A Keihin FCR how-to?

[Killerwhale]

Hi all!
...and the trx850.myfreebullshit is down again!
I had just before it went down put in a question if anyone has the time to put together a how-to on installing keihin 41´s...AND how to disassemble the old ones...where the heater hoses go etc. etc.

Thing is that the guy who was going to help me and then bench it has had a severe crasch on his insane gixxer...with extensive surgery as a result. There where another guy who i would trust to do it but he competes out in europe until end of september....so ANY help, input, "think of´s" would be appreciated!!

Cheers

[tz250w]

There's really not that much to it, if you have a set that was built for the TRX that is.

Carb heater hoses can be bypassed by inserting a small piece of tubing and joining them together (use lockwire or small hose clips to be safe).

With mine, the most difficult part was adapting a NSR250 throttle (and cables) to it... But I'm a cheap (poor) bastard and that's what you get for not having the correct parts to begin with. BTW, the NSR throttle works great.

With any carb swap, you will often run into problems with throttle wire routing. Make sure you don't have any kinks, binding or have them placed somwhere that they might get pinched by the steering.

Be sure to attach some sort of free flowing filter to the case breather if you are not going to be using the airbox.

This might be easier if done in a F.A.Q. format.


(I know this isn't much of a "How To"... More like mindless babble, but I'm still only 1/4 of the way into my first cup of coffee.)

[Killerwhale]

There's really not that much to it, if you have a set that was built for the TRX that is.

ANY input is appreciated!!

Thanks!

[Killerwhale]

I got the ramair sock you got only my text is white...faster???

Anyway, you have posted pic in the below thread with the sock on....you don´t have pics with it off?? Should be quite easy to see were to fit everything!?

I wonder why you went with NSR gasgrip, the TRX standard should fit right on there if i understood it right.

Another thing, do you remember what number of main jet comes standard on the carbs??
I think they come prepped for use with airbox so i guess they would be on the lean side wide open! ....and if you went up and live in warmer climate than me....mixture would be catastrophically lean wouldn´t it?

Cheers

[tz250w]

Sorry, I don't have any pictures handy with the filter off...

The NSR throttle is a 'quick turn', pretty much a racing style with slight rotation to full open. Gives you a heavier return spring feel though.

I really don't know what the 'stock' settings were. Mine were used as prototypes for adapting to a stock airbox before I bought them 'used' (but never having gas in them...). The guy that had them worked at Yamaha R&D and he pretty much gave up on the adaptation so he says. I think mine had #160s in them when I got them which were close I went up and down in mains but noticed only slight differences. Big twins are not as sensitive as fours in minor jetting changes.

With your temp, and lack of humidity I really don't know what baseline to give you. But, I would suggest just mounting them on, do a little light riding (not stressing the engine too hard) and feeling it out. Checking plugs along the way. Either that, or find someone in similar climate conditions and get their settings to start with.

Good Luck! You won't be disappointed in the long run.

[Killerwhale]

Sorry, I don't have any pictures handy with the filter off...

The NSR throttle is a 'quick turn', pretty much a racing style with slight rotation to full open. Gives you a heavier return spring feel though.

Done, and it took 5! hours...
A question, does your slides "clatter" on certain rpm´s??
First i thought i heard the valves....not a good sign....but it´s just at some rpm´s....vibrations make the slides clatter together???

[tz250w]

A question, does your slides "clatter" on certain rpm´s???

Yes, FCRs do that on just about any bike. Nothing to worry about and it will attract attention from knowing ears.

Now, make sure you don't let your buddies stand there and twist the throttle grip with the engine off or you will flood the engine with the accelerator pump.

[rsheidler]

....Now, make sure you don't let your buddies stand there and twist the throttle grip with the engine off or you will flood the engine with the accelerator pump.

But that IS a fun think to do to your buddies at a rest stop though

Used to be even more fun in the days when they had to kick start the bikes though.

For what it is worth, the Keihins on my Ducati also "chatter" -- that is a feature not a bug -- kinda like the rattle of my dry clutch.

[Killerwhale]

Now, make sure you don't let your buddies stand there and twist the throttle grip with the engine off or you will flood the engine with the accelerator pump.

I read on a forum that it´s a good idea to twist 1/2 throttle before start...once that is! ...just to help out the start a bit....for cold days maybe!?

Anyway, this will be fun...but i have to shorten the wires...and fit a copper tube or something instead of the plastic tube i used to route the carbheater cabling!

Thanks for all help, now the cams i got at home goes for a workover and they will go in next spring with a porting job.
And i will probably let Zorst make a 2-1-2 with a nice big bore for me!

Would be nice to land on an even 100 ponies!

[Wombat]

Yeah, my FCRs on the Guzzi used to "clatter" too

Wombat

[tz250w]

I usually give mine three quick flicks of the wrist and it pops right off!

Of course it lays around withought being used very often...

In the winter, it requires a little 'vibrating' massage with the hand to get it to warm up to the point where it will stand on its own...

But I can't complain, it always makes me smile!

And I am also talking about my bike with the FCRs.

[Killerwhale]

I usually give mine three quick flicks of the wrist and it pops right off!
Of course it lays around withought being used very often...
In the winter, it requires a little 'vibrating' massage with the hand to get it to warm up to the point where it will stand on its own...
But I can't complain, it always makes me smile!
And I am also talking about my bike with the FCRs.

Everything sorted now, got the wires shortened...pneumatic tube for the water return...did the TPS diagnostic stated in Haynes and as i thought the TPS was off...MUCH better low/mid now!!

I guess that the dealers sets ´em WAY fat...it feels that way and i got a surprise today as the bike went dead after 170km!! (ok, 80% illegal riding but anyway!)

How many turns out do you have on the mains?? I think my trix want´s more air! ....and it actually got hotter with the old carbs!

....i have to say though....it´s a big lump of cash buying them new...but money well spent!! I was racing a RSV today and he could not loose me!

Racecams, a port job, Zorstsystem and suspension....then the bike is a dream!!

[LozLul]

Killerwhale,

I would like to hear more about this "TPS diagnostic" you did as Im thinking that, disregarding my efforts, the TPS is not connected in my setup currently. Thank a lot in advance!

[Killerwhale]

Killerwhale,

I would like to hear more about this "TPS diagnostic" you did as Im thinking that, disregarding my efforts, the TPS is not connected in my setup currently. Thank a lot in advance!

If your TPS isn´t connected and you don´t have the TPS mod then your rev counter would indicate an error!

To check i think it was...ign. on.....yank the TPS contact out....off - on ign. and you should have values 1000 - 4000 - 8000 where 4000 is OK 1k & 8k is off to either end....

You can search in here it´s been up for discussion a couple of times...

Hope it helps!

//M

[LozLul]

Thanks, Killerwhale! This was just what I was looking for.