Topic: Chronicals of my 550 rebuild - over a month in with one day to go! PICS!

[mrbreeze]

Why wait till spring? I'd throw that Dyna in there now(JUST AN OPINION!!!!!) Peace!!!!

[paulages]

except that it only takes about 30 minutes to do and completely eliminates one variable when diagnosing potential problems. if it were me, i'd drop it in. but i understand wanting to get back on the road before the weather turns totally sour. my tank, seat and sidecovers got stuck at the painter for over two weeks in august. that was painful...i was stuck riding my 750. 

[Tim.]

I'd sure like to pop it on, but will see if it fires up immediately later today once I get it all done and new fuel lines on.

I haven't spent a lot of time looking at the Dyna, but know I need to run the red power wire to it from a switched source.  What's the preferred location for this?

Also, once it's on, what do you use to turn the crank to TDC etc.?  Put it in 1st and use the rear wheel?  Kick starter doesn't offer the fine adjustment that a wrench on the end of the crankshaft does, but without that big 'nut' on the end, how else does one do it?  Or am I being completely obtuse?

One last question if anyone knows - the two black tubes running off the backside of the carbs - not fuel lines - about 12 inches long and pretty small diameter.

What on earth are these?  They're listed as Fuel tubes, but they're 3.5mm and don't go anywhere.

[Jonesy]

The Dyna system gets the power feed from the coil power (black wire with white stripe). I just ran mine along the wire harness section that carries the blue/yellow wires for the points. It is recommended that you solder the red wire, rather than use the cheap wire tap provided in the kit.

Also, on the advance mechanism, all you replace is the breaker cam. The rest of the advance unit and the special endcap nut stays the same. You can still move the engine with a large socket is you have to.

It looks like the hoses are the carb bowl vent tubes (just like the ones on the CB750, but I can't directly compare to my 550 as I have the '78 no-smog model.).

[paulages]

tintin-

i can't remember exactly where i tied mine in as it is now buried beneath the (originally non-existent) airbox, but it was really easy to find where to do it. i want to say that there was already a bl/wh, blue, and yellow connection in the exact same place that just needed to be tied into. in any case, it works behind the elec. panel.

those carb hoses are indeed the bowl vent tubes, which supply atmospheric pressure the the headspace in the bowls. this pressure needs to be as constant as possible so that fuel will want to climb the jets when there is low pressure in the carbs on the intake stroke. if they are not routed to where they are supposed to be in front of the rear wheel, the jetting could get wacky when you get going fast, and that pressure changes.

[Tim.]

I would have thought the overflow tubes would have provided the venting.  Is there any reason tubes are required on the vents?  The parts manual specifies ~300 mm long tubes, which is a foot or so.  I'm likely going to put long ones on and zip-tie them in with the overflow tubes, but perhaps too-long might be a problem?

[Tim.]

So, got the rest of it bolted together and set the tappets.

Seems I have some stuck or failed fuel valves in my carbs, as a couple of them immediately overflowed - no big deal.

Didn't get it up and running - low charge on battery and tired legs didn't help.  Need to confirm spark etc. but it should get up and running in a day or so.

I did a very, VERY quick and rudimentary compression test on #4 just out of curiousity.  Of course the engine was stone cold and never has been fired.  With a few kicks it got up to 150psi which I think is pretty respectable given the conditions.  I'd expect it should improve when warm and broken in.  Factory spec is 170 so I'm pretty pleased with the results thus far.

Hopefully I'll get it fired up soon so I can synch the carbs.  Then the Dyna can go on!

[Tim.]

So, got it running on #1 and #2.  #3 and #4 aren't getting fuel - dry bowls.  So, either there's an issue in the T that splits fuel to the carbs or in both valves.

#1 and #2's overflow problem seems to have gone away with some vibration and use.  Might just swap out the valves with the ones from my other working carbs to see if that does it.  Fuel is getting to the T between the carbs, but not beyond for both.

The good news is that is sounds unbelievable even on two cylinders.  This thing is going to be killer once it's running on all 4. 

[Stevearino]

Got to say, reminds me of how I spent a lot of cold winter nights in the garage last year.  Nothing to warm me but the thought of hot summer days ahead.  That and a cocktail or four.

I took mine out of the frame.  I figured that a month on the bench was worth a couple hours of wrassling it back into the frame, rather than a month of crouching over it.  Also made cleaning the bottom of the engine that much easier.  With the carbs off, it only weighs 120 lbs.

BTW, since I worked out the carb issues, it screams.  Success is the sweet reward for ambition, time and persistence.

[Tim.]

Well it aint winter yet here.  I'll be riding this week.  Got it running on all 4 and synched up the carbs.  Putting the Dyna on tonight, as I don't like the points on #2 and #3 - I think I tweaked them with my wrench when turning the crankshaft at some point.

150 psi across the board - all 4 cylinders reporting the same pressure.  It's running great - better than it ever has.  Dyna tonight, then I'm riding again.

[paulages]

congratulations!

[bwaller]

Well done, here's hoping Indian summer treats us to some more good riding weather.

[ProTeal55]

Good job