Can this motor be saved?

[Hellion]

Dont take offense, but personally theyd all go in my aluminum pit bonfire and turned to ingots and id be off to harborfreight. At least I wouldnt throw them away like many would. Just depends also what your time is worth and other, if any, priorities. Of course being young and no money is a factor and learning to work on them is cool also. So, just depends where youre at.

I find your stance ...disturbing.

A few minor fixes and I could turn all those engines into a profit; $$$. They're "rusty GOLD" as they stand now. Melting them down into ingots.... not so much. The value of aluminum scrap has bottomed out these days.

I'd definitely fix up that Honda just on the name recognition principle alone. All it needs is some medium grit sandpaper applied to the cylinder bore, looks like.

Not everyone wants a HF predator. They make me yawn when I see them mentioned on CL ads, like it's some "added value" on a decent racing kart frame.


Back to our regularly scheduled program...

 

[Nosandwich]

Well said^^^^

 

[zogthegreat]

OK, so while I'm waiting for parts to come in, (rings and gaskets are here, still waiting for ball hone). Now, I've honed car engines before, but never tried porting and polishing. I thought since I have two identical heads from the clones, why not try porting and polishing one of them?

I started with 80 grit and was using 120 grit lapping compound for the second stage when I noticed what I thought was a deep gouge inside the exhaust port:

I was thinking how in the Hades did I do that? However, after taking a closer look, it appears that it's actually a crack in the exhaust port that extends to the outer edge:

I'm going over the rest of the head very carefully right now, but is this head toast?

 

[Whitetrashrocker]

It's a freaking industrial engine.
Grind it out and make a nice valley. Run a welded bead down said valley. Then take off the top of the weld and make smooth.
If that don't work you have an extra head.

I start porting with a burr bit, not sand paper.

 

[bob58o]

Well I cannot weld aluminum.
And it doesn't look cracked to me, but I can't tell.

Smooth out the nick. Sand the gasket surface. Use a new gasket.

EDIT: Maybe it is cracked?

 

[Whitetrashrocker]

Well I cannot weld aluminum.

I take for granted I can.

 

[Nosandwich]

JB Weld works on aluminum.

 

[KartFab]

OK, so while I'm waiting for parts to come in, (rings and gaskets are here, still waiting for ball hone). Now, I've honed car engines before, but never tried porting and polishing. I thought since I have two identical heads from the clones, why not try porting and polishing one of them?

I started with 80 grit and was using 120 grit lapping compound for the second stage when I noticed what I thought was a deep gouge inside the exhaust port:

I was thinking how in the Hades did I do that? However, after taking a closer look, it appears that it's actually a crack in the exhaust port that extends to the outer edge:

I'm going over the rest of the head very carefully right now, but is this head toast?

If it is a crack, i can weld it for you for free, you just gotta pay for shipping here (TX, USA) and back, which might cost more than a head alone.

 

[Hellion]

Just looks like a ding on the inner and a gouge on the outside. Sand or hone flat (the outer mainly, since it's a mounting surface) like with a bastard file or some such...and carry on.

Well done there Zog! Bring 'em back from the brink (of the dumpster).

 

[bob58o]

I didn't see anything that looked like a crack at first, but there appears to be something here. Hidden under the "C" I drew for Crack?

You'll have to refer to the original. I'm not sure if it is anything.

 

[zogthegreat]

I think that I'm going to have to polish it some more to be able to tell. I'm glad I choose this head to be my test subject!

 

[Hellion]

If it is a through and through crack venting to the outside, it could very well be a problem. J-B Weld could be your remedy.

What does the other side look like?

 

[Denny]

Where in the Sam Hill are you guys seeing these pictures? All I see are black boxes with Xs in them.

Denny

 

[bob58o]

Where in the Sam Hill are you guys seeing these pictures? All I see are black boxes with Xs in them.

Denny

Try restarting your phone/PC. That is always my go to move when things don't seem to be working right. Can you see other pictures in other threads? When was the last time you visited the eye doctor?

Can you see the one I attached? Are you just missing the images embedded in the body of the post?

