Author Topic: Help me rebuild some RC Webers? Or, just watch..some people just like to watch.  (Read 9904 times)

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Offline scottly

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If you decide to change shafts, make sure you have new seals.  Air leaks there will cause no end of tuning frustrations.  Also be aware that the shafts are very weak were the butterfly fits through, and will bend / distort easily, making them useless.  The screws holding the butterfly(s) are meant to be single use, however I have reused them, but added a drop of Loctite (blue).  Make sure to mark each butterfly's as to it's position /orientation, they have a tapered edges for proper sealing at idle.

I think I'll just hack off the excess instead of swapping.
That's what I would do. ;) The butterflies should never be removed on ANY carb, for the reasons Brian stated and more, unless absolutely necessary. 
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Offline 754

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Is it a rubber type seal on throttle shafts? Never had one out.. Are the ball bearings lubed by fuel/air mix, or sealed ?
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Offline Greggo

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I'm ordering 4 of the inner (cylinders 2 & 3) rubber boots to fit these as Bill instructed. 

Offline scottly

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Is it a rubber type seal on throttle shafts? Never had one out.. Are the ball bearings lubed by fuel/air mix, or sealed ?
Frank, as near as I can tell, the seal is made from leather, with the smooth side against the bearing, and the fuzzy side facing out.
I can't tell if the bearing was lubed at all, but it might have been lightly greased? It's really not much of an issue, as it's not like the throttle shaft is spinning thousands of RPMs. Here are some pics of the only one I've had apart:
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Offline Tintop

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the only ones I've ever seen / used were leather.
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Offline Greggo

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All done!  Big thanks to Bill and Scottly for the crucial spare parts.  I bought f16 emulsion tubes, and 60 spill jets.  If my memory serves me (crap, this was just three days ago!) I chose to start with the 110 main jets, and 180 airs.  I'm hoping the 34 chokes, and 24 venturis will work too.


« Last Edit: January 28, 2016, 10:41:11 PM by Greggo »

Offline Stev-o

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Looks good!   What will you use for an air filter?
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Offline Greggo

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Looks good!   What will you use for an air filter?

Thanks! I bought some filters for the velocity stacks. 

Offline BPellerine

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getting close now Greggo,they look nice.billp
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Offline Jerry Rxman Griffin aka MuthaF'er

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Offline scottly

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Gregg, those 34mm chokes are too big for a stock 736 motor. If you insist on trying them, go to a much larger main jet, maybe 125-130?
Also, before you mount the carbs on the bike, fill the float bowls with gas and verify the accelerator pumps are functioning properly. Once mounted, it's almost impossible to see the stream, as the nozzles are located deeply into the throats, and pointed the other direction. 
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Offline Greggo

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Gregg, those 34mm chokes are too big for a stock 736 motor. If you insist on trying them, go to a much larger main jet, maybe 125-130?
Also, before you mount the carbs on the bike, fill the float bowls with gas and verify the accelerator pumps are functioning properly. Once mounted, it's almost impossible to see the stream, as the nozzles are located deeply into the throats, and pointed the other direction. 

I was hoping filters over the stacks would choke them a little bit.  I have 120's and 130's in the Red Line kit.  My dad has also mentioned bench testing that they pump, but I can't seem to find much info on float height.

Offline scottly

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You can bench test the float level by removing one of the main jet assemblies on each carb, and inserting a "dip stick", like a bamboo skewer; the actual level isn't as important as that both are the same.
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Offline Bill/BentON Racing

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Nice work, what he said, 34's too big for 750cc. 30mm will work, but still can be too much for std ignition down low.
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Offline Greggo

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I also have the much richer f4 emulsion tubes if that would get me closer to a working combo with the 34mm chokes, and the foam filters over the stacks.  I'm using a Dyna ignition.

Offline BPellerine

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34s just too big to get any kind of velocity going on 736,dont think you can tune your way out of it.they will most likely start your bike though.billp
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Offline Greggo

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What size should I go with, 29's?  I'm going to put a hotter, slightly bigger motor in eventually, but it's stock for now.  I'd like to just buy one set of chokes ($100) and tune it out with jets.  It will always be a street bike.

Offline BPellerine

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I would go with 30mm,I run 29s,but that is what my carbs came with.bill
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Offline scottly

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1+ for 30mm chokes. Use the same 110 main/180 air combination you mentioned earlier. We are all looking forward to a ride report. ;D ;D
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Offline RAZZ

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Hi I have being seeing these videos about DCOE Webers great info, there is also one regarding float level adjustment:

http://www.weberperformance.com.au/information.php?info_id=13

Offline Greggo

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Thanks Razz, those are helpful. 

30mm chokes are ordered.  I've been getting stuff from Pierce Manifolds out of Gilroy, and they've been great.  $72 for the four chokes shipped with tax.

Question about the manifold rubbers: There's no groove on the RC manifold for the rubber lip inside the boot to sit.  Do I need to trim the lip down inside those carburetor side openings?  Look at the engine side of a set of Keihin carbs and you'll see the groove for the rubber lip.  There's no groove like that on the RC manifold.

Offline BPellerine

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only tried one set on an rc manifold and did not trim any off,sealed well.bill
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Offline scottly

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Thanks Razz, those are helpful. 

30mm chokes are ordered.  I've been getting stuff from Pierce Manifolds out of Gilroy, and they've been great.  $72 for the four chokes shipped with tax.

Another tip-o-the-hat to Razz. :)
Gregg, that's a good price for chokes, and it's good to hear another positive statement about Pierce. Thanks to Tintop (Brian) for mentioning them!
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Offline Greggo

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Thanks Razz, those are helpful. 

30mm chokes are ordered.  I've been getting stuff from Pierce Manifolds out of Gilroy, and they've been great.  $72 for the four chokes shipped with tax.

Gregg, that's a good price for chokes, and it's good to hear another positive statement about Pierce. Thanks to Tintop (Brian) for mentioning them!

Agreed on all counts.  I got the f16 emulsion tubes from them too.  The carb Bill sent me had two f16's already, so I only needed a pair of those.  I do have a full set of f2 tubes now.


Offline Greggo

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That's a pretty good difference between the 30's and the 34's. 



I poured in some gas and checked that they pump.  They squirt pretty far!



When I mock them up on my K4, the airbox tabs on the top rails interfere with the round jet access covers on the webers.  Has everyone with the RC manifold had to shave those?