Changing crankshafts

[mrbeggs432]

So Im finally getting around to doing something with these engines.

I have to change the crankshafts out because the ones that are currently on are tapered and non-key way shafts.

I saw a video on a different brand engine where they changed out the crank leaving the piston and head intact and only removing the connecting rod.

Would this process basically be the same for the Honda 390 ?
Im not very well mechanically inclined on internal stuff....only been inside them to remove governors and oil sensors.

 

[65ShelbyClone]

I've done what you're talking about with other engines and would think that it's possible with a GX390. It's probably going to be fiddly getting the crank out past the rod's big end.

I even once changed a connecting rod without pulling the piston.

 

[mrbeggs432]

I've done what you're talking about with other engines and would think that it's possible with a GX390. It's probably going to be fiddly getting the crank out past the rod's big end.

I even once changed a connecting rod without pulling the piston.

Well I already ordered a crankshaft....gonna cross my fingers...I think the video I watched was a smaller Briggs change out

 

[tgus3]

ive removed the crank without taking anything off except the rod on gx160s and predator. you have to wiggle it around a bit but i can usually do it. its probably about the same on those bigger engines.

 

[Joe-405]

You can compress the rings by hand if you go slow and have slight pressure on the piston as your sliding a flathead screwdriver around the ring to compress them. I’ve done it a bunch of times on my stuff. Or you can use a regular hose clamp as well.

 

[itsid]

if you leave the head on and remove the spark plug, you can move the piston up by hand a fair amount, the crankshaft taper (on the flywheel side) helps to tilt the crankshaft down a bit
once the weight comes near the conrod...

it can be done, but it's certainly a maze puzzle

IMHO, removing the piston and reinstalling it (even w/o sophisticated tools) might be less fiddly. *shrugs*

Whatever makes you feel more comfortable!

'sid

 

[mrbeggs432]

Im gonna try the supposed quicker version...If that fails I guess pull the head......looked easy on youtube....but,you know how that goes