Drones Build- 1974 Commando

***I renamed the thread in order to keep order. I will keep all technical questions here regarding my bike. Thanks for all the support so far. I have been a frequent member of a board for Honda Twins and cut my teeth on that bike.

I do not want to ham-hand the petcocks. Any advice to getting them to move again? I will be doing some varnish treatments on the tank starting today and I am really not in a hurry to get the PCs yet.

Are they rebuildable?

I tried to search for this info here. If I need a lesson in searching, lay it on me.

jon

Re: Petcocks not budging '74

Pull the whole tank, remove the taps carefully, and soak in carb cleaner or WD40.

You ought to start a project thread or have L.A.B. rename this thread, becasue you're going to have LOTS of this type of stuff coming up!

Re: Petcocks not budging '74

drones76 said:

Are they rebuildable?

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It depends which type they are?

If they are the original brass cone type, they can be dismantled and the cones lapped into the bodies with fine metal polish or T-Cut, however it's usually not worth the bother and I tend to regard them as disposable items and I simply replace them if they start to become stiff or leak. The cheap replacement types with the tubular rubber seal generally isn't worth even attempting to rebuild.

drones76 said:

I tried to search for this info here. If I need a lesson in searching, lay it on me.

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Alternative search words you can try are "petrol tap" and "fuel tap".

Re: Petcocks not budging '74

The brass cone type supply a bunch of fuel. If you're in the US, Old Brits has BAP ones for about $35 a pair, they don't supply fuel as fast, but enough. I've tried repairing the old ones because I like the look, and just lapping them with rubbing compound doesn't seem to work. I took a file and filed down the outer cone, then put rubbing compound on it with an electric drill and slowly seated it in the inner part. I haven't tried if it works or not, but with new o-rings they won't leak out the sides, the big issue comes with dripping through the petcock and if your needles in the floats aren't sealing, you will either get gas in the engine or evaporate all the gas out the tank and float bowls rather quickly. Ask me how I know.

The other search you can do is petcock.

Dave
69S

Here are a few pics as it stands.

Petcock-1


Petcock-2


Wiring right


Wiring left


Carb


Rectifier etc.


Tank funk


Oil was drained tonight. I was surprised how much it actually looked like oil. I was expecting some gloppy stuff.
Gas tank is full of vinegar and gets a shake every hour or so. That should break up the varnish in a few days. After a day or two, I will run the contents through a cheesecloth and then put the liquid back in. No sense rushing this process at this point.
For rust I will do the electrolysis thing for a few days after the varnish is clear.
After the tank looks good, I will pull off the petcocks and soak them as instructed above to see if I can get any movement and also see if they function properly. Replacements are probably in my future.

Since this is the build thread going forward, I figured I would repost the list of things that I am planning.....

Thanks for the congrats. I have just been looking at it as I throw back a few Bass Ales (I thought it was appropriate). The short term goal is to get it running. The tank is NASTY but I expected that. The plan is as follows:

1. Get the tank off and clean out the varnish. - Anything different I need to do with these tanks as opposed to Honda's? If rusty, I have used electrolysis before and have been very happy with the results.
2. Remove and clean the carbs. - recommended gasket and bits kits? I can make my own gaskets. Fuel lines need to be replaced also.
3. Front brake rebuilt. - again any recommended kits for caliper and M/C? The rotor has rust on it. I figured I would give a good cleaning and see how it is.
4. Change the oil. - What kind should I use?....just kidding. First fill or two will be cheap and run for a few miles a drained and examined.
5. Oil tank. - new to me. Never had a bike with one. What needs to be done here besides drained and cleaned? Is there a preferred method?
6. Motor mounts and Isolastics. How are they checked except for obvious cracking?
7. Front fork seals. I got a set with the bike. Probabaly on the shelf for 2 decades.
8. Rear shocks. Can they be rebuilt?
9. Replace throttle, clutch and brake cables.
10. Replace Battery
11. After she starts and seems safe to ride, tires.

Those petcocks appear to me an after market type. If you get them to work fine, otherwise replace them.

Carbs, might as well order the rebuild kit from Amal. Get the new stay up float (plus adjustable) and everything else, not real expensive. New o-rings, gaskets, etc. If the bike has miles on it, the slides may be worn. You will find out when you get it started. You should check the float needle valves for good seal when you get there. The seats can be polished to seal. Between leaky petcocks and leaky needle valves, a good way to start a fire.

The wires, you might want to look into new connectors, up to you. Or you can risk them working or being intermittent. I'm still using my original harness with no problems, but it's an early one without that connecter under the tank.

The rest, sounds like you're on track.

Keep us posted how it's going.

Dave
69S

I'd flood that tank with white vinegar and let it soak to see if it will get that junk out before I tried anything thing more harsh. The petcocks are not original, but I have seen the one with the red lever for sale someplace recently. I don't know if they are good or not. Get rid of the rubber block connector under the tank and make or buy new connectors for those wires. You are likely going to find lots of rotted rubber. So at some point you might as well plan to do isolastics, seals and associated kinds of stuff. This will get you into the bike far enough to learn your way around. First I would get it running and try to put a few very careful miles on it. It will give you feedback as to what things need attention and then next spring after you have gone thru the bike more thoroughly you can rejoice at how much nicer it is to ride!

I'm jealous, and I have my own project.

Russ

While you are waiting maybe turn the tank on its back and try some penetrating oil on the petcock threads. Repeat every day for 2-3 days then I bet they will screw right out. There are many favorites including homebrews to choose from for penetrating oil -- I like Kroil in a spray can aka Aerokroil. Google and get special deal. Saw some at a John Deere dealer recently. Also check out local auto store for PB Blaster. No WD-40.

