39mm FCR MX? jetting? powervalve?

[maddmatt02]

ok, I bought a 39mm FCR off ebay to put on my quad, got it in the mail today and cleaned it up and noticed I need a new accelerator pump diaphragm as well as the intake boot adapter. I got it all cleaned up and looked on the internet and came up with this link... http://keihin-us.com/am/products/fcrmx.php

thins is it shows in the parts list a spring/cover/diaphragm on the side as well, my carb is not tapped/drilled for anything there but you can tell its cast to be able to accept such drilling/tapping for another model designation maybe. anyways the fcr on my girls 04yfz does have whatever it is that is there, someone told me its a powervalve? whats this and is he right, I thought it was something to do with only 2 strokes but maybe Im wrong.

also stock jetting is 42/167 I think, cant remember the main but I know the pilot is 42. I got a 52/55 pilot and 170/175/180 mains coming in the mail, because of a post I read. is this a good place to start for my mods?

also it has a slow air jet and main air jet as well as starter jet, slow jet, and main jet.

only jets ive heard of are pilot(slow) and main, do I have to screw with the others at all?

also does anyone sell anything like an e brake block off plate for a TPS? I dont need it but I dont wanna leave the hole, even though the needle bearing looks like its got a seal outside of it, I just dont wanna leave the crevice for dirt to collect wether it can get in or not.

also where can I get this adapter so i can hook some kind of intake to it?

and lastly I heard I can get a hot start cable? does it come with a bracket that bolts to the carb and the cable has an end that pops onto the post like the little pull tab does?

thanks

[maddmatt02]

oh, also what clip position on the needle? it was in the middle when I got in there.

[GPracer2500]

Originally posted by maddmatt02
....shows in the parts list a spring/cover/diaphragm on the side as well, my carb is not tapped/drilled for anything there but you can tell its cast to be able to accept such drilling/tapping for another model designation maybe. anyways the fcr on my girls 04yfz does have whatever it is that is there, someone told me its a powervalve? whats this and is he right, I thought it was something to do with only 2 strokes but maybe Im wrong....


It's not a powervalve. It's an Air Cutoff Valve. It's purpose is to richen the pilot circuit under closed throttle, high vaccum (high rpm) conditions. The idea is to counteract the temporary lean condition that occurs in most carbs under closed throttle, high vaccum situations. Don't worry about not having it--you don't really need it and it won't affect performance.


Originally posted by maddmatt02
....also it has a slow air jet and main air jet as well as starter jet, slow jet, and main jet.

only jets ive heard of are pilot(slow) and main, do I have to screw with the others at all?....

Not really. Most people never mess with the main air jet and pilot air jet. In many carbs (including some FCRs) they're not even removable jets, just fixed orifice passages. For the most part, you'd have to be tuning on a dyno to get into changing that stuff anyway. Don't worry about them.

The starter jet also is rarely changed.


Originally posted by maddmatt02
....also does anyone sell anything like an e brake block off plate for a TPS? I dont need it but I dont wanna leave the hole, even though the needle bearing looks like its got a seal outside of it, I just dont wanna leave the crevice for dirt to collect wether it can get in or not....

I'm not aware of any TPS block-offs. If anyone makes one I haven't seen it. Just leave the TPS sensor installed on the carb body. You won't be using it, but that doesn't mean it can't still be there.


Originally posted by maddmatt02
....also where can I get this adapter so i can hook some kind of intake to it?

and lastly I heard I can get a hot start cable? does it come with a bracket that bolts to the carb and the cable has an end that pops onto the post like the little pull tab does?

thanks

Download Sudco's catalog. They are likely to have what you need.

[zrpilot]

I'm not so sure there are adapters available for the FCR-MX version...

[maddmatt02]

well, how does anyone run with with an air filter then? right now theres no throat at all to mount anything on on the filter side, ill get some pics today though and post em later after work, found the pump rebuild kit for 39.95, would it be better to just buy a boyseen kit or something? was thinking bout doing the mods to it where you plug the leak jet then tap the body and instal;l the screw to adjust the duration of the squirt.

[zrpilot]

Please post some pictures, the Sudco web site is not real clear about the adapters...

