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Re-Honing Piston Liner (Ringed)

Old 08-07-2022, 09:43 AM
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Eastflight
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Just a point to note please, when I have done the first few turns on the liner in a cyclic sweep should I then turn the liner over and do the same on the other end in order to make a cross hatch pattern or just corkscrew in one direction
Its my first time honing..!!
Old 08-07-2022, 11:02 AM
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Originally Posted by Eastflight View Post
Just a point to note please, when I have done the first few turns on the liner in a cyclic sweep should I then turn the liner over and do the same on the other end in order to make a cross hatch pattern or just corkscrew in one direction
Its my first time honing..!!
First make a clockwise sweep while going down in the cylinder with the hone or emery, then make a counterclockwise sweep. Repeat alternate until you have the whole liner covered in the cross hatch pattern.

If you've never done it before, take a random piece of pipe of comparable diameter and length, and practise a bit. Its a simple movement, you'll get the hang of it soon enough.

Old 08-07-2022, 11:41 AM
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Originally Posted by Eastflight View Post
So I should prep first with 400-600 then finish with a 320, Right?
On the liner I have there is only a miniscule amount of glazing.
I use 400 grit silicon carbide wet/dry abrasive with some oil on it. Clean extremely well, and install piston and ring. Use no other coarser grit abrasive than 400. Also, lubricate well!! Make note if the ring is pinned. The ring gap must be located over the pin before installation or you’ll break the ring.)
Old 08-07-2022, 12:21 PM
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Originally Posted by 1QwkSport2.5r View Post
Frank Bowman specifically stated in his instructions to use 400-600 grit emery cloth abrasive to prep the cylinder liner for the new ring. Anything coarser than that is too coarse. Maroon scotchbrite is 320 grit - AND - it doesn’t hold that for very long. While it will deglaze —just—okay, it won’t make any scratches capable of holding oil - which is necessary for the ring to properly seat. Green scotchbrite is non-abrasive and will be useless compared to maroon scotchbrite, which is close to useless in this situation.
Bowman rings are not at all like the factory made item. Bowman rings are very simple, basic low tension non-heat treated rings.

The factory rings, like most every production made iron ring are heat treated to provide proper tension as installed.

Is the OP using a low tension ring here?


Scotch Brite works great, provides adequate and uniform tooth to quickly seat a factory tensioned ring.
Most importantly it does the job uniformly ,without excessve metal removal.
No shortage of oil on cylinder walls or any other horror stories.
Contrary to what has been said, Scotch Brite was not designed for a specific "shiny" surface.
It is made, and used widely to provide a uniform, graded surface.


If you are lacking a bead type hone, the Scotch Brite is fine

Mr OP, choose as you see fit.
If you are using a Bowman type substitute then by all means do as Mr Bowman suggests.

Last edited by Jesse Open; 08-07-2022 at 12:34 PM.
Old 08-07-2022, 12:48 PM
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Originally Posted by 1967brutus View Post
First make a clockwise sweep while going down in the cylinder with the hone or emery, then make a counterclockwise sweep. Repeat alternate until you have the whole liner covered in the cross hatch pattern.

