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Old 05-29-2004, 04:08 PM   #31
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Er? Lap the piston, leave the sleeve? Why do you say?
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Old 05-29-2004, 04:53 PM   #32
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Originally posted by spenzalii
Er? Lap the piston, leave the sleeve? Why do you say?
Its too easy to damage the lining in the sleeve. Therefore it is best to just work on the piston and leave sleeve alone.
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Old 05-29-2004, 06:44 PM   #33
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The sleeve has a chrome coating & by honing or lapping you are removing it. A hone for automotive purposes is to remove the glaze from a bore, be it engine block, wheel cylinder etc. On a nitro engine the glaze (chrome) is our friend. The dude who lapped the sleeve with toothpaste, good luck with your engine but I think you may have decreased the life of it. If it runs hard now & you are happy with it I guess thats all that matters.
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Old 05-31-2004, 11:37 PM   #34
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Quote:
Originally posted by spenzalii
Er? Lap the piston, leave the sleeve? Why do you say?
Usualy sleeve has 3 tappers and it is realy art to make them and it is life important to have them. If you will try to relap sleeve ad you will change tapering-it will end of performance and reliability.
Piston has only one taper ( on the very top of piston, it is vary from manufacturer to manufacurer, and it is not that critical). In general piston id cilindrical, so it is pretty easy to work with that.
It is just my sugestion, based on ... years of expirience. After that it is up to you.
To lap piston for expirinced guy takes about 15-30 minuts. to relap sleeve for the same guy takes 2-3 hours and required much more presision tool and mesuring instrument.
Just try to belive on my words, do not mess with sleeve, even used sleeve with new piston much better then if you will try to relap it.
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Old 05-31-2004, 11:39 PM   #35
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Quote:
Originally posted by soc123_au
The sleeve has a chrome coating & by honing or lapping you are removing it. A hone for automotive purposes is to remove the glaze from a bore, be it engine block, wheel cylinder etc. On a nitro engine the glaze (chrome) is our friend. The dude who lapped the sleeve with toothpaste, good luck with your engine but I think you may have decreased the life of it. If it runs hard now & you are happy with it I guess thats all that matters.
We can relap sleeve and polish it again, that is not a point, point is-tapering ( please see post above).
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Old 06-01-2004, 05:46 PM   #36
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Very good point about the taper, I meant in my reply that honing will remove the chrome & all the polish in the world will not bring the sleeve to its correct ID. I am sure someone with the correct tools & knowledge could do it, but to a person who is not fully dialed in engine manufacture should proably steer clear of anything to do with inside the liner. I modify liners, cranks etc but I wouldnt touch the inside of the liner as I dont have the correct tools or knowledge. also TG777 I have learnt a lot from reading your posts over the past 8 months or so, Keep it up
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Old 06-01-2004, 06:54 PM   #37
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Quote:
Originally posted by soc123_au
Very good point about the taper, I meant in my reply that honing will remove the chrome & all the polish in the world will not bring the sleeve to its correct ID. I am sure someone with the correct tools & knowledge could do it, but to a person who is not fully dialed in engine manufacture should proably steer clear of anything to do with inside the liner. I modify liners, cranks etc but I wouldnt touch the inside of the liner as I dont have the correct tools or knowledge. also TG777 I have learnt a lot from reading your posts over the past 8 months or so, Keep it up
I am realy happy. that myposts help you and many other hobby addicted people to understand something and I will share what ever i know and collected for years in hobby. there will be some points which I will never open ( for instance-how to put bushings inside the conrod and make sure they will never come out, how to cast the cillinder, how much Si in crancase alloy etc,) But general procedure, numbers etc-I am realy open to share.
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Old 06-01-2004, 08:35 PM   #38
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Quote:
Originally posted by Top Gun 777
I am realy happy. that myposts help you and many other hobby addicted people to understand something and I will share what ever i know and collected for years in hobby. there will be some points which I will never open ( for instance-how to put bushings inside the conrod and make sure they will never come out, how to cast the cillinder, how much Si in crancase alloy etc,) But general procedure, numbers etc-I am realy open to share.
I would love to know your secret regards the bushing in the rod, or even better how to make it run on a bearing. I have kept up with the progress on your engines & am looking forward to seeing them on track in Australia. I will probably try one once the Carb is fully sorted.
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Old 06-01-2004, 09:45 PM   #39
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Quote:
Originally posted by soc123_au
I would love to know your secret regards the bushing in the rod, or even better how to make it run on a bearing. I have kept up with the progress on your engines & am looking forward to seeing them on track in Australia. I will probably try one once the Carb is fully sorted.
No bushing secret
About the bearing, yes it is possible, but for 21 size, for 12, so far we didn't find solutions for some issues, but we working on it.
You will see pretty soon couple of them there.
Carb is one of the thing which we are working now and progress is going no the way we want to, but eventualy we will be there.
Why you need secret for bushings on conrods-any way I hardly belive you will make them, but if I will release it, a lot of people will make their conrods much better then they are and this I don't want to for them-they have to work hard to find their way.
It is production seret-it has nothing to do with performance 9 onl the life of conrod)
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Old 06-02-2004, 08:54 PM   #40
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To prevent the copper bushing coming out on the conrod, you can plated the material rather than forcing 2 object together.

