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Shred Jesse

Care to explain the o-ring placement in the AP circuit for the WR-400 to me?

32 posts in this topic

Some one care to explain the o-ring placement on the WR-400 for me? The writeup says to just get one, but where the hell does it go, how do you get it to stay where you put it... etc etc.

A proper write-up with pictures would be rad. I'll gladly put one together with some help from you oh so awesome and knowledgable folk!

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Wow really... that's the O-ring mod? Damn that's ghetto!

So this works though to really help with the bog? This along with a proper size leak jet?

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Oh yeah, and this is a writeup for the newer FCRMX it would appear from reading downward. I would imagine (from the pic I saw) that I have the older style FCR and will need "The Taffy Mod".

Some one care to elaborate a bit more? Or can I get away with the oring mod and not the taffy mod?

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Oh yeah, and this is a writeup for the newer FCRMX it would appear from reading downward. I would imagine (from the pic I saw) that I have the older style FCR and will need "The Taffy Mod".

Some one care to elaborate a bit more? Or can I get away with the oring mod and not the taffy mod?

I'm almost certain the O-ring mod doesn't apply to the 400 carb. The Taffy mod does.

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Okay.. what's the taffy mod? Anyone find a good writeup? My google fu isn't delivering amazing results.

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Okay.. what's the taffy mod? Anyone find a good writeup? My google fu isn't delivering amazing results.

Remember, the YZ400s had the same (almost) carb too. The YZ stickies are your friend:smirk:

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I guess I never thought to check the YZ stickies.

I saw that article, but the html is all ****ed up. Plus the picture sucks. I'll fix it in firebug and try and make heads or tails of it.

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While checking that out, and looking for other notes about the taffy mod... I found the EDDIE MOD, which is widely hailed as a superior technique.

Instead of placing an o-ring on the plunger to help reduce the time it pushes... you wire the arms together, and grind the bottom of the diaphram off. This reduces the duration and intensity, and results in more of a mist than a prolonged SQUIRT.

I'm of course not positive that this will work... but it was worth trying!

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Okay so I now have a new issue, or maybe it's an old one I just noticed.

I have to pump the throttle multiple times to build pressure, and THEN the fuel will squirt. Until that time, it doesn't squirt as it doesn't have enough pressure built up.

Any ideas?

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Yeah, the old style slant FCR does not use the oring mod. Sorry about that.

You wire the linkage (you must ensure the assy. does not bottom out on the diaphragm rivet). You bend the forks slightly to adjust total throw (which changes duration)

Check the check valve in the float bowl and the diaphragm condition.

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You do more than that though! That's the first half of the eddie mod! Next you grind down the stopper on the bottom side of the Diaphram to ensure you don't bind up the linkage at full throttle. With that removed, you get a shorter duration as well according to eddie...

Bending the forks to adjust the duration is not something I read about though. Care to elaborate?

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I alluded to the stopper (Rivet) issue when I mentioned binding. I did not go into the complete explanation of the Eddie mod as I assumed you had found it.

I was making note that I brain seized and should of known that even though you asked about the oring mod, a WR400 is a candidate for the Eddie mod and I touched base on what it consists of...

The bending of the fork - Being you do not have a timing screw, you have to bend the arm to adjust the timing.

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Ah, well my timing is fine, it doesn't hit the slide and seems to be properly timed to me so it's on point. It does seem to spray a lot more than it aught to though... I get a smidge over one full second of spray. Is this too much? It's definitely significantly less than it was before. It would just friggen go and go and go!

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Typical target range is .75 to 1.5 seconds. If the bike runs fine, then do not sweat it however... the goal is to use the least AP squirt to get the job done. So it also depends on the level of effort you want to invest. Real way to know if things are right is by test riding and not visually. Video cameras can be helpful but riding is the real measure.

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Okay, well I've got my suspension off the bike right now, and since I was in there I decided to address this as well. I'll have to reassemble the bike to test it out.

So I'm pretty much done at this point with this until I test it more.

Upon succesfull testing, I'll create a fully documented writeup for this forum. The writeup here is lackluster, and doesn't address the WR400's older FCR pumper carb.

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Eddie is a man of few words and sometimes a more verbose explanation is a good thing.

Do a good job, include pictures if possible. I'll incorporate it into the sticky, we can make it an all encompassing thread.

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