V50 III carb questions...? Got it.. I think.

[radguzzi]

My Buddy Jim dropped off his '81 V50 III due to carb issues making the poor thing run badly.

Little back story from Jim goes like this...  The V50 III as purchased reportedly ran poorly, Jim took it to a local shop, the mechanic decided that instead of rebuilding the carbs Jim would be better off with NEW carbs.  Holy cow, I do not know what that guy found but, to my thinking, carbs are infinitely rebuild able unless the bores are badly worn similar to Amals with soft metal for instance..  So anyway Jim buys new instruments and Fred installs them. 

Even with the new PHBH 28 carbs the poor thing runs poorly down low, I have not ridden the V50, it arrived here with old fuel although it started right up, Jim claims that is stumbles.

My first thought is that the components might not be correct in the new carbs.

So, off with the bowls to have a peek, been sitting a bit so the old fuel smell filled the garage, it is nice and green in there, too bad to let new carbs gunk up like that... 
The jet sizes check out according to Guzziology except for the Idle Jets which are 50s vs 45s... Mains are 118, Choke 60.

I have not gone as far as to haul the tops off to observe the needle clip position.  Those air boxes are a pain to pull carbs from so I will try a quick jet cleaning, pull the floats and clean the needle and seat, must be gunky in there too and test ride it with new fuel.

The question finally is... Will the #50 Idle Jets make a big difference over the 45s...?  Will I need to adjust the Air Mixture Screws out a tad more to suit...?  They are right at 1-1/2 turns out now.

Thanks for any words of advice on the little rig.

Best,
Rob

[Antietam Classic Cycle]

"Stumbles" may not be carburetor related, but rather a sticky ignition advance unit. You'll want to check out the point gaps and timing anyway...

[guzzisteve]

Some put in 50's to combat the long tip mixture screws at the time, you want the euro jetting numbers.

[radguzzi]

"Stumbles" may not be carburetor related, but rather a sticky ignition advance unit. You'll want to check out the point gaps and timing anyway...

Yup, will do Charlie. 

Thanks,
Rob

Some put in 50's to combat the long tip mixture screws at the time, you want the euro jetting numbers.

So the Euro and US component specs are very close in sizes, Idles are 48 Euro and 45 US, Mains are the same and needles are different as are the clip positions.

Are you saying that the 48 idle is a better idea...?

I'll try the jet cleaning and check the points first and go from there.

Thanks,
Rob

[Chuck in Indiana]

Carburation issues are generally ignition. <shrug>

[guzzisteve]

On the V503's the needle and atomizer was the problem w/runability. I drilled out the atomizers to a 268 size, cause we got one similar to the accel pump model on the VHB in a 262. The needle is X6, you can get them from Hermy's in PA. Make sure it has short tip mix screws, and my book says 50 idle and 118 main w/a 50 cut on the slide.

[radguzzi]

So here's the deal...  The NEW carbs were outfitted with X6 needles as supplied from Hermy's... they were a bit green also, this thing say up for some time is my guess.  Cleaned them up with 0000 steel wool, nice and shiny.

The clip position calls for three from the top with US Spec needle so I went with the two down with the Euro spec needle.

Runs great.  There was a boot off from the air box on the right side, stuck that back on.  Oh, no points, an electronic ignition trigger of some make.. no idea what.

I took her for two short blasts, all dialed in.

Thanks,
Rob

[Chuck in Indiana]

Carburation problems are not always ignition.  <shrug>

[radguzzi]

Carburation problems are not always ignition.  <shrug>

     :wink