Twisted crank? '82 GS1100E

[woodman]

No and its a very different kind of high frequency vibration, I have a Fatboy too. How do you tell by taking the stator cover off, all I see is the crank end and a seal ?

 

[TheCafeKid]

the rotor threads will tell you...

 

[jwhelan65]

My 82 1100e has 28,000 miles on it, the date on the serial plate is partially rubbed off. all I can make out is a 2. So its either a Feb or Dec. Is there any other way to know other than a tear down? Bike seems to run fine.

 

[rapidray]

My 82 1100e has 28,000 miles on it, the date on the serial plate is partially rubbed off. all I can make out is a 2. So its either a Feb or Dec. Is there any other way to know other than a tear down? Bike seems to run fine.

If it IS an 82, it will NOT have been built in December! That would be an 83. Ray.

 

[bonanzadave]

There is a ton of info in the search on twisted crank. I think we kicked around engine serial numbers trying to find where the the welding started.

Mine was unwelded and twisted 146884.

 

[jwhelan65]

Thanks Ray Feb it is..than I guess my crank is prone to twisting...no one should have to go through life with a twisted crank!

 

[DMorris]

I don't know how to check for a welded crank without cracking the case, but the accuracy of crank throw timing can be checked with a degree wheel and a piston stop without major disassembly.
I built a piston stop by knocking the guts out of a spark plug and replacing them with a long allen head bolt epoxyed in place so that it projects maybe an inch into the combustion chamber. Mount the degree wheel, pull all the plugs, and install the piston stop in cylinder #1. Rotate the crank forward SLOWLY AND CAREFULLY until the piston touches the piston stop. Hold that position until you have recorded the reading indicated on the degree wheel. Now rotate the crank backward until the piston again touches the piston stop (again, SLOWLY AND CAREFULLY) and record the reading from the wheel. You will note that these two readings form a pie wedge on the degree wheel. Divide the angle in half and mark the result on the degree wheel and you have TDC. 180 degrees from that is BDC. If you repeat this process for each of the other cylinders, you will know to a high level of accuracy how your crank throws are timed.

This method is much more accurate than trying to find TDC with a depth guage because as the crank approaches TDC and BDC, the piston is moving very little in relation to the crank rotation. This method takes its readings where there is still significant piston movement on either side of TDC.

 

[Guest]

FWIW, I read in one of the old mags that mentioned this problem, an abrupt chopping of throttle from very high speed could also apparently cause it, apart from sudden loads like wheelies etc.
I've heard its possible to visually check the crank for welds, from the clutch side, with the basket removed. I haven't done this, but run with the assumption that it isn't welded, and try to ride & plan any performance mods accordingly.
Tony.

 

[posplayr]

This method is much more accurate than trying to find TDC with a depth guage because as the crank approaches TDC and BDC, the piston is moving very little in relation to the crank rotation. This method takes its readings where there is still significant piston movement on either side of TDC.

I actually set my piston stop length to catch the piston at 1/2 stroke which is where accuracy is highest.

 

[Guest]

As Baatfam stated you can see the welds if you remove the clutch basket.

 

[rphillips]

Hey Ray, please correct me if I'm wrong, but I think the journal you can see from behind the clutch hub, wasn't welded ,from the factory, even on the later models. The aftermarket weld jobs weld all of them.

 

[mike_of_bbg]

Yeah, the crank on my 82 gs550 was twisted. Compression test was very low on 1 & 2 (~60 psi vs 120 psi on 3 and 4). I'd estimate the twist at about 20 degrees. Never ran the bike in that condition. The PO apparently didn't notice at all, but he probably got the bike like that.

http://www.thegsresources.com/_forum/showthread.php?t=138429

+1 take measurements directly between TDC and PDC. I couldn't tell visually when we first got the head off with 1 and 4 at TDC. After turning the motor I was able to visually notice that 2 and 3 were not traveling together.

 

[trippivot]

take out the #1 and the #4 spark plugs.
remove the timing cover
put a plastic straw or a skinny tool into the plug hole to locate the top of the pistons.
turn engine over to TDC 1-4

if the piston crown level of both 1-4 pistons are uneven at TDC you have a twisted crank.

simple test

 

[mike_of_bbg]

if the piston crown level of both 1-4 pistons are uneven at TDC you have a twisted crank.

If they're uneven anywhere along their travel you have a twisted crank. Depending on how far it's twisted TDC/BDC may be the hardest places to tell. I'd measure in a couple of places if you suspect a twisted crank. Make sure that you also check between TDC and BDC. Like I said mine was twisted about 20 degrees. That's only a 7% difference in vertical travel at TDC. It's about a 34% difference (relative to crank offset) at 90 degrees.

 

[maro]

Just for the sake of including this in this thread. Let's say I twist my crank . What is the cost and process of replacement?

 

[rapidray]

Just for the sake of including this in this thread. Let's say I twist my crank . What is the cost and process of replacement?

MINIMAL, the cost of a GOOD used, or new crank, & all the gaskets. Depending on mileage on the motor I would do other things. Pull the motor, pull the entire top end, split the cases, replace parts & re-assemble. Ray.

 

[TheCafeKid]

Just for the sake of including this in this thread. Let's say I twist my crank . What is the cost and process of replacement?

Back when Dave and Isleoman did it, it probably fell under warranty...for you and I?? It would be cheaper to find a new motor, or buy another bike. You're looking at COMPLETE disassembly, sending the crank off to get straightened, welded, indexed, etc, New crank bearings all around...As Blowerbike said, and caused me to laugh as well as cringe, it would simply "blow your wallet apart" HA! In other words...DONT TWIST IT

 

[mike_of_bbg]

I was looking at a top-end teardown (and thus a full gasket set) anyway due to a leaky head gasket, and found a good used crank on eBay for about $50 shipped. So the "extra" costs were the used crank, seals, and threebond. Not that bad (~$100), but there's definitely some risk to buying the used crank. I probably should have replaced the timing chain too, but it measured well within spec so I kept it.

Of course there's also the time involved in removing the whole motor and tearing down the bottom end.

 

[TheCafeKid]

Hey Josh, If you're really that worried about it, when ya have the spare cash, id start shopping and eyeballing EBay and CL for an 83 motor or parts bike (yeah, its not going to be a dime a dozen, but they ARE out there) Keep in mind that the 83 motor IS welded, but its only welded at the pins, so its still possible to twist one (i dont think under NORMAL circumstances however. If you're riding like an idiot, maybe, or if you've got too much power over it...Maybe..) Then you could simply swap all your stuff over to it, and not really have to worry about it anymore..Plus.... The BLACK motor is FASTER:twistedevil:

 

[woodman]

"The Cafe Kid", at the risk of me being called a dumas, please elaborate on how the rotor threads will tell you if the crank is twisted. The threads on my 80 that spun the rotor were perfect, just the nut had come loose. I dont suspect anything is wrong, Im just curious about it