PHANTOM RESURRECTION 78 SPECIAL

[YamadudeXS650C]

I was just looking at the housing a few minutes ago. I see the elongated oval going up to the chamber. Some one mentioned the choke being off to accurately determine drop time. Anyway, it’s now longer than before. I guess I’ll get the red rubber grease off Amazon. I don’t like them much. They kind of did in book publishers

You should be able to get a small amount of red rubber grease at your local Autozone or a good hardware store for 5 bucks or so. It sometimes comes as brake cylinder assembly grease. In fact, if you get chummy with your autoparts guy, he/she might snag you one of the little packets that come with master cylinder rebuild kits


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[The Phantom]

If the choke seal is old and gone hard it can leak air and this can cause the slide to drop faster.

You are the man.

 

[The Phantom]

You should be able to get a small amount of red rubber grease at your local Autozone or a good hardware store for 5 bucks or so. It sometimes comes as brake cylinder assembly grease. In fact, if you get chummy with your autoparts guy, he/she might snag you one of the little packets that come with master cylinder rebuild kits


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Thanks, it kind of figures if your lubing rubber seals, it should be good for the diaphragm. All the best.

 

[The Phantom]

Hello fellow ,,,,, Yamahamians. Where would I go to remove the mechanical advance plate? I’m pulling the head now. HELP! Never mind, I found it.

 

[Wingedwheel]

Do you have a manual?
https://thexscafedotcom.wordpress.com/tag/manual/

 

[The Phantom]

So, at 5:15 pm Eastern standard time, I got the head off. Gastly little exhaust valve in my rt. Piston chamber. Is that #1 or #2? Anyway, it punched a hole through the piston. These pistons feel like aluminum. Am I correct?
I live in the country, in a converted hunting cabin. So my work is outside on my back porch. I’m thinking I might get a used piston, new rings and think about repairing the head.
I think I punched the hole kicking it over. Any suggestions would be awesome as the PHANTOM is relegated to the novice state.
Thanks

 

[YamadudeXS650C]

So, at 5:15 pm Eastern standard time, I got the head off. Gastly little exhaust valve in my rt. Piston chamber. Is that #1 or #2? Anyway, it punched a hole through the piston. These pistons feel like aluminum. Am I correct?
I live in the country, in a converted hunting cabin. So my work is outside on my back porch. I’m thinking I might get a used piston, new rings and think about repairing the head.
I think I punched the hole kicking it over. Any suggestions would be awesome as the PHANTOM is relegated to the novice state.
Thanks

A used piston will not be difficult to find.

However, I suggest that your next step as you ponder a top end rebuild will be to pull the cylinders and examine the small end bearing surfaces of the rods. If they are bad, (take photos), this could be a big decider as to where you might invest your money.



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[YamadudeXS650C]

If your small end bearings are bad, you would need to split the cases and have new rods installed on the crank. Expensive.
Or find a good used crank on Ebay, maybe $125.00



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[Kevin Werner]

If your small end bearings are bad, you would need to split the cases and have new rods installed on the crank. Expensive.



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How are the small ends lubed? Is there a jet, a pressurized passage through the rod or a splash?

 

[YamadudeXS650C]

Splashed oil gets through the hole in the top of the connecting rod.

 

[Kevin Werner]

Splashed oil gets through the hole in the top of the connecting rod.

View attachment 252302

Thanks @YamadudeXS650C , what splashes the oil up under the piston like that. I seem to remember Briggs and Stratton had a splasher on a big end nut or something. XS650 don't have fasteners on the big end so what does the splash. Also, come to think about it, a short time oil loss as described above would not be the catastrophic downfall of a small end if the shut down happened shortly afterwards.

 

[The Phantom]

Splashed oil gets through the hole in the top of the connecting rod.

View attachment 252302

So, I’m looking for play at the wrist pin? As well as the connecting rod bearings at the crank?

 

[YamadudeXS650C]

So, I’m looking for play at the wrist pin? As well as the connecting rod bearings at the crank?

Yes, it's in the manual. But a visual inspection of the small ends is easy and important. Look for how much of the copper plating remains.


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[YamadudeXS650C]

what splashes the oil up under the piston like that. I seem to remember Briggs and Stratton had a splasher on a big end nut or something. XS650 don't have fasteners on the big end so what does the splash.

Kevin, its been awhile since I read about this in my copy of the Hans Pahl book, so I'll leave this question to someone more informed than I. In fact, "splash" might not be the correct term....


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[Kevin Werner]

Kevin, its been awhile since I read about this in my copy of the Hans Pahl book, so I'll leave this question to someone more informed than I. In fact, "splash" might not be the correct term....


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Thanks, some motors have jets that shoot oil in that direction but I have not seen those in pictures here. Perhaps oil slinging off the crank wheels?

 

[The Phantom]

Yamadude, I’m guessing the upper connecting rod bearing surface is worn by poor/ dirty oil quality? Heat?
You think it best to remove both pistons for inspection? The rod to crank journals on both have no play. Is it common for the upper rod to wear excessively? The cylinders look good, no scratches. What do you think about boring them out and putting oversized pistons and rings. I know you don’t want to run hot.

 

[Jim]

The oil pressure main galley runs across the front of the cases. There's about 4 tiny holes drilled into the galley that act as small "jets" spraying oil back on the conrods. There's also holes in the piston where the oil control ring fits. There's holes in it to to pass oil onto the little end.

 

[jpdevol]

Is it common for the upper rod to wear excessively?

Jumping in here: the answer is yes. The connecting rod/wrist pin is infact "splash" lubricated and known to wear faster than either the " big end" or even the cylinders. They (small ends) bear scrutiny in any engine rebuild of an XS....

 

[Kevin Werner]

The oil pressure main galley runs across the front of the cases. There's about 4 tiny holes drilled into the galley that act as small "jets" spraying oil back on the conrods. There's also holes in the piston where the oil control ring fits. There's holes in it too to pass oil onto the little end.

Jumping in here: the answer is yes. The connecting rod/wrist pin is infact "splash" lubricated and known to wear faster than either the " big end" or even the cylinders. They (small ends) bear scrutiny in any engine rebuild of an XS....

Thanks to you both for filling in our collective knowledge base. These motors are really simple when we know everything about them...

 

[YamadudeXS650C]

You think it best to remove both pistons for inspection?

Yes, It is advised to remove the pistons to take a look see at the small rod ends. If you post a picture of the bearing surfaces we'll help you with your decision on what to do next.



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