Scissored crankshaft ?

[FDT]

What is the obvious signs of a scissored crankshaft in a dyna (or any model ). Currently i have dropped 10hp and it has more of a vibration than it used to have, especially at the higher rev range. Is there an easy check with the crank still in the case ?

[rigidthumper]

Runout can be easily checked with a dial indicator on the pinion or sprocket shaft, but it does require some engine disassembly.

[JSD]

Pull cam plate and check with dial gauge. 

[kd]

What is the obvious signs of a scissored crankshaft in a dyna (or any model ). Currently i have dropped 10hp and it has more of a vibration than it used to have, especially at the higher rev range. Is there an easy check with the crank still in the case ?

To answer your first question, low oil pressure.  A scissored crank will usually give the oil pump a beating with the extra runout on the pinion shaft.  If it started to vibrate about the same time of a drop in oil pressure that would be strike 2.

The compensator and cam plate have to be removed to get a proper measurement of both sides (which is the best case scenario).  If you start with the cam / pinion side and there is very little runout it is probable the other side is OK too but if you are OCD  you may want to check it too.

As Rigid said, the only way to know is to measure it. IMO, the symptoms I mentioned would have me doing just that.

[FDT]

What is the obvious signs of a scissored crankshaft in a dyna (or any model ). Currently i have dropped 10hp and it has more of a vibration than it used to have, especially at the higher rev range. Is there an easy check with the crank still in the case ?

To answer your first question, low oil pressure.  A scissored crank will usually give the oil pump a beating with the extra runout on the pinion shaft.  If it started to vibrate about the same time of a drop in oil pressure that would be strike 2.

The compensator and cam plate have to be removed to get a proper measurement of both sides (which is the best case scenario).  If you start with the cam / pinion side and there is very little runout it is probable the other side is OK too but if you are OCD  you may want to check it too.

As Rigid said, the only way to know is to measure it. IMO, the symptoms I mentioned would have me doing just that.

I did measure the pinion side runout and got .004" with the cam plate off. There did seem to be a noise coming from the primary side so i put a bit more tension on the chain tensioner ( it did sound like chain slap to me ) and it did make it a little better, but because the pinion runout was fine i never checked the spocket side. Will i tight primary chain rob 10hp ?

[Ohio HD]

How do you know it's 10 hp? Have you dynoed the bike as is and before the problem? Are you spitting oil out the breathers? Sumpimg will cause power loss.

[kd]

How do you know it's 10 hp? Have you dynoed the bike as is and before the problem? Are you spitting oil out the breathers? Sumpimg will cause power loss.

... and overheating too

The cover has to come off to adjust the chain (properly).  If you adjust it too tight you can cause transmission mainshaft damage along with the assorted bearings in the line of power.  Get out your wallet because it's a crap shoot any other way.  Feel lucky?  You really need to remove the cover and inspect everything if you heard a noise turning it over or running it.  The chain and adjuster compensator etc. has to be checked for damage too.  You really need to know all is well in there and the chain is properly adjusted.  There's a real good chance your vibration is in there and something may be ready to let go. 

Right now without knowing the year and model or what work may have been performed just before this started all you can expect in responses is mud thrown at the wall to see what sticks.  You didn't indicate you removed the primary cover to adjust the chain which leads me to believe it may be a Softail.  Do you have any further info that will help?

[FDT]

How do you know it's 10 hp? Have you dynoed the bike as is and before the problem? Are you spitting oil out the breathers? Sumpimg will cause power loss.

... and overheating too

The cover has to come off to adjust the chain (properly).  If you adjust it too tight you can cause transmission mainshaft damage along with the assorted bearings in the line of power.  Get out your wallet because it's a crap shoot any other way.  Feel lucky?  You really need to remove the cover and inspect everything if you heard a noise turning it over or running it.  The chain and adjuster compensator etc. has to be checked for damage too.  You really need to know all is well in there and the chain is properly adjusted.  There's a real good chance your vibration is in there and something may be ready to let go. 

Right now without knowing the year and model or what work may have been performed just before this started all you can expect in responses is mud thrown at the wall to see what sticks.  You didn't indicate you removed the primary cover to adjust the chain which leads me to believe it may be a Softail.  Do you have any further info that will help?

It is a 09 dyna model, the primary cover was taken off. It has just recently had a top end done and is now a 107. I have a feeling it may be more of a crank bearing problem now that i think about it a bit more. It has been riding hard before doing the 107 upgrade.

[MikeL]

is it possible to remove the crank position sensor and use a dial indicator to check run out. I have seen scissored crankshafts beat up the crank position sensor. Sounds like the oil pump is out of alignment causing sumping.

[Robb1178]

When my crank scissored it got a bad vibration, especially around 3k rpm

[Wookie3011]

When mine scissored it was so bad I hated running it past 3500RPM and 3500 sounded like 6000RPM. When all was said and done my runout was Total from side to side .015

[WhipLash96]

You mentioned that you think that you hear chain slap. Not sure what chain tensioner you are using but I would check that to make sure nothing broke there. I had a spring in the Hayden auto tensioner break on me once. I noticed the difference in my bike right away but didn't find it until I tool the engine out of chassis for the 124.

[FDT]

You mentioned that you think that you hear chain slap. Not sure what chain tensioner you are using but I would check that to make sure nothing broke there. I had a spring in the Hayden auto tensioner break on me once. I noticed the difference in my bike right away but didn't find it until I tool the engine out of chassis for the 124.

This turned out to be the main gear drive bearing was on the way out, i had about .012" runout on the end of the mainshaft which was throwing the clutch pack around causing the chain to slap, changed out all bearings and noise has gone and engine is running smooth now.