If you've never done it before, take a random piece of pipe of comparable diameter and length, and practise a bit. Its a simple movement, you'll get the hang of it soon enough.
Cheers Brutus !
Old 08-07-2022, 12:51 PM
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Originally Posted by 1QwkSport2.5r View Post
I use 400 grit silicon carbide wet/dry abrasive with some oil on it. Clean extremely well, and install piston and ring. Use no other coarser grit abrasive than 400. Also, lubricate well!! Make note if the ring is pinned. The ring gap must be located over the pin before installation or you’ll break the ring.)
Nice tip, thank you
Old 08-07-2022, 12:52 PM
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Originally Posted by 1QwkSport2.5r View Post
I use 400 grit silicon carbide wet/dry abrasive with some oil on it. Clean extremely well, and install piston and ring. Use no other coarser grit abrasive than 400. Also, lubricate well!! Make note if the ring is pinned. The ring gap must be located over the pin before installation or you’ll break the ring.)
To be honest, I have done the job both wet and dry, and prefer to do it dry: Easier to clean that way and as you say, cleaning is extremely important. On a machine hone I'd probably use some oil, but it has been 30 years since I last had access to one.
Old 08-07-2022, 12:59 PM
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Originally Posted by 1967brutus View Post
To be honest, I have done the job both wet and dry, and prefer to do it dry: Easier to clean that way and as you say, cleaning is extremely important. On a machine hone I'd probably use some oil, but it has been 30 years since I last had access to one.
I’ve done it wet and dry also. I feel it’s easier to clean with the oil because the particles are more likely to be in solution with the oil. A good wash with brake cleaner and I feel pretty confident it’s clean. Not to say doing it dry and cleaning the same will give any lesser results.
Old 08-07-2022, 01:14 PM
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Than you gentlemen for all your input. Much appreciated
Old 08-10-2022, 09:31 AM
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Hi,

There is a third way to engine cylinder honing, my 7.45cc .46 cu.in Force engine cost me about £85 new all in, now there are spare parts available to buy but a new piston and liner costs about £60, which is ridiculously expensive, so what I decided to do is run my current engine until it wears out and then sell it, With the proceeds, I will simply buy a new complete engine and do the same again.Now, I realise this approach has problems if your engine price is above £100.00 in cost.
Old 08-10-2022, 10:38 AM
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Originally Posted by 2W0EPI View Post
Hi,

There is a third way to engine cylinder honing, my 7.45cc .46 cu.in Force engine cost me about £85 new all in, now there are spare parts available to buy but a new piston and liner costs about £60, which is ridiculously expensive, so what I decided to do is run my current engine until it wears out and then sell it, With the proceeds, I will simply buy a new complete engine and do the same again.Now, I realise this approach has problems if your engine price is above £100.00 in cost.
That would be okay if you use a current engine on the market today like the Force 46 however when one has a discontinued engine then things are slightly different.
For example I've just replaced the piston ring on a OS 50SX. Its a super little engine with bags of power in its class. Luckily the Heli guys use the 50 Hyper which have similar internals. Not easy to source the 50SX engine Aero version these days.
The Force 46 has an ABC Liner whereas the OS 50SX is a ringed piston hence the honing procedure.
Nevertheless, as you said you can use the new Force 46 until its worn then buy another one 'new' after selling the old one however, based on the value price of the new F46 - you might not get so much for your money in selling the old F46 and therefore your no better off than you started.
Just another way of looking at the scenario.
Thanks for your comment
Old 08-10-2022, 10:41 AM
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So... you're selling a worn out 85 pound engine for which the worn out parts cost 60 pounds to replace?

Apologies if this comes across as a bit brash, but...IDK, that seems like a really dumb idea to me: If the buyer knows what he is doing, he's not going to pay more than a tenner for it because he'll be spending 70 pounds on a set of bearings and a new P/L set to get the engine in good condition again, which gives him a saving over new of a whopping 5 pounds. Which is not worth it, so he'll refrain from buying it. IF he knows what he is doing...
And you still have to spend 75 pounds of your own money to get a new engine. Better to just shill out those 60 (or 70 if you need bearings as well) pounds and keep your own engine in good condition. Cheaper for you in the end.

If you were going to ask anything over 15 pounds for that engine in worn out condition... well... there are words for that, none of them very friendly.

You could however, sell the engine for a fair price while it still has a decent amount of life in it, let's say you sell after a year for 50 quid or so and THEN get yourself a fresh engine which only costs you about £35. That way you have a yearly cost that is overseeable while having a new engine every year, while the buyer saved some money by buying a decent engine for less money than new.

