M-88 Carb floods on 42-WLAMy friend

[T. Cotten]

Once you line up your carb with the manifold, Folks,..

You don't want your apparatus so heavy that it might make the manifold move, particularly with O-ring and band assemblies.

And you don't want it to get in the way of inspection itself.

(That's why I make mine with ABS plastic and light vinyl tubing.)

TESTKIT.jpg

....Cotten
PS: Whole lot cheaper, too.

[Hack]

Holy ****!

[BigLakeBob]

Trying to not hijack this thread off subject. Cotten, I was just joking about the leak because you always refer back to it. I realize you take this seriously and are trying to help everyone and are very adamant on your theory. I want to say your leak test application helped me find a problem I had on my '69 FL, ended up being bad clamps pinching and causing a leak. I went ahead and made 4 manifold plates (Tillitson, 1, 1 1/4 and 1 1/2 Linkert, from some cast aluminum jig plate I had lying around, nice and flat, didn't make the outside pretty as it is irrelevant. I put a shut off valve before the pressure gauge so I could shut off the main supply and see leak down time. The hose fittings on the manifold plates swivel so as not to put any strain or twist on the manifold while testing and the hose length is about right so the gauge rests on the footboard. Thanks Tom.
DSC06911A.jpg

[T. Cotten]

Maybe his manifold leak equaled things out.

How'd it cure itself, BLB?

An aside on bubble-testing, Folks,..

There's an ad in the latest mag for a testplate, but its got a Schrader valve to prevent constant pressure, and it doesn't even have threads for the bolts. That makes it fun to install.

Two decades of crusading against the evil manifold leaks, foiled again.

....Cotten

[dukekleman]

What I was told is he was about 6 hours into his trip and many sets of spark plugs when he decided to pull into this hotel. He said he never had any trip time on the bike, just short little runs around the block, this being his maiden shake down run. Typical hurry up last minute get it done I've seen many times over my career in this field (How I viewed it...) Either way, the silly paperclip worked and allowed him to continue his planned journey for a couple thousand miles on one set of spark plugs.

[BigLakeBob]

It begs the question, Duke,...

How did it get so far out on the road in the first place?

....Cotten

Maybe his manifold leak equaled things out.

[T. Cotten]

... Either way, it was a good road side fix....

It begs the question, Duke,...

How did it get so far out on the road in the first place?

....Cotten

[dukekleman]

Yes, that is correct. I got a paperclip from the hotel lobby, bent the paper clip into the form in the photo. The High speed needle went through the looped end and the straight end was inserted into the jet which had been oversized by someone throughout the years I'll assume. This allowed the high speed needle to actually have influence when adjusted and he said he then was getting about 34 mpg on average. Either way, it was a good road side fix, he learned of the cause of his problem and we had good laughs about it.

[BigLakeBob]

For what it's worth, I'll share a story with you relative to your issue at hand. Back in 17' I was riding out to Sturgis and ran across a guy having the same issues you describe in your post. He was in a parking lot and I asked if I could help. The bike was a 1961 Panhead, fully restored 2nd owner he told me. I tried adjusting his carburetor and it would not respond to adjustment. I took it apart in the parking lot, checked the float, looked for debris and any obvious oddities, nothing. Knowing how people clean jets over the years on this freshly rebuilt M74 Linkert I had only one thought left. Being know one in the area we were had Linkert jets, I came up with this idea. Tried it and this paper clip worked wonders for his panhead, gas mileage and spark plugs. We exchanged numbers and he rode 2,800 miles with this paper clip in there with no problems. When he got home he wanted to leave it alone, I convinced him to take it apart and put in a new replacement correct jet I sent him for free. Friends still today. 20260.jpeg20261.png

Hard to see the picture, so you made the ID of the jet smaller using the clip?
Thanks, your insight on topics has been most helpful.

[T. Cotten]

So if he has a fixed jet on the bottom of the body stem AND what appears to be an adjustable needle, especially the high speed needle, would that be enough to cause the carb to run too rich?? We have gone over all the rest of the setup multiple times and and the bike runs great 5-8 seconds after we shut off the fuel, until it starves out and stops. If we turn the fuel back on before it quits it will run great until it floods and sputters. That is the crux of the situation.
Confirmed internal vented venturi.

Yes, Hack,

The #1 jet was enough for a stock motor on 1940s fuel, and although the needle might add more for an overbore, or ethanol fuels that require more volume, the needle would probably meter better without it.

Your symptoms still suggest a vacuum leak has you pouring fuel into it.

....Cotten

[dukekleman]

For what it's worth, I'll share a story with you relative to your issue at hand. Back in 17' I was riding out to Sturgis and ran across a guy having the same issues you describe in your post. He was in a parking lot and I asked if I could help. The bike was a 1961 Panhead, fully restored 2nd owner he told me. I tried adjusting his carburetor and it would not respond to adjustment. I took it apart in the parking lot, checked the float, looked for debris and any obvious oddities, nothing. Knowing how people clean jets over the years on this freshly rebuilt M74 Linkert I had only one thought left. Being know one in the area we were had Linkert jets, I came up with this idea. Tried it and this paper clip worked wonders for his panhead, gas mileage and spark plugs. We exchanged numbers and he rode 2,800 miles with this paper clip in there with no problems. When he got home he wanted to leave it alone, I convinced him to take it apart and put in a new replacement correct jet I sent him for free. Friends still today. 20260.jpeg20261.png

[Hack]

So if he has a fixed jet on the bottom of the body stem AND what appears to be an adjustable needle, especially the high speed needle, would that be enough to cause the carb to run too rich?? We have gone over all the rest of the setup multiple times and and the bike runs great 5-8 seconds after we shut off the fuel, until it starves out and stops. If we turn the fuel back on before it quits it will run great until it floods and sputters. That is the crux of the situation.
Confirmed internal vented venturi.

[T. Cotten]

... Diabolical seems to be the operative adjective at this point. How can something so simple be so troublesome?....

Imagine doing carbs for a living, Hack.

Do too many cooks spoil the stew?

Even my repops ain't perfect. (But at least Folks know where to find me....)

...Also there is a fixed jet screwed into the bottom of the body stem. Will need to research the whole internal/external vent thing.

88s came with a #1 fixed jet, but should be replaced with a gallery plug, like the other plugs, when used with an adjustable needle.

The M88, and a couple of other HD Linkerts, had their air correction vent cut into the bottom of the venturi like the majority of Indian Linkerts, and dubbed 'internally vented':
741-1VNT.jpg


The majority of HD Linkerts were vented with a hole through the side of the body, but it would be a booger on an M88.

....Cotten

[Hack]

Thanks for the information to all, I'll pass it on. Diabolical seems to be the operative adjective at this point. How can something so simple be so troublesome? Do too many cooks spoil the stew? Also there is a fixed jet screwed into the bottom of the body stem. Will need to research the whole internal/external vent thing.

[T. Cotten]

...Still runs like crap. Is consistently running rich even with the low speed needle turned all the way in...

These things are diabolical, Hack.

At speeds over thirty or so, the idle circuit reverses to supply air to the highspeed circuit. Thus a completely closed lowspeed needle would starve the highspeed for air!

Since the lowspeed knob bottoms out on the lift lever, and has a safety spring in case it really does hit the seat, it is hard to observe. Inking both needle points will give an indication of contact; Dry-erase markers are great for that, as well as for finding float-to-bowlstem interference:

DRYERASE.jpg


Often they hang up on the gallery quite high:

stemgall.jpg

A buoyant float set at a quarter-inch gives a fuel level in the bowl of five-eighths, and the rest of the carb depends upon that.

Hope this helps,

....Cotten