Cutting out
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Hooked
2006 PX 166 1980 P180X
Joined: 16 Oct 2008
Posts: 124
Location: England, Isle of Wight
Mon Aug 03, 2009 9:40 am quote
Need some ideas guys. Im handy with cars but not to clued up on 2 strokes
Was out today having a long ride for the first time in ages when all of a sudden the bike seemed to start bogging and the revs dropped off, i pulled the clutch in and it died. Kicked it back over and it idles nicely, pulls well in first and second but a second or two in to third and the scoot dies again. This happened all the way home, shifting down in to second does not help either Changed over plugs quickly and stll the same happens, not sure if it is a overheating issue or whether i need to up jet ect..
Thanks for listening.
Addicted
1980 P200e, 1956 ACMA, 1979 P200e, 1974 Ciao
Joined: 04 Jun 2009
Posts: 766
Location: Ithaca, NY
Mon Aug 03, 2009 9:49 am quote
I had a similar problem when my fuel petcock was failing. I was getting insufficient fuel flow. I would run off the fuel in the float bowl, and it would stall. By the time I restarted it, enough fuel trickled down to fill the float bowl again.. the net was I'd get about 1/10 of a mile at a time, between stalls. Might it be something like that? Have you tried swinging your fuel shutoff around a few times to see if it makes a difference?

Mike
Moderator
P200 PX150
Joined: 28 May 2008
Posts: 4373
Location: Hustletown, TX
Mon Aug 03, 2009 9:51 am quote
Not trying to be flippant... but do you have enough fuel in the tank?
Moderibbit
1980 P200E - "Old Rusty", 1976 ET3 Primavera
Joined: 12 Jun 2008
Posts: 8129
Location: Atlanta, GA
Mon Aug 03, 2009 9:53 am quote
Have you tinkered with your carb lately? Your fuel-air mixture screw might need a little tweaking.
Banned
Joined: 11 Jul 2009
Posts: 466
Location: Washington MFing DC
Mon Aug 03, 2009 10:00 am quote
Your fuel isn't flowing correctly.
Moderator
1965 Vespa SS180, 1963 Lambretta LI150
Joined: 05 Mar 2007
Posts: 6973
Location: Detroit, Michigan
Mon Aug 03, 2009 10:03 am quote
How new ( and unclogged ) is the tap ? What's the condition of the inside of your tank? Rusty at all ?
Hooked
2006 PX 166 1980 P180X
Joined: 16 Oct 2008
Posts: 124
Location: England, Isle of Wight
Mon Aug 03, 2009 10:15 am quote
Thanks for all of the replies I was feeling down about the whole thing but im feeling better with all of the kind help.
The PX is only 3 years old so a rusty tank is not the issue. I have a full tank of fuel, all of the jets are free from crap and build up. The only thing i have touched recently was the idle speed (i turned it down a notch) But i have not played with the tap/fuel shut off yet
Some great ideas there, keep them coming.
Moderibbit
1980 P200E - "Old Rusty", 1976 ET3 Primavera
Joined: 12 Jun 2008
Posts: 8129
Location: Atlanta, GA
Mon Aug 03, 2009 10:24 am quote
mudge wrote:
The only thing i have touched recently was the idle speed (i turned it down a notch)
I am not being patronizing - but are you sure you adjusted the correct screw to adjust the idle speed (i.e. are you sure you didn't touch the mixture screw?)? If the carb's the only thing you've touched prior to this problem I would be suspicious about the carb needing tuning.
Moderator
1965 Vespa SS180, 1963 Lambretta LI150
Joined: 05 Mar 2007
Posts: 6973
Location: Detroit, Michigan
Mon Aug 03, 2009 10:27 am quote
how's your float bowl float / needle? If those are sticking in the closed position for whatever reason ( crack or leak in the float, debris in the valve seat area, etc ), then you're basically shutting off fuel flow to the engine until it comes unstuck.
Hooked
2006 PX 166 1980 P180X
Joined: 16 Oct 2008
Posts: 124
Location: England, Isle of Wight
Mon Aug 03, 2009 11:09 am quote
Be as patronising as you want, some people are a bit 'special'
But it was the definitely the idle i turned down a notch as it was fast.
Eric the carb will be off tomorrow if i cannot solve the problem.
If i can pick your brains though The bike is now running a 166 malossi kit in favour of the 125. But would it make sense if the former owner did increase the idle speed to pump more juice in when the clutch was engaged in the higher gears to keep it feeding the thirstier piston?
Please say i have been a ~*@t and ruined my days riding and wasted all of your time
Moderator
1965 Vespa SS180, 1963 Lambretta LI150
Joined: 05 Mar 2007
Posts: 6973
Location: Detroit, Michigan
Mon Aug 03, 2009 11:17 am quote
It would make sense that a larger idle jet would be required in the same carb, if you're going from a 125 to a 166, absolutely.
Hooked
2006 PX 166 1980 P180X
Joined: 16 Oct 2008
Posts: 124
Location: England, Isle of Wight
Mon Aug 03, 2009 11:32 am quote
Sweet, so bump the idle back up for the time being and order a larger idle jet. I need a larger main jet any ways so, two birds with one stone
Cheers Eric, scoot safe fella.
Moderator
1965 Vespa SS180, 1963 Lambretta LI150
Joined: 05 Mar 2007
Posts: 6973
Location: Detroit, Michigan
Mon Aug 03, 2009 11:36 am quote
yeah, but you said earlier in the thread that your bike idles fine. If your jet was too small, it wouldn't be idling fine - it likely wouldn't even start!

Besides, the minute you give it more than 25% throttle, you're not even using the idle jet... so when you say you were driving down the road, i assume you're giving it 50%-100% throttle, and the idle jet is out of the equation.

Normally when you experience bogging or starvation at 75%-WOT, you should be changing out your main jet.
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