Last edited by 1967brutus; 08-10-2022 at 10:43 AM.
Old 08-10-2022, 12:55 PM
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Originally Posted by 1967brutus View Post
You could however, sell the engine for a fair price while it still has a decent amount of life in it,
If its sold on Ebay it's either new, used or parts for repair, I would simply sell as used but working engine, it is up to the buyer whether to buy or not and there are many buyers on Ebay. Next, used engines on Ebay fetch 40~50% of their new price, I've already done my homework.

If the engine runs, it is classified as working, irrespective whether its worn out or not.When you sell an used engine on Ebay the seller does not have to disclose whether it is worn out or not.It is simply sold as 'used'.These sales, of used engines, on Ebay are happening right now

Last edited by 2W0EPI; 08-10-2022 at 01:24 PM.
Old 08-10-2022, 11:02 PM
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Originally Posted by 2W0EPI View Post
If its sold on Ebay it's either new, used or parts for repair, I would simply sell as used but working engine, it is up to the buyer whether to buy or not and there are many buyers on Ebay. Next, used engines on Ebay fetch 40~50% of their new price, I've already done my homework.

If the engine runs, it is classified as working, irrespective whether its worn out or not.When you sell an used engine on Ebay the seller does not have to disclose whether it is worn out or not.It is simply sold as 'used'.These sales, of used engines, on Ebay are happening right now
I'm sorry but I have to politely disagree with you.
When you sell an engine on Ebay (other sites may differ) the buyer is assuming you are as honest as possible with the condition of the engine. For example 'well used but still has good compression' or ''for parts/repair'......Then you know what your getting!!!
If you don't do this then the buyer if not happy with their purchase will just return it to you for a Full Refund. Your credibility would be tarnished and you've gained nothing from the process.
Some engines are just not worth running into the ground and selling-on (Force 46 is one example because they are readily available at a competitive price. Your better off buying the parts for them or save some life in it then sell as a 'used but good condition engine'.
I don't think I've seen a used Force 46 on Ebay (if there was one then I missed it). However, an OS46AX for example is a popular motor and you'll see them for about 40-60% of the new value (good working order).
Manufactures make it expensive to buy certain components. Otherwise they won't sell their new stuff. It's a economics thing.
Buy an engine you like and does the job and it will last you for years and years if maintained correctly.
If your your lucky you'll probably sell it in later years for the same price you bought it - because it might be sort after (eg; Saito, K&B, Irvine 53, etc).
Food for thought, not a dig at you !!


Last edited by Eastflight; 08-10-2022 at 11:06 PM.
Old 08-11-2022, 12:47 AM
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Originally Posted by Eastflight View Post
If you don't do this then the buyer if not happy with their purchase will just return it to you for a Full Refund. Your credibility would be tarnished and you've gained nothing from the process.
The seller can choose between returns or no returns accepted.If the engine was sold used and runs and no returns accepted then the buyer does not have any recourse.

I just want to point out I myself have burnt my fingers on Ebay many times.I would never buy a used engine on Ebay, no way.

Last edited by 2W0EPI; 08-11-2022 at 12:57 AM.
Old 08-11-2022, 02:10 AM
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Originally Posted by 2W0EPI View Post
The seller can choose between returns or no returns accepted.If the engine was sold used and runs and no returns accepted then the buyer does not have any recourse.

I just want to point out I myself have burnt my fingers on Ebay many times.I would never buy a used engine on Ebay, no way.
Very grey area when selling on Ebay
Ebay will normally side with the Buyer (14 days distance buying policy) regardless of the disclaimer you put on the description.
If its NOT exactly as you described and buyer finds that the description does not fit the bill, 9/10 times you will have to do a refund. This is normal when buying on-line. Its a protection for the consumer because they cannot physically 'see before buy'.
On the other hand if you sell on Face Book Market Place then usually the sale is done locally and the buyer is able to pay on collection. That's a different policy rule all together!
Ebay feedback is a good indication that the item is worthy of buying. Feedback of 96% or less is generally 'Stay Away'. However IMO, 98.5-100% is pretty safe to buy from.
Old 08-11-2022, 03:17 AM
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Originally Posted by 2W0EPI View Post
If its sold on Ebay it's either new, used or parts for repair, I would simply sell as used but working engine, it is up to the buyer whether to buy or not and there are many buyers on Ebay. Next, used engines on Ebay fetch 40~50% of their new price, I've already done my homework.

