aprilia Tuono Fighter
'00 Scooby Sport Wagon
'76 TY250.
- phuk72
- Site Sponsor / Administrator
- Posts: 3522
- Joined: Thu Jan 06, 2005 1:47 pm
Re: FCR 39 or 41
If you want flatslides on the cheap get onto ebay usa and have a search around in the snowmobile section. Most (if not all) of the 2T skidoos etc use flat slides and some patient searching will find you some downdraft carbs.
I managed to get a set delivered for less than £100. Of course you will have to rejet, respace, make spiggots and velcoty stacks but it can be done. I got a set of FCR41s cheap so never finished (well actually other than having them in the garage I never actually started)
I managed to get a set delivered for less than £100. Of course you will have to rejet, respace, make spiggots and velcoty stacks but it can be done. I got a set of FCR41s cheap so never finished (well actually other than having them in the garage I never actually started)

- Kayla
- Site Sponsor
- Posts: 1670
- Joined: Fri Jul 04, 2008 7:49 am
- Location: County Durham
Re: FCR 39 or 41
Mine's got aftermarket pipes on standard headers (with the trumpety bit cut off the airbox). I spoke to PhilK about his FCRs over the weekend and I'm buying them off him when I get paid next weekidl1975 wrote:My bike, with non-expert dynojetted for K&N + micron slip ons made 79 bhp on Specials of Glasgow's dyno back in the day - if you already have cans on the bike, the extra £300-400 would seem to get you 6-10hp without head work or the 878 kit. Yours isn't on stock exhausts, is it?Kayla wrote:That's answered one of my questions, thanksGreg wrote:From the perspective of a 39 owner...
...bags more grunt all over, instant throttle response and of course 15 extra horses.I'd have expected better response and a bit more power and torque but that's a huge increase for a relatively small cost.
Not that I'm saying FCRs aren't da sh** though, 'cos of course they ARE.
-
dirty trix
Re: FCR 39 or 41
Mine has an 80.4 RWHP dynograph at 90,000+ kilometers, stock carbs with worn needles and unknown jetting, gutted stock pipes and K&N. As to what that means, not much. A dyno result is easy to tweak, but on seat of the pants feel and it's ability to lift the front that feels about right.idl1975 wrote:My bike, with non-expert dynojetted for K&N + micron slip ons made 79 bhp on Specials of Glasgow's dyno back in the day - if you already have cans on the bike, the extra £300-400 would seem to get you 6-10hp without head work or the 878 kit. Yours isn't on stock exhausts, is it?
As such, dynojet horsepower gains are probably maybe 1-2 horsepower max and the rest of the difference is dyno variation or production tolerance variation? I had promised to get a dynojet kit done for mine if I hadnt scored some FCRs or some TDMR's..... No FCR's and still no dynojet kit.
- steve speed
- Site Sponsor
- Posts: 1780
- Joined: Sun Jan 14, 2007 9:11 pm
- Location: rochdale England
- Kayla
- Site Sponsor
- Posts: 1670
- Joined: Fri Jul 04, 2008 7:49 am
- Location: County Durham
Re: FCR 39 or 41
Thanks! I talked it over with my bf and we decided to get some nice stuff for our bikes with my redundancy payment and we're going to the Manc bike show toosteve speed wrote:well done kayla![]()
welcome to the dark side
![]()
- steve speed
- Site Sponsor
- Posts: 1780
- Joined: Sun Jan 14, 2007 9:11 pm
- Location: rochdale England
Re: FCR 39 or 41
are you going to the manchester bike show to buy sweets ?? because thats all they sell ,, save your money for main jets for your FCRsKayla wrote:Thanks! I talked it over with my bf and we decided to get some nice stuff for our bikes with my redundancy payment and we're going to the Manc bike show toosteve speed wrote:well done kayla![]()
welcome to the dark side
![]()
TRX850 ,The thinking mans R1

