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Something is smelling fishy. I can only figure the bore is a tick big and causing the ring gap issues. But your piston clearance is correct at .004. would be nice to know true bore diameter.
I don't like it, but see no alternative but to assemble as is or buy a new top end exchange kit.
 

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Discussion Starter #142
I agree and I too would like to know the "true" diameter. Picked up the oil seal today, oil pump gasket should be here tomorrow.
I'm not sure I would trust my measurement if I were to do it. I could call around and ask a small engine repair or machine shop to throw me top, mid, and bottom bore measurements. I am not sure how that would change things moving forward. I guess if it is too big the option to resleeve and bore and hone would be the most affordable route.
 

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Discussion Starter #143
Cylinders are marked Y-1 and Y-2. I was placing Y-1 toward the front of the motor where I assume #1 goes and noticed there was dowel in the case and a dowel in the cylinder in the same corresponding hole. This made me question whether y-1 cylinder needed to be at the front of the motor or not. Also, the worst news, I am missing 2 dowels. I did not pull or replace these dowels. I now have to hope someone local has these or wait for shipping once again, per my usual bad luck.

If I were to replace all 4, how in the hell do you pull these suckers out? I dont guess it matters if I booger the old dowels out but I cant pull them. No access to acetylene torch, all I have is a basic propane torch.
 

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Cyl's are both the same. If it fits rear location without pulling dowel put it there. However I would order and replace missing dowels. They keep the cyl's located correctly.

However in future if you need to pull one. use a pair of wire cutters. Grab as low as possible and push down. Use the 15* angle is jaws as your lever. Or vice grips and twist.
 

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Discussion Starter #145
10-4 on cylinder locations.

Wirecutters, great idea, I was trying to pull using channel locks. Making some calls when these shops open!
 

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Discussion Starter #146 (Edited)
Pins were replaced. Vise grips and twisting worked for me on pin removal, paying close attention to not damage mating surfaces.

Appears the 3rd and 9th bolt holes, through the cylinder head and to the cylinders have become damaged ad stripped the holes. I need to replace these bolts as well as helicoil one hole on each cylinder.

I am under the assumption that the head bolts are coarse M10 x 55, can anyone confirm?
 

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Tommy,
The bolts are 8mm. Look for a set of used on ebay. Or order new. A generic 8mm bolt won't work.
You may also have to search by part number.
 

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Discussion Starter #148
M8x55, not sure where I got the 10 from, maybe quantity needed. My original question was what is the threat type/size on these head bolts? I need to order the correct helicoil kit to try and get this baby back together.
 

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M8x55, not sure where I got the 10 from, maybe quantity needed. My original question was what is the threat type/size on these head bolts? I need to order the correct helicoil kit to try and get this baby back together.
Sorry guess I misunderstood message 😬. To the best of my knowledge without one to check against. They are 8mm x 1.25 pitch. Check one against a nut in the hardware store. The nut box should have the pitch on it. Or find a pitch guage.
 

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Discussion Starter #150
Head bolts are M8 x 1.25 x 55mm. Coarse thread.

Ace had a perfect size match but bolt head numbers were different, replacement labeled 8.8, the head bolts are 10.

I ordered a heli-coil kit for M8 x 1.25 and I have 2 replacement head bolts on order.
 

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That's why I said a general bolt won't work. The 8.8 and 10, is the bolts hardness rating. You don't want mixed ratings or to soft a rating.
 

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Discussion Starter #155
Almost a month! I apologize. Weather got cold and I lost motivation. Got back to work today prepping both cylinders for helicoil and #3 and #8 if I am correct. Removed both cylinders so they would sit flat on bench. Taped up the cylinders to catch any metal shavings and had the shop vac near. Proceeded to install helcoil with the installation tool and the tab on the tool that holds the tang on the coil broke. The coil came right out but now I am stuck unless you guys have an idea, sounds like I'll have to buy/hopefully rent a helicoil tool to get the coil installed.
 

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Could you maybe screw it in using a long pair of needle nosed pliers holding the coils tab?

Be sure to clean the hole out well with carb cleaner and install coil using red locktite. Then screw a bolt in and remove and wipe away excess locktite from bolt.
Also use anti seise on head bolts when you reassemble.
 

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Discussion Starter #157
Admitting stupid mistakes because I was not paying attention or trying to rush are embarrassing but great teaching/learning moments. I did not do my research on helicoils and attempted a repair in the worst way possible. I was unaware a drill bit was needed before tapping hole. Original hole was tapped without drilling. Hole was then drilled with 5/16" as I did not have a 21/64th on hand. Tapped again, coil will not screw into hole. Went and bought a 21/64th, redrilled and retapped hole, still will not accept the helicoil. Besides buying a replacement jug, what options do I have? Does Yamaha manufacture a bigger hold bolt and I could redrill/tap to the next size up? Is there a "sleeve" I can pound into the hole to allow for the steps to be completed in the correct order?
 

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Admitting stupid mistakes because I was not paying attention or trying to rush are embarrassing but great teaching/learning moments. I did not do my research on helicoils and attempted a repair in the worst way possible. I was unaware a drill bit was needed before tapping hole. Original hole was tapped without drilling. Hole was then drilled with 5/16" as I did not have a 21/64th on hand. Tapped again, coil will not screw into hole. Went and bought a 21/64th, redrilled and retapped hole, still will not accept the helicoil. Besides buying a replacement jug, what options do I have? Does Yamaha manufacture a bigger hold bolt and I could redrill/tap to the next size up? Is there a "sleeve" I can pound into the hole to allow for the steps to be completed in the correct order?
If you learned from it it's not stupid mistake! Can you post a good pic of hole. I may have some ideas.
 
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