TM40 carb leaking from draining hose
 

New ProCycle TM40 carburettor dripping petrol from lower drain hose.
Just installed a new TM40 on my DR650 and noticed dripping petrol from the lower drain hose when bike is not running (parked on side-stand). It was a slow drip when the tank was near empty but is now dripping at a faster rate with the Safari tank filled. I understand that this leak could be occurring due to the float valve not being seated properly in a fully closed position which could be the result of debris trapped between the float valve and valve seat or deformation of the float valve tip however with it being so new could there be other reasons? Has anyone had a similar problem? Any suggestions on a fix would be really appreciated thanks.

I think your suggestion is the most likely culprit...something fouling the float valve's seal. Or it could be a leaky float filling with fuel.

Sucks, especially since it's new, but IMO your best bet is to take it apart and have a look.

You may not need to remove Carb at all.
First, try draining float bowl (outside of course). If still leaking, try refilling again with fuel, now blow into fuel hose to kind of bubble up fuel in float bowl.
Tap sharply on Bowl a few times. (old Triumph and BSA riders trick), now drain it again. Any luck? Sometimes times a few drains/re-fills required before you flush debris out.

Still No? Float bowl cover will have to come off. On some carbs you simply loosen up
metal straps on rubber boots and rotate Carbie side ways. Loosen float bowl screws and gently remove cover. Bit of air up under the valve needle may do it ... or remove float and needle (very carefully) and have a look.

My guess is manufacturing debris in there. Check float level while your at it. Should be perfect as it's new.

Good luck.

Let me know how you get on with the STIFF return spring on that TM40. (or did they change that by now?)
I've ridden friends bikes with them and could not do it for long rides, too stiff on old broken wrist injury.
Also, I'd love to hear what kind of Kms/liter you can squeeze out of a TM40. I'm getting 50 mpg on my BST stock carb.
Cheers!
bier

Tap sharply on Bowl a few times - it worked !
 

Thanks for both posts. I tried the easiest option first which was to "Tap sharply on Bowl a few times" - it must have freed up the float ! And to my delight no more leaking ! So simply a minor teething issue to be aware of after initial TM40 install. So thank you both for your input. I'm pretty happy with the new TM40 Mikuni carb kit. I opened up the standard air filter hole as recommended in the install instructions. It's a little noisier but performance wise it has improved my takeoff 2 fold. It really does feel like a new bike ! I'm also really interested to see how it performs on a longer trip. In late July I plan to take a month off from work and ride from Cairns to Broome return (about 7,500 km) via Savannah Way and Gibbs River road, so it will be an excellent opportunity to see how much better fuel economy I get on different surfaces. I will post those results when I return in August. Thanks again guys.

You got lucky with that one Rod! :clap:
Look forward to hearing how the DR (and new Carb) does out on the trail.

If she starts dripping again ...you may have some debris in there somewhere that hasn't been flushed out yet. All fixable.

Good riding, keep it on the wheels!
bier