TOPIC:

Has anyone removed a crankshaft from a Z or GPZ1100B1 without removing the barrel and head i.e can the pistons slide out the top engine housing, then back in again.
I need to replace a twisted crankshaft, if the barrel and head can stay in place that would save a lot of work(after removing the cams) I always wondered if this can be done, especially fitting the crank with pistons back into the barrel. I assume fitting the rings might not be easy.
Any help please.

Simple answer is NO.
Top end has to come off.

Thanks, thought so but no harm in asking

Inquiring minds would like to know how you twisted a crank. ???

From experience, a twisted crank can and will damage the case. Once you get a straight crank do a test install and shift the crank back and forth (taking up endplay) and view the thrust bearing's outer race. If the bearing moves in the bore while the case is torqued, the case is junk.

And like I've mentioned in other posts, the overlooked importance of adjusting the damper washer thickness on the flywheel side of the crank will be impossible with the extra movement of the thrust bearing being loose in the case.

As far as fixing the crank, Stan at GRC is the best, and well worth the $750 base price. It can prevent more headaches down the road by spending the money now for a quality crank.

My theory is that the press fit of a 30 year old crank can weaken over time, and hard riding on a stock engine my cause a twist. And of course engine mods increasing torque will do the same without welding. But some maintenance repairs can do it too. I've heard of folks torquing the drive chain drive sprocket bolt without a holding tool and simply keeping the trans in 1st gear, or holding the crank instead of the rotor while torquing the rotor bolt.

ajsfirehawk wrote: Inquiring minds would like to know how you twisted a crank. ???

Well its a long story, I left the bike with my son. I might add the engine itself had a genuine 5,500klms from new ( not rebuilt - new). It was stored in oil for around 30+ years . Anyway apart from the cams from an 83 model the engine is stock (some porting), my son (after spotlights on eyes with bamboo sticks in nails) admitting over revving having a drag against his mate.
I previously twisted my Z1R crank (see my previous forum) but that bike had an incredibly hard life with over 240,000klms.

Hey Bozo,

That is why my son is currently building his own bike! It is an 83 Katana; he likes the look and the name, and to be honest, the Katana is a cool bike to ride, has way more low end and mid range power than the GPz, and is very easy to work on....I now own an 83 GS1100ES project myself, too. My first Suzuki street bike, ever! I'd rather have an 86 FJ1200, though.....

Those GPz and KZ-J cranks aren't very robust, anyway. I have seen several that are twisted, especially at the center, between no.s 2 &3. I also have a few late GPz cranks that have destroyed the thrust bearing / washer under normal use. Those cranks are now junk / parts only. Of all the design features of the late 1000 and 1100's, the crank's poor design and assembly quality is my least favorite!

You are better off getting a crank properly rebuilt and welded. Don't forget to have the cheapo thrust washer assembly replaced with a quality torrington needle thrust bearing, and the thing will stand up to most any abuse. Falicon did my big block's crank, complete with Falicon Knife Rods. Fast By Gast (FBG) prepped and welded my buddy's big block crank starting from a NOS GPz 1100 unit he supplied. My beater 1200 is still looking for a good 18 mm pin crank; I'm leaning toward either FBG or that GSM GRC place. All worth spending the money....

Kray-Z good story line.I have got two FJ1200 3CV models, for touring they are fantastic but I still love my Z and GPZ a bit more.The crankshaft on my Z1R went through hell when I was young so when it went there was no surprise but GPZ was new and the engine was basically standard. I bought a welded second hand unit from Germany for $250Aust in top condition. As for the original crank, there is a person in Brisbane Australia that fixes these so I'll give him a go.

ajsfirehawk wrote: Inquiring minds would like to know how you twisted a crank. ???

Besides the usual burnouts, clutch dropping, and racing abuse, and adding stuff like NOS and 1500 cc big bore kits, turbo's, etc. on a stock crank, one way to twist a built up / pressed together crank is to severely shock load the drivetrain. For example, spinning out the rear tire then suddenly gaining traction HARD under power, or, in one dead crank that I have, breaking the final drive chain and having it lock up the front sprocket...not many useable parts left from that one...

I worked out what happened to the crank after Scotty Lynch ( Australia Z repairer) was puzzled about the crank springing out before he could weld the pins. I then remembered the story of why I got the motor over 30yrs ago. It fell off a truck while going to a motorcycle track race. I had to replace the second gear because it had the teeth stripped.
I now believe that the shock caused the crank to stress and after a good rev the crank twisted. Scotty managed to weld the pins and it is now sitting in oil if I ever need it