MV Agusta Forum banner

1 - 12 of 12 Posts

·
Registered
Joined
·
344 Posts
Discussion Starter #1
ok...
the bike runs GREAT. Idles quick off the line and is great for the first 10 min of the ride then...
When i get into 4th or 5th gear i lose all power from the engine and it sputters on and off with power. The plugs arent fouling it just seems like all of a sudden it is either getting too much fuel or not enough. Im at high altitude and have tried to adjust the mixture and I thought I had it until this whole thing started.
Its usually only when i hit about 90kph in 4th and 5th. Any ideas?
 

·
Cyber SPOTTER
Joined
·
6,101 Posts
When you put these posts up you need to tell us WHICH of the 350's, you have 2 remember? ;)

With the Ipotesi - I had a similar problem, & it has an electric fuel tap - it would intermittently turn itself off usually when I was getting into 3-4th gear. Insane really, it would turn off & sometimes fire up again as I clutched it using the momentum.

I had enough of that fitted a manual fuel tap & I don't have a problem anymore - except if I forget to turn it on when I leave and it stops 500 metres down the road - lol.
 

·
Registered
Joined
·
344 Posts
Discussion Starter #3
sorry sorry...
i keep forgetting
this is the 350 b

the ipotesi is still quarantined in the garage with no brakes
 

·
Registered
Joined
·
178 Posts
sorry sorry...
i keep forgetting
this is the 350 b

the ipotesi is still quarantined in the garage with no brakes
Hi,

What size are the main jets ?
With the modern fuel, the original settings are wrong. With the 95 unleaded french fuel, i had to fit five points lower main jets and 3 points lower idle jets
 

·
Registered
Joined
·
344 Posts
Discussion Starter #5
everything is original. I can run aviation fuel which is 110 leaded. Ill give that a shot and see what happens
 

·
Registered
Joined
·
178 Posts
I had another problem with my 350 BE last year. At the medium / high rang of revs, the bike had bad running and spoiled the plugs. This was due to the float valves that were "shaked" by the vibrations of the engine and let the fuel over fill the bowl and flood the left carb.
The inlet tubes were too tightened to the cylinder head, squezzing the gum gaskets and the vibrations of the engine were totally transmitted to the carbs.
The screws should not be too tightened and use the action of the springs to avoid any air leack.
 

·
Registered
Joined
·
344 Posts
Discussion Starter #7
I will try to loosen them up and see what happens...
One problem that was DEFINITELY an issue was my petcock was all screwed up. The seal on the inside had rotated so the holes didnt line up and it was getting no fuel. Probably an issue...
Fixed that.
So today I was riding and it was great and then BAM same thing happens. No power at about 6000 rpm it just dogs out on me.
I stopped at a light and then it ran fine again till i got after it and hit some high revs.
Then when I was stopped i leaned the bike to the right and it almost died. Like it was starved for fuel.
Any ideas??

Also what is redline on the 350b? I dont think im getting close to it but I just want to be safe...
 

·
Registered
Joined
·
34 Posts
Perhaps it is ignition.

Under load (which it would be in 4th and 5th) it may be that the ignition is failing, i recall some one saying under load there is more resistance for the spark to jump across the plug gap. Perhaps check the points gap and condition and swap out the ignitions coils to test.
 

·
Registered
Joined
·
4,296 Posts
Perhaps it is ignition.

Under load (which it would be in 4th and 5th) it may be that the ignition is failing, i recall some one saying under load there is more resistance for the spark to jump across the plug gap. Perhaps check the points gap and condition and swap out the ignitions coils to test.
Good call, sounds like ignition to me
 

·
Registered
Joined
·
344 Posts
Discussion Starter #10
Thanks guys Ill give it a shot and see what happens...
 

·
Registered
Joined
·
344 Posts
Discussion Starter #11
Ok I figured it all out.
Put some sock filters on the carbs so I adjusted the mixture a little and its running great. Fantastic power band in the high revs just awesome.
What my problem was....
The seals INSIDE my petcocks keep rotating and its constricting all the fuel.
How do I keep these from moving around when i turn off the fuel. Its great for a while but when I turn it on and off a few times it just rotates around inside and nothing lines up to let fuel into the lines.
Anyone else had this problem? Easy fixes?
 

·
Registered
Joined
·
34 Posts
Wow, yeah, this makes sense but the problem remains, your bike is starving for fuel and adding the socks has just richened the mixture.

The rubber seals inside the fuel taps should be prevented from rotating by on of the holes having a very short piece of tubing protruding into the rubber.

When I restored my 350B I sourced a set of new taps off Ebay, they ended up being the wrong ones (thread different etc) but I used the internals to recondition my existing one (the rubber gasket is all I really needed but try finding just the rubber gasket). If you pulled your taps apart and find the little piece of tubing that prevents rotation has disappeared perhaps start looking for a new one on Ebay or somewhere else.
 
1 - 12 of 12 Posts
Top