OK, some updates.
Long post warning again!
First of all my homework: I remembered to verify these again with the bike running 2M.
Blocking the pilot ports at idle will stall the bike.
Blocking the pilot ports at 3000-3500 rpm’s causes dramatic rpm drop.
Blocking the main port has no effect as that circuit only comes into play at full throttle.
I figure this proves the pilot circuit is clear and operating properly.
On proboards.com com 5twins said re: Advance rod;
“It wasn't easy to measure, but near as I could tell, I had about .015" end play. I shimmed it down to about .005". You can't go too tight or the advance rod won't advance - it will bind up when you tighten the disc down. Check it by rotating it by hand."
I checked mine and I have a good 0.5mm or better than .020” end play. Gonna need a bunch of shims.
When I started the bike this time it wasn't running on the left side. Huh. Pulled the plug wire and it started firing if I rested the cap on the plug, Was this in essence increasing the gap? Switched the plugs side to side, problem followed.
Plugs looked glossy wet, not sooty. Thought maybe they were still rich. Put in a new plug, all good. This has happened to me before, and I thought it was from rich carbs. Didn't know enough then to understand what this might mean.
Used Paul Sutton's piece of cardboard throttle stop screw shim idea to hold the rpm’s @ 3000 - 3500.
Wanted to check the timing before doing anything else.
My timing on both cylinders at idle is jumping around a lot worse than seen in 2M’s video.
Right side: Will sit on the full advance line then will advance about 3°, then will drop 4° - 5° and “bounces” around back up to the line. This continues to happen back and forth. I would say the total range of movement back and forth across the full advance mark is about 8°, maybe a little more.
Left side: Sits on the full advance line with some definite “bounce” past the full advance line.
So at this point I think I'm done.
Not done as in throwing in the towel, but done with this stock ignition. Looks like an upgrade is imminent.
Just had to test carbs again to rule them out. Figured it would only take a couple minutes to swap them to my other bike, the 78 Black. 4:11.6 actually. Idled really smooth, so I knew carbs had to be good, and my timing and other problems on the 77 Blue are ignition related.
Mix screws now set right 1 ¾, left 1 ¼. And that was done in a few seconds. I’m sure I can get them closer.
After Black Betty (the 78), warmed up it started backfiring through the exhaust on the right side, so I suspected an exhaust leak.
I guess this is a pretty good tell on that.
Even with that leak, it still idled well, and pressure on the pipes felt good so sync is close. A little hard to tell with that backfire but close.
Rule out carbs (I hope)
But…....................man I hate that word these days.
Looks like I'm receiving a baptism by fire on this old girl. I’m getting beaten ‘Black’ and ‘Blue’.
When I had the Blue revved up and holding at 3000 - 3500 to check full advance timing, I saw a lot of smoke from the exhaust. Hadn’t noticed a lot of this before and when I did I passed it off to burning off carbon on the pistons then to rich carbs.
Thought maybe still rich, but looked more white/gray than black. So I put the carbs back on Ol’ Blue to see if that little smoke problem might have just cleared itself up……...lol.
Once it warmed up, at 3000-3500 rpm it would blow white/gray smoke, more on the left side than the right. I knew this wasn’t a good sign and probably meant bad rings, valves, seals?
Checked oil level, definitely down, so it’s been burning oil since the last oil change 04/23/17.
No fuel smell in the oil though.
Mileage 33844 Kms, 21029 miles.
These look oil fouled to me.
Checked compression when warm:
Left 155 / 160 /160
Right 150 / 150 / 150
So I guess my rings are OK?
Was going to build a leak down tester out of some odds and sods but haven't been able to find a Schrader/check valve yet. Figured after reading some comments by gggGary, seeing if and where it is leaking air is more important than how much pressure it's losing.
So I just used this in the plug holes, cylinders TDC, carbs off, exhaust still on.
Air leaks out both carb manifolds and with my hand blocking the carb manifold inlet, can hear it out each muffler.
Looked at intake valves, they look pretty carboned up I think.
Right
Left
Haven't pulled the exhausts yet to inspect exhaust valves. Guess I should do that as both sides are leaking out of mufflers as well. Looks like the biggest challenge doing that is separating the cross over pipe. I like Fred's idea of pushing it apart with a bolt/all thread rig. Any other tips on removing the exhausts?
I have read gggGary’s meatball mechanic valve carbon clean up thread and I have looked at Farrell's instructions on changing valve seals while the engine is in the bike.
Other than visual inspection, is there a way I can tell if it’s carbon build up versus bad valve seals?
Any other tests I should be doing?
Hoping to avoid pulling the engine and doing the top end, should I:
Not too excited about this idea. The last motor I tore down and rebuilt was a lawnmower motor in High School Auto Shop class and I’m not sure it ever ran again. Not a good track record.
Boy, I don’t know which will be smokin’ worse, my bike or my credit card.
I was sitting a spell thinking maybe I should have just left this bike in storage.
But, then I wouldn’t have met all you guys, and would have missed out on all this fun.
I thought I’d be wrapping this thread up soon but it looks like it might go on for another page or two.
You guys are sure going to get sick and tired of me…..lol.
I'm sitting down, holding my breath, looking at engine stand plans, waiting for feedback. Thanks again guys.
Long post warning again!
First of all my homework: I remembered to verify these again with the bike running 2M.
Blocking the pilot ports at idle will stall the bike.
Blocking the pilot ports at 3000-3500 rpm’s causes dramatic rpm drop.
