V50 Lazy Cylinder

The Pearl doesn’t get a run out that often these days. On fire up from cold it can take a short while for the second cylinder to chime in.

Took her out on the station run this morning after not having been run for some weeks. Required quite a bit of cranking to get her started at all. And got to the roundabout at the end of the road before that second cylinder was starting to light up. To be fair, with 160 miles on the tank and having had some fuel leakage it was only then that I thought switching the taps to reserve might not be a bad idea.

Guessing I’ve either got low compression on that side or the carb needs a good clean. The rings aren’t that old so I guess if compression is down I’ll be lifting the head to check valve seating. Not sure I have the appetite for that this side of Autumn now.

I fitted a big block Guzzi engine to a Pembleton Morgan style three wheeler many years ago. However carefully I set it up it would only ever start on one cylinder. The other would chime in after a few revolutions. It always ran perfectly thereafter. I have never had this happen with my LMV or V50iii. I think that it must be just part of the Guzzi experience!

So back at the station last night I gave the bike a shake to check fuel level in the tank – didn’t sound like there was very much at all. Taps onto reserve and choke lever pulled out and she pretty much started on the button … both sides. Just a very occasional pop from the lazy side.

Stopped at the nearest forecourt on the way home and got just over 16 litres in, which seemed like a lot. Checking specs at home I’m thinking this bike has a 16 litre tank, and mine also has a small dent in one side as well. So how does that work … laws of physics and all that?

Anyway, good again this morning, so whatever the problem is – being left standing certainly exacerbates the situation.

When was last time taps were pulled for a clean-up? Reserve holes at the the bottom so they’ll get all the cr4p.

I thought the tank was 24 litres?

I got my figures here;

Regardless. I get 180 miles to reserve, and it’s been a while but I’d guess no more that another 20 on reserve. 200 miles on a 24 litre tank gives 38 mpg. I’m not that heavy handed, and my taps don’t leak that much.

Sorry I must pay attention, I thought you were talking about the 850T :confused:

The RH one just the other day, because it was leaking. Was all a bit swampy it has to be said.

I have had the same problem on my V50II. Carbs cleaned, new jets and choke, still does it. So gave the offending cylinder HT lead a twist at the plug cap, it fired up on both! Seems the 40 year old cables are rather corroded, might just cut them back and re-attach the plug cap. Just a thought, its usually a simple cure, if you have gone and spent a shed load of money and not fixed it.

Doh! This is why I put new HT leads on occasionally. NGK plug caps are good too or they used to be.

The caps with the resistors in, can suffer with old age and go high resistance or open-circuit, guess how I know. :smiley:

Coils, leads, caps and plugs are all fairly recent. Though that is not to say the problem doesn’t lie there of course.

Pal dropped in his compression tester last night so I’ll give it a spin t the weekend. There will be tears if the prognosis comes out less than good.

Just a thought, my SP went a bit like that when the electronic ignition unit was on its way out (Piranha system). It would start on one and then the second one would kick in after a while. Once both were running, you would never know anything was wrong. I also noticed the control box started getting quite warm.
Replaced it with a new unit from Newtronics and it’s been fine ever since.

Compression tested on Saturday. 145 on one side and 150 on the other. Didn’t even look at what units they were, but I figured that was high enough and close enough.

Bike is a mk II so has OE electronic ign - a separate box for each side. Had one side fail a couple of years ago. Fitted a s/hand replacement from Paddy Ducati, and have since swapped both sides out for a pair from a V35. Don’t think it is that. Coils and plugs are also pretty recent.

I’m going to pull and clean both carbs again. I think this problem has persisted through the last time I did this so I’ll be more vigilant on the slow run circuit this time. Not sure when I’ll find the inclination for this mind.