If the engine runs, it is classified as working, irrespective whether its worn out or not.When you sell an used engine on Ebay the seller does not have to disclose whether it is worn out or not.It is simply sold as 'used'.These sales, of used engines, on Ebay are happening right now
Well, be that as it may... when you're selling via e-bay, the buyer has no chance to inspect the engine or see it run before the deal is done. That is quite a difference with someone buying the item directly from you.
Abeit within the rules, it is an utter misrepresentation of the real condition of the engine and that kind of business will get you a lot of negative feedback. And rightfully so.
Doesn't matter if it is happening right now (I know it is and that is why I stopped buying from e-bay a long time ago), it does not change the fact that you are bluntly telling everyone here that you are an untrustworthy seller. That is up to you of course, but I have an opinion on that, that you probably can guess right now.

No respect at all for that attitude...
Old 08-11-2022, 03:22 AM
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Originally Posted by 2W0EPI View Post
The seller can choose between returns or no returns accepted.If the engine was sold used and runs and no returns accepted then the buyer does not have any recourse.

I just want to point out I myself have burnt my fingers on Ebay many times.I would never buy a used engine on Ebay, no way.
So what you are saying is; "They" did it to me, so now I am doing it to "them".

Two things wrong with that; Treat others how you WANT to be treated, NOT how you WERE treated. Because the first leads to a better world, the second does not.
The other thing wrong with that, is that the "they" that did it to you, are NOT the same people as the "them" you're doing it to.

Really... if it were possible, you would have lost even more of my respect, but you allready lost whatever possible in the previous post...
Old 08-11-2022, 03:29 AM
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Originally Posted by 2W0EPI View Post
I have not sold any engines on Ebay to date, its your system that we all abide by which is disgusting.
I do not know WHOSE system it is, but a system being disgusting, NEVER is an excuse for oneself to do likewise...
Old 08-11-2022, 04:25 AM
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I've sold a few things on Ebay this year and so far I have not had any bad feedback as a seller.
Still I maintain a 100% rating (over 1240 items - a mix of buy & sell). However, I have been stung in the past but I've learnt from it and I can honestly say I have not had any more bad experiences to date.
If you know what your looking for and play by the rules then usually the out come is a happy experience.....IF ONLY it were true all of the time!!!

Anyway, back to honing cylinders. I've replaced the engine liner & piston ring with a bit of honing as advised from the contributors to this post (thank you) and I'll give it a break-in this evening on the bench with a couple of tanks before installing it to the model.
Hopefully it'll purr once again.........!

Last edited by Eastflight; 08-11-2022 at 04:28 AM.
Old 08-11-2022, 04:52 AM
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Originally Posted by Eastflight View Post
I've sold a few things on Ebay this year and so far I have not had any bad feedback as a seller.
Still I maintain a 100% rating (over 1240 items - a mix of buy & sell). However, I have been stung in the past but I've learnt from it and I can honestly say I have not had any more bad experiences to date.
If you know what your looking for and play by the rules then usually the out come is a happy experience.....IF ONLY it were true all of the time!!!

