Ambo help - not starting

[Gringer78]

Having some trouble with my Ambo and starting.

Background info. 1971 Ambo - sat for a long time.
Bike came with a Sonny Angel 2 into 1 intake with a mikuni carb, and some delortos in a box. - i was able to start the bike with the single intake
for a moment to make sure it runs.

After i got it started i decided to replace the cylinders and pistons with a nikisil kit and put original dellortos on with K&N pod filters.
Delortos were cleaned and rebuilt with a kit, new cap, rotor, wires, plugs ngk bp7es, condensor, points. Timing set, valves adjusted.

The bike fired up and ran for a couple of mins and then it stalled out.- i thought it was flooding so i replaced the choke plungers on the carb as there were old.


Ever since it stopped running after the inital start up, i could get it to start again. Compression is 150 in both cylinders.

After trying to start it, i pull the plugs and they are soaked. I dry them off, set them on the valve cover and crank the bike, i have spark!.


To add to the mess, when a timing light is attched, it only flashes when the plugs are out of the head, if the plugs are in the head the timing light will not flash....

Anyone in Michigan with some experience? :-)

[fotoguzzi]

do you still have the old metal covered plug caps? I'd try new NGK caps.. just for kicks..

FYI, I bet the Sonny Angel manifold is worth some good money..

[John A]

also test the coil. I won one of those single carb setups at an Italy Texas rally years ago. I looked at it for a long time then I donated it to an Oklahoma rally in the mid '80s. The guy that owned Atlas Cycle won it and I never heard if he put it on a bike. as I remember it there was a difference in the internal diameter of the runners so I wonder why that was. test the condenser too, I think you have a weak spark.

[pehayes]

Change the coil.  I had one cylinder not running on my SPII.  Same symptom as you.  Sparks with plug outside but won't spark under compression.  Takes a LOT more amperage to generate a spark through compressed air.  I changed the coil with a temporary loaner from a Ducati and zoom.  Changed both of my coils and it starts, idles, runs, accelerates just fine.

Patrick Hayes
Fremont CA

[Tom H]

For the coil, use can use one from an old VW. It's a little larger, but it will fit. It's what I use in both my loops. Bosch Blue would be great, but I think they were discontinued a few years ago. Most auto parts carry the VW generic. thisoldtractor.com may have a listing for the P/N.

Good luck,
Tom