My What Am I Getting Myself Into Combat Build Thread

Yeah, not sure i have the patience to wait to spring anyways.

There's a lot of debate on breaking in procedures (almost as many opinions as engine oil :)). From what i've read, this is my plan (the cam and lifters are orginal so no break needed for those, just the rings)

- 1 min @ 2500 (until oil starts flowing back to tank)
- 1-2 mins @ 2500-3500 until it gets to 70% high temp (~ 280F) (“mid-RPM WFO blasts”)
- Let cool (~ 175F)
- Restart, run at 2500-5000 and check timing with strobe. Make any carb adjustments. Run for another ~5 minutes 2500-5k
- Change oil and filter (still use break in oil)
- Get engine to temp
- Ride 25 miles modulating rpms (bed brakes during this time)
- 75 miles normal riding
- Change oil/filter to synthetic
- Re-torque bolts, check valve lash, and check belt/chains after 25, 100, 250, 500, 1000 and 1500 miles
Yep all of the above
Don't let it idle
Don't let it lug
Don't baby it
Don't be afraid to rev it out
 
Got the carbs hoses on and in-line filter attached. A little worried about how close it is to the barrel, but will keep tabs on temps and see if i need to relocate

View attachment 101394

All that's left now is fueling it up and kicking it over. But do i wait to spring (temps here are winter like)
What's your spec on these miks ?
 
What's your spec on these miks ?
It was a while ago :)

 
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I'm contemplating oil leaks, gas leaks, not firing (electrical issues), not firing (timing issues), gearbox problems, and/or gearbox problems :)
The above things have not happened yet, right?

So the bike is ready, but you aren't? :)

First kick start after a build can be intimidating. All those negative thoughts come up. Got to forget about all the time and money you poured into it, and just do it.

Ignore if you are already familiar with Norton twins:

Turn the gas and ignition off and repeatedly kick it over with the plugs out until you get some dribble at the return pipe in the tank. (If you can see the return pipe.) If you know of a better way to prime the oil system do that instead. Once oil starts dribbling out of the return pipe reinstall the plugs, turn on the fuel, pull up the choke levers, get the crank/pistons just over the top of the compression stroke with the kick start, switch on the ignition, and try to start it.

Mikuni carburetors on the choke tend to run the idle RPM up kind of high, so be prepared to turn off the chokes and keep it running with the throttle until it settles into something like an idle. If you don't have any air leaks, the carburetors are synched, and the ignition close, the standard adjustments should let it run. If the cam and lifters are previously used and are already broken in, the engine break in can be done on the street. None of the 15 minute multiple sessions at 2500 RPM nonsense is required.

If it is wet out, don't ride it. Riding in the wet won't make you feel super manly if you go down in a turn on cold wet new tires. Well, never made me feel like more of a man anyway.

I was hesitant to post the above, because there is nothing new in my drivel, but did it anyway.
 
So the bike is ready, but you aren't? :)
Pretty much LOL. We've had a cold front last couple of weeks. Should be over 50 tomorrow.

And don't plan on kicking it until i get oil return. From what i understand, that could take a while. I used copious amounts of assembly lube and total seal. I also pre-oiled the filter and sludge trap and plan to fill the oil returns. Think i should be good until i get oil return
 
And don't plan on kicking it until i get oil return. From what i understand, that could take a while. I used copious amounts of assembly lube and total seal. I also pre-oiled the filter and sludge trap and plan to fill the oil returns. Think i should be good until i get oil return
Look Here!
 
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Please record it. You can decide later if you want to share it.
 
Well went to start it yesterday. There was good news and some bad news.

Good news, it started! Had to give it some throttle but it started.

Bad news. My convoluted fuel system is air locked

IMG_1862sm.jpg


The gas hose is higher than the petcock so it won't flow to the carb. There's only like an inch between the petcock and the carb inlet so not much room to work with. The setup i had hoped would work was a 'T' off both petcocks that fed a 1 in 2 out filter that then fed the carbs better seen here.

IMG_1834sm.jpg


Well i just could get the carb hoses below the petcocks without them kinking. I then tried it without the filter in an 'H' pattern with the petcocks feeding a 'T' then to a single hose going to another 'T' that then feeds the carbs. Couldn't get that below the petcocks either. Ended up directly feeding each carb from each petcock. That works, but i have no secondary filter and each carb is dependant on each petcock, i.e. if i loose fuel from one petcock, i loose one carb. If anyone has solved plumbing dual Mikuni's, i'm open to recommendations.

That was the easy problem, this is the harder problem

IMG_1863sm.jpg


IMG_1864sm.jpg


Oh, and i have no oil return

Other than that, Happy Thanksgiving

IMG_1866.GIF
 
That’s a bummer. Fixing that breather will be a PITA.

But fuel line air lock theory is wrong IMO. Provided the height of fuel in the tank is above that looped hose, fuel will flow. The location of the petcock is irrelevant. You WILL probably see air in that loop when the engine is not running as, with it being the high point, air will always end there. But that’s not the definition of an air lock.