Regarding to the cylinder question. Here are some of my own opinion ( I am not a engine manufacturer and is not in the machinary industry. I just have an genuine interest in model engine production.)

Even the best CNC machine we have today, the manufacturing tolerance is about +/- 0.02mm, unless you start doing machining under control temp, atm etc. But the production cost willl be very very expensive. being massly produced engien, at novarossi etc I don't think every piston and sleeve is made to spec. Pick up a caliper or if you have a height guage and meaure the port on the sleeve. it is at different height from sleeve to sleeve. Some of the line aren't even cut straight. The inside of sleeve and piston is not in perfect roundness (+/- 0.0015). In fact it is not very round at all ( some of you will argue it is made to be elliptical on purpose, but trust me at the cost these engines are exported out of italy, they are not made to be elliptical on purpose).

Personally I think lapping or grinding on the sleeve is better than working on sleeve. because when the engine heats up, the piston usually expands more (that;s why it seizes), working on cylinder making sure it is round will enable the piston to "grow" into something good ( the secret in all modified engien is piston and sleeve fit, not the extra cut on the transfer port). If you work on the piston and make sure it is round but the cylinder is not...... more friction and leakage may result.

Yes cylinder taper is very important. But honing cannot reproduce the tapering. Honing simply removes the coating on the inside of the cylinder ( but the honing stone follows the basic geometry from the brass liner, in other words, if the cylinder is not round, it will not be round). Honing produces the crossweb surface finishing you see on novarossi, rb, jp engine. So see, they are massly produced, not that accurate as you guys have thought.

Grinding can correct any defect in the linder, make sure it is perfectly round and also maintains the taper. But is would be best to grind both piston and sleeve so both are in perfect roundness.

Correct me if i am wrong, any suggestions.....
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Old 06-02-2004, 10:48 PM   #41
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Quote:
Originally posted by ERL2004
To prevent the copper bushing coming out on the conrod, you can plated the material rather than forcing 2 object together.

Regarding to the cylinder question. Here are some of my own opinion ( I am not a engine manufacturer and is not in the machinary industry. I just have an genuine interest in model engine production.)

Even the best CNC machine we have today, the manufacturing tolerance is about +/- 0.02mm, unless you start doing machining under control temp, atm etc. But the production cost willl be very very expensive. being massly produced engien, at novarossi etc I don't think every piston and sleeve is made to spec. Pick up a caliper or if you have a height guage and meaure the port on the sleeve. it is at different height from sleeve to sleeve. Some of the line aren't even cut straight. The inside of sleeve and piston is not in perfect roundness (+/- 0.0015). In fact it is not very round at all ( some of you will argue it is made to be elliptical on purpose, but trust me at the cost these engines are exported out of italy, they are not made to be elliptical on purpose).

Personally I think lapping or grinding on the sleeve is better than working on sleeve. because when the engine heats up, the piston usually expands more (that;s why it seizes), working on cylinder making sure it is round will enable the piston to "grow" into something good ( the secret in all modified engien is piston and sleeve fit, not the extra cut on the transfer port). If you work on the piston and make sure it is round but the cylinder is not...... more friction and leakage may result.

Yes cylinder taper is very important. But honing cannot reproduce the tapering. Honing simply removes the coating on the inside of the cylinder ( but the honing stone follows the basic geometry from the brass liner, in other words, if the cylinder is not round, it will not be round). Honing produces the crossweb surface finishing you see on novarossi, rb, jp engine. So see, they are massly produced, not that accurate as you guys have thought.

Grinding can correct any defect in the linder, make sure it is perfectly round and also maintains the taper. But is would be best to grind both piston and sleeve so both are in perfect roundness.

