Silver Star ignition advance

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My Silver Star has developed a problem similar to that reported with a Saxon here: viewtopic.php?f=26&t=5638. The symptoms have happened a few times over the years, and I've messed with this and that and seemed to have made the problem go away. Over the past couple of days the problem has come back and stayed, giving me a chance to really diagnose it.

The problem manifests as low power at higher RPM. As with the Saxon referenced above, the idle is great and the bike pulls fairly well at low rpm, but just runs out of steam at higher engine speeds. On a ride yesterday top speed on the level was around 100kph in both 4th and 5th gears.

While telling myself that 90% of carburetion problems are ignition problems, I proceeded to go through the carburetter, check valve clearances and decompressor action, check camshaft timing and belt tension, and replace the spark plug before viewing the ignition timing with a stroboscopic light.

Timing at idle is exactly correct, but on accelerating the engine it simply stays at 3 degrees BTDC.

Not entirely believing the manual, which says that "there is no provision for timing adjustment", I removed the right side engine cover and found nothing at all of mechanical interest in there, so I put it back together again.

So here am I, hoping that some one here will know how the advance is supposed to work, and can tell me what next step to take to restore this lovely motorcycle to its former liveliness.

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I've discovered the trouble-shooting document here:
https://docs.google.com/file/d/0B0BD_Mk ... t?hl=en_GB

I was somewhat encouraged by the statement there under "Poor Running" regarding degraded performance. I performed Tests 3, 4, and 5; all results were within published limits.

Unless I hear something to the contrary here or in my other research it looks like I'll be ordering a CDI unit from Rex's Speed Shop. I will post my finding here when the motorcycle is fixed.

[DAVID THOMPSON]

mine has a bing carb
and once the fuel line from the tank had a kink in it,,
check that fuel line and clean the tank petcock also
while your at it clean out the tank

do this outside as its a mess because the tank petcock has to be remove before the tank is empty

and while in this far replace the oil line from the top of head to top oil tank in frame

trust me its not some thing you want to do on a road trip
dave

[comanche91]

Roger that. Before I converted the Silver Star to a cafe with a new tank it was doing the same thing at higher RPMs. Not all the time but off and on. I did have a spare CDI unit I swapped out and it didn't help. Now, with the new tank, it will RPM smoothly all the way to 7K and keep pulling. I had never pulled the petcock before on the original tank, but did pull it after it was removed from the bike. LOTS of crud and mung all over the petcock filter. So I attributed the missing and limited high RPMs to fuel starvation in my case. It's definitely worth a shot.

[DAVID THOMPSON]

mine is a saxon tour

and the catch 22 is carb comes off tank comes off but the petcock blocks carb removel
so petcock has to come off first
resulting in a big MESS
i use a piece of brake line and hose with a pump to suck tank dry but it is still is a mess
draining does not get it all neither does the pump

so take the bike out side to make the mess ...so you do not flame the shed or house
fire extinguisher on hand a good idea and no smoking

dave

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My Silver Star seems to be fixed.

I ordered a CDI unit from Rex's Speed Shop on 26 March and it arrived here in Schoharie County New York yesterday 6 April. The unit is nicely finished, and installation is a doddle. I started the bike and watched the ignition timing advance which it did nicely. I then took the bike for a short ride (it's pretty cold here) and performance seemed to be just as it should be.

Now if the wind would stop howling and the temperature would go up a few degrees....

Thanks for the helpful suggestions.