(Updated):vibrations and slightly hard cold starting '77 lemans

[amamet]

I now have it stuck in my head there is a problem with parts that were balanced.  I don't remember the vibrations being as bad as they have been lately.  Then again I have been taking it out on longer rides.  I retorqued the heads after my heat cycles about 300 mile ago.  Also I have a little trouble cold starting the bike each day.  The first time I hit the start button after the rebuild, the bike started right up.  now its a little fiddlng with the choke and/or throttle.  the bike responds well on the road and accelerated like a freight train.  carbs have been synced but I can sync them again to make sure.  I guess I can also retorque once again and check the valves again.  plugs look good too.  I can feel the buzzing from my feet to my hands, even the mirror is unusable due to vibrations

[pehayes]

I now have it stuck in my head there is a problem with parts that were balanced.  I don't remember the vibrations being as bad as they have been lately.  Then again I have been taking it out on longer rides.  I retorqued the heads after my heat cycles about 300 mile ago.  Also I have a little trouble cold starting the bike each day.  The first time I hit the start button after the rebuild, the bike started right up.  now its a little fiddlng with the choke and/or throttle.  the bike responds well on the road and accelerated like a freight train.  carbs have been synced but I can sync them again to make sure.  I guess I can also retorque once again and check the valves again.  plugs look good too.  I can feel the buzzing from my feet to my hands, even the mirror is unusable due to vibrations

What sequence of service are you using?  Balance and Sync must be the last.  If you torque the heads, you will surely disrupt the carb balance and sync. Torque the heads, then adjust the valves, then balance and sync via vacuum.

Patrick Hayes
Fremont CA

[amamet]

yes, I usually do head work then carbs. I was just wondering if I would need to look at the heads (valves and torque) after I just did them 300 miles ago. again, only 350 miles since it was rebuilt.  I can revisit the Dyna timing I guess too just to be sure

[bodine99]

Acell/pumps weak or too much choke. New engine might just need a few squirts & no choke cold.  Tight valve after retorque? Ign. timing, point gap closing up?
Vibration exhaust grounding out?

[chuck peterson]

Just asking...

Balanced the rotating parts to the counterweight on the crank, right?

Isn’t it a percent difference that guzzi keeps in a locked draw somewhere

or is that a percent difference that engine builders commonly use?

[guzzisteve]

Unless you have the flip-up chokes the cables can be sync'd w/carb sticks, just like throttle cables.

[moto-uno]

 Is this vibration road speed or motor speed related ?   Peter

[amamet]

road speed, no vibration when clutch is pulled in.  im going to retorque heads, adjust valve clearance and go through the Dyna timing bits next chance I get.  then carbs. 

[amamet]

well, just looked at my timing bits, the rear most part of the left cylinder sensor of the Dyna was rubbing on the rotor and actually caused a noticeable wear in the rotor between the set screws.  maybe the plate was a little off when it was screwed to the dizzy housing.  it also chamfered the corner of said sensor a little.  also noticed that the rotor line matched up with the right cylinder sensor at tdc but did not with the left sensor while at tdc.  I  remounted everything and there is now space between the rotor and sensor for both cylinders.  maybe that was the issue?  do you think both rotor and sensor are fine to reuse?  I can add picts tomorrow if someone know these parts well

[blackcat]

road speed, no vibration when clutch is pulled in. 

Does the vibration increase with speed? Is it possible that this is related to out of balance tires? Front suspension issues?  Have you rechecked the nuts on the triple trees?

"Also I have a little trouble cold starting the bike each day."

With the Dyna being re-adjusted, does it start quicker now and how is the vibration?

[amamet]

still messing with the Dyna and ignition timing.  I can't seem to get the rotor to clear the sensor.  the 2 set screws pull the rotor out a bit and when it come around, it contacts the sensor

[blackcat]

still messing with the Dyna and ignition timing.  I can't seem to get the rotor to clear the sensor.  the 2 set screws pull the rotor out a bit and when it come around, it contacts the sensor

I think that there might be some play in the sensor when you loosen up the nuts. Either that or you could put a small shim behind the rotor.