Need carb help

[fotoguzzi]

Seems like a hundred years since I’ve had to deal with carbs. I have a V750 with 29mm delOrtos. I do have fuel flow and spark on both sides. Swapped plugs around and same side (right) not running and plug is wet. Where should I look now? Left header heats up to 150f and above right header only warms to 100f. So yeah, I will pull carb but what should I look for? Carbs are both clean drained and dry, stored right proper for 6 years.

[moto]

If you're absolutely certain you have strong spark, arriving at the right time, on both sides, maybe your choke (enrichener) circuit is plugged or fouled on one side. This is easy to check.

[fotoguzzi]

I had just thought of that after posting but it’s so hot in my shop I’m putting it off until tomorrow. Thx

[John A]

I’d put new plugs in it before I did much else.

[fotoguzzi]

I’d put new plugs in it before I did much else.

I could but when I swapped plugs the problem stayed on the right side and the other plug fired like new.

[John A]

 Yeah, you did say that 

[nc43bsa]

Do you have a way of showing that both plugs are actually firing when it is running?

[Paul_Tim]

I'd look at float valves as they have a tendency to leak. Dry both carbs and turn the fuel on and leave it for a while then check both are still dry internally, if the valve isn't sealing the carb will tend to get damp internally with subsequent rich running. Other easy thing to check is that the needles are correctly seated in their mounts, but this has more impact on faster running.

[czakky82]

I’m with nc43, I’d check both sides for spark. Not super familiar with loop frames, but single coil/distributor? Could be plug wire and or cap.

How about compression?

[Antietam Classic Cycle]

Carbs are both clean drained and dry, stored right proper for 6 years.

I would still rebuild the carbs with new gaskets and o-rings, making sure all passages are open, float levels set correctly. If the float needles have black tips, replace them with ones with orange Viton tips. Carb rebuild tutorial:
https://www.thisoldtractor.com/moto_guzzi_loopframe_carburetor_rebuild_-__vhb.html

[fotoguzzi]

The choke plunger operates fine.
So how does the carb come off, with the ring clamp over the intake manifold loose shouldn’t the carb at least rotate so I can drop the float bowl? It’s solid and not budging.  I do have the original airbox and rubber boot, looking like new..






I see in Guzziology that the main and idle jets are the same thread size on the VHB 29. One is a #45 and the other a 145.. he says they can be mistakenly assembled in the wrong places.. if this were the case would I be getting too much fuel ? And would That keep that side from firing?
If the choke is not stuck what other reason would the spark plug be wet? Valves and timing are set proper.

And yes I have an inline spark reader so I’m pretty sure there is strong spark.
And yeah Charlie I can do a full rebuild but the carb looks spotless and like new.

[guzzisteve]

Carbs come off manifolds w/a little heat & rubber mallet plus a squirt of silicone spray around the plastic sleeves. I just did a set on a Morini not long ago.

[Antietam Classic Cycle]

The choke plunger operates fine.
So how does the carb come off, with the ring clamp over the intake manifold loose shouldn’t the carb at least rotate so I can drop the float bowl? It’s solid and not budging. 

I use a wooden dowel and a hammer to drive the stubborn ones off. Put the dowel against the carb, as close to the manifold as possible to avoid damage. Alternate where you put the dowel - up top and then down low. Once it's off, a little anti-seize smeared on the manifold stub and carb plastic sleeve will make it easier next time.

I see in Guzziology that the main and idle jets are the same thread size on the VHB 29. One is a #45 and the other a 145.. he says they can be mistakenly assembled in the wrong places.. if this were the case would I be getting too much fuel ? And would That keep that side from firing? Yes, definitely a possibility. I had an Ambo here that had new aftermarket replacement choke springs installed. They weren't long enough to provide adequate pressure to seat the plunger in the body. Put good used springs in and it fired up and ran perfectly.

