Fuel reserve issue

[BillR]

I'm having fits with Reserve. I hit it about 150 miles routinely and have poor fuel flow after that, and there's still over a gallon on board.
I think the petcock is going south, so that's first thing to replace (I've already cleaned the carbs out).
Tank vent is clear, "decent" stream of fuel into a jug.
I am running a clear in-line filter and I can see the fuel level drop when it hits reserve??
It has an Acerbis fuel valve on it now (stocker), thinking about a Pingle, which is way overkill, but works well according to one of the guys over on the MZ forum.
Ideas??
Bill R

[FastDoc]

Maybe the screen on the petcock is clogged?

[Weldangrind]

What is the actual symptom Bill? Does the bike run poorly on reserve, or is it just that the filter is less full? The reason I ask is that my filter is never full.

[BillR]

Doc,
I've had the petcock apart and cleaned it all out. Nothing really in there.
Now, it is 11 years old and isn't "shiny new" any longer.

W&G,
Yep, the filter is rarely "full" but I can see a change in the level when nearing reserve. It goes from 1/4 to 1/2 full to barely a streak on the bottom.
The symptoms are stuttering and poor acceleration, occasional pop, just like you're running out of gas. On reserve and plenty of fuel sloshing around???

I've tried opening the gas cap for more venting, switching the petcock around to clear any possible debris.
I can barely make it to the gas station. Ride a couple of miles til it barely runs, sit on the roadside for a bit and it'll run again for a few miles.
Fill it up and all is well, even on Reserve???
All I gotta do is get gas at 150 miles... :wink:
That tells me that I'm not getting enough of a pressure head to flow well when it starts getting empty and that's where I'm stumped.
Guess I need to go into the carbs again and check the float needle.
Bill R

[Weldangrind]

Originally Posted by BillR

That tells me that I'm not getting enough of a pressure head to flow well when it starts getting empty and that's where I'm stumped.

I think you're exactly right, but that's a supply problem, not a float needle problem, IMHO. A restriction to flow will create the same result as poor pressure. To me, the key is that you can run fine with a full tank on either main or reserve, and I think that's because the additional head pressure compensates for a downstream restriction.

Have you dismantled the petcock? The rubber gasket inside might be dislodged or partially blocked in the reserve port. I recently revived an old bike, and the petcock passages were completely blocked. I let it soak in carb cleaner for awhile, and then I extracted the rest of the debris with a dental pick. I wonder if there's any debris in the reserve passage on your bike?

[FastDoc]

Would maybe a petcock for a Yamaha Single retrofit?

[BillR]

W&G, I did dismantle it and blew carb cleaner thru the passages (retrograde). Everything seemed clear to air. Once I buttoned it back up, I can see how the gasket may have malformed and created a blockage.

Doc,
It might, but the Acerbis units are readily available for about $15 and the Pingle model is $34, all metal, smooth like butter and flows fuel for a dragster engine... :o
The one I know of in use is working well. Only issue is that when you pull the tank you can inadvertently open it cause it moves so easily... 8O

Probably go with a new Acerbis unit for now and see how that works.
Also planning a set of V-Strom handguards for cooler weather. Saw a very nice set-up on a FJR 1300 in the garage at work... :wink:
Bill R

[FastDoc]

$15 or $34, either one is cheap compared to a OEM part.

[Weldangrind]

Acerbis makes nice stuff; I'd try their valve.