Rally 200 no power at high revs
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Lurker
Rally 200
Joined: 24 May 2020
Posts: 4
Location: Texas
Sun May 24, 2020 11:41 am quote
First post for me here and hoping you can help. I have a 76 Vespa Rally 200 - bought it a few years ago and got it running. Ran well at first but i found the Femsa CDI to be pretty unreliable. I swapped over to a Ducati CDI with a BeedSpeed pulse converter so I could still use the Femsa stator and not have to swap out the crank and all that. Ran perfectly. Fast forward 2 years and now i do not get power at high rpms.... but only when I have the lights on. With the lights off, the bike runs great. As soon as the lights are on....it will not rev out. I have pulled the flywheel and it appears to have good magnetism. I have cleaned any corrosion and rust off all surfaces, replaced the woodruff key, and reinstalled the flywheel, torqued down at 45 and still same issue. At a loss here- I don't have a spare Ducati CDI to test. (I may try the Femsa again and see if that changes anything but for now I'm at a loss.) I have heard this type of issue is sometimes cause by weak magnets....I don't think that's the case here but i do not know how to test the magnets...they will hold an 18mm wrench but not anything like a hammer. Also- if it matters the battery does not hold a charge -

TIA for any assistance
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2226
Location: London UK
Sun May 24, 2020 11:50 am quote
Partially broken wire?
Lurker
Rally 200
Joined: 24 May 2020
Posts: 4
Location: Texas
Sun May 24, 2020 11:58 am quote
@Jack221- I cannot see any damaged wires and everything on the stator looks to be in order.

runs perfect with the lights off, as soon as I turn the lights on, the engine will bog at high rpms.....like the lights are stealing power from the ignition coil?
Hooked
P Series / Li / LML / Motobi
Joined: 24 Jun 2019
Posts: 399
Location: UK - 3rd Rock From the Sun
Sun May 24, 2020 11:59 am quote
Re: Rally 200 no power at high revs
"but only when I have the lights on. With the lights off, the bike runs great"

I HAVE HAD THAT!!! The scoot revved on cleanly with the lights off - lost bags of power when the lights went on

I chased all sorts down and change multiple parts. wiring loom, stator, etc you name it i changed it.... only thing i didn't change was the CDI.. as that was only a few months old.

In a fit of desperation I changed that as well...... turned out for me changing the CDI cured the problem..... fast forward many years and i now keep a spare genuine CDI in stock
AustinRally wrote:
First post for me here and hoping you can help. I have a 76 Vespa Rally 200 - bought it a few years ago and got it running. Ran well at first but i found the Femsa CDI to be pretty unreliable. I swapped over to a Ducati CDI with a BeedSpeed pulse converter so I could still use the Femsa stator and not have to swap out the crank and all that. Ran perfectly. Fast forward 2 years and now i do not get power at high rpms.... but only when I have the lights on. With the lights off, the bike runs great. As soon as the lights are on....it will not rev out. I have pulled the flywheel and it appears to have good magnetism. I have cleaned any corrosion and rust off all surfaces, replaced the woodruff key, and reinstalled the flywheel, torqued down at 45 and still same issue. At a loss here- I don't have a spare Ducati CDI to test. (I may try the Femsa again and see if that changes anything but for now I'm at a loss.) I have heard this type of issue is sometimes cause by weak magnets....I don't think that's the case here but i do not know how to test the magnets...they will hold an 18mm wrench but not anything like a hammer. Also- if it matters the battery does not hold a charge -

TIA for any assistance
Lurker
Rally 200
Joined: 24 May 2020
Posts: 4
Location: Texas
Mon May 25, 2020 3:16 pm quote
Thanks GravelRash- I'll try that next- fingers crossed that's what it is
Lurker
Rally 200
Joined: 24 May 2020
Posts: 4
Location: Texas
Sat May 30, 2020 9:35 am quote
nope...Changed the CDI and still the problem persists. At a loss-
Member
Rally 200, Lambretta Li125
Joined: 12 Jun 2018
Posts: 15
Location: Austin Tx
Tue Jul 28, 2020 2:35 pm quote
I've had this issue. I bought a Rally a few years back with the CEAB aftermarket CDI already in place of the original Femsa. It would start sometimes sometimes not, after reading some articles and on the advise of a friend who had a Rally, I opted to change out the CEAB for a DUcati CDI and use a "pulse converter" made by Beedspeed. This converter allowed the Femsa stator to be used with the DUcati CDI by retarding the signal so the timing would be correct. Worked awesome at first until I had issues at high revs with lights a few years later. Tried a second Ducati CDI to no avail I removed the flywheel and inspected the stator, found some rotted out wiring at the junction- thinking this was the issue- had the stator rewired to no avail, same deal. Ditched the Ducati and converter for a known working CEAB and problem resolved. full power at high revs with or without lights. full circle.
Member
Joined: 15 Jul 2020
Posts: 9
Location: Brea, CA
Wed Jul 29, 2020 11:01 am quote
I think there must be problem with the engine Magnet. Check if power is coming after CDI and check wires.
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