One Amal won't stop shut off and overflows

Hi Guys,

I have a problem with one of my Amals only. I just rebuilt them because one of them had a sticky needle or a bad float and it would start overflowing when i tickled it after a long run. Never did it when the bike was cold. Odd, i know, but either way i said "screw it, lets rebuilt both.

Now, the amal that was doing it is fine but the other one won't stop overflowing the second i open the petcocks. sometimes it will shut off but as soon as i tickle it it stays open.

I took the float bowl off and checked it to see if the height was set right and it was actually too low! So its definitively problem of something making the bowl stay down.

I have genuine Amal gaskets, i haven't messed / trimmed them at all, new style needles, etc.

i didn't mess with the ticklers so they're still as they were when i took them off the bike.


What could be another cause here?

drsus said:

I took the float bowl off and checked it to see if the height was set right and it was actually too low!

I have genuine Amal gaskets, i haven't messed / trimmed them at all, new style needles, etc.

Click to expand...

If you've fitted the alloy float needles in place of brass, then I would suggest you check the fuel level as now recommended by Amal rather than by the usual float height method.
http://amalcarb.co.uk/optimising-mark-1 ... uel-levels

Or, refit the brass needles, and see if that cures the problem?

Gasoline destroys rubbers and plastics sooner or later. My guess is you need newer type float needles , Also inspect the 2 brass inserts they land into ,they could have gunk preventing a good seal. That's all it takes to prevent the seal to shutoff the fuel flow. :|

L.A.B. said:

drsus said:

I took the float bowl off and checked it to see if the height was set right and it was actually too low!

I have genuine Amal gaskets, i haven't messed / trimmed them at all, new style needles, etc.

Click to expand...

If you've fitted the alloy float needles in place of brass, then I would suggest you check the fuel level as now recommended by Amal rather than by the usual float height method.
http://amalcarb.co.uk/optimising-mark-1 ... uel-levels

Or, refit the brass needles, and see if that cures the problem?

Click to expand...

ill recheck them but i actually had run into that page with the new levels and set them to that. rechecked bowl level off the carb and when i re installed it same problem...this time it didn't overflow at first but as soon as i hit the tickler it went.

i have the new style float and alloy needles, all Amal parts, no aftermarket stuff.

the other thing i find curious is that the ticklers now work right away on the first try. before i had to press them for a good 3-4 seconds before i get the spill..now its right away...which tell me the float levels are too high right? or is that how its supposed t be and they were taking too long before?

Torontonian said:

Gasoline destroys rubbers and plastics sooner or later. My guess is you need newer type float needles , Also inspect the 2 brass inserts they land into ,they could have gunk preventing a good seal. That's all it takes to prevent the seal to shutoff the fuel flow. :|

Click to expand...

i rebuilt the carbs. changed the needles to the new style alloy ones and the new stay-up floats. all amal parts, no aftermarket. I checked all the brass parts and they all seem in good shape, no debris etc.

the ticklers now are super sensitive. not sure what a proper tickler is supposed to feel like, but before i had to hold them down for a good 4 seconds to get the spill...now i don't think i get half way down before fuel comes out. Feels like that tells me the float levels are to high OR they were too low before?

Check to see if the float is getting caught up on the bowl gasket. You may have to trim it up a little

Deets55 said:

Check to see if the float is getting caught up on the bowl gasket. You may have to trim it up a little

Click to expand...

This crossed my mind. I played around with the bowl off the carb and the gasket to see how it might getting in the way but couldn't really determine anything. I'll trim it anyway.. Seems like a the best next step for sure thank you... For sure good hearing that this can be an issue, I had abandoned looking further into it since I didn't see if it was a problem off the carb.

Also check to see if the tickler is returning to the full up position. Odd that it didn't leak until you forced the float down with the tickler

Deets55 said:

Also check to see if the tickler is returning to the full up position. Odd that it didn't leak until you forced the float down with the tickler

Click to expand...

yeah this was the original problem but on me other carb and only after the engine ran for along time, never when cold. this is why i decided to take them off and rebuilt them...but now the other is doing this and all the time, nit just after running.

i looked at the ticklers when i took the bowls off and they both seem to retract up completely and enough into the upper carb assembly to be out of the way..

I would have thought using genuine gaskets, that they would need to be trimmed. Something is wrong there. I replaced one of my float bowls on the 750 because I could not stop it flooding even with the new viton tipped needles. It is mostly fine now. [ I will deal with the problem seat on the discarded bowl at a later stage ]. I have to hold my ticklers down for several seconds before fuel appears. So should you. the fact that you just have top touch the ticklers and fuel appears means the fuel levels are tooooooooo high. [ notice I did not say float level- they may be correct but something is causing the needles to leak, giving a high fuel level. [ provided they were set right in the first place ]
Some-on mentioned they drilled another set of drain plugs and fitted tubes and clear plastic hose held up above the carbs so they could see exactly what was happening. In you case, it appears obvious the fuel level is too high. take the bowls off and check them out. Make sure there is no shit in the needle area etc. Use a microscope [ joking but you do need good eyesight to spot these things ] to make sure the seats are not marked/scratched/damaged in any way.
If all else fails, take the bike to a bike mechanic.

