Yam_Tech314's official build thread

You want to sync the butterflies with 'em closed. The carbs spend most of their lives down in that range. I also suspect the sync is causing (a lot of) your problems. Sync 'em so both just start to open at the same time. See what that does.

If you think about it, if it's popping, the plug is firing. Get the sync sorted, then see where you're at.
I got em dialed in as close as my eyes can get em.when I open them the smallest amount using just the throttle plate I see an equal amount of the port holes showing on the top of the venturis.

They weren't off by a shit load but I guess anything is possible. Gonna run it again tomorrow and see if it makes a difference. If it doesn't, I'll move onto coil swappin'. If that shows a change I'm getting all new coils and wires to prevent any kinda dumb future failures.
 
Picture one is left carb.

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Picture two is right carb.

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If that isn't close enough I'm not sure It'll ever be. Lol
 
It does not appear the butterfly screws have ever been removed. Sometimes when butterflies are reinstalled they are not exactly centered leaving a small gap on one side. Look carefully. I think in the Tech section Carb guide there is a mechanical sync procedure using a spacer in a partially open butterfly set. I recall a 1/8 drill bit (shank end) set under the partially open butterflies for a good repeatable mechanical sync.
 
It does not appear the butterfly screws have ever been removed. Sometimes when butterflies are reinstalled they are not exactly centered leaving a small gap on one side. Look carefully. I think in the Tech section Carb guide there is a mechanical sync procedure using a spacer in a partially open butterfly set. I recall a 1/8 drill bit (shank end) set under the partially open butterflies for a good repeatable mechanical sync.
I thought the same thing. No marring on the screws, and very little side to side play on the butterfly shaft. I'm going with them never being removed. Which means it's probably a good idea to replace the seals on the ends of the shafts. If I get it running good and get a decent plug reading on it then I'm not gonna worry too much about them. It's already really close to performing as good as it should (I think...) I've had seat time on a lot of different bikes and know about what to expect from a parallel twin 650 at this point. I saw a dramatic difference in power output today before and after setting the timing correctly.

Maybe I'll see a bit more when I get the temps more equal and know for a fact I have good strong spark, but I'd be surprised to see it run much better. I'll always hope to see improvement but I can tell I'm really close to where it needs to be.

I'll give the carb section a solid read through tomorrow when I get time! I'm back in the zone on this build. I'm determined to ride it for real this summer.
 
my exhaust temps are considerably closer than they were...

It isn't running as erratically either. Maybe the warmer weather plays a part in it...

I was looking at things and discovered a leaking head gasket. That's enough to really get me discouraged... However... I'm thinking I can try retorquing the head? Once it starts leaking is it too late for me? What do the more experienced folk think about it?

Perhaps this is another factor as to why it's running kinda cruddy.
 

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Head re-torque is ALWAYS worth a try when you consider the alternative.

No, likely has nothing to do with any problems you've had.
 
I'm definitely gonna give it a whirl. I assume it's probably best to let it cool all the way down?
I know the answer to this... I'm just pissed, and impatient. I'm gonna wait til tomorrow night to retorqued the head. Gonna set the wrench to 15, then 20 then 27ft lb for final torque. I hope this fixes the darn leak. I'll be pretty upset if I gotta rip this engine out to replace a head gasket. I guess this is all part of earning experience. Gotta fuck up to learn sometimes.
 
I sat a box fan next to her and sped up the cool down process. I wouldn't have slept tonight if I hadn't done the re-torquing.

There were definitely some bolts that weren't as tight as they needed to be. Here's to hoping I got some more squish outta the gasket and it's sealed back up... Going to be really happy when this thing is done and riding. I rode it today. It was fun. It's keeping me sane. I'm aware the maintenance will never end. However, I'm hoping I'm nearing the end of this troubleshooting nonsense.
 
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My RED Bike is a daily rider. It was a 17009 mi kind of ratty Special when I got it. It recieved retorqueing and basic maintenance and a make over and is a good runner. It is a good daily runnner. I will take it to the Dick Russel Memorial Rally in Arkanansas and run 700 mi next month. There was evidence of a weeping head gasket on this bike, gone now.
 
My RED Bike is a daily rider. It was a 17009 mi kind of ratty Special when I got it. It recieved retorqueing and basic maintenance and a make over and is a good runner. It is a good daily runnner. I will take it to the Dick Russel Memorial Rally in Arkanansas and run 700 mi next month. There was evidence of a weeping head gasket on this bike, gone now.
Thanks for the sense of hope! I'm thinking I just need to start from a level head and go over each and every piece of hardware on this puppy And be sure the past me didn't let the beer make too many decisions... I can say for a fact there was lots of beer involved in a good bit of the process. Stupid kid... Lol
 
So I retorqued the head as I previously mentioned... I put the top motor mounts back on and fired it up, rechecked my timing and somehow managed to get it right without needing any adjustment.

I flogged the livin' piss out of it up and down my street to heat the motor up and give it a good load... (I know... It isn't broken in! How could I?!?) I wanna enjoy this thing while I can. If it does need a new head gasket at least I can say I got to have a little fun on it before replacing it.

I'm gonna let it sit overnight. I saw some bubbles weeping from the left rear portion of the gasket but no puddling or dripping oil. I'm HOPING maybe it's bubbling/weeping as it's burning residual oil. If not? Well, I'll cross that bridge when I get there. The bike was running exceptionally well. Excellent throttle response, no dead spots in the throttle under load, no popping on deceleration, or any kind of real backfiring (minus when it was cold and first started but even that was minimal)

I gotta say, I'm happy with it. I'm hoping I can get away with continuing to move forward rather than taking a large leap backwards. Live and learn. I'll happily do the head gasket over again if it means I learned from it.


Here's to hoping...
 
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Yes, after a rebuild, you need to check the head torque several times in the first 1000 miles or so. By then, after numerous heat cycles, the new gaskets should be all compressed and the torques should stabilize. After that, it's still a good idea to check the torques every year.

I see you used Athena gaskets? I've discovered their head gaskets have a life expectancy of about 10 years. After that, even if you've kept them torqued, they can fail. I've encountered 3 so far that have done this. Needless to say, I won't be using them anymore.
 
I see you used Athena gaskets? I've discovered their head gaskets have a life expectancy of about 10 years. After that, even if you've kept them torqued, they can fail. I've encountered 3 so far that have done this. Needless to say, I won't be using them anymore.
When I see the tell-tale green of Athena base gaskets peeking out of the bottom of barrels, I expect trouble in store for somebody, too.
They had a very bad rep for creeping out under load. Might be Athena have fixed that, by now.
 
Might be Athena have fixed that, by now.
Not as of 4 or 5 yrs ago they ain't. The Athena base gasket and the ones on the cam covers crept big time on my top end. Cam covers leaked big time 'cause they split into pieces. . That base one ain't yet, but it will eventually. Pretty shitty when your gaskets leak at 4yrs and about 4k miles.
@grizld1 rest his soul, warned us about 'em. Unfortunately, I never got the memo.


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