Do it yourself honing?

[wmk0002]

What's the boards opinion of diy honing using a drill chucked ball hone on 2 stroke outboards? I have a few 25hp Yamaha motors to rebuild and was planning on rebuilding myself, including the honing... so I asked a question on a Yamaha facebook page looking for advice on which hone to buy. Had a few supportive answers, but got a lot of negative feedback about using those vs getting it done by a machine shop. Most of the guys in these pages are offshore guys probably thinking in terms of huge outboards so it can be hard to get a good read on them. In my mind I agree that I wouldn't diy some of this stuff on a huge V8 outboard that is worth a ton of money and will be taking people out offshore. But not really apples to apples when comparing to a little 2 cylinder motor that's probably only worth $1500 in really good condition.

 

[wmk0002]

FWIW, two of these motors I have to rebuild were torn down when I got them so I can see the bores and the condition of the pistons/rings and both seem in pretty good shape imo. I have not mic'd them or anything yet. But they were sold to me as having "bad cranks" and came with new crank assemblies. I don't see any type of damage to the bores or rings, just some slight scars on the side of the piston like maybe it had a stuck ring issue in the past or something. Basically I'm not anticipating needing any machining done to the bores hence why I was wanting to do the honing myself.

 

[RaisedByWolves]

Check the bores to see if there egg shaped first. If not or even if they are but within spec check piston clearance.

If that all checks out a hone and new rings should be good for inshore work.

 

[wmk0002]

Check the bores to see if there egg shaped first. If not or even if they are but within spec check piston clearance.

If that all checks out a hone and new rings should be good for inshore work.

Ive been cleaning one of the blocks up a bit and I have a better view of the bores. Top cylinder is in good shape as well as the top piston and rings. Bottom cylinder has some markings from piston aluminum transfer over the exhaust port. Cant tell anything there until I get the aluminum off. Never done it before but may try to get it off with some muriatic acid. I have a chrome lined mercury with a similar issue I've yet to tear down so ill probably eventually have to try it on that powerhead too.

I have a friend whose family owns a machine shop and he offered to stop by one evening and measure the bore for me and give his opinion.

 

[Mark McConnell]

Check the bores to see if there egg shaped first. If not or even if they are but within spec check piston clearance.

If that all checks out a hone and new rings should be good for inshore work.

 

[MrGiggles]

Depends on a many things. As you mentioned, those smaller motors typically don't have a lot of hours on them, and any damage is likely the result of overheating or a fueling issue.

Two strokes can be a little problematic to hone. If you use a ball hone make sure it is sized correctly to the bore, as the balls can snag in the ports and cause problems if it is too large. A three stone hone will generally work okay but you still need to be careful on the down stroke.

You will need to do your bore checks before doing any honing. A quick and dirty test for bore taper, push a ring down the cylinder and measure the end-gap at the top, middle and bottom. It shouldn't vary that much. Obviously it isn't very precise, and doesn't measure for roundness, but it gives you an idea. You will also want to check for pitting or deep scratches, neither of which should you attempt to hone out.

Use lots of oil, and wash the cylinders with hot soapy water when you're done. The grit gets everywhere and can be hard to clean out.

I have never used acid for aluminum transfer but I'm sure it works quite well. Still, if you are installing new rings I would lightly hone it.

For your plated cylinder, the plating it typically quite hard and you don't really have to worry about breaking through it with any kind of abrasive. I fashioned a bit for a die grinder (just an old screwdriver shank with a slot cut in the end) that will hold a short strip of emery cloth, works pretty well for removing that aluminum.

 

[eeshaw]

Not telling you what to do but my experience with you doing this is leave it to a professional. The hones with the round balls are meant to be glaze breakers. The hones with three or four stones on them are what you're wanting to use to establish a cross-hatch for oil retention purposes. Measurements should be done with telescoping gages and micrometers. Is it really worth taking a chance on your build using a hodge-podge approach?

 

[thill]

I've used a spring-loaded 3-stone deglazer. Quick and light, in and out and done. Hot soapy water is your friend no matter what you use.

 

[wmk0002]

Not telling you what to do but my experience with you doing this is leave it to a professional. The hones with the round balls are meant to be glaze breakers. The hones with three or four stones on them are what you're wanting to use to establish a cross-hatch for oil retention purposes. Measurements should be done with telescoping gages and micrometers. Is it really worth taking a chance on your build using a hodge-podge approach?

