OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Hand and Power Tolls Power Tools Tuning the walbro carb - help needed

Hi

I recently bought an Alpina HTM60 hedgecutter, with a mitsubishi engine. It's got a walbro carb. The problem I've got, is that it's been years since I've worked with petrol tools, and never used a walbro carb (as far as I can remember), and I can't even see where the high speed adjust is. Someone mentioned that it might have a fixed jet carb (and so just have one adjust). The manual is useless as it covers various models.

It's cutting out when I rev up, but intermittently, and definitely craps out after a while (if I've been lucky enough to get it working) - but then it won't start at all when try and restart.

So 2 questions really. Does this engine have a high speed adjust, and if so where is it? I can obviously locate the pin that sets the low speed (at rest), as it affects the throttle arm, but not the screw for the other.

Thanks in advance.

petrolnature

petrol11,

Usually on a walbro carby (if it is a metal one) you have two screws one stamped 'L' and the other stamped 'H'. If it is the plastic walbro carby then you only have the one screw which is down the centre of the carby spindle.

It could be a fuel filter problem in the tank as well causing you the problem because if it is a little bit dirty then you would get the symptoms that you are describing.

If you can post a picture of the carby it would help.

Thanks for your response,

my camera can't take close-ups, but herewith the pics (if I did it right) - does it look like a single spindle type from this far off? I don't want to dismantle anything right now.


Even though it's a new machine, one think I did check was the air filter, and noticed some dead bugs on the outside of it. Maybe the same ones have got inside somehow, when in storage.

cheers
petrol11

petrol11,

The adjustment jet is in the centre of the area where the cable is connected.

Bruce,

Thanks for that...

hmmm... does that mean it's a single jet carb? If you mean the screw next to the red bit, where there's an indentation in the yellow plastic for the screwdriver to go, I've seen that one.

Or am I being blind?

cheers
petrol11

p.s. type'walbro carb spindle'into google and it picks this thread up 2nd from top (already!!) - that's a bit quick isn't it, good going outdoorking

No that is the idle speed screw, the one I am talking about is in the small brass bit that the throttle cable is connected to.

Hi,

The manual calls the screw which pushes on the throttle wire 'slow speed adjusting screw', and the brass ring bit 'slow speed fuel adjusting screw' - the screw for the revs obviously and the brass ring connects to the choke for extra fuel by flicking over the red bit.

The manual shows the high speed adjustment screw lower down on the casing but it doesn't exist. Do I have a fixed jet carb unit, but they haven't bothered updating the manual? The mitshubishi manual has obviously nothing to do with Alpina themselves. And it's ironic that under Support on their website, the link to Call Center doesn't even work (http://212.103.198.99/alpina/support.jsp)

And if it is a fixed jet carb, what kind of adjustments can I do to it.

Cheers
Petrol11