I am stil trying to get to the bottom of a backfiring left Cylinder and weak tickover coupled with an unresponsive left air screw. I have previously replaced both exhaust gaskets with no effect on backfire and still suspect a Carburettor, issue, leading to over lean running on a fully closed throttle. As such I have dismantled and u/s cleaned the left carburettor and now have carb cleaner flowing from the air screw adjusting hole into both the jet hole in the main throttle body and also incomer ahead of the slide. I expected to find some form of O ring present somewhere along the air screw, but did not find one: could anyone advise please, should there be one fitted.
I have a eurocarb rebuild kit which contains several small o rings, however none are shown in the exploded diagramme in the manual, hence question.
I should add, V50 Mk 2, running standard airfilter, ignition and carb settings, front pipes but with non std silencers.
For good measure, I have added a new manifold to Cylinder Gasket, just in case.
Many thanks, Gareth
Seen these diagrams?
Seems there’s an o-ring or washer on some of the adjustment screws, but I’ll let you get your own magnifying glass out. Once you know what you’re after, I’d recommend talking to Eurocarb.
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Hey thanks for the diagrams Barry… they suggest not, but I do wonder if there is something very small buried in the depths, so as you suggest magnifying glass required.
Meanwhile, a very close look at the inlet rubber suggests a small split… ie another potential air ingress point. Hey ho, new ones on order from Gutsibits.
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Of course there are orings, and they are visible on those diagrams, no. 47 and 49, for both screws. The idea is, the screw is supported by spring, but spring , to keep things airtight, ends up with tiny washer, and oring underneath, so spring cannot damage the oring, it has no direct contact with it.
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Try removing the air screw and have a close look in the body, I have a fellow member that was having similar problems on his LeMans, on closer inspection there were several washers in the bottom of the recess that had been left behind during previous rebuilds.
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Indeed. And the ‘part numbers’ for those items can be lifted from the accompanying lists, typed into the search box on the Eurocarb site, and there they are, available.
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Thanks Folks. I now see re the diagrams which have a lot more detail than my workshop manual. Nothing visible and I had a good poke around in the depths, with a very fine jewellers screwdriver and if there is something there it’s very very well stuck in place. There was some white alloy corrosion product underneath the spring which again maybe suggests moist air being sucked in, ie suggests there is a seal missing. I’ll go get a couple of o rings and washers and let you know how I get on. Again thanks for the info. Gareth
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Yep Eurocarb sure is well useful. This is what it should look like… I’m not 100% convinced this is the ‘correct’ kit for a the V50, but definitely confirms what is needed. I do have a couple of rebuild kits and there are several spare o rings, so I guess I’ve got these, now to find a couple of suitable washers.
Don’t forget the idle screw has an o ring as well.
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With this sort of problem it is a good plan to go right back to basics. With Dellortos you need to make sure that the float height is correct according to Guzzi specification. I messed around for ages on my old T3 before Pietro Marino told me to check my float heights. They were different to each other and followed the Haynes Manual not the proper Guzzi workshop manual. Once I had adjusted them, setting up the idle speed etc was very straightforward.
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Quick update Folks. Firstly thank you for all the useful thoughts and suggestions.
Over the course of Saturday pm and yesterday evening I successfully reassembled the LH Carb now with an o ring and washer on the tick-over screw, where none was previously present and replaced the old o ring below the washer on the air screw… yes with a bit more poking around it was there all the time. I’d previously fully stripped and cleaned the LH Carb, checked float level etc. On the RHS, did the same with tick-over screw, but in the depths of the air screw hole was a jammed oversize (Green) o ring and no washer… so this now corrected.
The O rings I used came via two Dellorto rebuild kits and I found the two smaller washers in the bits box and the larger (tick-over) washers were created by filing down two old BA brass washers… these are available from Eurocarb, but I needed them now and postage would probably be >> price of the parts.
Result!, no backfiring anymore AND she’s now ticking over fairly reliably… off to see a Mate who has a set of vacuum gauges at the weekend to finish the set up.
…. then on to the next task… new master cylinder and more effective non linked side front brake.
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Let me disagree… Linked brakes are one of the most ingenious and efficient inventions used in those Guzzis. Yes you can improve hand-operated brake by upgrading to 11-12mm handlebar-mounted master cylinder, but giving up linked brake is just a downgrade. Which of course may suit you, for reasons unknown to me:)
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Hey maybe I should have worded my last para better Mate and, of course, thanks for continuing the discussion…
……but no way do I plan to get rid of the linked brakes; they’re brilliant and with a bike as light as the V50 (and maybe the way I ride it as a 44 year old machine) one front plus the rear is pretty much all that is required. Rather, I was alluding to adding a c12mm hydraulic single master cylinder set up as with the MkIII as opposed to the current cable set up for the non linked disc. I think in day to day riding, the second non linked disc maybe adds little extra stopping without a huge squeeze, which given I’ve also a somewhat newer 650 with conventional twin discs is a bit counter intuitive….
Overall, the Brakes are more than fine with a 1st proper post carb rebuild ride up Weardale, over into Tynedale and back down Teesdale on Sunday, involving sone quite big Hills. The weak ‘front only’ control has maybe the greatest impact whilst manoeuvring around the Car on our very short and steeply inclined drive… hence plan to change…
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Yeah, I find front brake useful in one situation only: to hold bike stopped at traffic lights - and only on the flat, as it isn’t trustworthy enough even on the mild up-hill:)
And opposite for linked one: capable to do anything, absolutely anything. Did plenty of sidecar 3-up(adults) riding, and it was always up to the task. I love it. Why they gave up with this idea in early Nevadas? No idea!
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