I think I am going to for sure give it a go myself on the first one. If anything, I just want to give a try for the experience. I ultimately may get the others done by a shop though. Overall, I'm not really trying to save a buck just want to see if I can do it all myself on at least one of them.

I got lucky when I bought this Yamaha 25 parts lot. I only paid $1400 for it consisting of 2 fully torn down motors which included 2 brand new oem cranks, 2 complete motors with one marked as having a bad crank and the other as having a dead top cylinder, another complete motor in good shape but ignition issue, and then 7 or 8 mid/pan/cowl assemblies with no powerheads or lowers. I fixed the one with the ignition issue right off the bat by simply replacing the pulser coil and sold it for more than than I paid for the lot so I'm basically back down to net zero on what I have into it all.

Speaking of the pros, do yall have any recommendations on shops that you can ship the blocks to for this work? If I do get it done by a pro, I'd probably prefer to ship it out to a place that specializes in 2 stroke outboard work rather than go local. These 25's are so small once broke down shipping wouldn't be much of an issue. Since I have all of these spare mids and cowls, I'd like to do one motor as a full restoration not just of the powerhead but also cleaning, sanding, painting the entire outboard. Basically try to make one mint restoration for me to hang onto.

 

[wmk0002]

Depends on a many things. As you mentioned, those smaller motors typically don't have a lot of hours on them, and any damage is likely the result of overheating or a fueling issue.

Two strokes can be a little problematic to hone. If you use a ball hone make sure it is sized correctly to the bore, as the balls can snag in the ports and cause problems if it is too large. A three stone hone will generally work okay but you still need to be careful on the down stroke.

You will need to do your bore checks before doing any honing. A quick and dirty test for bore taper, push a ring down the cylinder and measure the end-gap at the top, middle and bottom. It shouldn't vary that much. Obviously it isn't very precise, and doesn't measure for roundness, but it gives you an idea. You will also want to check for pitting or deep scratches, neither of which should you attempt to hone out.

Use lots of oil, and wash the cylinders with hot soapy water when you're done. The grit gets everywhere and can be hard to clean out.

I have never used acid for aluminum transfer but I'm sure it works quite well. Still, if you are installing new rings I would lightly hone it.

For your plated cylinder, the plating it typically quite hard and you don't really have to worry about breaking through it with any kind of abrasive. I fashioned a bit for a die grinder (just an old screwdriver shank with a slot cut in the end) that will hold a short strip of emery cloth, works pretty well for removing that aluminum.

Great advice. Thanks!

 

[wmk0002]

I've used a spring-loaded 3-stone deglazer. Quick and light, in and out and done. Hot soapy water is your friend no matter what you use.

Any issues with the stones catching the ports?

 

[thill]

Any issues with the stones catching the ports?

No, they don't catch anything. its not like the ball hones. These are long, flat stones. They are just deglazers, in my opinion. In the way I use them, they don't do a lot, just give you a nice surface for a new set of rings to seat into without the need to oversize your rings or pistons.

 

[MrGiggles]

No, they don't catch anything. its not like the ball hones. These are long, flat stones. They are just deglazers, in my opinion. In the way I use them, they don't do a lot, just give you a nice surface for a new set of rings to seat into without the need to oversize your rings or pistons.

Yep. There is a type of hone that can be used for oversizing, but that tool and the associated measuring tools are pretty expensive, not worth it for most people.

 

[Sinkingfast]

Back 1985 or so a friend of mine bought a .010 oversize piston with rings for his suzuki 250. He brings it to me and asks if I can fit the piston to the cylinder. The only thing I had was the 3 stone honer. Stones were worn so he went to napa and bought new stones for it. Using cutting oil and a ring to measure end gap, 2.5 hours later we had a pretty good fit it seemed so we put it together. I gotta tell ya it worked very well, was quiet and had great compression....kick starter compression gauge that is.

These days I use a method taught to me many years ago to refinish cylinders....by old men who spent their life smelling like gasoline..

Use true stones to just spot the cylinder to check out pattern..where stones touched or not. At that point ya can measure the bore using the witness marks left by the stones. If light honing is good do that with trued flat stones to your liking. Now use a fitting brush that one uses to clean copper fittings for soldering. Cut off handle loop for the drill chuck to accept. With oil run clockwise then counter wise. Move up and down just like ya would for the hone. Much better finish. Not done yet..wrap leather belt around brush and burnish cylinder to remove the sharps.

