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| Posted: Thu May 24th, 2012 03:57 am |
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1st Post |
ken moss
Member
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Picked up a 91 over the weekend with a new piston and and a new bore the guy I got it from didnt know any thing about it. I pull it down to check it out the piston has .003 clearance from what I have read it should be about .005-.006. But the bad thing is the bearings just fall off the crank I got the mics out and check the crank its under at the bearings by .0015 so I need a crank for it. I also need one for a 49C. thanks Ken
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| Posted: Thu May 24th, 2012 11:43 am |
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2nd Post |
Ted Johnson
Member
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It's not all that big a deal. I have a West Bend here that the bearings just slide on and off the crank. If it bothers you, get a new bearing, clean heck out of the bearing and crank and apply a little red Loctite. At any rate, the engine should run just fine. The crank will center itself under load. TJ
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| Posted: Thu May 24th, 2012 05:22 pm |
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3rd Post |
Steve Welte
Member
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I agree. Use just a bit of locktite and she'll be just fine. It could be that a previous owner set it up so the race couldn't put pressure on the balls. Gotta always be careful of pressure on your balls. LOL I am also going to be in the need of some cranks but I can get by for a while.
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| Posted: Sat May 26th, 2012 01:40 am |
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4th Post |
ken moss
Member
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The rod journal is out of round by .002 so I would call it junk .ken
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| Posted: Sat May 26th, 2012 03:00 pm |
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5th Post |
David Luciani
Administrator
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ken,
if you're junking it i'll take it for 20$ plus shipping!!!
mc91 cranks are getting harder to come by all the time.
i have about ten with trashed keyways.
the chips are big enough to cause concern.
dave
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| Posted: Sat May 26th, 2012 05:49 pm |
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6th Post |
Steve Miller
Member
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ken ., im no mcculloch expert by any means .. if it were i ... id run a rigid hone threw it a few times to clearance piston to around .006 polish up the crank where the rod goes slap it together .. lots of guys run really loose motors .. you have few thou. up and down befor piston ever hit the head ..i might be wrong but im guessin your not gonna race with the motor twice a week 6 heats and two featurs .. also to me .002 under on crank isnt the worst thing ive seen inside an engine ..
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| Posted: Sun May 27th, 2012 02:12 am |
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7th Post |
Steve Welte
Member
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David they can really be bad before they can't be repaired. Have them welded up/no keyway/lap the clutch to crank. Be sure you get it really tight and forget the keyway.
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| Posted: Sun May 27th, 2012 02:18 am |
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8th Post |
David Luciani
Administrator
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they can be fixed just not rekeyed on the back.
a couple have about a third chonked off.
the actual correct way is to anneal the crank then weld and machine then retemper.
we've discussed this whole idea ad naseum in the past.
what we will need eventually is new rods and cranks being made or we are sunk.
dave
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| Posted: Sun May 27th, 2012 01:00 pm |
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9th Post |
Ted Johnson
Member
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If you can find the 3/4" straight cranks, Terry Ives is getting them taper ground with a 3/8-24 stud installed in the female thread. I have one here that's going into Charlie Craibe's Mc101D. Terry has an exchange policy set up. The new crank looks very nice. Terry rocks, as always! Ted Last edited on Sun May 27th, 2012 01:01 pm by Ted Johnson
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| Posted: Sun May 27th, 2012 02:19 pm |
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10th Post |
Steve Miller
Member
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dave no worries ... when all the mcculloch stuff gets used up there will be plenty of west bends to go around .!!! then everyone will have a good motor .!! since there good enough that they still make them ..Lol hehehaha .
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| Posted: Sun May 27th, 2012 04:11 pm |
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11th Post |
David Luciani
Administrator
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Steve,
pbbbbbbb
ted,
didn't think he was doing any but the mc49's.
i guess i have alot of decent cranks then.