Dereck

Have you tried swapping the bowls to see if the problem continues or swaps sides? That may tell you where the problem lies (above the bowl or below it).

Also something to possibly check is the true "roundness" of the brass seat in the bowl. Sometimes with adjustment the hole can take a slight ding that causes the needle to not seal against the seat. I had that issue once.

Scott

You know the stay up floats are easily adjustable ? All you have to do is bend the tabs that control float needle shutoff time, A whole new can o' worms to piss you off. Lose air filter until you figure this one out.

kernel65 said:

Have you tried swapping the bowls to see if the problem continues or swaps sides? That may tell you where the problem lies (above the bowl or below it).

Also something to possibly check is the true "roundness" of the brass seat in the bowl. Sometimes with adjustment the hole can take a slight ding that causes the needle to not seal against the seat. I had that issue once.

Scott

Click to expand...

i see,ill check that, than you.

ill swap bowls as well, good idea

Torontonian said:

You know the stay up floats are easily adjustable ? All you have to do is bend the tabs that control float needle shutoff time, A whole new can o' worms to piss you off. Lose air filter until you figure this one out.

Click to expand...

yeah, the only reason i hadn't messed with the tabs is because the fuel levels seemed ok when off the carb just looking at the bowls, but now it does look like ill have to adjust them to a much lower level than spec to see f for some reason this fixes the problem.

the confusing part is that th fuel level is good when the bowl is off the carb, then its too high (apparently from the ticklers behavior) once re install don to the carb assembly.

drsus,

Kerrinorton had a good idea. There is a way to take the drain plug and install a clear tube on it. Holding the top of the tube higher that the top of the bowl and turning on the fuel will fill the bowl and the tube. Where ever the fuel level is in the tube is will be the same in the bowl. I think all you have to do is take an old drain plug, drill and tap a hole for a barbed fitting and slide the clear tubing on it.
You just have to be sure that the needle is not leaking and the float is good.
Pete

We had an identical issue with my Dad's dommi

The thread was moved to the non-commando section.

There is a massive difference between the plastic needle/brass needle/aluminium needle and the singable float versus stay up-float


When you make your measurements, be double careful how you hold up the float for measuring.
Be sure to push down on the tabs of the float, and not on the needle itself.

With the new parts, because the groove on the aluminium float is wider, and the tab on the float is thinner, the difference between pressing on the tab and pressing down on the needle is over 5mm!

I had that problem when I bought my bike a few years ago and the PO had rebuilt the carbs....turned out the float to bowl clearance was too tight in the pivot area., I filed the floats slightly and no more problems.
Definitely fix that ASAP, before I did a float stuck while I was starting the bike, overflowing gas pooled in the split loom the PO had put on the alternator wires, and the bike caught fire :shock:

Deets55 said:

drsus,

Kerrinorton had a good idea. There is a way to take the drain plug and install a clear tube on it. Holding the top of the tube higher that the top of the bowl and turning on the fuel will fill the bowl and the tube. Where ever the fuel level is in the tube is will be the same in the bowl. I think all you have to do is take an old drain plug, drill and tap a hole for a barbed fitting and slide the clear tubing on it.
You just have to be sure that the needle is not leaking and the float is good.
Pete

Click to expand...

yes, that is a good idea,i didn't quite get it at first. mine have the drain plugs so it would be pretty simple test

cheers

gtiller said:

We had an identical issue with my Dad's dommi

The thread was moved to the non-commando section.

There is a massive difference between the plastic needle/brass needle/aluminium needle and the singable float versus stay up-float


When you make your measurements, be double careful how you hold up the float for measuring.
Be sure to push down on the tabs of the float, and not on the needle itself.

With the new parts, because the groove on the aluminium float is wider, and the tab on the float is thinner, the difference between pressing on the tab and pressing down on the needle is over 5mm!

Click to expand...

ah! this might explain why my level is so out of spec, thank you ill check that making sure i pay attention to the tabs.

cheers
nic

bluto said:

I had that problem when I bought my bike a few years ago and the PO had rebuilt the carbs....turned out the float to bowl clearance was too tight in the pivot area., I filed the floats slightly and no more problems.
Definitely fix that ASAP, before I did a float stuck while I was starting the bike, overflowing gas pooled in the split loom the PO had put on the alternator wires, and the bike caught fire :shock:

Click to expand...

holy crap! yeah that would suck.