 

[zogthegreat]

OK, so I finally got my parts in and I went ahead and disassembled the motor and honed the cylinder. Nice results, IMO:

The piston showed signs of wear also, so I ordered a replacement for that:

I know that there is a lot of debate over painting these engines, so I went and spoke to some small engine repair mechanics. They told me that they have painted these cases with no problems with over heating, so I sandblasted the parts and I'm going to paint them this week. The painting is to test a concept that I have for my chopper build.

 

[Hellion]

OK, so I finally got my parts in and I went ahead and disassembled the motor and honed the cylinder...

I know that there is a lot of debate over painting these engines...

Which engine is that? This thread is kind of all over the place with different engines.

As long as there's no major damage to the piston, you can re-use it, perhaps with just the next size up rings if they're available. Otherwise you're on the verge of polishing the proverbial turd (it's just a cheap small engine) and wasting good parts on account of mere cosmetic concerns.

I know refurbing this engine or the whole set of them is your project/"baby" and I get that, but for the average Joe just cleaning everything, fixing what is truly broken and reassembling the engine would be more than adequate. After all, they were likely running well before put out to pasture... Something to keep in mind.



I don't know where you're seeing much of any debate over painting engines. Not here I must say. It doesn't even have to be special 'high heat' paint, just lay on some Krylon or Rustoleum.

 

[zogthegreat]

Which engine is that? This thread is kind of all over the place with different engines. [/IMG]

LOL, yeah I tend to wander a bit. The motor is a 6.5 clone that I got for $10.00, (2 for $20.00 actually).

I know refurbing this engine or the whole set of them is your project/"baby" and I get that, but for the average Joe just cleaning everything, fixing what is truly broken and reassembling the engine would be more than adequate. After all, they were likely running well before put out to pasture... Something to keep in mind.

The engine had only 35 psi, so I really didn't do anything that was unnecessary. I fixed what was truly broken. I know that it's just a cheap small engine, but I learned something rebuilding it that will help me when I want to start doing performance mods.

As for putting things out to pasture, I feel that this is one of the problems with society in general. Nobody wants to fix things anymore, just toss it and go out and buy a new one, when with a little effort, you can have good as new at a lower cost. (Full disclosure - my earliest memories are of being told to put a screwdriver down! I've always had a desire to know how and why something works.).

I understand that anyone can buy something off the shelf. But I would encourage the"average Joe" new to go-karts or mini-bikes to rebuild an engine for themselves. As you said, it's not necessary, but still a good experience to have. Plus, it's a lot of fun!

I ordered most of my parts from China, so my total cost for this is, with the engine, is $28.00, not bad considering that a new Predator is $100 + tax.

 

[Whitetrashrocker]

LOL, yeah I tend to wander a bit. The motor is a 6.5 clone that I got for $10.00, (2 for $20.00 actually).



The engine had only 35 psi, so I really didn't do anything that was unnecessary. I fixed what was truly broken. I know that it's just a cheap small engine, but I learned something rebuilding it that will help me when I want to start doing performance mods.

As for putting things out to pasture, I feel that this is one of the problems with society in general. Nobody wants to fix things anymore, just toss it and go out and buy a new one, when with a little effort, you can have good as new at a lower cost. (Full disclosure - my earliest memories are of being told to put a screwdriver down! I've always had a desire to know how and why something works.).

I understand that anyone can buy something off the shelf. But I would encourage the"average Joe" new to go-karts or mini-bikes to rebuild an engine for themselves. As you said, it's not necessary, but still a good experience to have. Plus, it's a lot of fun!

I ordered most of my parts from China, so my total cost for this is, with the engine, is $28.00, not bad considering that a new Predator is $100 + tax.

Glad to hear you like to fix things rather than throw a derp on it

 

[zogthegreat]

So I ran into a bit of a bump on reassembly. The wrist pin appears to be slightly to long and the clip won't pop into the grove:

Should I try to freeze the pin to get it to contract? Or carefully file it? I've never had this problem with car pistons, so I'm not sure which way to go.

 

[Kentucky Boy]

I would slowly sand it down or file until it fits.