Very much helps to heat cycle it to break up and crush down the fussed corrosion.
Heat gun hair drier are not much a kaBoom risk, nor boiling water but cost to heat that much up. Hope your tap ain't corroded inside or new seal soon don't. I guess as last resort could saw off, drill out thinner and just an eze-out tap. ugh.
BTW best stuff to shove interference fit metal into metal is caster bean oil.

Machinist's Workshop Mag (tm)recently published some information on various penetrating oils that I found very interesting. Some of you might appreciate this. the magazine reports they tested penetrants for break out torque on rusted nuts.
They are below, as forwarded by an ex-student and professional machinist.

They arranged a subjective test of all the popular penetrants
with the control being the torque required to remove the nut from
a "scientifically rusted" environment.

*Penetrating oil .......... Average load*
None ........................... 516 pounds
WD-40 ..................... ... 238 pounds
PB Blaster .................... 214 pounds
Liquid Wrench ............... 127 pounds
Kano Kroil .................... 106 pounds
ATF-Acetone mix...............53 pounds

The ATF-Acetone mix was a "home brew" mix of 50 - 50 automatic
transmission fluid and acetone. Note the "home brew" was better
than any commercial product in this one particular test.

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Tank is full of vinegar so the petcocks will have to wait. 50/50 ATF and Acetone is a favorite of mine. Sometimes I used a little paint brush to get it where I need it.

I spent the evening reorganizing the garage so I can have the back portion to work on the bike. I was just too tired to get to the carbs.

Every connector will get a good cleaning and gentle scrubbing with a brass brush to get the gunk off. If I need new connectors, where do I get them from?

Interesting about the petcocks not being original. It was a one owner bike and he was very forthcoming with any questions I had about work that was done on the bike. Never mentioned it, although he may have forgotten.

How do I determine the model of the bike regarding MK1 MK2 MK2A etc? The carbs are 932 stamped on them. I want to be sure I get the correct rebuild kit. Is getting it direct from AMAL the way to go?

Petcocks fail and plenty to pick form over the decades. Leave engine serial number and experts will nail it down, though of course C'do's are modular inter changeable for a bunch of stuff. 932 carb appears on all but the earliest experimental C'do's and they got replaced too by now.

drones76 said:

How do I determine the model of the bike regarding MK1 MK2 MK2A etc?

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Mk2 or 2A would have a frame plate/engine/gearbox serial number 307311 or higher (unless it's got one of the strange 235*** serial numbers?) so "314954" (your previous photo) makes it a Mk2/2A.

The 850 Mk1 and Mk2 had peashooters and a metal peforated airbox, the Mk1A and Mk2A had the annular discharge "black cap"/"bean can" silencers/mufflers and black plastic airbox and your photos appear to identify it as a Mk2 model.

drones76 said:

The carbs are 932 stamped on them. I want to be sure I get the correct rebuild kit.

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The carbs should also have an aditional number stamped on each pad next to the 932. I can't read that number from your photo as it isn't sharp enough, but it's probably R35 (and L36 on the left carb) if so, that would be correct for a Mk2. That number identifies the original internal jetting, needle, spray tube and slide specification, however I suggest you check those items first before ordering new jets, slides, needles etc.

The Right Carb does have R35 on it.

I got the left carb off ok. The right slide is stuck. What is the best way to unstick it so I can get the body removed from the bike?

Here is a pic.

Are you saying the you have the bolts removed? I would say hold a block of wood to is and wack it. Are you removing the manifold with the carbs first? That is the right way. However, now that you have one off you can remove the nuts from both side and pull the carb from the manifold and then pop the manifold from the jugs.

pvisseriii said:

Are you saying the you have the bolts removed? I would say hold a block of wood to is and wack it. Are you removing the manifold with the carbs first? That is the right way. However, now that you have one off you can remove the nuts from both side and pull the carb from the manifold and then pop the manifold from the jugs.

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It's the slide that's stuck in the R/H carb.

The right slide is stuck. What is the best way to unstick it so I can get the body removed from the bike?

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Soak it in carb cleaner? Petrol/Gasoline? WD40? Thinners?

Soak it in carb cleaner? Petrol/Gasoline? WD40? Thinners?

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It is still connected to the cables. I have removed the top two screws and since the slide is not budging, I cannot get the carb on the bench. I have sprayed some carb cleaner in there and it may just take a few treatments like that.

drones76 said:

Soak it in carb cleaner? Petrol/Gasoline? WD40? Thinners?

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It is still connected to the cables. I have removed the top two screws and since the slide is not budging, I cannot get the carb on the bench. I have sprayed some carb cleaner in there and it may just take a few treatments like that.

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Yes, that was what I meant.

Drone try hanging it by the cables in a container full of metho. You guys might know it as alcohol?
I've found it works better than any carb cleaner for disolving any fuel deposits. Try and keep it covered as it evaporates pretty fast.

Regarding Carbs. How can I check to see if they will need to be resleeved?

Also what type of carb rebuild kits should I be looking for and what is generally done to Amal carbs that have been sitting this long? Floats? Float valves?

drones76 said:

Regarding Carbs. How can I check to see if they will need to be resleeved?

Also what type of carb rebuild kits should I be looking for and what is generally done to Amal carbs that have been sitting this long? Floats? Float valves?

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Just about any Amal carb should perform better after a resleeve, however it isn't absolutely necessary or it can at least be done later as a "winter job"?

http://www.amalcarb.co.uk/

You will at least need two gasket kits
Maybe needles and needle jets?
Main jets
Throttle slides (unless you decide to go for the re-sleeve)
Float needles
And antything else you think needs replacing?

If the floats are in good condition they can be re-used or you could buy two of the new Stay-Up floats .

http://www.amalcarb.co.uk/ProductDetail.aspx?Id=37372

http://www.amalcarb.co.uk/Technical.aspx