350 bogging out - MVAgusta.net
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post #1 of 11 (permalink) Old 03-15-2011, 05:16 PM Thread Starter
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350 bogging out

Ok
I cleaned up my carbs all pretty and nice and found a hole in a float. Patched the hole and put them back on. Now the bike bogs out after a block or so and is backfiring like a bitch. I know the mix is rich so I fixed it up a little but it's still bogging out. Any ideas? Just too rich still?

'70 Triumph T100R Flat Track
'74 350 Elettronica
'64 Tevere Motocarro
'76 350 Ipotesi
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post #2 of 11 (permalink) Old 03-15-2011, 07:15 PM
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I don't understand the term 'bogging out'.

I am thinking certainly adjust the mixture more to start with - I'd be fiddling with that and perhaps spark plugs - if it is fouling them try a slightly hotter plug.

Also, basic as it may seem - what fuel is in there? Is it old? ethanol content? Are you running a lead replacement additive as well?

The old story of eliminating things one by one, you'll get it right sooner or later - enjoy the (emotional) ride


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post #3 of 11 (permalink) Old 03-15-2011, 07:53 PM Thread Starter
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I'm trying to get some high octane from the airport here to run in it. By bogging out I mean just dying. Backfires and then just dies out. I'm going to adjust mixture more but is there a way you have found to sync the carbs?

'70 Triumph T100R Flat Track
'74 350 Elettronica
'64 Tevere Motocarro
'76 350 Ipotesi
'68 Vespa Super
'64 Vespa Cushman 150
'73 Honda Z50
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post #4 of 11 (permalink) Old 03-15-2011, 08:23 PM
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Ok so it just stalls - that's what I assumed when I answered above.

I sync my carbs by ear & feel - you can 'hear' when they are both right and when you give it a slight rev you should feel an even output from both exhausts, I just use my hand to feel the exhaust output. It is certainly not as scentific as having gauges to balance them but it works for me.

Here in Australia - the old leaded "super" fuel had an octane of 98 or higher as I understand, it was phased out here from 1986 and completely disapperaed Jan 1 2002. Fuel has become progressively crappier since then. I use premium fuels such as Shell V-power and add lead replacements with octane boost , as a result I run slightly hotter plugs. One of the pitfalls is that it makes it harder to start but once it does it works awesome.


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post #5 of 11 (permalink) Old 03-16-2011, 04:49 AM
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Sounds like a float needle sticking and starving the carb of fuel - or maybe you upset the float level somehow when you had the bowls off?
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post #6 of 11 (permalink) Old 03-16-2011, 02:51 PM Thread Starter
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I had it at a perfect idle today. I turned it off for about 30 min and when I started it again it had trouble starting and then when it started I rode it about half a block and it sputtered out and died. It seems like the needle might be sticking that sounds right. Any ideas?

'70 Triumph T100R Flat Track
'74 350 Elettronica
'64 Tevere Motocarro
'76 350 Ipotesi
'68 Vespa Super
'64 Vespa Cushman 150
'73 Honda Z50
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post #7 of 11 (permalink) Old 03-16-2011, 07:47 PM
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Quote:
Originally Posted by gunnar View Post
I had it at a perfect idle today. I turned it off for about 30 min and when I started it again it had trouble starting and then when it started I rode it about half a block and it sputtered out and died. It seems like the needle might be sticking that sounds right. Any ideas?

Hi gunnar

I've no real knowledge of the carbs used on the 350, but generally if a thorough cleaning of the components doesn't help I check the float mechanism & float bowl for any signs of physical contact. If one's rubbing against the other anywhere it can restrict its operation. If the float can't fall freely, its needle will block the jet.

Just a thought.. How did you patch the hole in the float? Are you sure it's not leaking? Adding weight to the float (..or anything leaking into it) would cause it to settle lower into the fuel, and this would result in a higher level in the bowl before the needle cuts its supply. This would mess up the mixture.
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post #8 of 11 (permalink) Old 03-16-2011, 07:57 PM
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Quote:
Originally Posted by 750four View Post
Hi gunnar

I've no real knowledge of the carbs used on the 350, but generally if a thorough cleaning of the components doesn't help I check the float mechanism & float bowl for any signs of physical contact. If one's rubbing against the other anywhere it can restrict its operation. If the float can't fall freely, its needle will block the jet.

Just a thought.. How did you patch the hole in the float? Are you sure it's not leaking? Adding weight to the float (..or anything leaking into it) would cause it to settle lower into the fuel, and this would result in a higher level in the bowl before the needle cuts its supply. This would mess up the mixture.
+1. This is 99% certain a fuelling problem.

I had a smiliar experience recently with the Ipotesi and to get professional help. It idled fine but as soon as I put it in gear & released the clutch it stalled.

They serviced them & re-set carbys, making it work fine. I generally just fine tune them as the shake rattle & roll nature of these little babies is forever altering settings.


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post #9 of 11 (permalink) Old 03-17-2011, 01:30 AM Thread Starter
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I patched it with a little JB weld. My father has been a BMW mechanic for about 30 years so he is pretty much my go to when it comes to mechanics. I think I will give them a good soak and maybe get a rebuild kit for the carbs and see how that all works.

'70 Triumph T100R Flat Track
'74 350 Elettronica
'64 Tevere Motocarro
'76 350 Ipotesi
'68 Vespa Super
'64 Vespa Cushman 150
'73 Honda Z50
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post #10 of 11 (permalink) Old 03-19-2011, 01:15 AM Thread Starter
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well after pulling the carbs apart again i see that my left carb has no more brass on the seat where the float needle sits. So now I need to try and find a new lid for the bowl...

'70 Triumph T100R Flat Track
'74 350 Elettronica
'64 Tevere Motocarro
'76 350 Ipotesi
'68 Vespa Super
'64 Vespa Cushman 150
'73 Honda Z50
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