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The O-Ring Mod for an FCR

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not really the way all these people are complaining about. but if it can make even the littlest of differences for the better i will do it....

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Just wanted to jump in here and say thanks to William for posting, just bought my new FCR and completing the mod before putting it on was a breeze since the post already specified the size of o-ring. Thanks again for posting all the helpfull stuff on this forum!

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Pat4wd: took the words right out of my mouth

Sixdays4: Is your base jetting perfect (pilot/fuel screw/needle/clip position/main jet? They must be before you address and bog. The next question is when does the bike bog, if at all?

Wiring is only good if the linkage does not bind. You must ensure a full, unestricted stroke. I still prefer a oring or a siffer cam sping. If you want to adjust the timing, you must remove the wire, adjust, replace the wire and retest. If you adjusted the screwCW. you must recheck to confirm no binding.

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Wiring is only good if the linkage does not bind.

Well yes, true, you do have to do the entire MOD, not just part of it.. Checking for linkage binding is just part of the MOD.

I stopped doing the O ring, as no matter what brand or style, they just did not last a full season.... Much easer to wire it and know it will stay that way until I choose to change it...

As for removing the wire to adjust timing.. true... if that was needed you would have to cut the wire, adjust and rewire... thats a fast simple procedure, worth it to me to know it will stay secured on the trail, street or track. :cheers:

To each his own, we all choose what works best for us. :ride:

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The jetting i believe is spot on, but there will always be a tiny split second of bog or hesitation on anything, even the tiniest, but all im asking is if the o-ring mod is a good thing to have to just help that much more in making throttle response awesome?

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The jetting i believe is spot on, but there will always be a tiny split second of bog or hesitation on anything, even the tiniest, but all im asking is if the o-ring mod is a good thing to have to just help that much more in making throttle response awesome?

It may help. Takes no more than a few minutes to pop the cover off and fit a oring (or wire for those that break them, I still have the original on my SM, been ther 3~4 years now;)). Once you have done it, you may benefit from tweaking the AP timing screw but keep good notes regarding how much and what direction you turned it. Test only by riding, not with the bike sitting on a stand in the garage.

My previous comment was because many people have perfect running bikes and they think there is hidden power or that they must have every mod, whether they actually need it or not.

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thanks. no i understood what you were trying to say in the earlier post.

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If you run the Merge spring, you dont have to worry about O-rings or safety wire and can easily adjust your AP timing as intended by Keihin... :cheers:

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If you run the Merge spring, you dont have to worry about O-rings or safety wire and can easily adjust your AP timing as intended by Keihin... :cheers:

True, if you have an FCR MX.. that is a great option and one I recommended to any whose bikes with that aftermarket carb come in to my garage. :ride:

Thanks for the reminder Justin

Merge Racing APS - Accelerator Pump Spring

At $15.20.. a deal to not have to mess with wire or O rings

Problem is,,, few have the FCR MX, so safety wire or O ring MOD are the choices. If you have the OEM FCR or bought an FCR Slant Body carb which for many years was the best and only option for a good after market carb.

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Yup, I do think for the slant/oem FCR, the wire is the by far the best way as part of the adjustment is manipulation the linkage fingers.

I have the Merge spring on my WR250 and just the oring on my FCR-MX on my SM. Perhaps next time I have to pull the carb off, I'l put a Merge on it too.

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We sell tons of them to the guys buying the FCR conversion for DRZ's, perfect time to do it!

P.S. I didnt think the Slant Slides were supposed to use O-ring/safety wire/etc, I thought those injected too much to begin with and the fix was to use a collar to limit the AP shot? (Taffy mod or something?)

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We sell tons of them to the guys buying the FCR conversion for DRZ's, perfect time to do it!

P.S. I didnt think the Slant Slides were supposed to use O-ring/safety wire/etc, I thought those injected too much to begin with and the fix was to use a collar to limit the AP shot? (Taffy mod or something?)

Slant benefits as well, collar was the old way to deal with it.Eddie MOD is better.

The Eddie Mod is a better way to deal with getting the AP duration back to the correct spec, when you turn the throttle the engine responds as it should. Eddie developed this method of correcting with the worn linkage problem. It is not done with the taffy mod, but is done instead of that old method. There are three steps to the Eddie MOD. 1) Use a bit if safety wire to tie the metal fork and the plastic arm together. 2) Grind off the lower metal protrusion on the AP diaphragm (bottom of the rivet). You may also need to 3) either squeeze the fork together or spread it out to make the linkage work for the entire stroke. This HAS to be checked as well as full travel without binding..

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The goal of the oring/wire/spring is to remove slop from the linkage. The taffy mod, bk mod, stopper length are used to limit squirt.

Once you wire the AP arm on a slant and adjust the fork,, you gte a package deal that works well.

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hay yall long time reader first time writer 06 yz250f did the o ring oh man what a friggen difference its like a whole new bike thanks i used a silicone o ring from napa part#407125 its for ac system thanks again TT rocks

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i used an left over x-ring from my chain, did the job, the bike goes heaps better

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OK... My 04 525 exc was running great except for a bog that just showed up while riding. Carb had the o-ring mod (Used Wire) on it already. So I figured card was dirty and needed cleaning! Cleaned all jets and slide... Took off the Diaphram and it was black muck in there...So bought the Honda Diaphram and installed the entire package...rod and cover... Then went to re-wire it and overtightened it like I do everything else...broke the Plastic AP lever...duh!! Got my new one, reinstalled with o-ring and now bike would not idle at current settings. Had to turn idle all the way in and 4 1/2 turns out of fuel strew to get it to idle. At this setting it runs rough, popping on decileration. I also replaced all o-ring gaskets on covers. Why does it seem like now I need to go up in a pilet jet? was perfect before!!! Did the Honda diaphram change things? Help!

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