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Turn the page... #440491 06/16/12 6:19 pm
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Bronson Offline OP
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[Linked Image][Linked Image][IMG]

This is a result of forgetting your spark plugs on a plug chop and not calling for help. I'm really bummed out and have not decided what to do with this hefty hunk of dripping junk...I was so close to getting it dialed in. What a pisser...
[Linked Image]




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Re: Turn the page... [Re: Bronson] #440496 06/16/12 7:17 pm
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OUCH! But I can't believe mixture was responsible.

Last edited by LarryLebel; 06/16/12 7:18 pm.
Re: Turn the page... [Re: Bronson] #440498 06/16/12 7:25 pm
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Shades34 Offline
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I'm with Larry on this one. That looks like an oiling issue or ????

Re: Turn the page... [Re: Shades34] #440505 06/16/12 8:09 pm
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conhawks Offline
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did it throw a rod?

Re: Turn the page... [Re: Bronson] #440507 06/16/12 8:27 pm
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shel Offline
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Only one thing to do, Bronson. Start stripping and see what's salvageable.


When given the choice between two evils I picked the one I haven't tried before
Re: Turn the page... [Re: conhawks] #440509 06/16/12 8:28 pm
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LarryLebel Offline
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.... because rod bolts missing?

Re: Turn the page... [Re: Bronson] #440513 06/16/12 9:01 pm
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triton thrasher Online Content
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Mixture can make a small end seize and strain the rod, but on a BSA you would always suspect an oil supply problem.

I don't get the enigmatic story about plugs and calls for help.


Amateur Loctite enthusiast.
Re: Turn the page... [Re: Bronson] #440514 06/16/12 9:16 pm
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Blown Income Offline
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WOW!!! Looks like a grenade went off in the case. Thats a total bummer.


1955 BSA Bantam D1 Plunger
1956 BSA A10RR Street and LSR Bike
1961 BSA C15S
1966 BSA spitfire
1969 Triumph T100C
1970 Triumph TR6R
1970 Triumph TR6C
1972 BSA Lightning LSR Bike
1974 Triumph T150V
Re: Turn the page... [Re: Bronson] #440530 06/17/12 12:51 am
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John Healy Online Content
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That's not the worse one I have seen, but you are damn close. The worse one I have seen was a non-unit Triumph at Daytona. The owner lightened flywheel exploded.

Ouch!


Re: Turn the page... [Re: Bronson] #440544 06/17/12 3:47 am
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KC in S.B. Offline
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I've got a few orphan motors that need a home if you decide to transfer the guts............ of course these offers always come from the opposite coast!! If so, PM me,........ KC


Down to 1 BSA, 2 Triumphs, 1 '56 Chevy
1 '65 XLCH, Hernia Gift, on the way to Japan!
Re: Turn the page... [Re: Bronson] #440592 06/17/12 2:35 pm
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gavin eisler Online Content
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Ouch! What a shame, LHS rod snapped, at least it will breath easily now.


71 Devimead, John Hill, John Holmes A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: Turn the page... [Re: triton thrasher] #440623 06/17/12 6:30 pm
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Bronson Offline OP
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I had left colder range plugs at home. It was just that simple.




Re: Turn the page... [Re: KC in S.B.] #440624 06/17/12 6:33 pm
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Bronson Offline OP
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Thanks KC, I'm considering dropping a Royal Star motor back in her. Mike Carter is a wee bit closer to where I live. I will keep in it mind for sure.




Re: Turn the page... [Re: conhawks] #440625 06/17/12 6:38 pm
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Bronson Offline OP
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I still need a bit more time before I tear into it. The left connecting rod did brake in three pieces. Used new lock nuts on the connecting rods when it was built.

Last edited by Bronson; 06/17/12 9:30 pm.



Re: Turn the page... [Re: Bronson] #440860 06/19/12 2:53 am
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KC in S.B. Offline
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Did the sludge trap get cleaned out?? Sorry, had to ask........


Down to 1 BSA, 2 Triumphs, 1 '56 Chevy
1 '65 XLCH, Hernia Gift, on the way to Japan!
Re: Turn the page... [Re: ] #441159 06/20/12 8:35 pm
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Bronson Offline OP
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Allan-

I was using NGK B7ES, a step hotter than B8ES. I was doing a plug chop and grabbed the wrong plugs in my haste. I am starting to tear down the beast and see what went wrong. As of now, I don't think it was a result of jetting too lean. Bill Getty of JRC sent me 130 mains for my PWK carbs but had not given me any data on any A65's he had tuned. 135 mains reportedly are the norm on these carbs. I was running very rich before. I was experimenting when things really turned south on me.




