I had exactly the same issue on my DR650 with a Safari tank. It turned out to be nothing to do with the fuel supply. It was a skinny little breather pipe that comes out the back of the carb. Mine got pinched and trapped in my swing arm mount after I gave my wife a lift on the back of the bike.
The bike could do about 5-10 mins max of running and then die like fuel starvation. I just leant on the seat with my chest to compress the rear end and freed the pipe from the suspension. Done.

Tell me I'm wrong!!

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@ Chris. The tank/petcock setup is not vacuum operated. Spark plugs do not need replacing or the air filter - The bike goes like a bat out of hades for 100's of KM before I get about an inch from the fuel line/carby intake height. I'm starting to think that this is just the lowest it can go before pressurization is needed, and maybe the first time I ran it lower I was just really lucky.

Actually the first time I ran it low (lower than last this week) I was using the normal Safari tank cap. Now I use the lockable version with tank filter (which I know doesnt create a seal on the top of the tank). So maybe the change in tank cap has made the difference?

Turn the carb inlet counter clockwise to about 90 degrees that will let use most of the gas.
Another thing you can do when the gas gets that low. Put the bike on the side stand and the gas will all run to the left side. Close the right petcock and trap the fuel on left side.

Yes done all those tricks (except moving the inlet pipe) What my issue is - is that before I could run the bike lower on fuel than I now can. I used to get an 1.5 inches from the bottom before it was all over. Now im over 3 inches from the bottom before im out. Im starting to think the change tank cap, as well as the addition of a tank filter has made the difference, as the new filter means the top doesn't seal (its a bad fit).

You've misunderstood what I said.

Good luck with sorting your situation.

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TBS.com

DR650Bandit,

The intermittent symptoms you describe are similar to what happens when you have water in your gas tank - are there any blobs down by the petcocks?

if so drain and clean the tank, drain the float, clean out the fuel hoses and filters

If not:

How close does your right side fuel hose get to the exhaust, any chance of a vapour lock from the manifold ?

The BST40 inlet when vertical can cause a vapour lock too with the curve of the hose getting heated up - if you can turn inlet as Bigdon mentions and make sure the fuel hose is straight from the petcock to the inlet with no loop and keep it as cool as possible this might cure the issue. Remember too that as you get to the bottom of the tank the fuel is prone to being warmer - especially if you run slowly in traffic and with high ambient air temperatures - this can also contribute to vapour locks

Just to check, did you remove the small carb inlet fuel filter as AndyBev mentioned - when partially blocked (it blocks up very quickly as it has a small surface area) can cause fuel flow to reduce and this in turn can cause a vapour lock in hand with any of the other factors.

Are you using inline filters, are they clean ? - back flush them, maybe also remove the petcocks and clean them.


The last thing I can think of is the petcock(s) not flowing properly, do you use fuel with ethanol ? this can degrade the petcock o rings and make them stick
The OEM petcocks that come with the Safari tank are not very good and I have had one stick closed in the open position before - avoid using ethanol if possible or use a fuel stabiliser (Sea Foam etc.)

post photos of each side of the bike if possible and lets have a look at the setup.

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Cheers
Grif

'11 KTM 450 EXC
'09 Suzuki DR650
'00 Discovery Series 2 V8
'95 Defender 90 300 Tdi Overlander
http://gipperstravels.blogspot.ca

Fuel flows freely on both taps and through the in line filters. The plumbing is pretty similar to the instructions given, only I have shortened the length to the inlet, raising the T closer to the inlet in the process. The fuel pipe is also not close enough for the fuel to be getting too hot.

I did however just check the inlet filter and there was s### in it. I cleaned it out, so hopefully this might be the end of my problem. Agreed about the safari petcocks. I had mine only 3 months before I replaced the rubbers but they are fine now.

hi bigdon, you mention here to turn the inlet at the carby approx 90 degrees , can you please advise how to do this ?

Thanks

rodney

I used an big adjustable wrench.
Put it along the inlet pipe and carefully turn to 90 degrees.
The inlet is push fit. It needs to turn in the carb body, not bend.
Mine turned pretty easily, some have had more trouble.
Good luck.

__________________
Cheers
Grif

'11 KTM 450 EXC
'09 Suzuki DR650
'00 Discovery Series 2 V8
'95 Defender 90 300 Tdi Overlander
http://gipperstravels.blogspot.ca

Here’s how I fixed mine. Removed carb, let inlet pipe/carb connection steep in Liquid Wrench overnite.

Used my vise with some rubber strips to protect the inlet pipe metal.

Position inlet pipe in the vise and tighten vise. I had mine between the two clamps on the left side of the vise.

IMPORTANT – you want the pipe connection point to the carb as flush & tight as possible in the vise. This is to prevent kinking the pipe. If you have even 1mm or 2mm space you risk kinking the pipe.

So with the pipe connection as flush & tight in the vise as possible, you move the full carb. It took a LOT of force to move it and yes it is a little nerve-wracking. Finally, it gave way just slightly -- you can feel it give.

I removed from vise, examined, and repeated the procedure about four times until I had it where I wanted it (9 o'clock, which has worked fine). It gets a little easier once the first movement is made.

One time I was a little careless and didn’t have the pipe fully flush in the vise. Result – a slight kink. No big deal but lesson learned.

Some guys have tried to do this with vise grips or some kind of wrench, with bad results.

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