first start messy

sprocket750 · Apr 6, 2013

Hey, I've finished putting a 73 750 commando back together after a head rebuild, new rings, new cam, I got it to start up awhile ago and it smoked and spit oil out the exhaust. I let it run for awhile as I adjusted the idle but it was getting pretty smokey and the oil concerned me so I shut it off. now I cant get it started again. the plugs are coated with oil, I've clean them off and can get a little puff but not a start. Help me out here, what's going on?

iceteanolemon · Apr 6, 2013

Wet oil on the plugs?

Ugh, the head or the gasket or the rings right?

That oil galley is right next to the cylinder and if the gasket is wrong or not annealed maybe oil go right into the jug? Maybe oil coin in from the head through valve guides?

If its straight oil set and everything comin into the cyl I would think about head off inspection myself. I'm sure the experienced guys will chime in soon, they are REAL good at giving the correct first check items advice so your in good hands here.

Give it a few hours and check the easiest options given in the thread first!!

Cheers,

concours · Apr 6, 2013

sprocket750 said:
Hey, I've finished putting a 73 750 commando back together after a head rebuild, new rings, new cam, I got it to start up awhile ago and it smoked and spit oil out the exhaust. I let it run for awhile as I adjusted the idle but it was getting pretty smokey and the oil concerned me so I shut it off. now I cant get it started again. the plugs are coated with oil, I've clean them off and can get a little puff but not a start. Help me out here, what's going on?

Basics.. compression test. Fuel, ignition, timing. Is the battery topped up?

pete.v · Apr 6, 2013

Drain the sump, measure, and then tank. See how much oil you got in there. Refill with no more than 3 quarts. Don't worry about what the dip stick reads until a good warmup.

Dances with Shrapnel · Apr 6, 2013

You might as well tear into it. That much oil is radical. See if the oil return is blocked in the cylinder head (pooling oil by intake valves springs)

My hunch is one or more of the oil control ring expanders is overlapped. It's really easy to do.

The expanders are the squiggly thing between the two rails and should butt together in the groove.

Hobot · Apr 6, 2013

Suspect the rocker spindles installed with groove turned away from oil passage to block the excess oil into head that might flow down the guides. Its worth while to buy a V8 set of plugs for just this fouling occasion that can still stimmy ya even after the initial cause fixed.

Matt Spencer · Apr 6, 2013

Have you checked the Oil return , ?

somebody mightve used SILICON 7 clogged it , or a kinked pipe / hose .

If all thats right , PANIC . or kick it through with the plugs out .
Certain types have been known to invert the motorcycle to drain the water out if theyve got in over there heads , or up to their knees / tank .

So could drain oil from cylindres thus . :shock:

AIR / FUEL / SPARK , o.k. & it has to run .

Could use ' soft ' plugs , a couple of grades hotter for start up , if youre not going W.F.O.

times of old the heat ranges wernt as elastic , so was necessary for warm up of Grand Prix / Tooned Engines .
just dont run it flat out on them . rumoured to be the cause of surtees debacle with the Lola aston ; lead to uprated design of the AM V8 though .
So wasnt all bad . :lol: 8)

rpatton · Apr 7, 2013

iceteanolemon said:
Give it a few hours and check the easiest options given in the thread first!!
Cheers,

+1

pvisseriii said:
Drain the sump, measure, and then tank. See how much oil you got in there. Refill with no more than 3 quarts. Don't worry about what the dip stick reads until a good warmup.

+2

You could have a crankcase full of oil. When you go to drain it you need to watch out for a weird possibility, I came across this myself a few months ago. After a few months of sitting my oiltank was just about empty. I pulled the crankcase drain plug and just a few drops of oil came out. I pulled off one of the exhaust valve covers and it was a gusher. The PCV valve was airtight and it was submerged in the sump. It would have drained sooner or later, but if one was to just go ahead and top off the oil tank then it would have been an oil $hit Storm when the engine was fired up, along with a shot crank seal.

rpatton · Apr 7, 2013

rpatton said:
I keep hitting quote instead of edit

Hobot · Apr 7, 2013

Say what? Ya mean the sump mount flapper valve finally made it possible to hydro lock a Norton the engine? Good to learn form others.

rpatton · Apr 7, 2013

hobot said:
Say what? Ya mean the sump mount flapper valve finally made it possible to hydro lock a Norton the engine?

