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V50lll running rough when open up throttle.

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Aussie View Drop Down
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    Posted: 31 Mar 2018 at 07:36
Hi Guzzi owners,

My 1981 V50lll was running well, but now when I open up the throttle it misfires and splutters. It still idles well. I've cleaned the carbs and it's still doing it. Could it be ignition coils and leads?

Any ideas would be greatly appreciated.

Regards,

Jason
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c13pep View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote c13pep Quote  Post ReplyReply Direct Link To This Post Posted: 31 Mar 2018 at 09:27
Do you know if it`s misfiring on 1 or both cylinders and is the bike still using standard points ignition
CHRIS
you can`t have any fun in a straight line

Monza project
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Aussie Quote  Post ReplyReply Direct Link To This Post Posted: 31 Mar 2018 at 09:48
Hi Chris,

The points have been changed to electronic before I purchased it. I'm not mechanically minded, so any ideas would be good. Thanks mate
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Post Options Post Options   Thanks (0) Thanks(0)   Quote c13pep Quote  Post ReplyReply Direct Link To This Post Posted: 31 Mar 2018 at 12:17
Is the misfire accompanied by backfiring in the exhaust or in the carb, the more information you give the easier it will be to diagnose by the expertise available on the forum. If it was running ok previously then it will likely be something simple.
CHRIS
you can`t have any fun in a straight line

Monza project
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Aussie Quote  Post ReplyReply Direct Link To This Post Posted: 31 Mar 2018 at 13:31
No backfire.
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Mike H View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mike H Quote  Post ReplyReply Direct Link To This Post Posted: 31 Mar 2018 at 13:35
Have you changed anything on the bike?


I only ask 'cause I've lost count how many times someone comes along with a problem, 'X' forum pages (and some time!) later we find out there was a modification or something was disturbed that turned out to be the cause of or contributed to the problem.

HTH

"Chicken nuggets don't dance on a Tuesday."
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Aussie Quote  Post ReplyReply Direct Link To This Post Posted: 31 Mar 2018 at 14:48
No, nothing has been changed since I've own it for 3 years. It had been running well.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rapheal Quote  Post ReplyReply Direct Link To This Post Posted: 31 Mar 2018 at 15:46
Try a new set of spark plugs first, and unscrew the HT lead from the plug cap and look for verdigris, if so new leads and plug caps
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Baldybloke Quote  Post ReplyReply Direct Link To This Post Posted: 31 Mar 2018 at 16:12
Blocked vent in the filler cap or filters in the petrol taps? Try new plugs and caps and clean the earths to the frame.

Whilst working on a Monza once I tried everything to get it running consistently on both cylinders. Sometimes it ran on the left and sometimes the right never both. After about thirty hours of checking electrics and stripping the carbs several times I discovered that the fuel line crossover pipe had a blob of jellified petrol in it. So depending on which petrol tap got turned on first dictated which pot ran. Needless to say the crossover pipe got binned and I just had lines direct to each carb.

Edited by Baldybloke - 01 Apr 2018 at 19:22
Only dead fish go with the flow.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mike H Quote  Post ReplyReply Direct Link To This Post Posted: 31 Mar 2018 at 17:27
THAT was a good discovery! Shocked



"Chicken nuggets don't dance on a Tuesday."
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Aussie Quote  Post ReplyReply Direct Link To This Post Posted: 31 Mar 2018 at 23:42
Thanks guys, I will check and replace spark plugs and leads.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote c13pep Quote  Post ReplyReply Direct Link To This Post Posted: 01 Apr 2018 at 08:49
Which electronic ignition is fitted?
Both my V50/3 s have coils with the plug leads bonded in to them so changing plug leads is not that straight forward without using HT connectors. This does of course then introduce another potential source of trouble ie. another joint to worry about.
CHRIS

you can`t have any fun in a straight line

Monza project
BMW R1150RT
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Aussie Quote  Post ReplyReply Direct Link To This Post Posted: 01 Apr 2018 at 22:14
Hi Chris. I have leads that are bonded to the coils. I'll buy a whole new set and fit them.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote c13pep Quote  Post ReplyReply Direct Link To This Post Posted: 02 Apr 2018 at 09:45
Originally posted by rapheal rapheal wrote:

Try a new set of spark plugs first, and unscrew the HT lead from the plug cap and look for verdigris, if so new leads and plug caps


Before replacing coils follow RAPHEALs advice it may save you unnecessary expense
CHRIS
you can`t have any fun in a straight line

Monza project
BMW R1150RT
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Aussie Quote  Post ReplyReply Direct Link To This Post Posted: 02 Apr 2018 at 23:57
Cheers fellas for all the advice. I'll let you know how it goes. Thanks again
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