Freshening up an FCR39 MX?

[MattZig]

I've got an FCR39-MX, the straight one from thumpertalk, and it has about 20,000 KM on it.

It had a throttle hesitation even with the o-ring mod, and while cruising it would surge. So I pulled it, and want to freshen it up. Turns out the mixture screw broke off inside, too, so who knows how many turns that thing is. Here's what I want to do:

*Give it a soak in Yamaha carb cleaner (doesnt hurt rubber bits it says - anyone used this stuff before?)

*Set the float bowl height properly (it was leaking out of the overflow)

*Buy a new EMN needle (Where would I get this in Canada?)

*Buy a Kientech fuel mixture needle (they say it doesnt work with E models, is this true? Why E vs S?)

*Safety wire instead of o ring mod

Anything else I should do/change? Does the needle jet wear out like it does in a CV carb? IE, should I replace the needle AND the jet?

[Wayward Son]

no use in going any further if the tip of the screw is broke off in the carb. it will never work correctly.

[MattZig]

The tip didn't break off. It was an extended screw and it broke half way into the carb, with a snap in a perfect shape to get it out with a flat head screw driver. It will come out easily enough, that's not an issue.

Any tips Eddie? As far as jetting goes, I have a 434, 3x3, Yoshi RS-3 full (with insert/spark arrestor), e model cams, K&N air filter (stock airbox).

I believe 160 main, PAJ removed, 45 pilot, EMN clip 3, 2 turns out on mixture screw is right? Correct me if I'm wrong.

[MattZig]

Yeah I got the screw out no problem.

I definitely have the newer style, so the Kientech mixture screw should work for me.

Big question is about jetting, which needle (EMN?) and whether or not to replace the emulsion tube.

[Dirtymutt9]

Just a warning.

I have headed down this path with used fcr's. They can become a nightmare to get to work correctly.

FYI- the most important part of that carb is the o ring on the slide. It costs 16 bucks from sudco and makes a massive difference. I would highly suggest you replace that o ring.

Also, do not use carb cleaner on these carbs! It does all sorts of bad things to them. Sudco told me to use simple green water and compressed air. Works well.

Good luck!!!!

[MattZig]

What does a bad slide o ring do? And what kind of a difference did it make to your bike?

I think the carb is only a couple years old with 15-20,000 KM on it - is that 'old' ?

Edit: Which part here? http://www.sudco.com/Diagrams323728/expfcrmx.gif

Also it appears that the reason not to dip the carb is because of the gasket between the halves - Yamalube Cleaner/Soaking solution apparently doesn't harm rubber or plastic at all. Would you still reccomend simple green?

Edited August 12, 2011 by MattZig

[rumplefester]

Edit: Which part here? http://www.sudco.com/Diagrams323728/expfcrmx.gif

#22

Recently had to replace the same on my YZ250F.

- KeVin

[Erik Marquez]

Refreash for an FCR..

Seal for the Vacuum Release Plate

Oring for the Float needle seat

Needle jet

Needle

Main, Starter,and pilot jets

Fuel screw o ring.

AP Diaphragm

As long as the body itself, or the slide are not worn out, and there is no physical damage, you can bring a FCR back in to service

[MattZig]

Just the post I wanted, great.

Where would one order all this stuff? Is the 160 main and 45 pilot standard, or do I have to special order those?

[Erik Marquez]

Just the post I wanted, great.

Where would one order all this stuff? Is the 160 main and 45 pilot standard, or do I have to special order those?

SUDCO

Carb Parts Warehouse

SSW

OEM

I think you can guess my recommendation

[MattZig]

Already sent Eddie an email! Would much rather deal with him.

[bill1960]

Refreash for an FCR..

Seal for the Vacuum Release Plate

Oring for the Float needle seat

Needle jet

Needle

Main, Starter,and pilot jets

Fuel screw o ring.

AP Diaphragm

As long as the body itself, or the slide are not worn out, and there is no physical damage, you can bring a FCR back in to service

What are the symptoms of a leaking AP diaphram or Vacuum Release Plate Seal ?

I have TT-FCRMX which a bought new and it now has 22,000 miles on it.

The bike runs great except for small throttle openings . Requires a lot of enroute FS adjustments when riding offroad. ie cruising fire trails vs slow going technical requires around 1 turn difference in the FS to maintain the correct idle fuel mixture.

[yu130960]

I got a Honda AP Diaphragm on order (part #16021-MEB-771) and I bought new EMN needle, 155 main and 45 pilot jet. I am in Canada so Sudco doesn't seem to deliver up here. Are there OEM part numbers for the remainder of the items for the TT FCR39MX carb? Any other ideas of how to get a "freshen up" kit in Canada would be great. Does Eddie offer a kit?

Refreash for an FCR..

Seal for the Vacuum Release Plate

Oring for the Float needle seat

Needle jet

Needle

Main, Starter,and pilot jets

Fuel screw o ring.

AP Diaphragm

Edit: Sent email to Eddie

Edited October 10, 2011 by yu130960

[yu130960]

If I am only after the float needle and seat oring as well as the slide valve gasket are the Honda parts interchangeable for the FCR39MX aftermarket since they use a FCR37 (250F) and a FCR40(450F)? Should I stick with the KTM sx250f as they use a FCR39MX carb? Just curious as to which manufacturer is the best source for parts for the FCR39MX aftermarket.

[yu130960]

With respect to the slide plate and gasket, I just noticed that Honda sells part # 16037-meb-671 which has the plate and gasket for $57.83 on TT Parts store.

http://shop.thumpertalk.com/oem.asp?manufacturer=3∂=16037-meb-671+

Does anyone know whether this Honda part that fits their FCR41MX work on the FCR39MX aftermarket carb?

Did a search and didn't find the answer.

[Wayward Son]

i didnt get a email. please resend.

[yu130960]

Thanks Eddie. I resent the e-mail, but it was a long weekend up here in Canada so I was doing some research and put together the following chart of OEM fast moving parts.

Can't get the image clear so here is the direct link.

http://i59.photobucket.com/albums/g310/yu130960/fc.jpg

I am not sure whether any of this stuff is interchangable. Since I am in Canada I pieced together most of it through OEM orders, so I have most of it coming in. The prices are sky high except for Honda.

I asked about the wear plate and gasket kit from Honda above because I think it is reasonable. Do you know it if works?

[Wayward Son]

it is all interchangeable.

[yu130960]

I ended up paying $30 for the vacuum plate seal from Yamaha dealer in Canada (I am still hurting over that one). In hindsight, I probably should have bought the Honda $70 wear plate and seal together, but I can't see any wear to the original wear plate and I think Eddie has posted elsewhere in another link that he hasn't had to replace one (that by the time the wear plates are gone the body is gone to).

EDIT: Should I be putting some type of oring grease on the new orings in the carb to extend their life? If so, what type of grease? Will silicone spray work?

Edited October 11, 2011 by yu130960

[Borgschulze]

EDIT: Should I be putting some type of oring grease on the new orings in the carb to extend their life? If so, what type of grease? Will silicone spray work?

Gravedig.

I'm going to do some work on my FCR soon, get the idle fixed properly I hope.

Would also like to know if that seal needs any kind of lubricant on it?

Anyone know a cheaper place to get the vacuum wear plate from? $70-$100 is a lot for a little plate like that in my opinion. I saw aftermarket ones that are apparently stronger.