Nope. My point was that if you don't see any oil when you take out the drain plug in the crankcase that you could assume the case is empty and try to start the engine full of oil. It is pretty much established that it will overcome the crank seal, especially if you rev the engine before the oil has been cleared. This would happen no matter where the flapper PCV valve is situated, as long as it's reasonably airtight. It might be that in sprocket750's case that the valve guide seals and the oil rings could have had trouble keeping the oil where it belongs too and that could have caused the problem. Add the seal on the cam at the points, for that matter. BTW, new plugs might work better than tying to clean the fouled ones.

Like iceaolemon said, try the easy stuff first. This could have nothing to do with what's going on at all. I wanted to add it to the list of things that could cause the engine to be overcome with oil. It's just that it recently happened on my bike and I wouldn't have believed it if I had't seen it myself.

donmeek · Apr 7, 2013

happened once to me years ago when my 3 year old "helper" stuffed a crayon into the end of the breather hose.

sprocket750 · Apr 7, 2013

no, I'm not getting any return to the oil tank. I used the Right Stuff to put the case back together,,think I might have squeeze some out and blocked an return?

sprocket750 · Apr 7, 2013

The head work was done by Leo Goff. I doubt I have any problems there. :?

sprocket750 · Apr 7, 2013

Dances with Shrapnel said:
My hunch is one or more of the oil control ring expanders is overlapped. It's really easy to do.

The expanders are the squiggly thing between the two rails and should but together in the groove.

I know little about the head. Like I mentioned I had that work done professionally. but in this quote are you referring to squiggly things on the rocker spindle that sandwich the rocker arm?

Not sure what to do here, I guess I should drain the case first, somehow clean the jugs out with the head on, then what?

concours · Apr 7, 2013

sprocket750 said:
Not sure what to do here, I guess I should drain the case first, somehow clean the jugs out with the head on, then what?

As previously suggested.. check the easy things first. Remove the rocker covers, check for excess oil, if so, figure out why no drainage/excess flow. If not, continue on. Sump excess oil?

pete.v · Apr 7, 2013

sprocket750 said:
no, I'm not getting any return to the oil tank.

It is WAAYY easy to get the plumbing crossed up. "Triple" check your routing.

sprocket750 · Apr 7, 2013

pvisseriii said:
sprocket750 said:

no, I'm not getting any return to the oil tank.

Click to expand...

It is WAAYY easy to get the plumbing crossed up. "Triple" check your routing.

wouldn't put it past myself..but, that all checks out. took off the lines mounted to the case, I've got oil coming out both feed from the tank and return to filter. I blew through both and they are clear of blockage and it appears oil is coming out of the case ok....going to open up the rocker covers and see what it looks like.

mike996 · Apr 7, 2013

The intake side of the rocker box has a 1/8" diameter drain passage from the head through the cylinder barrel casting which is marginal in the best of conditions re oil draining. Any gasket sealer squeeze-out when installing the head or cylinder barrels can totally block that passage and prevent oil from leaving the intake rocker box as fast as it arrives. Also, as noted, if the rocker arm spindles are installed 180 out, oil will fill the rocker boxes faster than an UNOBSTRUCTED drain will clear it.

If either of the above occurs, the valve stems will be submerged in oil above the level of the seals and seals are not designed to deal with that.
Also of course, the valve seals themselves may be faulty or missing. Don't assume anything regardless of who assembled it.

sprocket750 · Apr 7, 2013

I remember this oil passage when fitting the head gasket...my gasket had a hole on each L/R side to a accommodate other models. Maybe gasket is the problem, it's a paper kind with metal rings around each cylinder, fitted dry.

I just took a look inside the rocker and there doesn't seem to be any excess oil anywhere and the cylinders look dry flashing a lite down in them. Plugs were still wet with oil. haven't opened up the drain to the case yet but I wonder how much I'm carrying in my exhaust pipes.

first start messy

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