82 550LZ - Newly rebuilt - Carb Proble - Break-In

[BillGS550LZ]

Hello everyone,

Hope you are doing well and for all us northeast people I hope winter ends soon. I need your help.

I rebuilt my motor. I think I made a rookie mistake in that I also fiddled with the carbs. The motor fired right up on the second attempt, not relevant but the first attempt I had the timing cam 180 degrees off so plugs were firing at BDC.

The motor runs like crap and won't idle. Over revs with choke on and stalls with it off. Idle screws are set at 2 3/4 turns.

I was plenty scared to start it for the first time, I am even more scare to try to break-in the engine the way it is running. Based on other posts I've read, It's not good to let a newly rebuilt motor idle for too long, but it will take time, in my case lots of time, to adjust/synch the carbs.

Any suggestions what I should do would be greatly appreciated. Thanks

 

[DimitriT]

Rebuild means a new top end?

Lots can go wrong with a top end tear down/reassembly. Your cams might be one pin off from the correct timing position or the number of pins between them might be off.

Just for my sanity I would pull the covers and double check that.

Turn the motor over with a socket and make sure it comes back to the same position.

If that all checks out then we go back to fuel delivery.

 

[Nessism]

Is the airbox installed? Just for kicks you might want to check the Newbie Mistakes thread linked in my signature.

 

[tom203]

Yeah,as DimitriT asks, what does rebuild mean here? and how did you fiddle with carbs? did you get this bike as a non runner ?
If you had carbs off, you disturbed boots and o-ring seal at head interface, did you replace o-rings ?
A bench sync of carbs is adequate to get things reasonable-fine tuning comes later.

 

[DimitriT]

Also forgot to ask if you had checked the valve clearances once the cams where back on.

 

[BillGS550LZ]

Hi there. Thanks for your input. Sorry i had to step away for a bit.

Betsy and I go back two years. Some of our history is documented in my album.

Wanting to fix second gear prompted my opening her up but pandora is a bitxx. Rebuilt, as in complete tear down, head, valves, jugs, split case, trans and crank. Issues found, bent shift rod and clutch push rod, broken crank (#4 cyl journals separated about 1/4", I could see evidence that the PO had a bad chain break, but can't image what else could have caused this), don't know what they are called but one of two sheet metal plates found directly under #2-3 cyls had broken completely off, and of course broken second gear and bent shift fork. I can't believe it run this way, amazing motor!

The motor was running before. As I said she started on second try after assembly. I fiddled with the carbs since i figure new rings voided any synching done prior. Cam timing seems good, valve clearance checks out, stock air box is in place, did carbs bench-synch, I did not apply glue to the new intake boots o-rings so it's possible though unlikely there is a vacum leak, will recheck.

The questions I am trying to answer are:
a-How much time do I have to adjust idle enough for it to run smooth before the ring seatting process is ruined?
b-How bad is it to do beak-in procedure without proper carb synch?
c-I've read alot of blow-by can be produced until new rings have properly seatted. Seems logical a second crankcase breather port will keep too much pressure off all the seals during break-in, except head gaskets I think, but how bad will it be to have near zero crankcase pressure?

Thank you all for your time and input. Best regards.

Side note:
Have head cover off now because after 5-10min running, trying to adjust idle, exhaust cam plugs blew out (slight poof). I definitly didn't let it sit long enough after assembly. Another issue to deal with, too much blow-by, unsettled glue, idk. I was very careful honing bores, installing new rings and assembling head so don't suspect these. Thinking about adding another vent port in the oil filler cap to allow more blow-by to scape during break-in period. Also worried lack of crankcase pressure will keep rings from seatting, again idk.

 

[Steve]

If you have ANY pressure building up inside the cases, I would first check out why your present vent is not working. You would have to have a hole in a piston to build up pressure in the crankcase faster than the stock vent could bleed it off. Verify that all of that is open and working before you do any unnecessary modifications.

Your problem with no idle might be simply that the idle speed screw is not in far enough to raise the idle to a proper speed. Every bike is going to be a little different, but one or two turns after the screw contacts the linkage should be enough.

Not sure what "glue" you are talking about, there is not usually any that is needed during re-assembly.

.

 

[BillGS550LZ]

The crank case breather is not restricted in any way. On the cam end plugs (half moons) I used the same glue I used to seal the case, threebond.

I doubt a hole in a piston would generate much pressure at all but i think i get what you are trying to say.

Again i think I didn't let the glue I'd applied to the cam end plugs set/cure long enough and that is why they popped out. Perhaps I'm being too paranoid about it happening again that's why I was thinking adding another vent port at the oil fill cap.

 

[DimitriT]

Can you do a compression test?

 

[BillGS550LZ]

Hi DimitriT sorry for the long time to reply.

I just got the new VCG and new half moon plugs. As soon as the weather gets a little better, in a few weeks sorry to say, I will get them installed I will do a compression test and report back. Right now I'm focusing on things I can do away from the bone chilling garage/basement like electrical stuff. Just built a new circuit to replace the six bulb gear indicator.