Droiddr

Hi,

I am taking appart a tt pro 46. All is going well except taking out the piston.
I have the head out, the back off, the sleeve, but I can't take the piston out. The piston orientation, up down, side does not matter I can only slide the connecting rod only partially from the crank shaft.

Am I missing something? The crankdhaft not seeted far enough? I need to remove the bushing on the crankshaft connection? It looks brass-colored but does not budge. See attached pic. It shows the rod partially out, as far as it can go.

All the best to all!

vicman

My Feedback: (10)

I can't tell from your pic, but make sure the sleeve is completly out of the case. Rotating it around as you pull on the rod will allow the rod end to come off the crank. Its a little bit of a bind but works.
Don't take the bushing out of the rod.

You might also have trouble getting the crank out of the prop hub, I usually take a piece of wood and give the crank a good whack and will break everything loose.

Are you doing a bearing replacement?

downunder

With the liner out of the crankcase the piston needs to be laying against the back of the crankcase and the top of the rod has to be slid back on the wristpin as far as it will go (touching the wrist pin boss inside the piston). All of that moves the whole rod as far to the rear as possible and at that point the rod can slide off the crankpin. Put a mark of some sort on the rod before you remove it to make sure it goes back in the same way because rods only fit properly one way on the crankpin.

vicman

My Feedback: (10)

The rod has an oil hole on forward side

1QwkSport2.5r

My conrod and piston was a real PITA to get out of my TT PRO .46 as well. The piston had a little shoulder hanging over the wristpin just enough that didn't allow the rod to move the last 1mm to come off the crankpin. I had to dremel that shoulder off and all is well. (I changed the metal caged bearings for phenolic caged bearings).

In your case, there could be oil crud preventing the conrod from moving far enough inside the piston.

jaka

Hi!
The only thing you have to do is remove the cylinder liner! Then the piston/conrod easily will come loose.
You don't have to do anything else to remove the piston!

1QwkSport2.5r

In the original post, the OP said he had the head, backplate, and sleeve out.

My TT Pro .46 is from '91 (blue box, straight NV) and like I said, was very difficult to get the conrod off the crankpin because of a mis-cast piston. How they got it assembled in the first place is beyond me.

Droiddr

Wow,

Thanks for all the replies, I will check if the conrod can slide properly on the wristpin ( if I can see properly there that is) Maybe with a needle I can check if it moves properly.

I was taking appart the engine to check its state after 10 years, I will probably change the bearings unless I am sure they are ok. Any way to tell aside from checking for rough turning? On the rear bearing I can see no rust or damage.

I will try again the piston and see.

Thanks

vicman

My Feedback: (10)

If your rear bearing has a metal cage, I would change it out. They are very prone to letting go and going into the rest of the engine.

flybyjohn

My Feedback: (2)

They all have it right as stated above. The rod has to be to the back of the piston on the wrist pin. Sometimes if there is a build up of crud on the wrist pin, it can hold the rod forward of this position and it will not come off. Sometimes soaking the engine in hot water or antifreeze will soften up the crud and it will slide back. Boiling water might work if you do not want to try antifreeze or try and stick it in the oven for a few minutes.