If in doubt, fill the tank, remove the float bowl plugs and turn on the petcock. I guarantee you’ll see fuel.
 
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Did you grind down a cheap wrench and try to tighten that breather a little more? Maybe you'll get lucky, and it just needs a bit more torque. If not, you are in for a fluster cluck of a job.

No return oil is not good. Did you try the method I suggested to get return oil flowing before starting it? Are you sure you have oil pressure? Only thing the puddle under the reed valve leak proves is you have crank case pressure and oil in the sump from a little wet sumping.

Thoughts about the fuel line:

(Caveat is I do not have a Commando, and I have some room for fuel line plumbing as well as air filters on my version Norton. That and I don't care that much about what it looks like.) Move the rocker oil feed line outside the carburetion so you have room for the fuel line between the carburetors. Use two T's up high in an H configuration. You would not be able to use the big secondary filter though. The filters on the petcocks do an OK job at keeping fuel blocking junk out of the carburetors. An alternative (if there is room) would be to leave the rocker feed line where it is and swap the petcocks so they point toward the rear and the handles are to the outside and build your H fuel line plumbing from there. Maybe figure out how to use the dual output filter with one T. You might be able to get really small plastic fuel filters on if the dual filter is too large to use anywhere. Third alternative is leaving the fuel line plumbing like it is and fix everything else first. Once you get out on the road you'll find out if it is starving for fuel.
 
Did you grind down a cheap wrench and try to tighten that breather a little more? Maybe you'll get lucky, and it just needs a bit more torque. If not, you are in for a fluster cluck of a job.

No return oil is not good. Did you try the method I suggested to get return oil flowing before starting it? Are you sure you have oil pressure? Only thing the puddle under the reed valve leak proves is you have crank case pressure and oil in the sump from a little wet sumping.
Tom and I have talked about all this.

He has tightened - that's not the problem. The kit for 1972 is very nice - however, the gaskets that come with it are not made correctly. I wish cNw would warn people. The holes are too small and not perfectly aligned. If you don't correct that before installing, the gasket rips and if you don't notice it, you'll have a leak. Tom will pickup gaskets from me, I have extras - when I buy new kits, I ask cNw for extras as even being careful you can tear them while opening the holes.

I would have thought that Tom is not waiting long enough since he pre-filled the system, but the breather is continuing to return oil after any wet sump should be cleared. He has excellent oil pressure. He's working on verifying that there are no blockages in the return but it's all new so that's unlikely.

Since there should be nothing but air in the breather, that oil is leaking goes along with the breather returning oil.
 
Yeah i re-tightened the breather but it actually made it worse. The problem is the gasket. It's a little off at the holes. If i recall correctly, it's slightly too small so it bunches the gasket when you put the bolts through the holes. The holes need to be expanded which is not easy because they are small and the gasket is thin and there's not much room to the outside on the gasket for expanding. I optimistically thought it would flatten out when compressed and wouldn't be an issue. I also used some loctite sealant (forget which one of the top of my head, but it's red and thin). That did not work. I am hoping i can get get it off from the bottom, but there's like one bolt that might have a clearance issue with the gearbox.

Not sure why the oil is not returning. I have a temp oil pressure guage at the left rocker inlet. I'm getting pressure there. Maybe it's that i just can't see the return because the breather is constantly gushing over the return tube. Maybe that's a clue, i don't think the breather should be constantly doing that. I pulled the return hose and checked the tube that goes to the tank and that is clear. Next i plan to either kick it or start it to see if i get return at the hose that connects to that tube.

The gas line is the least of my problems at the moment. I have a temp gas tank on and will address the fuel line when i go to replace that

EDIT: I was typing as Greg replied :)
 
Tom, on the bright side, at least you found all this now and not next spring !
Yes, and 60+ (15c) degree days are a shame to waste in late November! Hopefully he can get it all resolved by tomorrow or Monday - supposed to be warm and sunny both days.

The oil leak can be fixed over the winter - it's not that bad and once oil is returning properly there shouldn't be any oil there to leak except after a wet sump.
 
Excuse this underthinking diversion.

I shredded one of the cNw gaskets when removing the cNw breather during an engine teardown. Due to being a shade tree barnyard mechanic I made a new gasket out of card stock. Doesn't leak, tear, or squeeze out. For the bolt holes in the gasket, I used a hole punch or one of those paper punches used for putting holes in paper for a 3 ring binder. Whatever was the right diameter. I do that kind of thing frequently. Who wants to wait 4 days to get a small simple gasket, when you can just make one? OK everybody but me. lol
 
Yeah the CNW gaskets are crap IMO. Jim Schmidt should make gaskets for their breather. I'd gladly pay a couple extra bucks for a better gasket.
 
Yeah the CNW gaskets are crap IMO. Jim Schmidt should make gaskets for their breather. I'd gladly pay a couple extra bucks for a better gasket.
Ha, Jim would be helping the competition in that case.

Jim sells a sump plug position reed breather and a cam, timing case, or rear of crank case reed breather. If I had a different exhaust, one that did not go right under the sump plug, I'd use his low profile sump breather.
 
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