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clark4131

New Bog Eliminator?

10 posts in this topic

I'm going to bet that does about the same thing as the AP mod.:applause:

Which AP mod? There's quite a menu to choose from...SC

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Which AP mod? There's quite a menu to choose from...SC
Well, the BK mod, AFAIK, is only for older bikes and the Doc mod is really nothing more than a zero LJ, so that leaves the Redbeard AP mod (am I missing any mods?). I'm not sure, but it looks like it would replace the link lever and either change its geometry to alter the AP pushrod action (similar to changing diaphragm stud lengths) or connect hard to the cam follower (similar to wiring it up). :applause:

Purely speculation on my part, though. :lol:

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Clark....thats not a new mod........it does exactly what Redbeard's mod does when you safety wire the linkage together.......I currently use an oring because among others, Eddie Sisneros says it alleviates some of the stress on the linkage. I use a 90 leak jet and it works well......the Honda guys use this same setup. Check out Rebbeard's PDF file on his mod. Personally I wouldn't pay a dime for that bog eliminator thing.

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I looked at the Red Beard deal and I'm curious about the increased size in the leak jet. A 90 is huge! The general consensus has been the best course of action is to decrease the jet size. I'm running a 42 with a different AP diaphragm that gives me a strong .8 second squirt. With the 90 jet, you must have a much shorter duration. I would think that would cause a lean bog. If I can find the proper o-ring locally, I'm going to tie my linkage together as well. I just have to get down to Lowe's...SC

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I looked at the Red Beard deal and I'm curious about the increased size in the leak jet. A 90 is huge! The general consensus has been the best course of action is to decrease the jet size. I'm running a 42 with a different AP diaphragm that gives me a strong .8 second squirt. With the 90 jet, you must have a much shorter duration. I would think that would cause a lean bog. If I can find the proper o-ring locally, I'm going to tie my linkage together as well. I just have to get down to Lowe's...SC
When you wire the link lever to the cam follower you force it, and therefore, the AP push rod, at the same rate as throttle twist. Without, you rely on the spring pressure only to follow the cam. You can see the lag if you wack the throttle. This extra force creates a huge squirt which needs to be bled off, hence the 90 LJ.

I used two o rings rather than wire and didn't change my LJ, but I didn't change the diaphragm, either. I noticed a slight improvement, but nothing drastic. I think the wire method and short diaphragm stud require the bigger LJ because there's absolutely no lag in the link lever and you get the extra AP volume.

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I agree with most of whats said but to refine it;

An OEM AP setup squirts stronger with smaller leak jet....true. Since its on a spring when you whack the throttle, if you stop the throttle say at 3/4, the AP continues to squirt because of residual pressure on the diaphram from the spring.

A safety wired linkage leaves no residual pressure (there is no hysteresis), hence the squirt stops as soon as you quit twisting the throttle because the diaphram stops. If safety wired, you must have a short diaphram stop so it doesn't "bottom out" and bind. An oring allows the diapharm to bottom out without binding because it stretches a bit. The stronger the oring, the more "solid" the linkage and the stronger the squirt, hence the bigger the leak jet that is needed. In past posts, they have determined as big as a #100 leak jet which is equivalent to 1.0 mm works best when wired or when using a strong oring like I'm using. Each bike is a little different so there's no universal recipe.

What would be ideal is to have a strong short squirt when vacuum drops (throttle is whacked) and the mix is lean but a fast "shut off" after vacuum recovers so there is not a rich condition.

Happy trails.

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I get quite a kick out of this kind of thread. The FCR carb reminds me of the attempts of the automakers in the early - mid eighties to make a carburetor work in an emission controlled environment. They got so complicated and so "sophisticated" that they would only provide good drivability if everything was perfect, with very tight tolerances. As you might recall, non FI cars from the eighties were terrible after a few miles. How about KISS. I struggled with the FCR carb for too long before I changed to an Edlebrock carb, which is extremely simple and easy to adjust. I now have perfect, fault tolerant, carburetion under every circumstance. I have a Rekluse clutch, which requires good throttle response. Until FI comes to the off road bikes, the simple approach is the best. Just my two cents (and years of experience).

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From what I've read the edlebrock can be fine tuned on a 450 for low or high rpms but usually not both. Some love em and some hate em. Guys on here with a lot of experience say they don't like edlebrocks on most motorcycles.

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