Author Topic: My old 1124 sohc drag bike motor, final report. Post Mortem.  (Read 9237 times)

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Offline Big Jay

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Re: 1124 sohc drag bike motor, I'm back at it one more time.
« Reply #25 on: May 01, 2017, 02:01:33 PM »
Modern welded strokers are light years different than "Back in the day" Today all of our cranks are nitrided and straightened to deade nuts.

Offline dragracer

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Re: 1124 sohc drag bike motor, I'm back at it one more time.
« Reply #26 on: May 01, 2017, 02:12:14 PM »
Modern welded strokers are light years different than "Back in the day" Today all of our cranks are nitrided and straightened to deade nuts.

Jay,

What's your ballpark number to do a similar stroker crank today??

Offline Don R

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Re: 1124 sohc drag bike motor, I'm back at it one more time.
« Reply #27 on: May 01, 2017, 02:30:16 PM »
 Main bearings say D5H-A std. or D5K-A std.  They have a logo that is a double circle with a circle inside with a line through it similar to original, still no color.   
 The case is painted, so no paint marks exist. The mating edges of the bearings seem proud of the block halves even when I push them down.  I'm going to check for bearing codes and see what turns up.
 Highly suspicious. L0L!

 
« Last Edit: May 01, 2017, 04:16:32 PM by Don R »
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Offline Medyo Bastos

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Re: 1124 sohc drag bike motor, I'm back at it one more time.
« Reply #28 on: May 01, 2017, 02:41:12 PM »
Modern welded strokers are light years different than "Back in the day" Today all of our cranks are nitrided and straightened to deade nuts.

Jay,

What's your ballpark number to do a similar stroker crank today??

frankie he's got matic strokers on the website

Offline Don R

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Re: 1124 sohc drag bike motor, I'm back at it one more time.
« Reply #29 on: May 01, 2017, 04:28:38 PM »
 Back in the day this bike terrorized the street scene and the bar bike crowd. Nothing in town could touch it and the owner was a good friend. I'll get it running whatever it takes, hopefully as close to how it was back then. I have the rest of it with a hog rim and a 5" M&H or an 18" aluminum rim with a modern Sticky Shinko and a fibermold gas tank lined and ready for race gas. In one form it ran .02 off the NHRA class record.  It has a set of grounded points on the triple tree and a lanyard with a piece of leather between them for a dead man switch to ground the mag.
 I plan to ride it by this August.
No matter how many times you paint over a shadow, it's still there.
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Offline Big Jay

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Re: 1124 sohc drag bike motor, I'm back at it one more time.
« Reply #30 on: May 01, 2017, 05:37:54 PM »
Modern welded strokers are light years different than "Back in the day" Today all of our cranks are nitrided and straightened to deade nuts.

Jay,

What's your ballpark number to do a similar stroker crank today??

Stroked and race balanced $1199.00

Offline scottly

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Re: 1124 sohc drag bike motor, I'm back at it one more time.
« Reply #31 on: May 01, 2017, 06:19:47 PM »
 
 The case is painted, so no paint marks exist. The mating edges of the bearings seem proud of the block halves even when I push them down.
 Highly suspicious. L0L!

 
The case marks are stamped; the bearing shells had paint marks. The edges of the bearing shells are supposed to be proud; this is referred to as "crush" and forces the shell against the bore when the two halves are torqued together. The crush is what keeps the shells from spinning in the bore, not the alignment notches. The same holds true for rod bearings.
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Offline Don R

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Re: 1124 sohc drag bike motor, I'm back at it one more time.
« Reply #32 on: May 01, 2017, 06:28:32 PM »
 Thanks for that info Scottly. I always thought it was the notch.  I'd love to just buy a big block and an ARP crank with carillos but still need to measure bearings.
 
 I've kept a 7 second dragster running for a few years but this is a different animal.
No matter how many times you paint over a shadow, it's still there.
 CEO at the no kill motorcycle shop.
 You don't need a weatherman to know which way the wind blows.

Offline scottly

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Re: 1124 sohc drag bike motor, I'm back at it one more time.
« Reply #33 on: May 01, 2017, 06:36:43 PM »
Your Chevy bearings are also proud; you just never noticed. ;D
Don't fix it if it ain't broke!
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Offline Don R

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Re: 1124 sohc drag bike motor, I'm back at it one more time.
« Reply #34 on: May 01, 2017, 07:04:53 PM »
 We used to mix top and bottom bearing sets on the 383 to get the exact rod clearance my engine guy wanted, one +.001 and one +.002 equals +.0015. The upside is we always had a spare set left over. 