Re: Turn the page... [Re: KC in S.B.] #441161 06/20/12 8:37 pm
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Bronson Offline OP
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Yep. Put an allen head plug in to boot.




Re: Turn the page... [Re: Bronson] #441214 06/21/12 1:33 am
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Mark Z Online Sleepy
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Maybe it doesn't matter at this point, but I would think an inspection of the upper engine would tell if this was a result of running too lean; that is, I would expect to see piston seizure. Running too lean can also hole a piston, but that usually just kills the engine.

The left-side big-end bearing is the farthest from the oil feed, and the oil must travel through the sludge trap to get to it. When there is an oiling problem, the left rod bearing is usually the first thing to go, melt, bang, break.

As many other posters have speculated, this looks more like a rod bearing failure than a piston seizure. Were you going full speed when it blew up, or did it go when you slowed down? Was there any warning, like a knock?





Mark Z

'65(lower)/'66(upper, wheels, front end, controls)/'67(seat, exhaust, fuel tank, headlamp)/'70(frame) A65 Bitsa.
Re: Turn the page... [Re: Bronson] #441267 06/21/12 2:23 pm
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Instead of jumping to conclusions, how about we get some actual data first. Is the rod bearing seized? What caused the seizure? Is the piston seized? What does the break on the rod look like?

I've never seen nor heard of a lean condition or improper plug selection causing a rod or bearing failure. But, since we're speculating without the facts (it's a fun game to play), my money is on a rod failure.


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Re: Turn the page... [Re: Alex] #441288 06/21/12 3:56 pm
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Mattsta Offline
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Originally Posted by Alex
Instead of jumping to conclusions, how about we get some actual data first. Is the rod bearing seized?


Yup. That's what I'd be looking for first.

Must have made quite a bang when it let go


1952 Triumph T100 in a BSA A7 Frame
Re: Turn the page... [Re: Mattsta] #441295 06/21/12 4:19 pm
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Alex Offline
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Originally Posted by Mattsta
Must have made quite a bang when it let go


The sound a motor makes when it seizes is like a cry from the depths of hell. I've never managed to penetrate the cases on a motorcycle, but the one I had on a car about 25 years ago still sticks in my craw.

Funny, of all the rod bearing seizures I've had on motorcycles, I've never had one break the cases or the crank...even at high speed.


A smattering:
'53 Gold Flash
'67 Royal Star
'71 Rickman Metisse
'40 Silver Star
'37 Rudge Special
sixtyseventy Lightboltrocket road racer...and many more.
Re: Turn the page... [Re: Bronson] #441425 06/22/12 1:59 pm
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It looks like the rod failed from what we can see, rod bearings failing usually just spin and start knocking. I've had one rod split up the oil drilling so only half the rod was still attached to the piston. I've had one Norton rod through the case similar to that, one through the cyl on an A10, both those were just old rods failing. We are fortunate that people make high spec replacement rods that are not overly expensive.


mark
Re: Turn the page... [Re: Bronson] #441444 06/22/12 4:28 pm
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John Healy Online Content
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If it is free from the flywheel/crankcases, does the rod still turn on the crankshaft?

Does it appear the the bearing itself didn't have a catastrophic failureó not a case of lack of lubrication/cooling, and the bearing clearance seems to be normal (or near normal).

When you take the rod off the crankshaft, check the area of the bearing shell just under the "I-Beam" of the rod. Is there a patch that looks like the bearing surface is distressed?

If it is, it could very well be a case of detonation.

That BSA rod is basically a very good item and not prone to do this without being subjected to some abnormal abuse. It is why it is important to measure, and verify the big end i.d. for concentricity and rod length for stretch. It is not wise to resize the big end of any aluminum rod!!!!!!!!!!!!!!!!!! It is the one and only indication that the rod has been abused and beyond its serviceable life.


Re: Turn the page... [Re: Mark Z] #442503 06/29/12 10:56 pm
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Bronson Offline OP
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It hesistated and struggled to transition smoothly to 3/4 throttle. That was about the only indication I had when I'd rode the bike. I was going about 50 mph when the blow out happened. Next thing I knew the left air box had blown off and hit me in the leg. I wasn't an army guy, but the noise I heard sounded like a shotgun going off.




Re: Turn the page... [Re: Alex] #442505 06/29/12 11:06 pm
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Bronson Offline OP
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The rod broke near the wrist pin and near the bottom near the big end bearing. The rod bearing did not seize. It broke with such force it tilted the entire engine to the left. Sorry for a late reply as I have been working a lot of OT lately. The piston did not seize in the barrel. A piece of the rod got launched thru the cases into the tranny. This weekend I will remove the bottom end. So far I am thinking rod failure. [Linked Image][Linked Image][Linked Image]

Last edited by Bronson; 06/30/12 12:27 am.



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