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Any ideas what is wrong?

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Paul-l View Drop Down
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    Posted: 10 Jun 2019 at 21:16
having just done the last 200 miles of a 1500 mile trip on a recovery truck can I have suggestions on what to look at please. 1970 V7 special.

The first two days fine, no problems, overnight rain, first thing day 3 misfiring, cutting out at idle - checked fuel ( OK) refilled, used different petrol tap - ran fine for next 5 days ( rain and more rain!)

Garaged overnight then next day misfire back, lack of power getting worse quickly, tried opening filler cap - no apparent improvement - drained and rinsed petrol tank, cleaned carbs, and filters, cleaned and reset points - ran like normal again

200 miles later misfire is back and getting worse quickly so called recovery.

Paul
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Post Options Post Options   Thanks (0) Thanks(0)   Quote johnno Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jun 2019 at 21:31
Change points and reset if I have read this post correctly
1100 sport corsa , Yam R1, guzzi 650tt rider
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ranton_rambler Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jun 2019 at 21:36
90% of problems are ignition related. I've found that heel of points can wear which closes the gap, but have also had condensers fail twice on my loop.
Having said that, have you had the taps out? Mine were full of rusty flakes.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jun 2019 at 21:52
I'd certainly check the ignition timing Paul. Have you checked to see if there is a decent spark on both plugs? And as said above, check the points gap.

You can easily check the taps by pulling the fuel pipe off a carb and turn the tap on. If fuel doesn't run out it's blocked. Are there gauze filters on the taps? Could be blocked.

What colour are the plugs? White or light would suggest fuel starvation, black and/or wet would suggest lack of sparks.
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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: 11 Jun 2019 at 16:46
I don't know nuffink abaht it having never had one but I do recall Kate W (kateguy/guykate on the forums) saying once that the distributor is a weakness and doesn't lke getting wet, hence a good soaking with WD40 may help (other brands are available!) (She told us this in person at some time, not wrote it on the forum I don't think) There may be other things you could do for it as well.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 11 Jun 2019 at 17:25
Water anywhere near the HT system can cause problems, especially if it can't then dry out.
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Dave P. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 11 Jun 2019 at 18:33
All of the above plus..


Check that your choke cables have sufficient free play at the carb end,around 4mm.last year in Belgium I had similar symptoms on my 850GT.How the left hand cable lost its' clearance halfway through the trip I don't know but it did.The bike ran like a bag of nails until I found the problem,the choke was open!!
Best of luck.
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1971 V7 Special. 1972 850GT.
1970 T120 Bonnie. 2009 500 Bullet.
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Dave P. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 11 Jun 2019 at 18:38
Oh and another thing,check that the dizzy securing bolt hasn't come loose.
TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.

1971 V7 Special. 1972 850GT.
1970 T120 Bonnie. 2009 500 Bullet.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Paul-l Quote  Post ReplyReply Direct Link To This Post Posted: 11 Jun 2019 at 19:23
Lots of things checked and to do:
Taps off the tank so gauze checked and appears OK, and get good flow through to both carbs.
Tank rinsing showed some dirt and what looked like varnish flakes

Plugs both look brownish, not black ( though after the first stripping one was black and the other brownish)
The Sparks are better on the right cylinder , but look a bit yellow to me

I did check the condenser with the tester mentioned on a different page - 25 nF! So replaced with another that tested at 250 nF
Points cleaned and reset

The dizzy bolts are tight, and the choke cables loose

Currently waiting on many parts, and I can't try it out till they're here since the fibre washers for the taps fell apart when removed!

What HT leads should I use ( currently copper from the coil, and silicone / graphite from the dizzy to the plugs) is the difference in spark intensity due to the different length leads?

Paul
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Dave P. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 11 Jun 2019 at 19:28
Copper every time.
Lead lengths make no difference. The variation is too small.

Edited by Dave P. - 11 Jun 2019 at 19:31
TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.

1971 V7 Special. 1972 850GT.
1970 T120 Bonnie. 2009 500 Bullet.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mike H Quote  Post ReplyReply Direct Link To This Post Posted: 11 Jun 2019 at 19:39
"and silicone / graphite from the dizzy to the plugs"

That could be the problem right there. OK when new maybe ...

What Dave said copper is simpler and more reliable, and easier to fettle.



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Dave P. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 11 Jun 2019 at 19:47
The only other thing I can think of if the problem isn't water would be an intermittent bad connection or short on the LT feed to the coil,the ignition switch terminals or bad battery connections. See "Sicily Trip" in Guzzi go touring section.
.
TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.

1971 V7 Special. 1972 850GT.
1970 T120 Bonnie. 2009 500 Bullet.
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Dave P. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 11 Jun 2019 at 19:59
And check the connections at the fuse board and distribution board in the headlamp shell.Cant think of owt else at the moment but I am on my third glass of red.🤔
TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.

1971 V7 Special. 1972 850GT.
1970 T120 Bonnie. 2009 500 Bullet.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 11 Jun 2019 at 20:09
If you have those conical end fuses, they are notorious for poor connections. Spin each one in it's holder.
Brian.

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Dave P. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 11 Jun 2019 at 20:13
+1 to that. Longer term, fit blade fuses and the appropriate fuse box.
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Edited by Dave P. - 11 Jun 2019 at 20:21
TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.

1971 V7 Special. 1972 850GT.
1970 T120 Bonnie. 2009 500 Bullet.
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