Topic: Turn the engine upside down and attack!

[mennedy]

I was hanging with a friend on the weekend who owned a Yamaha dealership years ago and is an auto mechanic. He worked on motorcycle engines (Yamaha) for years and is now building hot rods and doing frame off resto's for a very good living.

I told him about how I have to do the engine bearings and after a while he said to me, "Before you tear it all down, why don't you turn the engine upside down, undo the casing bolts, etc etc ....and use a 2"x4" to gently tap out the crank."

Is that possible?

[MRieck]

I was hanging with a friend on the weekend who owned a Yamaha dealership years ago and is an auto mechanic. He worked on motorcycle engines (Yamaha) for years and is now building hot rods and doing frame off resto's for a very good living.

I told him about how I have to do the engine bearings and after a while he said to me, "Before you tear it all down, why don't you turn the engine upside down, undo the casing bolts, etc etc ....and use a 2"x4" to gently tap out the crank."

Is that possible?

Yes...take the top bolts out first. I'd tap off the lower case first.

[Sam Green Racing]

 

[JonnyHonda]

I tried this method on a K100 Beamer and found to my dismay the pistons would not pass through the upper casing. A real pain.

[mennedy]

Yes, of course, I would take the lower case off. The point was to avoid all the top end work.

However, with all the eye rolling, am I to assume that this is a stupid question?

Is that to say that to get the lower case off, I would have to pull the engine bolts/cylinder studs and to do that I would have to pull everything off the top end; ipso facto, no - it won't work?

I've never done this before so how do I know? The easier I can make this for myself before I start, the better.

Thanks

[MRieck]

No need to take out the cylinder studs. Just remove the bolts that attach the lower case to the upper case. On the top case there are 7 6mm bolts (with one under the starter cover and another down by the counter sprocket shaft), 2 8mm bolts and 1 10mm bolt. One of the 8mm bolts and the 10mm bolt can be removed after flipping the engine. Flip the engine and remove the remaining bolts. Be sure to remove the points cover, points plate, generator cover and transmission cover.

[scondon]

 "Flip the engine and remove the remaining bolts. Be sure to remove the points cover, points plate, generator cover and transmission cover."

  Does anything in the gear shifter assembly need to be removed in order to split the cases? Reason I ask is I tore apart a bottom end "for the hell of it" and seem to remember having to having to take the shifter assembly apart in order to split the cases. Otherwise it was just covers and bolts as you say.

[jtb]

Right Sean, The holder for the outboard bearing on the countershaft attaches to both cases.

[MRieck]

Thank God for you two.

[mennedy]

Awesome guys! I really appreciate your help. I don't expect this to be easy for a first timer but it should shorten the learning curve for this project.

All the best.

[jtb]

Good Luck, Man.  Go easy, If I could do it, you can.

[bryanj]

Why do you have to do the engine bearings? and what bike?
If 500/550 fit a new primary chain and if the engine bearings are worn so will the crank be and they cant be reground

[gtyler5]

Yes flipping the engine over will help you avoid the top end, make sure to put down some carboard or something to soak up the oil.

[mennedy]

Okay Bryan, I will owe up. It is a '78 CB550K. I was in a rush and forgot to check my oil. When I finally realized 90 miles later, there was just enough oil to touch the bottom of the dip stick. It stalls at idle and there is the matter of high pitched screeching when it is running. It is the same sound my '67 Merc had when the oil pump failed - bottom end toast. I therefore assume it is the bottom end. Would the primary drive chain make that kind of screeching noise? It is not a grinding sound but a high pitched screech.

Hey, at least I'm honest. I could have blamed it on the fictitious failure of the oil pump. I just wish my wife would quit with the "I don't believe you did that! It's not like you." thing. 

So I cannot regrind the crank? Oops!

[bryanj]

If there was any oil  on the dipstick at all it should have been OK if the oil light didnt come on. Most common problem with lack of oil is the camshaft siezing in the head, being honest the cheapest/best way is a replacement used engine--any 550 will fit the only difference 77/78 to all the rest is the carbs

[mennedy]

Yes, I agree, Bryan. I have just managed to get my son (the closest grunt) to help me switch in a 74 550 I located. Now I am putting it all back together. Hope to ride in the next week or two. I've been off since Aug 1!!!

Interesting, the oil light never came on.

I was cleaning some parts yesterday (yes, I managed to pull myself away from this site) and decided to clean the pan I drained the oil from the old engine into. I rinsed it out with old gasoline I had and at the 3rd rinse noticed a film of shiny bits on the bottom of the pan - metal fragments in the oil. The screeching, by the way, came from the lower part of the engine. When I topped it up with oil, it continued to screech. However, I'll check the cam first.

Cheers!