Blocking the main port has no effect as that circuit only comes into play at full throttle.
I figure this proves the pilot circuit is clear and operating properly.
On proboards.com com 5twins said re: Advance rod;
“It wasn't easy to measure, but near as I could tell, I had about .015" end play. I shimmed it down to about .005". You can't go too tight or the advance rod won't advance - it will bind up when you tighten the disc down. Check it by rotating it by hand."
I checked mine and I have a good 0.5mm or better than .020” end play. Gonna need a bunch of shims.
When I started the bike this time it wasn't running on the left side. Huh. Pulled the plug wire and it started firing if I rested the cap on the plug, Was this in essence increasing the gap? Switched the plugs side to side, problem followed.
Plugs looked glossy wet, not sooty. Thought maybe they were still rich. Put in a new plug, all good. This has happened to me before, and I thought it was from rich carbs. Didn't know enough then to understand what this might mean.
Used Paul Sutton's piece of cardboard throttle stop screw shim idea to hold the rpm’s @ 3000 - 3500.
Wanted to check the timing before doing anything else.
My timing on both cylinders at idle is jumping around a lot worse than seen in 2M’s video.
Right side: Will sit on the full advance line then will advance about 3°, then will drop 4° - 5° and “bounces” around back up to the line. This continues to happen back and forth. I would say the total range of movement back and forth across the full advance mark is about 8°, maybe a little more.
Left side: Sits on the full advance line with some definite “bounce” past the full advance line.
So at this point I think I'm done.
Not done as in throwing in the towel, but done with this stock ignition. Looks like an upgrade is imminent.
Just had to test carbs again to rule them out. Figured it would only take a couple minutes to swap them to my other bike, the 78 Black. 4:11.6 actually. Idled really smooth, so I knew carbs had to be good, and my timing and other problems on the 77 Blue are ignition related.
Mix screws now set right 1 ¾, left 1 ¼. And that was done in a few seconds. I’m sure I can get them closer.
After Black Betty (the 78), warmed up it started backfiring through the exhaust on the right side, so I suspected an exhaust leak.
I guess this is a pretty good tell on that.
Even with that leak, it still idled well, and pressure on the pipes felt good so sync is close. A little hard to tell with that backfire but close.
Rule out carbs (I hope)
But…....................man I hate that word these days.
Looks like I'm receiving a baptism by fire on this old girl. I’m getting beaten ‘Black’ and ‘Blue’.
When I had the Blue revved up and holding at 3000 - 3500 to check full advance timing, I saw a lot of smoke from the exhaust. Hadn’t noticed a lot of this before and when I did I passed it off to burning off carbon on the pistons then to rich carbs.
Thought maybe still rich, but looked more white/gray than black. So I put the carbs back on Ol’ Blue to see if that little smoke problem might have just cleared itself up……...lol.
Once it warmed up, at 3000-3500 rpm it would blow white/gray smoke, more on the left side than the right. I knew this wasn’t a good sign and probably meant bad rings, valves, seals?
Checked oil level, definitely down, so it’s been burning oil since the last oil change 04/23/17.
No fuel smell in the oil though.
Mileage 33844 Kms, 21029 miles.
These look oil fouled to me.
Checked compression when warm:
Left 155 / 160 /160
Right 150 / 150 / 150
So I guess my rings are OK?
Was going to build a leak down tester out of some odds and sods but haven't been able to find a Schrader/check valve yet. Figured after reading some comments by gggGary, seeing if and where it is leaking air is more important than how much pressure it's losing.
So I just used this in the plug holes, cylinders TDC, carbs off, exhaust still on.
Air leaks out both carb manifolds and with my hand blocking the carb manifold inlet, can hear it out each muffler.
Looked at intake valves, they look pretty carboned up I think.
Right
Left
Haven't pulled the exhausts yet to inspect exhaust valves. Guess I should do that as both sides are leaking out of mufflers as well. Looks like the biggest challenge doing that is separating the cross over pipe. I like Fred's idea of pushing it apart with a bolt/all thread rig. Any other tips on removing the exhausts?
I have read gggGary’s meatball mechanic valve carbon clean up thread and I have looked at Farrell's instructions on changing valve seals while the engine is in the bike.
Other than visual inspection, is there a way I can tell if it’s carbon build up versus bad valve seals?
Any other tests I should be doing?
Hoping to avoid pulling the engine and doing the top end, should I:
- Try gggGary’s meatball mechanic carbon clean up fix, then test?
- If no joy, replace valve seals with engine in bike, then test? (Although I see this isn't an easy thing to do even for an experienced mechanic.)
- If all good, then install new Pamco / E-advance?
- Or, please say it ain’t so. Pull the engine, lap valves, new seals, new cam chain and guide, and whatever else I should do while I’m in there. Would head have to be machined?
Not too excited about this idea. The last motor I tore down and rebuilt was a lawnmower motor in High School Auto Shop class and I’m not sure it ever ran again. Not a good track record.
Boy, I don’t know which will be smokin’ worse, my bike or my credit card.
I was sitting a spell thinking maybe I should have just left this bike in storage.
But, then I wouldn’t have met all you guys, and would have missed out on all this fun.
I thought I’d be wrapping this thread up soon but it looks like it might go on for another page or two.
You guys are sure going to get sick and tired of me…..lol.
I'm sitting down, holding my breath, looking at engine stand plans, waiting for feedback. Thanks again guys.