Author Topic: Help me rebuild some RC Webers? Or, just watch..some people just like to watch.  (Read 9259 times)

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Offline Greggo

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I'm diving into these Italian beauties, but I need some help!  These were pulled from an old drag bike, and I'll be fitting them to a stock K4 motor for now.  I pulled all the brass I could from one bank, and before I go any further I'd like to get some advice from those with more experience.  Some of the jets I pulled don't match the adjacent setup, the accelerator bypass jet is completely frozen, and stripped, and the pump rod at the top of the carburetor is frozen.  I did some slight damage to the starter valve, which can be seen at the 2 o'clock position in the 4th picture down.









How much further should I be diving?

Offline Jim F

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better put all of that in an ultra sonic cleaner for a week and see whats left after a good cleaning.
good luck
Jim
2002 RC51 1000 (SP2)
1983 GS1100EC Suzuki
2002 998 Dukati (Customers Bike)
1992 KTM500 2 stroke
1975 CB750/836 Honda
1978 GS750/840 Suzuki

Offline scottly

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The pump rod rides on a cam, and moves down under spring pressure when the throttle is opened. With the throttle all the way open, can you move it downward? The brass pump piston is attached to the rod by a small hook, and if excessive force is used to pull it up out of the bore, the hook can become bent or broken. The cover plate with the split has to be removed first; I have a tool I made for this. I'll get a pic or two.
What size chokes?
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Offline scottly

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better put all of that in an ultra sonic cleaner for a week and see whats left after a good cleaning.
good luck
Jim
I wonder if methanol was run in these?
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Offline Greggo

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It's not as bad as the pictures make it appear, I think..I don't see much beyond surface corrosion..no pitting, and all the threads are solid. 

They definitely got put away wet 
« Last Edit: September 26, 2015, 02:41:31 pm by Greggo »

Offline Greggo

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The pump rod rides on a cam, and moves down under spring pressure when the throttle is opened. With the throttle all the way open, can you move it downward? The brass pump piston is attached to the rod by a small hook, and if excessive force is used to pull it up out of the bore, the hook can become bent or broken. The cover plate with the split has to be removed first; I have a tool I made for this. I'll get a pic or two.
What size chokes?

I could move the butterflies easily on this pair, but the pump rod doesn't budge.  I started on the better looking carb :o

I'd like to see that tool, please.

Offline Stev-o

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I like to watch. +1 need a good ultrasonic clean or blast.
'74 "Big Bang" Honda 750K [836].....'71 Honda 750K project.....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline Jerry Rxman Griffin aka MuthaF'er

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Oh geez, now I don't want to open mine! Good luck with that. I'll be watching.
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)


Offline BPellerine

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greggo those are really rough,did you get the little ball underneath the square brass weight,they call it the stuffing ball,acts like a valve.when you get the split plate off the pump you will be able to see the piston.billp
1978 CB 750K ard and webers
another anfob

Offline Greggo

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greggo those are really rough,did you get the little ball underneath the square brass weight,they call it the stuffing ball,acts like a valve.when you get the split plate off the pump you will be able to see the piston.billp

Got both weights, but one ball is still stuck...soaking with liquid wrench and spritzing with berryman's...

Offline scottly

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If you look closely at the right side of the hook on this rod, you can see the weld where my buddy tig welded it, after I broke it off. You might want to try the AFT/acetone soak on the piston.
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Offline BPellerine

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If you look closely at the right side of the hook on this rod, you can see the weld where my buddy tig welded it, after I broke it off. You might want to try the AFT/acetone soak on the piston.
that is the same idea I use,working my way from front to back in the slot until it comes out on one side.bill
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Offline Greggo

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Ok..used a very small flathead to easily pry that cover off with the spring underneath.  Soaking in liquid wrench (best stuff I have aside from Berryman's)

Offline scottly

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Have you pulled the guts out of the throats yet, or are they stuck too?
Don't fix it if it ain't broke!
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Offline Greggo

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Have you pulled the guts out of the throats yet, or are they stuck too?

Where do I start to get those out?

Offline scottly

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Remove the nuts, washers and the tabs that push on the flange on the stacks, and it all slides out (hopefully ;)). Some of the drawings show a locking screw and locking nut on the underside of the carb, but none of the Webers I've seen have them.
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Offline Stev-o

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Scott - how long have you been running the Webers?
'74 "Big Bang" Honda 750K [836].....'71 Honda 750K project.....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline scottly

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They were on my bike when I bought it in '79, with three 33mm and one 30mm chokes, soldered and drilled jets, and linkage that was horribly impossible to synchronize. :o 
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Offline Bill/BentON Racing

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Damn, that's like having 3 carbs one size and one different. Glad you stuck with them, I'm in on this one, see why I decided to turn them, I'm too busy on other bikes for the challenges they presented! Good luck Gregg! Bill
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Offline Greggo

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Scottly, I got the throats removed, and the pump rod to move slightly...I can hear it crunchy with corrosion in there.  Is the rod supposed to just lift out?  How do I remove it?  Thanks, Gregg

Offline jaguar

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Fairly sure these started in my shop.

I tend to soda blast carbs when they look like that.  Have had great results.
In my new location I can not make the required mess so I never did it.

Offline scottly

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Normally the rod, with the piston attached to the hook, slides straight up and out. The flat part of the rod with the hook is a loose fit inside the piston, so there are a few degrees of rotation either way to help get the rod loosened up. If the piston is also stuck, there is no way to unhook it from the rod while it's still in it's bore, so go carefully.
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Offline Greggo

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Thanks.  I will keep soaking and wiggling gently. 

Offline seanbarney41

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Best thing I have found for stuck carbs is HOTTTT soapy water....just be sure to dry stuff off real good as soon as they come out.
If it works good, it looks good...