[Dill]

Originally posted by maddmatt02
well, how does anyone run with with an air filter then? right now theres no throat at all to mount anything on on the filter side, ill get some pics today though and post em later after work, found the pump rebuild kit for 39.95, would it be better to just buy a boyseen kit or something? was thinking bout doing the mods to it where you plug the leak jet then tap the body and instal;l the screw to adjust the duration of the squirt.

it sounds like you were NOT shipped a bell adapter for your carb.

[maddmatt02]

so I need a bell adapter, im going to the yamaha dealer in a minute, also I called sudco and they told me go to yamaha, but I did find the AP rebuld kit from them, gonna see how much yamaha wants for it locally first though.

[maddmatt02]

alright, went to yamaha today, got my air filter joint and op ring, AP diaphragm and spring and the screws for the joint. said there was no way to have it by friday so I blue labeled the shipping for more money.

I also aquired a 07 YFZ thumb throttle/cable for 20 bucks off a buddy who went twist.

so now with jets and parts and the carb itself Im into it 285.00 not too bad I guess seeing as I seen the carb new for 510 bucks, and is still need cable/jets.

anyways so far Ive tapped the upper cable hole and plugged it with a bolt so no dirt can get in, hooked up some tubing to the vents and ran em through their brackets.

this weekend i will be installing the softer rotor spring, filter joint, jets, plumb the fuel line, figure out the air box situation.

bad thing is the choke and hot start are gonna be hard to get to. ill get cables for both eventually I think.

I will be tuning the carb out where there is no parts shop, so i need to have the jets with me I might need. got stock, and 52/55 pilots and 170/175/180 mains, should I get a 50 pilot jet just in case?

anyways heres pics of the carb, then the beauty its going into, and then of course my arch rival, lol (my girlfriends quad) hopefully I can get it dialed in down in oregon and beat her but who knows, even if I do theres gonna be that 07 YFZ with the full titanium GYTR system, and a few other mods that I wont be able to touch. http://i164.photobucket.com/albums/u9/maddmatt02/quad023.jpg http://i164.photobucket.com/albums/u9/maddmatt02/quad021.jpg
http://i164.photobucket.com/albums/u9/maddmatt02/P1000813.jpg
http://i164.photobucket.com/albums/u9/maddmatt02/quad030.jpg http://i164.photobucket.com/albums/u9/maddmatt02/quad027.jpg http://i164.photobucket.com/albums/u9/maddmatt02/quad028.jpg http://i164.photobucket.com/albums/u9/maddmatt02/quad033.jpg http://i164.photobucket.com/albums/u9/maddmatt02/quad031.jpg

[maddmatt02]

forgot something, noones reccomended a needle clip position.

[zrpilot]

Be careful when installing this, a friend used the same carb on his 400EX and he hooked it up to the stock air boot coming from the airbox. After about couple of minutes on the track, we noticed his carb had dis-lodged from the airbox intake boot and had been running un-filtered air :eek:

[Dill]

ditch the Sand Geckos for some Haulers and it will make a huge difference!

[maddmatt02]

well, havent gotten that far yet, cuz the air filter joint isnt here yet. anyways what did he do with the choke? right now the fuel line comes off the shut-off right in front of the choke, and is close enough to where you cant redirect the fuel line somewhere else. that and the mixture screw is almost impossible to get to, even with an aftermarket one with the knurled thumb wheel on it. just tried to get it to pop with no choke and it wasnt too bad, didnt run it though cuz I got no AP and lean jets still. I did get it on the manifold at least but I gotta get a new clamp cuz with the stock clamp opened as far as it wiould go it wouldnt let the bot stretch enough to fit the carb. I am also gonna port match the manifold, the heads been ported and the manifold is way smaller than the intake port. the gas tank fits at least so theres a plus, as well as the cable will fit. airbox boot looks like it is in the right area but not sure about the diameters of the two, maybe they wont fit, but im most likely gonna fab up an airbox elminator anyways.

are sand stars much better than geckos? thats what shes got.

[Dill]

yea they're better, not a lot, but Geckos are the worst sand tire I've ever used.

