Guzzi running on one cylinder

[johno74]

Got hold of a little Guzzi V50 mark 2 which i was hoping to trike. Trouble is i cant get it running properly...
Its the electronic ignition model.
Both sides sparking. One cylinder seems to drop out about 3500 revs. If you ride it its flat and gutless compared to how it runs proper.

Just had a new clutch which is correctly adjusted. Ive swapped out the CDI boxes and the coils to no avail. Ive checked the resistance of the 2 pickups and the clearances.

Anyone had similar problems? Know whats wrong? Keen to get cracking on the build (thanks trike tek) but stuck on this problem.

cheers
Johno

[Lone-Wolf]

Wotcha.

If you've swapped the ignition, and the fault remains on the same cylinder then it's either carb or valve gear.

If it makes you feel any better, my 500 Guzzi only runs on one cylinder.
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there again - - it's a Nuovo Falcone, and they only have one cylinder :D

[Bosun]

if runnining ok electrically

does soiund like carbs

are the cables working right, choke not sticking etc

the moto guzzi club have an active club and a website .. not sure if a FAQ on there but may be worth a look

good luck

[johno74]

It will run for a bit then start playing up.
Was wondering if it was fuel starvation, the fuel pipe takes goes over the top of the air filter, which makes for an awkward route for the petrol but it pours out ok.
Guzzi's apparently known for half hearted electrics, thats what made me think the problem was electrical. I was hoping someone had had similar probs.
Could do with a test of some sort to check ignition is ok...

cheers
Johno

[Dougie]

Mebbe a bit obvious,but have you tried a new spark plug and cap?

[johno74]

Thats the sort of thing i was wondering so i replaced em not long ago.
Caps are new and plugs are less than 35 miles old....So if theyre bad then somethings destroying them.

Maybe this crap performance is whats meant by 'CHARACTER'!!!!

[Bosun]

one other thing check air filter and that fuel cap ok.. there is a air breather in there as well

[dracken1]

the valve clearance could be two tight, sa that as the engine warms up the valves are not closing fully.
the other thing could be fuel starvation

[johno74]

I checked the valves, if anything they are a touch tappety.

Will check the tank cap. What do i need to check in the air filter Fayji? I couldnt see any obvious obstructions.

Does anyone know how the petrol pipe is supposed to be routed on these bikes? Its a one piece pipe fed by both taps to both carbs, it just doesnt seem long enough to either go over or under the airbox.grrrrr

cheers

[Bosun]

if no obstructions and airfilter clean should rule that out
once had similar occurance on bike, airfilter was smegging ( so much for motorcycle city ) took out ran a dream

[mr.chaz]

had an old V50 as a kid.
used to start on two , and drop onto one if you gave it a little too much poke before it warmed up fully.
was the head gasket blowing on one cylinder from cold -got better as it warmed up.
went up and down the country on it until I figured it out.

[johno74]

Surely if it was the gasket it would give crap pressure when tested tho, both sides give 115 hot or cold. Unless thats not enough of course!

Definitely seems to be something warming up and malfunctioning. Runs fine from cold for about 1 minute or so..
Bloke selling stuff on ebay broke up his bike because it would run then stop, whereas mine runs then power drops right off.

Anyone got any further ideas?
Could do with a way of telling if its fuel or electrical? Any straightforward tests?

thanks again

[Dougie]

From what you've said already it's unlikely to be electrical.Strip the suspect carb,clean all the passages and jets with carb cleaner and monofilament fishing line (not wire,that can enlarge jets causing serious trouble) and check settings and float levels.You're as well doing the same to the other carb as well,to make sure the settings there are correct too.

[johno74]

Will check it. I did the carbs with the float settings and stuff a while ago, blew out the jets etc.

Surely with a fuel fault tho it would not work. Ie i wouldnt get it working a bit then stopping until it cools down again tho. Or would i?

cheers

[BlackPig]

What type of carbs are they?
Do they have a diaphram? Is it sealing properly?
Does it work on a decompresion system?Maybe the pipe is blocked?
Only ideas,never had a Guzzi so I don't know what the carb's are like........

[johno74]

Carbs are pair of slide type Dellortos. (non diaphragm)
Checked seal by running bike and spraying around stub and carb with wd40 to check if engine is affected-doesnt deem to be...

Is there anything else carbside i should be checking?

cheers

[Dougie]

Are your float heights equal,and are your pilot circuits adjusted properly giving the proper mixture?

[johno74]

Dougie:
Float heights are as near to 23.5mm(what book states) as i can with eyeing up the float [upside down carb] level against a ruler.

Mixture circuit im not sure about-cleaned out venturi on both carbs sequentially with an airline. no blocks or crap that i could find. Can see thru jets and holes etc.

Fiddled about with mixture on warm engine right thru range-it doesnt want to play. As soon as the bike is warm (couple of minutes..) it doesnt respond.

A bit awkward this one!
Looks nice tho.

[BlackPig]

Right ,slightly off tangent at the mo' but,does this bike have one or two coils?
The reason I ask this is that maybe the coil on that cylinder is cracked/shot, and will only work up to a certain point.On the other hand it wouldn't suprise me if I'm talking garbage again!!!

[johno74]

Two coils, one per cylinder.
I suspected them so I swapped the coils with known good pair-didnt make any difference.

There cant be much left...

The pickups are on the outer boundary of resistance range 240 where book states 220+_15. Not sure what this would do...?

cheers
Johno

[wegit]

Is the Spark Plug on the bad cylinder fouling up under high revs ??

Just one more thing you can check for

[johno74]

Turned out to be loose pickup connections.

The last thing i checked of course.

Thanks for input everybody...

[lowrider]

Rig up a temp feed to carbs and a prob i had once is a petrol tap that seemed to work then after a few miles started to starve the engine.Stripped it ,cleaned it put it back on bike .Great.
10 or 20 miles later and bike is dropping cylinders.New tap and everything fine.Sorted.
Never did find out what the prob was even though i stripped the tap agian just to see if i could figure it out.
Worth spendind £15 or so.