Motoscrubs.com

Good morning-
This is my first post to the forum, as I am a new subscriber- perhaps there is a thread on this somewhere, but I was unable to find it.

I have a pair of 1966 Ducatis, a Mach 1 and a scrambler- both have been in my barn for many years. This past August, I finally rolled them out into the sunshine this past August, hoping to get one or the other running, to trailer down to North Carolina for a week on the Outer Banks. But... I was not successful in getting either to fire up "on demand". The scrambler would fire, sputter... die... and not restart. The Mach 1 simply wouldn't fire. I didn't have time to sort them further, so pushed them back, ordered a few parts, and here we are in mid October.

The problem of the scrambler was the condenser. The connecting wire had corroded badly, internal to the plastic sheathing. After replacing points and condenser, it starts... but does not idle well.

I ordered more parts, (moto guzzino) carburetor gaskets and float bowl filters for both bikes. After replacing the float bowl filter on the Mach 1, cleaning the petcock passages and replacing fiber gaskets on the ss1 29d, it fires, idles, and revs fine. BUT... the float bowl cover leaks. Also, maybe I will end up replacing the petcocks- one of the thin tubes is broken off, and the tower filter on the other side is broken, damaged.

The kit of gaskets did not include anything for the float bowl lid itself- just fiber washers for the union. But my float bowl cover has a thin black hardened rubber ring under the lid, which is now broken. Also... on that lid- there is a screw that threads downward into a hole on the lid (180 degrees opposite of the tickler). On the underside of the lid, is a tab that connects to the threads of the screw-on-lid... and it SEEMS that the screw should "lock" the float bowl lid in place. I say that, because there is a "cut" in the side of the float bowl lid that would allow for some movement of the threaded portion of that lid.

However... the lid has that hardened black rubber ring melted/mushed into the cut, so that it seems to want to seal that cut.

So my question is, what seals that float bowl lid? Is there supposed to be a ring gasket? Should I clean out the broken ring, and replace it with something? Or should I clean out that broken ring gasket and expect metal-to-metal sealing on that lid to bowl?

pic of the float bowl lid here-

https://picasaweb.google.com/1114071129 ... 6542018882

Note the broken black ring. Note on the backside of the lid, the black "cut" in the lid.

I will try to post some pictures of the bikes later.

Sincerely,

Bob Woolner
Hillsboro, New Hampshire USA

Hi Bob,

It's been a long time since I did anything with my float bowl but I don't recall having the plastic ring you have.

I am just "shooting from the hip" now, but the fuel height in the bowl is limited by the proper operation of the float and the float valve. That is to say that as the float 'floats' and the float valve seats into the lid the fuel level I expect would be only be about halfway up the inside of the float.

If that's the case, I am not sure why you would need a gasket on the top lid of the float bowl as the fuel would never be at a level so high as to seep past the threads and spill out.

I don't see the 'ring gasket' in the exploded view of the SS1 either.

My gut feeling is that the ring was some add-on by some fellow that did not realize there was no need for a seal at the top of the float bowl canister. I would suggest that you get rid of it and let those fine threads form the seal as the only time you get fuel that far up is when you tickle the carb, and the fuel seepage then serves as an indication that the bowl is saturated and the bike is ready to be kicked over for starting.

Jim

If the gas cock filter is missing then the float will have a problem seating with the sediment from the tank getting in the way.

Bevel bob wrote:If the gas cock filter is missing then the float will have a problem seating with the sediment from the tank getting in the way.

there is a filter in the banjo . part nr 082 in the diagram . so no sediment gets into the floatbowl .

Eldert

It's common for the lid locking bolt not to work, but not usually a problem that it doesn't.
No gasket on SS1 chamber float assembly, some weepage always likely with these, but shouldn't be too bad.
Perhaps the float valve isn't working properly, allowing fuel level to rise too high?
A test can be made with a clear plastic hose and a modified bottom carb plug. The level should be at the bottom edge of the lead plug on the carburettor, beneath the air slide.

Good morning All-
Thanks for the suggestions and comments- I will remove the hardened black broken ring, and try it without. As I have owned the bike since... 1978? ... more than likely, the young and stupid person who put that o-ring there was me. (I am no longer young...but I am still other things...).

I know the filter in the banjo fitting of the float bowl catches most of the debris from the tank, and I did change that out. However, the lack of "filters" in the petcocks still concerns me a bit. I may order 2 sets of petcocks, but it seems a shame to replace the entire unit when only the filter is bad. Does anyone know of replacement filters? I suppose I could get some thin brass tube, and slot it, and fill it with an inner tube of fine mesh...

Over the next day or so, I will gather some pics of the 2 bikes, to post.

Sincerely,

Bob W

filters are to be found on E Bay for some taps.

Maybe you put the ring in, maybe you didn't. Not really what I would call a stupid mistake as it did no harm.

That you kept these two bikes for so long and did not foolishly sell them at a time when the market would have valued them at 'just above worthless' or put them on the curb for the trash collector:

That was smart. Very smart.

HI again-

While I have been way too busy with school stuff to work on the bikes, I did manage to gather a few pictures to throw into the picasaweb folder-

https://picasaweb.google.com/1114071129 ... 99/Ducatis

The black&white is a scan of an image of the bike, my girlfriend at the time (We were married shortly after that, and still are.) on the northern tip of Block Island, Rhode Island 1984?). Most of the others are older images of the bikes, from the last time they were rolled out of the barn... 10?15? years ago? And there are a few recent images of the carb of the scrambler. There is also a last-weekend 1-minute MOV file of the Mach 1 running, but I can't get it to "play" predictably. (Sometimes it "plays", sometimes not. I may have to try Youtube.)

With luck and spare time, this weekend, I will clean out the broken black ring, re-seal/tighten the new fiber washers, "lock" down the float-bowl lid with the set-screw, and see if it floods.

Thanks for the help/suggestions.

Bob W

Hi Bob,
Interesting Mach 1 you have there. A few observations on your fuel level control problem: That rod that is clipped into the float is the needle in the needle valve assembly. The cone shaped tip seals the valve; the seat of the valve is just a hole in the float bowl cap. This seat needs to be clean and undamaged in order for the needle to seal and prevent fuel from entering the bowl. The float should be empty. If you shake it and it feels/sounds like there is liquid inside it, it has a hole and needs to be drained and re-sealed or replaced. The pin in the float has two grooves in it as I recall. The float clip should be seated in one of the grooves. Also make sure the tickler pin is retracting. There should be a spring that raises the pin when it’s released. If the pin stays down, it will prevent the needle valve from closing. The needle valve seat is located in a hole in the brass plug at the bottom of the float bowl. The pin should move freely in this plug.
The seat on your Mach 1 appears to be an original optional bum-stop seat. Very rare to see one in original condition. If you’re taking more pics this weekend, I’d be interested in some details of the seat, especially the underside if you feel like removing it. Also, would you care to identify the engine and (if there is one) frame number? I’d like to see where yours falls in the chronological order. If your chassis has a frame number, it would be stamped on the main frame tube adjacent to the battery. Most Mach 1’s are stamped with a frame number but a few have turned up with no frame number.
Good luck with getting it sorted out! Matt