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1988 sportster Bad Crankshaft ... what now? HELP!

dbmg said:
S&S recommended rod side play is .015" to .035"
Click to expand...

Will measure to check.

fin_676 said:
By watching the video it does look a wee bit more than .035" however a quick test may be to try a .035" feeler gauge in the gap and see if there is still some movement



Update on this post as I got round to opening the relevant book but this is for post 1990 sportsters I do not have info for the 1988 but it may be similar

connecting rod side play at the crankshaft 0.005 to 0.025 service limit 0.030 so best check with a 0.025 feeler gauge between flywheel and connecting rod



Brian
Click to expand...

Checking right now



dolt said:
Guys, that's not "side play" we are seeing. Side play would mean the rod moves side to side; the center line of the rod moves side to side but stay perpendicular to the centerline of the crank. That rod does move side to side but the centerline of the rod does not say perpendicular to the crank.
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This makes sense I guess ...

----------------------------------------------------
Ok... I measured the gap in between the rod and the wheels...
0.24"
That's what I got...
I'm at the mercy of y'all's opinion
What next
 
As dolt said if you have the necessary skills and tools strip out the crank shaft and send it for a repair
Now is the time to sit down and read the relevant books to see what specialist tools/skills are needed to proceed
However if you think the task is going to be beyond your skills or the tools needed are going to cost too much approach your mechanic and see if he will give a revised quote with you handing over the engine half stripped
Some places may not take a half stripped engine for further work

Brian
 
With that much movement, I would also send an oil sample to Blackstone for analysis to see what the metal content, if any, is in the oil.:coffee
 
Thank you gentlemen
I'm reading the shop manual collecting as much info as possible before jumping in to anything here
 
dolt said:
Guys, that's not "side play" we are seeing. Side play would mean the rod moves side to side; the center line of the rod moves side to side but stay perpendicular to the centerline of the crank.
Click to expand...

I agree. If the needle bearing and the bearing pressed into the rod (I'm assuming like the bearing pressed into top of rod) were good, you shouldn't have that angular rod movement.
I've got a brand new crank from a two stroke motor, not apples-to-apples but a pressed crank w/lower needle bearings similar to topic. There is side to side movement but very little angular movement.
Now the question of the metal marker numbers on the crank in question. That
looks like a inventory number from a used parts warehouse of some sort..??
Is there already a used crank in there? Was this bad crank put in at the time of the 1200 build?

dolt said:
With that much movement, I would also send an oil sample to Blackstone for analysis to see what the metal content, if any, is in the oil.:coffee
Click to expand...

Me thinks our good friend dolt is wondering the same.
 
I think I found the Ghost !!!
I decided that since the freaking thing is going to have to be rebuilt from the bottom up I'll just put the cylinder back together and run it till stops.
And than rebuild it :)

I went out to the local HD dealership to get all the gaskets (just because I'm impatient and wanted to start putting it together)
They sold me all the gaskets and just for kicks I came home and compared the new gaskets to what was installed in the bike.
First thing I noticed was that all gaskets were similar except for the cylinder head gasket *
The new gasket was slightly smaller in diameter and thinner and the holes for the guides where a lot smaller (see pic..the one on top is the used one)
2d55dbb2a2ad34302e5a47e82d072f88.jpg

Kept trying to figure it out and check the parts catalog to make sure HD sold me the right part...
After deciding that the new gasket was the right part I kept investigating and discovered that in order to make up for the difference in the size of the guide holes they had added 2 rubber O-rings
Now that's messed up ...
2e7a7d33d4a429b7d7333ade4eb7619f.jpg

Started inspecting all parts in detail and found that the valves have been hitting the piston (both of them ...one more than the other)
The piston has some marks but otherwise is intact.
1acd8904aeefa6f569cdad0da31363ce.jpg

f7306b21782557c72bdb6867a100e79e.jpg

The valves are good

Now I'm new to all this but it seems to me that's the big deal here. Isn't it ???

Now... What next? Should I ad a thicker base gasket, a thicker cylinder head gasket or both?

Since it is just a bit I think that will do it...am I correct?

I really believe that the fact that I've only ran this bike for about 250 miles total since it was put together is what saved from getting a cracked piston or else.
 
Last edited by a moderator:
Some one did some shoty engine work here.
Do you have adjustable push rods?
Is the stock cam in it?
What was the compression when you checked it?
 
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