Hi all, was wondering if someone could give me some insight as what the problem is with this evolution. I just had the piston rings break apart in the rear cylinder of my 1991 FXR. The rear barrel was galled in the process so I had a shop nearby supply me with a good used one. I then had them both machined 30 over and purchased Weisco 30 over pistons and new rings. The engine still was running OK even with though the rings came out in pieces. The rear had low compression however and there was a lot of blow by through the breather. I have Delkron cases and SS super stock heads. Now for my Gomer Pyle question of the day. After assembly of the engine I turned the engine over by hand and while doing so after turning it almost a complete revolution it stops dead. I spin it the other way and same thing after almost a complete revolution boink stops. I'm a auto tech by trade so I am mechanically inclined however new to the engine rebuilding of a Harley motor. I oiled up the new rings and barrels plenty, made sure to have the piston arrows and ring clocking correct. But still the damn thing stops after almost a complete revolution. I can feel what appears to be the crank hitting something but haven't been able to figure out what? I was also sure to keep all the heads etc.. marked and in proper location. Any help would be greatly appreciated from one of the many motor builders this great site has before I take this thing apart again for the third time now grrrrr

 

Whoever put it together probably didn't endgap the Rings...


also oiling the rings almost guarantees an oil burner..

On the half revolution????
Gotta look

 

Old ring bits in crankcase?

 

I'm betting a Service manual might be of some help BTW

 

Did you verify piston clearance before mounting the heads?

 

All the ring bits were collected in the rag I put around the rod before removing the piston. I have a service manual and followed all the torque sequences. The ring gap according to the guy who did the machining and ordered the pistons and rings from said it wasn't necessary. And that's the one thing that I was suspicious of. I put it together and no because what I was told didn't bother end gapping the rings and by not doing so that could cause it to lock up like it's doing? Thanks ahead of time for the help.

The locking up is occuring before I even have the push rods or heads installed.

 

Higher lift cam hitting the case?

Have you tried pulling the cylinders and pistons to verify that the crank turns freely?

 

The guy probably fibbed about the endgap...unless he did it?
I always...always gap.
You will need to take the thing back apart...First rockers...does it roll over? then Heads, does it roll over? finally Jugs, does it turn over?...if no....guess we gotta go deeper.

 

Yes I have pulled the cylinders back off and the crank then spins freely. Yep this time I didn't torque down the heads so tomorrow I'll pull them off and see how it spins while holding the jugs by hand and let you all know what the problem is..well hopefully know lol. Thanks again all for the help it's greatly appreciated. And I'm gonna talk to the machinest about the ring gap. I hate knocking a shop since I'm in the auto trade myself but this place has had mixed reviews but it's close by so...

 

??? Lost me there.