 I plastigauged the bike engine's main clearance and it's consistently .001, except one spot on a center main was .0015. The rotating torque is vastly easier for which I have no explaination yet. Dried assembly lube causing drag? I re-oiled things.

 On the upside I'm a lot better at getting the case halves on and off. On the downside I found a spring from a seal on the bench. It might be from the spocket seal or the points end seal.
« Last Edit: May 02, 2017, 02:27:00 PM by Don R »
No matter how many times you paint over a shadow, it's still there.
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 You don't need a weatherman to know which way the wind blows.

Offline scottly

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Re: 1124 sohc thinking of going down the 1/4 mile.
« Reply #35 on: May 09, 2017, 10:01:13 PM »

The motor was tight after re-assembly and checking, It had a spot where it would turn easier and then get tight.
If it was tight all the way around, the problem might be with the cases, but if it's only tight in certain positions of the crank, then the crank isn't straight.
Don't fix it if it ain't broke!
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Offline Don R

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Re: 1124 sohc drag bike motor, I'm back at it one more time.
« Reply #36 on: May 10, 2017, 10:40:59 PM »
 That's the scary part. And it makes sense, I just don't want to hear it yet.
  My brother has a 750 with a claimed 900kit, I bought an unused HA 900 kit in the box from the same PO so it may really be a 900. Anyway, it may need to do until I sell some bikes to generate the $$$ to do this right.
No matter how many times you paint over a shadow, it's still there.
 CEO at the no kill motorcycle shop.
 You don't need a weatherman to know which way the wind blows.

Offline Don R

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Re: 1124 sohc drag bike motor, I'm back at it one more time.
« Reply #37 on: May 10, 2017, 10:42:15 PM »
Apologies for the two threads, I thought a new bearing clearance question would yield best results.
No matter how many times you paint over a shadow, it's still there.
 CEO at the no kill motorcycle shop.
 You don't need a weatherman to know which way the wind blows.

Offline scottly

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Re: 1124 sohc drag bike motor, I'm back at it one more time.
« Reply #38 on: May 10, 2017, 10:47:19 PM »
No worries, Rosie. ;D
Don't fix it if it ain't broke!
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Offline Don R

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Re: 1124 sohc drag bike motor, I'm back at it one more time.
« Reply #39 on: May 15, 2017, 12:13:33 AM »
 Rosie, that's the second time that happened today. My Dad was a Rosie to some of his friends and my favorite boss called me that too. Made me smile.
No matter how many times you paint over a shadow, it's still there.
 CEO at the no kill motorcycle shop.
 You don't need a weatherman to know which way the wind blows.

Offline Don R

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Re: 1124 sohc drag bike motor, I'm back at it one more time.
« Reply #40 on: September 28, 2023, 09:21:54 PM »
  1124 final report.

I'm not sure if I ever confessed what was wrong with this hunk. The new yellow bearings when they came back out showed signs of contact on the top, bottom, top, bottom, top. The case is obviously tweaked and was welded where something happened near the points end. A leak down test showed two cylinders leaking badly where the sleeves were too low in the deck to seal against the copper head gasket.
  The main journals on the stroker crank run pretty true with a dial indicator when I can turn it with two bearings in a case and it doesn't climb up.
  The tight spot was caused by a scored piston and cylinder down low where it wasn't exposed during rotation. I'm pretty sure it had a folded oil ring. The piston was missing that ring when it came apart so that explains why the PO abandoned a 72mm stroker motor.
  I've pretty much written off the cylinder, sleeves and engine case. I doubt that I'd use the crank and for sure not the aluminum rods. The head and rocker towers still look good though, that can still go on the new motor however it ends up.
  So much for "just getting it running" Thanks for the advice and sorry I didn't just tear it down to begin with. It was a learning experience.

 Oh, and that "900" I mentioned a few posts up was as stock as it could be, it was a nice F1 motor though, and I gave it a good cylinder head with no broken plugs and sold the F1 that I put it in. Edit, later a "stock" K0 engine ended up having a 900 kit in it. It all works out.
 
« Last Edit: February 11, 2024, 08:59:15 AM by Don R »
No matter how many times you paint over a shadow, it's still there.
 CEO at the no kill motorcycle shop.
 You don't need a weatherman to know which way the wind blows.

Offline Tracksnblades1

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Re: My old 1124 sohc drag bike motor, final report. Post Mortem.
« Reply #41 on: October 09, 2023, 11:35:10 AM »
Those proud standing bearings are in most every engine I’ve seen,  excepting some roller bearing mains..

I believe the desired bearing crush has more to do with proper and adequate bearing cooling.  Without adequate cooling the already mentioned crush benefits won’t matter..

. Most manuals stress the main bores and the backs of the bearings to be clean and dry with no coatings or oil….
Age Quod Agis