Yamaha TRX850 Enthusiasts Forum

Hey Ho - crispmas is on it's way to being over so I gave myself an hour in the garage tonight... had a quick squint at these FCRs i bought from Georg in Germany - I've never had an erection looking at carbs before but damn it got close tonight!! They cost me a shade over £400 but they look like new, no gunk on any of the linkages nor any smell of old fuel - all the bowl screws still have the yellow sealing paint on them...

Now here's a thing - they were sold as 39's but me being a cynic thought I'd check the bore and bugger me if the manifold flange (? the bit that slips into the cylinder head) didn't come up as 37mm!! Needless to say I was a wee bit perplexed (they weren't the words I used at the time, trust me!) and I was beginning to think I'd been taken advantage of. Then I noticed that the flangey bit on the carb looked like it screwed into the carb body - sure enough I gave it a twist and out it came. I put it on the bench to mic it properly and a quick tweak with the vernier showed that the bugger was tapered !! I measured it properly and found that the ID of the manifold tube reduced from 39.6mm just past the main jet to 37mm at the head end. Is this normal?? Is it significant?? Do I need to machine it back to parallel ID?

The other thing is - the K&N's that came with it are the big can sized jobs. They appear to be dry at the moment so I guess they'll need to be oiled prior to use. This might seem a silly question, but is there a particular oil to use?? I have a can of Putoline foam filter oil - could I use this ?? what about - dare I say - two-stroke oil..??

Lastly - I haven't pulled the jets to see what's in there but does anyone have any idea where I should start if a 2:1 Akra is fitted ??


Muchos grassyarse..


Greg

When i don't have K&N oil laying around i use WD40 to spray the filters

CULater, what's the dimensions of those K&Ns in the photo?
When I had FCR41s on the Guzzi, I had to use K&N "pancake" style filters (as seen on '60s Triumphs etc) because of lack of space with the frame rails - from memory the ID of the filter flange was 52mm.

Bob

I personally wouldn't use anything other than the K&N oil but ......

Not sure about the sizes and the taper - I would give Allens a ring and have a chat with him. We would only be guessing?

Start with 155 main jets.

My filters are the RD-0620 from K&N

So flange dia is 57 mm

I have Mikuni's, don't know if there's a difference between Mikuni en Keihin sizes ?

http://www.knfilters.com/search/product ... od=RD-0620

CU did you have to modify the fuel tank to fit over these large filters ???? WiCk

I'm after some jets for these FCRs... they've arrived with 135s which by Phuk's reckoning will be a touch on the lean side - anyone have any bigger ones spare/for sale ??

I have tried Allens- they seem to be on perennial holiday and their answerphone must be bolloxed cos they haven't phoned me back yet..!

TIA

G

wicky wrote:CU did you have to modify the fuel tank to fit over these large filters ???? WiCk

Nope, we measured the dimensions first, so it clears the fueltank by a few mm's.
But, to my knowledge, on a TRX their is less space under the tank than on a TDM

CULater wrote:

wicky wrote:CU did you have to modify the fuel tank to fit over these large filters ???? WiCk

Nope, we measured the dimensions first, so it clears the fueltank by a few mm's.
But, to my knowledge, on a TRX their is less space under the tank than on a TDM

well they look like something an Iraqi Kurd would use on their bike to mortar bomb a settlement

my mint carbs have now arrived with 155 main jet and 200 slow air if anyone can tell me what jets i need to by and what air filter to buy

dillthedog wrote:my mint carbs have now arrived with 155 main jet and 200 slow air if anyone can tell me what jets i need to by and what air filter to buy

Mine where delivered with jetting for standard airbox wich was 150/200...my god it was lean when cold outside!
I got 175 left 180 right main now and it´s a tad fat...but awaiting dyno it seems safer!
I got the sockfilter Max got...just pull ´em over the velocity stacks and shove the enginebreather in there.

...anyway, the info was taken from the site so everything´s in here!

I use K&N pods on mine (and another for the breather)

Non standard motor but I'm using 158 mains

Don't anyone tell me that the TDM carbs are different to the TRX jobs... These have got an accelerator pump on the RH carb, and the bleeding thing fouls the oil filler tube.
So - is this accelerator pump standard? Do I need longer carb manifold stubs... ? or do I just move the fekkin oil filler tube...!

I'm a cheapskate and am not buying anymore carb bits yet - I'm moving the damned tube!

G

Greg wrote:Don't anyone tell me that the TDM carbs are different to the TRX jobs... These have got an accelerator pump on the RH carb, and the bleeding thing fouls the oil filler tube.
So - is this accelerator pump standard? Do I need longer carb manifold stubs... ? or do I just move the fekkin oil filler tube...!

I'm a cheapskate and am not buying anymore carb bits yet - I'm moving the damned tube!

G

well what ever you do don't use TDM carbs from a 1999-2002 bike because they are not as rebuildable or as tune-able as the 1996-1998 ones. And the earlier 1991-1995 carbs have no TPS fitted.

Aren't pumpers standard Japan market carbs. The European TDM ('96 - 98, Wicky's right there) /TRX are identical externally. The TRX ones have the facility for the pumper (different float bowl) inside and as such can be a bassad for overflowing if the float height is set a little high.......