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Discussion Starter · #1 ·
Rebuilt a Rivera Eliminator II SU Carb for an 80" Shovel with an Andrews J cam. It's running well ( I think) but the slide is in constant motion when the rpms rise. Just watched a video of the slide under various speeds and it rises and falls with the rpms. Mine is bouncing up and down ( sounds like a bad lifter)

The Rivera sheet says to add a few drops of WD40 every week. Should the slide cup be filled with WD40 or should it be dry and you only run the carb with a few drops?

Or is the bouncing slide due to some other issue with the set up?
 

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Gov't Mule's piece in the Tech forum covers the SU and its discontents pretty definitively. See:

 

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Bouncing at idle is good.
 

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Discussion Starter · #4 ·
Gov't Mule's piece in the Tech forum covers the SU and its discontents pretty definitively. See:

Read it, a great piece but doesn't cover specifics about the Rivera versions.
 

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Discussion Starter · #5 ·
Bouncing at idle is good.
Yes, but it continues to bounce at higher rpms. Found a lengthy article on tuning SU's last night. I think (?) it's a dampner issue. I'm going to increase the amount of oil to see if that effects it. Apparently if you over oil it, it just come out the vent with no ill effect.
 

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On the subject of the slider, couple of months ago I was at a local caffe and there was a guy there with an SU, so we got chatting, old grey beard, he must have been in his 70s I'd say.

He was telling me the best way to run the SUs is with no slider in it. I was a bit puzzled by that, but he did show me, got the cap off his and no slider in there!

Interestingly, SU factory is like 15min from me and I know the owner.
Rivera SU eliminators are simply SU carbs, built in England, shipped to the US, where Rivera adds the fuel tickler and some other bits and sells them on.
 

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How many springs are you running in your top?
 

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Discussion Starter · #8 ·
How many springs are you running in your top?
A single 6oz spring. Had tried several others, either bogged or hesitated. I think I've got the right size.

I think the issue with the "dancing slide" ( that's what some English Gent called it in a video) has to do with the volume of oil in the dashpot. Since Rivera states "only WD40" the viscosity factor is eliminated, so I experimented with the volume.

So far, I seem to have worked it out. I added until I got a smooth(er) idle and still got a good snappy throttle response. The carb is silent except at idle which I understand is normal. Will get some miles on it this evening and see how it goes.
 

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An easy way to check on the dance is to just pull the air cleaner and twist the wick and hold... you can see it dance or not.

Personally, I found Marvel to work pretty well, and that shit needs to be pretty full on my setup. I think WD is probably about the right viscosity, but they call for just a few drops, which I suspect is incorrect for many H-Ds running that carb. Or at least it's not optimal, as you've discovered.
 

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Discussion Starter · #10 ·
I think your correct. A few drops and the carb cycles rich/lean with each intake stroke. The average being OK but at idle it favors lean and at 1/4+ throttle is favors rich. Filling the dashpot dampner has certianly cured that and the slide reacts smootly instead of rapidly jumping up and down. Having gone through this carb, I really apprciate the enginering behind it !

I suspect the original tech sheet's language is vague. "A few drops" must refer to "after" the dashpot is filled to the proper level. Then, as it says "a few drops" will keep it topped off.

Was considering Marvel or Fork Oil but I figured Rivera had worked out the viscosity issue so the variable had to be the volume of oil.

Anyway, thanks again for the help, really appreciate ! The Shovel seems happy with it's new carb set up.
 

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I bet the two are very close in viscosity. As Jason McElroy has said before, Primo just boxed 'em up and left the user to figure out the rest.

Some did.

Others went on to become dedicated S&S customers. :LOL:
 
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The rise and fall with every breath of the engine and for the noisy lifter sound that is why they were nicknamed "clackers". The bottom of the slide has a sacrificial piece of plastic to dampen the sound of the clack but they get pounded out and then get real noisy. I kind of like the way they sound.
 
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