DR650 - Am I getting vapour lock?
 

Hello HUBB denizens

Sean here. Proud owner of a 2016 DR650 at the start of my RTW trip. Been through Canada, Alaska and now in the southern part of the Lower 48.

I have a 30L safari tank installed and was getting ~560kms before the old girl conked out. I am now riding through 40+ degrees every day and am struggling to get 300km before it starts to struggle before eventually dying. When I look my inline filter has no fuel in it but the tank is still more than half full. After I let the bike cool for a bit (hard in this heat) fuel started running back into the filter and I was good for another 20km or so. Am i getting vapor lock running the bike in this heat? If so are there any good fixes apart from keeping the bike as cool as possible?

I also cracked the fuel line 10,000km ago and am now running fuel to the carb from only 1 of the 2 petcocks. Could this be making any difference?

I also heard that the safari tank filters can get clogged and contribute to poor fuel flow....

Advice

Make sure your fuel cap is breathing properly. Why run with only 1 petcock open? Open it to see if that's the problem. I've run in hotter temps & never had that problem. Good luck & ride safe

I once found a plastic fuel filter on my bike had deformed in the heat .. and that was restricting the flow. The extra heat was caused by my extra luggage restricting air flow.
I'd be looking for anything that has a deformed form its original shape.
Good luck.

1 petcock should easily be enough, I always ran my R80G/S on one, giving me three reserves - with my memory, very handy...
Note you can't possibly burn the amount of fuel ONE tap gives much less two.
ALL in tank filters will clog!!! Quick check - pull off a line and open the tap - it should pour a solid steady stream. It's SLIGHTLY possible that the WEIGHT of a full load of fuel is enough to push fuel through, and as the fuel level goes down, no longer enough weight.
If ANY doubt, take them both off and clean them, it's also possible the tank wasn't perfectly clean when you got it, or that you've taken on a load of dirty gas or...
Let us know what the solution is!

Another few things specific to the DR650 - the BST 40 carb has a tiny plastic cone filter sitting in the metal inlet pipe - it has very little surface area, I took mine out and left it out - and just rely on the 2 inline fuel filters (one close to each petcock)

If you are using the locking Acerbis cap that the Safari tank comes with, they are renowned for not letting air in, get a regular dirt bike cap with vent hose.

Lastly, how have you run the fuel hoses to the carb? the BST has a vertical fuel inlet and ideally this should be turned 90 degrees to the left, if you have a loop in the fuel hose going to the inlet you may get vapor locking and you wont be able to drain the tank fully on reserve.