Involuntary Engine Rebuild...HELP!

Prasinos

Prasinos

Member
OK, here's the story.

I had done all the mods I could do without taking my engine apart and I decided my next logical step would be to port the exhaust and intake, so I took my head and cylinder off of the engine and matched up the exhaust and intake ports as well as removed the head gasket. I then went back to put it all back together. A buddy of mine said it should be easy to put the piston back in just by pinching the piston rings.

Long story short I now have a broken piston ring and the gasket between the crank case and cylinder is gone. Also, in my panic I washed all of the parts including the crank case with gasonline, I dont know how much of an issue this is but there is probably a small amount of dirt/debris inside the crank case.
I need to know:

A. What parts should I order and where?

B. How do I install these parts?(especially how do I put the piston back in the cylinder)

C. Do i need to take apart the crank case to clean it out?

D. Is there anything else I should do while the whole engine is apart?

You guys are always a great help so I hope you can get me back on the road ASAP!
 
there's so many types of these engines out there Your best bet is to order the parts from the seller you bought the engine from or call one of the vendors here and give them the dia of the piston length of the piston dia of the wrist pin hole and the height of the wrist pin hole. also if its a bushed or bearing wrist pin.
order only the parts you need I reread your post you broke a ring and a head gasket I'd re order those first.
Look in my post on total engine tear down for installing the piston into the cylinder the wood tool to hold the piston will make it easier to do.
You washed out the crank case with gas you could spray it with wd-40 or better some engine oil to keep it from rusting and keep it covered until you can work on it.
I would not split the crankcase the gasket is a booger to make but if you have them my post on total engine tear down will help.look here.http://motorbicycling.com/f39/bicycle-engine-total-tear-down-391.html hope this will help
 
you will need to take off the head and cylinder a new cylinder base gasket and head gasket. find the correct rings for your engine make sure you have the proper end gap on the rings and then install them the locater pins in the piston ring grooves need to line up on the ring gap, the pins are offset to it makes a difference which way the rings will go on. You can do it with patience.
Norman
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ive been working on my buddies bike waiting for the rings and gaskets to come into the mail from spookytooth but they waited 5 days to ship the order so i figure it should take 3-4 more days, il let you know how it goes as soon as i get em.
 
you can look at the total tear down thread it will help you for your rebuild and the simple piston holding tool will make the cylinder installation easier.
http://motorbicycling.com/f39/bicycle-engine-total-tear-down-391.html check this out. you will find that tool is nothing but a piece of wood to hold the piston steady. You can use plastic or metal but wood is easy to get use and make the part and it won't scratch the engines surfaces
 
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Thanks norm you were a huge help. My problem the first time was that i didint realize there were aligning pins on the piston so i tried to force the ring around one of them. anyway i installed the new piston ring and it runs great, ive been keeping it at low speeds. do you guys think i need to go through the break in process again now that i have a new piston ring. I started my trip odometer and plan on going 50 miles or so with 16:1 oil ratio, what do you think?

PS.
I know i could find it on another post but what oil do would you recommend (available locally) for after break in?
 
I use the wallmart cheap oil super tec cheap and it works some say do not use the watercooled out board oil I have, no ill effects on me or the engine.
I will use castor oil made for 2-stroke engines only cause I like the smell. It a mental thing make me think of my child hood days, model airplane smell.
I've used the amsoil from Pablo and it is very good stuff.
So you see I don't use just one type. I say some oil is a heck of a lot better than NO oil.
Norman
 
I use a wooden plate to let the piston set on lube up the cylinder and the piston and rings line up the locater pins on the ring pinch the rings with my fingers a little and the cylinder will almost slide right on if it don't recheck the rings end for being in the proper position on the locater pins. look here on page 2 #11 first picture
http://motorbicycling.com/f39/motorized-bicycle-carburetor-install-rebuild-302.html


Norman
 
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