Anyway, back to honing cylinders. I've replaced the engine liner & piston ring with a bit of honing as advised from the contributors to this post (thank you) and I'll give it a break-in this evening on the bench with a couple of tanks before installing it to the model.
Hopefully it'll purr once again.........!
Mind you: a honed liner and a new ring, means a full break in period, since liner and ring are THE parts that are most in need of a proper break in as well as needing the most time to do so. No shortcuts here. A piston barely needs breaking in, a rod doesn't, not really, 5~10 minutes or so, but a ring on a liner easily takes 1,5 to 2 hours.
Old 08-11-2022, 07:20 AM
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Hi Brutus
I was hoping to break-in with two tanks of fuel (my test stand has a 20oz/600ml tank). Then i'll go and do some very gentle flying to help with the cooling.
Its pretty hot weather here at the moment.
With two tanks of fuel on the bed it would probably give me about 1 hour 10mins. But if needs be then I'll do 3 tanks then go and fly it gingerly.
Old 08-11-2022, 08:49 AM
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Originally Posted by Eastflight View Post
Hi Brutus
I was hoping to break-in with two tanks of fuel (my test stand has a 20oz/600ml tank). Then i'll go and do some very gentle flying to help with the cooling.
Its pretty hot weather here at the moment.
With two tanks of fuel on the bed it would probably give me about 1 hour 10mins. But if needs be then I'll do 3 tanks then go and fly it gingerly.
Oh, if you trust yourself enough, the entire break-in can be done while flying, and if you know what you're doing, it is THE best way because everything beds in with the temperatures, but more important, the cooling airflow, to which the engine is exposed in flight.
A quick 15 minute run-up on the bench if you trust yourself less, then the remaining break in in the air is also OK.

It is not about the bench or the plane, I merely wanted to bring attention to that the engine basically needs a full break in period, because the ring is the determining factor for that.
FWIW: for ringed engines, the best way to break it in is short burst of full throttle (like the 10~15 seconds it takes to get airborne and say, a 100 ft altitude) then throttle back as far as safely possible for a short duration, then fly and vary throttle a lot between full and minimum. You want the gas pressure against the ring to press it against the liner (that is what seats it properly) but on a new ring this generates quite a bit of local heat. Since the heat is local, you can NOT judge this heat by checking the engine temperature. So you have to let it cool down for about the same duration by running low power. As the process progresses, you can hold longer periods of full throttle because as the ring wears in, it gets smoother and friction and heat get less and less. 8 t 10 15 minute flights should do the trick completely. After that, the ring has not yet fully seated (that takes in total about 10 hours) but it is by now smooth enough not to burn up from continuous full throttle.

Last edited by 1967brutus; 08-11-2022 at 08:59 AM.
Old 08-11-2022, 08:50 AM
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I have been buying and selling on eBay for over twenty years feedback of 2000 plus, always been 100%. Sold all over the world, sold and shipped items internationally costing over $2000 including a $2500 WW2 military transmitter weighing 770 pounds that was air/freighted to a museum in Barcelona Spain. No problems selling but I have had a few (very few) sellers whom I have bought from who thought they were slick. In every case eBay was quite helpful. For the most part the purchases were very good. Found a lot of good engines, planes and parts on eBay. Many fine pieces of vintage amateur radio equipment, hard to find tubes and parts etc there as well.

Done a lot worse in forums,after "trusting" people to follow thru with payment for items shipped in good faith.

You learn to sort em out quickly

Last edited by Jesse Open; 08-11-2022 at 08:53 AM.
Old 08-11-2022, 09:00 AM
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Originally Posted by 1967brutus View Post
.Abeit within the rules, it is an utter misrepresentation of the real condition of the engine and that kind of business will get you a lot of negative feedback. And rightfully so. Doesn't matter if it is happening right now (I know it is and that is why I stopped buying from e-bay a long time ago).
Yes, its happening right now and not just rc engines but everything else as well. BTW, if you are not sure what the system we all find ourselves in its called turbo supercharged capitalism and its main driving proponent is human greed.
I see everyone posting here doesn't like it when I explain it as it is?

Last edited by 2W0EPI; 08-11-2022 at 12:32 PM.

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