[moto]

I just take the manifold off the cylinder with the three Allen bolts. I never bother to remove the carburetor from the manifold. This may have been said before, but a likely possibility is that one of your floats is no longer floating, so that the gas is never being shut off and your float bowl is too full, flooding one cylinder. Once you get the float bowl open, remove the floats and shake them. If one is full of gas, you have found the problem.

The one thing I don’t like about this theory is that it doesn’t explain how your bike became nonoperational while it sat in storage (as I understand it). Maybe it is more likely that the float bowl needle has become stuck, which you could fix after removing the floats.

[Scout63]

Check to make sure your idle jet didn’t come unscrewed. I’d so, then the piston would suck up lots of fuel and flood the plug.  IIRC the idle and main jets have different thread pitches or sizes but better minds (Charlie’s) will come to bear.

[John A]

If I want to remove the bowl and check inside, I rotate the carb and pop the bowl off. Then if I plan on taking the carb off,  I put it back on to protect the float

[Antietam Classic Cycle]

Check to make sure your idle jet didn’t come unscrewed. I’d so, then the piston would suck up lots of fuel and flood the plug.  IIRC the idle and main jets have different thread pitches or sizes but better minds (Charlie’s) will come to bear.

The idle jet and main jet are the same thread and look identical, so are quite easily mistakenly put in the wrong hole.

[MattP]

A engine needs 3 things to run you checked 2 , it should at least fire run to rich is my thinking pull plug out start rev a sec or 2 re install should run duh you just cleared . How ever my gess no 3  how do you get the kaburator off ?  That is a tough one sawzall, or take the head off , sou ds like the next step 4 you could do 3first how ever. Mabey not much profit left.

[fotoguzzi]

A engine needs 3 things to run you checked 2 , it should at least fire run to rich is my thinking pull plug out start rev a sec or 2 re install should run duh you just cleared . How ever my gess no 3  how do you get the kaburator off ?  That is a tough one sawzall, or take the head off , sou ds like the next step 4 you could do 3first how ever. Mabey not much profit left.

very funny.. turn your spell check back on.

[MattP]

Thank you, i think you mised my point are you pumping croimium through the engine? What is the psi? Aparently everthing has to be speeled out tooooo you. I see no mention of nicasill

[fotoguzzi]

The motor has been completely rebuilt with the Gilardoni kit. Has run perfectly since then but was stored 6 years… in the proper way, tank off carbs clean and drained etc..it’s like the right side has an air restriction. Running original airbox. If the filter was clogged I don’t think the left cylinder would run so nice but I’ll be looking for something upstream from the carb today.

[fotoguzzi]

And yeah I tried a new spark plug.

[Chuck in Indiana]

You *did* check the idle jet to make sure it truly is one..right?  Float height? Enrichener seal? Slack in that cable? It's not rocket science..
A guy had me come over one time because "the damn thing won't run on one cylinder.." Wet plug. The idle jet was laying in the float bowl..

[MattP]

But it did tun when parked? What cuuld haved changed, it did didit not?  What is the compreshen

[wirespokes]

If this is the first start after a six-year nap and it ran fine when parked, then there may be a mouse nest in the exhaust. I'd think it could start with something like that, but maybe not.

Since the plug is wet, it IS getting gas. It's either too much fuel, too little air, or weak spark - or a mouse nest in the intake or exhaust.

[MattP]

Thats correct

[John Ulrich]

Brad, you got that “ditch pump” running?

[DodgeBoy]

I had so much similar problems a few month ago and it turned out it was a faulty ignition condenser (the small barrel next to the distributor).
The bike had spark on both sides but wont run for even a second. Since its easy top swap maybe give it a try.

And btw: How the heck do you guys manage it to get those zinc carbs that shiny/polished???

[John Ulrich]

And btw: How the heck do you guys manage it to get those zinc carbs that shiny/polished???

Bench mounted buffer & Dremel tool.

[fotoguzzi]

Brad, you got that “ditch pump” running?

yes, it just took some fiddling, one choke was sticking. She’s all smooth now.