But the mc91's were odd balls with the roller bearing on the pto so they are still a problem unless a sleeve is available to pad out the smaller od of the ball bearing sized cranks.
dave
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| Posted: Mon May 28th, 2012 11:59 pm |
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12th Post |
ken moss
Member
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Well this engine turns out not to be a 91 it has dual 6203 bearing on the crank modle # 400165D s/n starts 16- XXXX so in the looking around on the net I think its a 93? Ken
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| Posted: Tue May 29th, 2012 12:23 am |
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13th Post |
David Luciani
Administrator
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thats either a mc92 or mc93.
i think the crank is usable as is.
if you want i have a few nice mc92/3 cranks but i won't sell on approval.
the bearing surfaces are clean and shiney which is about all i check.
dave
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| Posted: Tue May 29th, 2012 12:58 am |
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14th Post |
Ted Johnson
Member
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Dave, I haven't asked Terry what his solution is for the '91 crank. It's worth calling him. I sure see a lot of the '91 cranks on ebay. TJ
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| Posted: Tue May 29th, 2012 02:07 am |
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15th Post |
Steve Welte
Member
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I just bought one off the Flea. I'll see how good it is when it arrives. About a year and a half ago i bought this ugly POS that someone auctioned off on here. As it turns out with a bunch of cleaning I was able to use every piece of it. The crank and rod looked junk but they run just fine with a light hone on the rod and some 1500 paper on the journal. Sized out pretty good. You just never know until you get all the rust and mud off.
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Steve Welte
Member
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So I get my E bay crank. Buyer Beware. Advertised with good keyways and threads. Yep. The real problem is that the PTO bearing surface had been rusted/pitted. Kind of hard for a bearing to survive on that surface. I took the chance, reconized the sellers name but got burned. Something like that I wouldn't put out there to stick people but I guess some in Vintage will. I know who you are and you won't get me again. Better to pay premium from a Valued rebuilder than get burned on Fleebay.
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David Luciani
Administrator
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steve,
how bad is it?
i've run some pretty bad looking pits on bearing surfaces before.
if it was a bushing it's one thing but roller bearings are a little more sturdy.
i'm not talking rasp surfaces here but a few small holes don't seem to do much harm.
second option which i've yet to explore is doing a repair on cranks like the yamaha crank saver sleave repair.
dave
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Steve Welte
Member
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Well first off Dave I used some 100 grit paper on it and removed some. Enough to get a better look at it. Next option I am going to the lathe and use my dremmel grinding holder I made for the tool bar. I recently took the stepped saw cranks down with this so I can run a 9 tooth inboard. I will do a touch up grind and see if I can get it runnable without removing much meterial. I know they don't have to be all gone. We'll call some of them "oil retention pockets". He He
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Steve Welte
Member
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We can get right into this if neccessary. I have my friends at S&S that are the proto type machineist that can always help me out. I just hate to lean on them to much.
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Scott Kneisel
Member
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I try to buy up every good crank I come across, they are getting rare.
I have an Mc6 crank that is pitted on the PTO bearing surface and also some on the crank pin. Someone other than me tried to file off that bad spots on the bottom side of the rod journal and by the time I got it smooth and even it was egged a little over 0.003".
I wanted to see how it would do in an engine so I built an Mc6 clone from saw parts, gave it an oversize hone and piston and did a full porting job. I put on a good manifold and ran the heck out of it for 3 days out last year. It was a real good runner too. Over the winter I tore it down and was amaized that nothing was damaged, not the crank, rod or needles (the needles were used to begin with). I think those parts are soooo hard that it really takes a lot to damage them. I have come to the conclusion that as long as everything is smooth and the rod split transitions are oriented properly and smoothed out so the needles drop off the edges rather than smack into them, these engines will be fine for the kind of running we do in vintage.
I am more squirly about ring pins coming out, had a few of those come thru the shop lately. That causes big time damage and there is no warning or even a way to tell before you put one together.
Guess that is what makes this so much fun!!
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