When starting for first time run only 15 seconds. Let cool for 15 seconds. Run for 30 seconds than cool for 30 seconds. One more time at 1 minute then cool for 1 min. That will keep the sharp peeks from smearing..It is a microscopic thing that happens.

Nobody in business would spend the time doing this. For those who want better than just good enough...this is the way..
.

 

[Zum]

Youtube the "aussie boat guy" ....he just made a video on this

 

[RaisedByWolves]

Back 1985 or so a friend of mine bought a .010 oversize piston with rings for his suzuki 250. He brings it to me and asks if I can fit the piston to the cylinder. The only thing I had was the 3 stone honer. Stones were worn so he went to napa and bought new stones for it. Using cutting oil and a ring to measure end gap, 2.5 hours later we had a pretty good fit it seemed so we put it together. I gotta tell ya it worked very well, was quiet and had great compression....kick starter compression gauge that is.

These days I use a method taught to me many years ago to refinish cylinders....by old men who spent their life smelling like gasoline..

Use true stones to just spot the cylinder to check out pattern..where stones touched or not. At that point ya can measure the bore using the witness marks left by the stones. If light honing is good do that with trued flat stones to your liking. Now use a fitting brush that one uses to clean copper fittings for soldering. Cut off handle loop for the drill chuck to accept. With oil run clockwise then counter wise. Move up and down just like ya would for the hone. Much better finish. Not done yet..wrap leather belt around brush and burnish cylinder to remove the sharps.

When starting for first time run only 15 seconds. Let cool for 15 seconds. Run for 30 seconds than cool for 30 seconds. One more time at 1 minute then cool for 1 min. That will keep the sharp peeks from smearing..It is a microscopic thing that happens.

Nobody in business would spend the time doing this. For those who want better than just good enough...this is the way..
.

I did a Suzuki for my nephew years back.

He brought a box of parts to my 4th of July party and we semi drunkenly built a bike out of it.

The cylinder was oversized and tapered when we were finished(.010 over) but doing this on a lark out of a &50 assortment of semi matching parts we didn’t care.

Thing ran like a scalded ape!

Missing one radiator, wrong tank, wrong forks stubbed in via spacers, it was a godaweful looking thing but we had a lot of fun.

I don’t think a bike was ever so overloaded (300lbs guys on an 80) nor hit the rev limiter so often, but we certainly got $50 worth of fun out of it.

 

[bigcity]

A lot of people are intimidated by 2strokes and by boat engines in general. Having done many, many 2strokes while I and later my kids raced dirtbikes it's not really that big a job.
If it were my stuff, the first thing I would do is get a fine pick and try to pick the transferred aluminum off the cylinder. If that didn't work, I would use some sort of emory cloth or super fine sand paper on a shaft to see if I could maybe scuff it off of the cylinder wall. But I would definitely have my rotation going toward the ports so I didn't snag it on any sharp corner of the plating. If you do happen to snag (and chip) the plating, you will have to address that. Still may not be a huge deal. I would take close look at any marks/impressions/chips with GOOD lighting and some sort of magnification to make sure I knew what was needed to fix anything further. If, you happen to round an edge of the port it shouldn't be a big issue as the ring doesn't seal until it's past it anyway. I would run a 3 stone glaze breaker to clean up and see if I could get it to seal any better. Then I would put it back together, check my compression. If it's acceptable I would run it on muffs/in a tank and see where it's at. After that I would enjoy my engine, there isn't a whole lot more you can do other than send out the block for repair. And if the compression is too low, you're out a couple hours and a set of gaskets. But you'll know what you have to work with.

 

[wmk0002]

Just a little update. I haven't had much luck on removing what I thought was aluminum transfer, so it probably is scoring. On this one, I was prepared to buy some new rings and a gasket kit and toss it back together but now I think I'm going to send the block off and get it bored over one size. I changed my tune on this one because of a few reasons but mainly because it's standard size now so has a lot of life left in it and it and it came with a brand new crank assembly. If I get this one done right and pair it with the new crank it will essentially be a brand new motor on the inside. The only additional expenses past what I was prepared to spend will be the machining and having to buy new pistons.

Now the other one I have, I discovered it is already oversized to the max 0.5mm. The bores on it have no scoring though. So I'll probably give it a go on a diy job for that one.

Any recs on outboard machine shops I can ship the block to?