V50 monza carburettor set up - Event Date: 01 Oct 2020 - 10 Oct 2020 |
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MGGGG
Falcone Joined: 24 May 2018 Location: Swansea wales Status: Offline Points: 22 |
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Posted: 01 Oct 2020 at 09:55 |
Help! Been struggling with carburettor set up since getting this bike 2 years ago. Came with pod filters, which I renewed with replacements from Gutzibits. Runs very rich, tick over is fine, and when cold it’s fine, but after 5 miles it misfires Badly at anything under quarter throttle - unrideable! Plugs will be black with soot. Carbs have been thoroughly cleaned (more than once!) choke slides have been renewed, made sure there is play in the choke cable, though no need to use choke to start. Currently has 125 main jet, 50 pilot, 50 slide, and what I think is the starter jet is 60. Any recommendations on jetting? which I think must be the cause of the problems. Any help greatly appreciated.
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c13pep
Senior Member Joined: 31 Aug 2017 Location: Doncaster Status: Offline Points: 2110 |
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What position are the needles on, also these engines are upset if float heights are not as per the manual
Jet sizes look ok but its the needle and its jet that need to be spot on (preferably new) and ensure that the pods are not causing a restriction because their connecting rubbers are too small in the throat (this caused me endless problems on my first V50/3) My own Monza does run rich low down but once out on the road this tends to clear but if started regularly in the garage plug fouling can become an issue CHRIS
Edited by c13pep - 01 Oct 2020 at 11:14 |
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you can`t have any fun in a straight line
Monza Honda CB77 project |
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MGGGG
Falcone Joined: 24 May 2018 Location: Swansea wales Status: Offline Points: 22 |
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Checked floats, exactly 24mm, needles 3rd from top.both cylinders affected, so assume must be to do with jetting.
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c13pep
Senior Member Joined: 31 Aug 2017 Location: Doncaster Status: Offline Points: 2110 |
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Apologies I hadn`t noticed the comment about below quarter throttle which suggests that the problem is prior to the needle valve starting to work. Recently I have changed my plugs to BP7ES to cure the same problem of plug fouling which seems to have done the trick. All the bikes previously have come with
BP8s in and I never bothered to cross reference the ones in the manual. CHRIS
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you can`t have any fun in a straight line
Monza Honda CB77 project |
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Ken-Guzzibear
Moderator Group Joined: 13 May 2014 Location: Sileby Leics Status: Offline Points: 9454 |
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The usual set up for pod/k&N filters is 10% up on standard for main leaving the others alone, Eurocarbs are very helpful in setting up the Guzzi Carbs
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The Older i Get, The Better I Was
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c13pep
Senior Member Joined: 31 Aug 2017 Location: Doncaster Status: Offline Points: 2110 |
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https://guzzitek.org/plm/pb/V50_3_PLM.pdf
I find this very useful and a lot clearer than the manual for looking at the finer detail, the numbers correspond to the Fowlers spares pages Apologies if you`ve already got it but `every little helps` CHRIS
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you can`t have any fun in a straight line
Monza Honda CB77 project |
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Ken-Guzzibear
Moderator Group Joined: 13 May 2014 Location: Sileby Leics Status: Offline Points: 9454 |
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Must have been the lockdown re builds there seems a fair few small blocks with carb/timing issues recently
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The Older i Get, The Better I Was
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MGGGG
Falcone Joined: 24 May 2018 Location: Swansea wales Status: Offline Points: 22 |
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Thanks Chris. I have BP6 at moment. I’ll try the BP7. At moment I have the carbs in bits, so I’ll wait to see what response I get regarding the jetting just in case I need to change anything there. I am assuming that as it’s running far too rich I need smaller jets? Especially the pilot jet which is the operative jet under quarter throttle. It is 50 at the moment, while standard I believe is 52.
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Ken-Guzzibear
Moderator Group Joined: 13 May 2014 Location: Sileby Leics Status: Offline Points: 9454 |
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the NGK BP6ES is hotter than the BP7ES and 2 grades hotter than BP8ES
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The Older i Get, The Better I Was
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AdrianW
Senior Member Joined: 05 May 2019 Location: Bristol Status: Offline Points: 993 |
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My V35II arrived with Pods (PO invoice from Gutsibits) and ran rich.. Jets were standard spec. I replaced choke mechs (manual in place of cable but it's really the plungers that need checking). Then I replaced the float needles, needle jets and needles themselves (mine were corroded, bike had allegedly been stood a while at one point). Plugs I think are B7's.. Now runs fine, nice plug colour. Tickover is a bit fast when warm but I'm not touching anything for the time being !! Good luck with yours.. Adrian Bristol UK
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c13pep
Senior Member Joined: 31 Aug 2017 Location: Doncaster Status: Offline Points: 2110 |
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I would think that the plugs are the source of your problems as the jetting seems ok
Strangely on the NGK website cross referencing the plugs in the manual gives BP7ES whereas checking using MOTO GUZZI gives B8ES CHRIS
Edited by c13pep - 01 Oct 2020 at 18:50 |
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you can`t have any fun in a straight line
Monza Honda CB77 project |
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MGGGG
Falcone Joined: 24 May 2018 Location: Swansea wales Status: Offline Points: 22 |
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Thanks for all the responses, just great. I believe that standard main jet on monza is 118, a 10% upgrade would be 130! Going to stick with the 125 jet currently fitted for now (especially as it seems to be seriously over fuelling already) and try the bp7 plugs. If that does the trick you’ll here me whooping from wherever you are! Thanks again, and stay safe.
Post an update When I’ve put it back together.
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George
Senior Member Joined: 28 Sep 2018 Location: Prestwich Status: Offline Points: 113 |
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Hi and good morning. I have an ongoing post with my V50 (initially posted as ignition problems by George) and I'm almost at a point where I am about to give it another try (after I can get a 4.5mm countersunk screw that holds the choke chamber in place). I have done all the normal checks and replaced all jets as suggested in previous posts. The engine 'seemed' to run best on the left cylinder with the mixture screw set at a half turn out from full in position - it ran very rich with the screw one and a half turns out . An inspection of the taper tip at the very end of the mixture screw showed the tip to be in very poor condition (actually spirally grooved and rough when checked with a 20 times magnifying glass). I have recently renewed the mixture screws, which have a nice smooth taper, and during recent engine runs it seemed to be running better even with the screws set at around the one and a half turns out as suggested in the manual. It may be worth checking the condition of the mixture screw tips. My project is ongoing and I'm going to try another set of plugs now that I've had a quick look into he LHS cylinder head.
Best Regards - George
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Take care - be aware
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MGGGG
Falcone Joined: 24 May 2018 Location: Swansea wales Status: Offline Points: 22 |
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Thanks for the information George just been out to check mine and they do seem ok, not perfect, so if plugs don’t improve it they’ll be my next move. My understanding is that they control the air flow, so screwing them in is richening the mixture, while screwing them out is weakening it?? Have I got that wrong??
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iansoady
Senior Member Joined: 23 Jul 2017 Location: Redditch Status: Offline Points: 2402 |
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That sort of damage is usually caused by someone screwing the mixture screws tightly home. It often damages the seating as well......
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Ian
1952 Norton ES2 1986 Honda XBR500 1958-ish Greeves/Triumph in progress |
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