[maddmatt02]

actually maybe she has gbc sand sharks, I think they both look the same anyways, an angled paddle that goes from outside almost all the way to inside then angles back towards the front for about 2-3 inches. how is the handling on haulers though, ive been told they only wanna go in a straight line.

[Dill]

I don't have any problems with them, once you ride with Haulers, you are hooked. I do have Mohawks on the front though, my bike turns great.

http://syracinginc.com/pics/albums/LSApril2007/normal_LSApril2007070.jpg

[maddmatt02]

oops, thats what I got on the front too.

[CDCHONDAS]

for that carb I suggest a noss adapter from noss machine, (search the net) with the noss adapter you can hook it up to your stock intake and carb boot, you will need to cut or grind the inside to the boot and intake in order to accept the larger size though, if I remember correctly with the carb you have its too high and last one we did had to heat the bottom of the fuel tank and cave it in to fit over the carb. theres a couple different versions of that carb and i didnt look at your pics real good.

[maddmatt02]

Ill take some pics of it when im replacing the diaphragm this sunday. actually I have it barely rotated clockwise, and the top of the carb is about 1/4" away from the tank, the fuel line now runs right above the hot start lever and right in front of the choke, this also lets the aftermarket mixture screw clear the starter better and lets me get to it, cable is ran through stock location.

also a guy I know from a class builds inline 4's from streetbikes for racecars, and he told me to go to sudco because they all bolt on the same and they just have different lengths and diameters for different applications, so if I take a meaurement od diameter and approximate length required they should be able to hook me up. he has tons of these carbs also but he just sent all his adapters to california for some reason.

[maddmatt02]

plus I just looked at the adapter, and it works if the carb already has the flange on it, mine doesnt, so nothing for me to put that adapter on.

[drsnugfit]

Originally posted by maddmatt02
plus I just looked at the adapter, and it works if the carb already has the flange on it, mine doesnt, so nothing for me to put that adapter on.

just found this while looking at sites regarding FCR carbs, looks interesting and may be the answer to the adapter you have ben looking for.

http://www.performance-design.net/flo_commander_2000.htm

scroll down and you will see they make one for fitting an fcr to a 400ex, at least you know it will be the right size for your airbox boot and if there claims are true you will gain a bit of performance too.

[zrpilot]

Originally posted by drsnugfit
just found this while looking at sites regarding FCR carbs, looks interesting and may be the answer to the adapter you have ben looking for.

http://www.performance-design.net/flo_commander_2000.htm

scroll down and you will see they make one for fitting an fcr to a 400ex, at least you know it will be the right size for your airbox boot and if there claims are true you will gain a bit of performance too. I looked closely at this and it seems really cool and I think it probably works, however there is one thing I don't like. If you use this system, it needs a supply of air for the air jets. That can be from a remote filter or form your airbox. Yuck, both alternatives could introduce dirty air into the carb on my quad...

[drsnugfit]

Originally posted by zrpilot
I looked closely at this and it seems really cool and I think it probably works, however there is one thing I don't like. If you use this system, it needs a supply of air for the air jets. That can be from a remote filter or form your airbox. Yuck, both alternatives could introduce dirty air into the carb on my quad...


the remote filter and the section going into the airbox both filter the air as much as your air filter would.

[zrpilot]

Originally posted by drsnugfit
the remote filter and the section going into the airbox both filter the air as much as your air filter would. Really? I ride a lot of fine dusty and sandy conditions and the inside of the air box is caked with dust therefore the air coming from the airbox IS not filtered and I'd prefer not to rely on a remote filter.

[maddmatt02]

Id have to somehow pop a fitting in the tube kinda like the stock crankcrase breather vent. cuz I have no airbox, well I do but theres about 15% as much material to it as there use to be.
Im gonna go check that link right now, I actually made an aluminum plate that fit the carb, got a 2" pvc bushing that was 2 5/15 O.D. so it fit the boot and had a small flange at the other end, and recessed the bolts on the first plate, then made another that just fit the pvc and sat on the flange, drilled holes through it, and tapped holes in the first plate and clampedthe 2 together and bolted it all the the carb, got my pump diaphragm in and fired it up again, sounds pretty mean.