Heartbreaking pictures

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If the single Mikuni and 1 into 2 manifold is going back on it again, maybe consider drilling the inner bolts and simply lock wiring them to each other?
 
The Norton atlas manifold has two csk slotted head screws
You centre punch each end of the slot to secure them
I'd still only use a manifold with a screw each end tbh
 
baz said:
I'm sure there's a gynecologist joke here
But I've decided not to go there in these current climes
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Yea
I looked at the link from L.A.B. at #4.
Rethinking that one... and you are probably going to use blue Loctite, 242 or 243.
Or go to a Nord-lock washer if it fits in those sockets.
 
I'm guessing my SU plus associated paraphernalia must weigh at least three, possibly four times the single Mikuni set up (I have had both here :-) ), yet that hangs happily on just the two outer fasteners. Assuming your mating surfaces are true I'd ditch the inner bolts/screws/studs.......
 
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EstuaryBoy said:
I'm guessing my SU plus associated paraphernalia must weigh at least three, possibly four times the single Mikuni set up (I have had both here :) ), yet that hangs happily on just the two outer fasteners. Assuming your mating surfaces are true I'd ditch the inner bolts/screws/studs.......
Click to expand...
I have had people on here tell me that two mounting screws won't work
Won't be strong enough etc I have been running various 2 into 1 manifolds held on by two screws for years, never had a problem yet
 
Sorry I missed the Mikuni part earlier. But I do not use the inner bolts! I fill the voids with epoxy, blend in with air grinder. On the flat face I will grind a small groove around the intake ports( like making a o'ring) Add gasket sealer of you choice. Never had any leaks! Food for thought!
 
Fast Eddie said:
A manifold screw cannot get into the valve spring area. That chamber is completely separate to the intake ports and combustion chamber. Do you mean it got into the port and caused damage between the valve / guide / seat ?
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Yes, sorry, that’s what I meant. Doh!
 
Shoot that is unfortunate Larry, I too have a two into one manifold to check out now that your sharing that info, although since my bike isn't registered and on the road yet (6 kids and a new house--well--a fixer upper, will do that, right). never the less I'll be checking those on my PWK Flatslide with single manifold that I was able to get from JS Motorsports a while back.
 
Been there Larry, but many moons ago, running an 850 race motor to 7200 at about 135mph!

Late season and a race entered the following week....purchased and collected a wrecked 750 with a bent frame and no front end on the Monday evening, stripped both motors and built the best I could from the collective parts.

Set the timing and tappets and on the trailer Later Saturday, ran it at the race track Sunday, practiced, went well. Went into first corner of first race (hairpin) in second and got punted off....I watched it go up in the air, come down and land on the tank.....season over....

Tyre rubber marks on my helmet and footrest dent in the timing cover gave me an idea of the real impact!
 
Thought I'd do an update. I got my head back from the machine shop finally. They reamed the guides to fit the valves. Pretty reasonable at $30.00 US. So today I lapped the new valves and installed with new springs. Next up I refit the rockers and installed the spindle plates and gaskets. After that I annealed my head gasket and refit the head and torqued down in the correct order. After setting the valve lash I quit for the night, I'll finish up tomorrow.
 

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Almost finished the rebuild today, almost. I was refitting the fuel tank for start up when my main petcock snapped off in it's bung. Son-of-a-bitch! New petcocks ordered. Hope I can get that broken off piece out with an Ez-out.
 

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I had a petrol tap break like that once, it will unscrew easily enough. A wide bladed screwdriver in the hole is all it will need to turn it out.
 
Larry S said:
I was refitting the fuel tank for start up when my main petcock snapped off in it's bung. Son-of-a-bitch! New petcocks ordered.
Click to expand...

With the nut, flat washer and Dowty washer, the tap/petcock only has the thin spigot screwed into the tank (looking at your second picture).

That section has an external thread (for the tank) and an internal thread (for the filter) cut into it resulting in the remaining metal between the two threads being extremely thin so it doesn't take much for it to snap at that point as in the picture below.
Heartbreaking pictures


When you fit the new tap I suggest you thin down the nut as much as possible, maybe not fit the Dowty washer (use PTFE tape etc.) or extend the tap thread until you can get at least one full turn of thread where the metal is thicker below that section into the tank thread.

That probably applies to the other tap too.
 
robs ss said:
Oh - I don't know!
Loctite 577 is excellent for fuel unions like that. Sets almost immediately.
Not all loctites are "red" you know.
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Quite right. A sealant would be fine (but also unhelpful in this application as the sealing is done by the washer, not the thread).

I was indeed referring to thread lock, if that’s used then clearly the chance of such a failure, if ever the tap is turned, is greatly increased.
 
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