Topic: Weber MPD idle stops and prep for use.

[Don R]

  I didn't want to piggyback my question on other guys posts so here is mine.
  While looking at my Weber's linkage, I was reminded that my right-side carb (as seated on the bike) has two idle stops, and my left carb has none. I'm wondering if the outboard stop should be moved to the carb that doesn't have one and if so, should it go inboard or outboard?
  The pic also shows how simple the MPD/Weber linkage is compared to any I've seen online and also the result of some fool sanding smooth and chroming the tops of the Webers.

https://www.ebay.com/itm/302396526694?chn=ps&_trkparms=ispr%3D1&amdata=enc%3A1pjHv3rtsTc-pUYmY8mtXcw13&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&mkscid=101&itemid=302396526694&targetid=2321310837104&device=c&mktype=pla&googleloc=9021994&poi=&campaignid=21214302385&mkgroupid=161029887581&rlsatarget=aud-1317302328365:pla-2321310837104&abcId=9407524&merchantid=112296499&gad_source=1&gad_campaignid=21214302385&gclid=CjwKCAjw56DBBhAkEiwAaFsG-tyNMwpOju1pKYolBcfsCdji3p8fvgKB--JK-VA_mZnahVYzBwxuoxoCmdkQAvD_BwE
 

[BenelliSEI]

Don….. I’ve set up a lot of twin weber combos on race cars, but never on a bike, so take my comments with that in mind! The carbs should be linked by what I call the “soft joint” with an adjustable screw/spring between them. This creates the soft connection to the “slave carb” from the “master carb”. The throttle cable should b attached to an arm on the “master carb”, also between the two carbs, as should both idle adjustment screws.

Sounds complicated but the thing to avoid is any controls or stops at the outboard end of either carb. The centre shafts on the Webers are quite soft and easy to twist which then knocks the butterflies inthat carb out of sync.

The best systems (made in England) are actually alloy brackets that bolt to the Webers tops and have a solid rod connected to a bell crank at the end of the throttle shaft. You bolt one on each carb and then connect them with another solid rod (with tiny adjustable rod ends). Hooking the throttle cable to either bracket then operates both. Somewhere I have one of these brilliant set ups. I’ll try and post a picture over the weekend.

[Don R]

 There is the soft connection in the middle, I'm just wondering why one carb has two stops and one is only relying on the adjusting screw on the soft connection to set that carb. I wonder if the left end stop may be installed under the left center bracket of the stopless carb.

 That ebay seller has a lot of linkage options available.

[BenelliSEI]

There is the soft connection in the middle, I'm just wondering why one carb has two stops and one is only relying on the adjusting screw on the soft connection to set that carb. I wonder if the left end stop may be installed under the left center bracket of the stopless carb.

 That ebay seller has a lot of linkage options available.

Looking closely at the picture, that might work!

[Don R]

 Today I Helicoiled the throttle cable hole in the MPD bracket and clearanced the manifold where the carb bodies were binding. Got on the Pegasus web site and ordered a pair of "in the carb" Weber fuel screens and a set 8 of proper fitting lined hose clamps, the set I had were a little oversize and missing a pair anyway.
  For the moment I'll leave the idle stops as they are, there's no room to move a stop to behind the linkage in the center. the set worked before so they should work now. I don't think Bill Benton ever used these, they might just have come along in a parts buy.
  Next decision, which bike do they go on. They have been waiting for the stroker motor to get repaired, but that choice is waiting on other parts becoming available.

[scottly]

The "soft joint" that John mentioned is for manifolds that have the throttle shafts inline, but the MPD manifold splays the carbs apart. Don, I suspect your soft joint may have been modified or fabricated from levers bent to a curve to allow for the slippage as the shafts rotate at different angles? (BTW, even though the RC manifold has the shafts inline, the carbs are so close to each other the ends of the shafts have to be cut off, so the soft joints don't work.)
Here are some pics of what I finally ended up with. I had to modify levers to get two that fit at 90*, with idle stops for each. The connecting link angles from one extreme to the other as the throttles are opened, which looks funky but works. The thin blue wire shows where the cable goes.

[Don R]

 Here's what I did with mine, on one of my first test fits the previously welded bracket broke so I made it a bolt together deal, that helps get the rubbers over the splayed out intakes two at a time. The carb cable mount was drilled out perfect for a helicoil so I put a 6X1 mm in there so a Honda carb cable end can thread in for a little more adjustment.  The cable end clamp is a little wobbly on the lower side of the carb lever, I still need to firm that up.
 That spring/screw arrangement could be moved towards the center of the brackets also. I'll mount them to a head before I get too busy moving things.
 

[BenelliSEI]

Don…. here’s a kit (first photo) that converts the pull of a throttle cable to the push of a throttle operating rod. Somewhere I have one! The second photo shows the “soft connection” to the slave carb. Installed this way it allows for a bit of misalignment too. If I find the darn thing, you are welcome to it!

[Don R]

 That's awesome of you to offer, but I think I'm satisfied enough with the simple parts that I have. I'm going to slip them onto a head and check the clearances.
  I was remembering why I welded the bolt-together brackets on and realized it hadn't broken, the previous weld was misaligned, and the intakes didn't fit up correctly. This design makes it difficult to get the rubbers in place with a one-piece manifold, the split makes it easy.

[scottly]

Don, have you tried opening the throttle and watching how that linkage has to slide back and forth as the throttle opens and closes? And back to you original question, there should be an idle screw on the inside of both carbs with a stop on both levers.

[Don R]

 I did move the end idle stop to the middle, the two carb shafts are very close, and can see how the slave carb's adjustment screw has to track across the flat tab. It's now bent a little to optimize the flattest area of the tab. I can see the track mark where it has been working, I'll polish that out too.

[Don R]

 The top plates really need to be stripped of chrome and polished since they are already almost ruined. I'd like to know they work before going any deeper on the cosmetics.
 You can see the stop moved to the inside of the shaft, the button head that holds the two halves together is under the cable adapter. This cable is an old pull off cable, I'll solder the strands together to stop the unravelling.
 Those are aircraft style clamps that have a layer of metal under the worm gear slots so they don't bite into the rubber. I got them and the rubber hose from Pegasus Racing supply.