Correct me if i am wrong, any suggestions.....
About the bushings in conrod-no comments!
About sleevs. You are absolutly right-honning doesn't create tapering or fixing non round, it just simply repeat what was made on base. Grinding and apping realy can fix all this stuff which can't be fix by honning. It is very expencive proces and you are absolutly right-there is climate control ( basecaly clean tool room environment).
On all mass production engines the fitting i done theoreticly and this is why it nees to be run in. On top of it, I don't belive they follow heat threating cycling during the metalurgy and tis required heat cycling during the run in process. But all this thing is realy hirt.
Nothing got to be eleptical in our engines, I don't think anybody will start this discusions. There are tolerances and anything which is ut of limit is just defective part. Very simple. But in some cases tolerances wider or narrower. Let's say in piston rounding limit is 1.5 microns. it is just for instance. But inside piston tolerances arent't that narrow.
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Old 06-04-2004, 10:11 PM   #42
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I read this, and the other engine thread, and it's quite interesting stuff.

My thoughts on it all are somewhat all over the place though.
As part of his motorcycle business, my father spent a great deal of time reboring and honing 4, and of course 2 stroke engines, and generally when it comes to chrome, or as is more common in bikes, nikasil plated bores, there is actually bugger all you can actually do to them come rebuild or rehone time.

For a start, to the guy that used toothpaste on his bore, I would not be worried, I'd say it's a safe bet that toothpaste would barely make a dent in the stuff, chances are it's just a little cleaner than it was before you started.
We are talking about linings that basically outlast pistons, rings, hell even whole engines in some motorbikes, it's tough stuff.

I do tend to agree in general though that it's not really worth touching the liners, at times when they get a little rough with age, you can run a very lite brush hone through it to clean it up a little on bikes, the same may be true of RC motors, I don't really know, but a brush hone does very little to change taper, it's just a cleaning tool really.

The piston lapping idea is interesting, I kind of like the reverse logic about it, plated liners have no real crosshatch like base metal liners, so why not reverse the process and put the crosshatch on the piston?
It makes some sense in a crazy kind of way, also because you can't alter a plated bore to match a piston (the traditional method), make the piston match the bore.

About the only problem I see with it all, is that you can't always count on a perfect bore with a plated liner, I have seen the same story on some bike engines, you start off with a dud bore, and it just chews pistons.
But then it's not like you can do anything about that, so you either live with it, or replace it.

In a perfect situation, you would all start with an oversized piston, and then using very fine measuring tools, carefully hone the piston to exactly match the bore you have.
Or really, the exact reverse of the way it's done with say an iron cylinder on a car or bike.

You know worst case scenario here is you take a piston from a new engine, and just give it a real light outer hone, and then you got that whole cross hatch thing going for you, and maybe a more free and easy piston fit, which is not a bad thing on a race engine (shorter break in time), so I suppose it's not a bad way to go, sounds like it could be worth a try to me...

Hmm, now of course there is thoughts of a proper tool for this, say a reverse hone tool, sprung in rather than sprung out...
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Old 06-04-2004, 10:46 PM   #43
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Quote:
Originally posted by Bishop
I read this, and the other engine thread, and it's quite interesting stuff.

My thoughts on it all are somewhat all over the place though.
As part of his motorcycle business, my father spent a great deal of time reboring and honing 4, and of course 2 stroke engines, and generally when it comes to chrome, or as is more common in bikes, nikasil plated bores, there is actually bugger all you can actually do to them come rebuild or rehone time.

For a start, to the guy that used toothpaste on his bore, I would not be worried, I'd say it's a safe bet that toothpaste would barely make a dent in the stuff, chances are it's just a little cleaner than it was before you started.
We are talking about linings that basically outlast pistons, rings, hell even whole engines in some motorbikes, it's tough stuff.

I do tend to agree in general though that it's not really worth touching the liners, at times when they get a little rough with age, you can run a very lite brush hone through it to clean it up a little on bikes, the same may be true of RC motors, I don't really know, but a brush hone does very little to change taper, it's just a cleaning tool really.

The piston lapping idea is interesting, I kind of like the reverse logic about it, plated liners have no real crosshatch like base metal liners, so why not reverse the process and put the crosshatch on the piston?
It makes some sense in a crazy kind of way, also because you can't alter a plated bore to match a piston (the traditional method), make the piston match the bore.

About the only problem I see with it all, is that you can't always count on a perfect bore with a plated liner, I have seen the same story on some bike engines, you start off with a dud bore, and it just chews pistons.
But then it's not like you can do anything about that, so you either live with it, or replace it.

In a perfect situation, you would all start with an oversized piston, and then using very fine measuring tools, carefully hone the piston to exactly match the bore you have.
Or really, the exact reverse of the way it's done with say an iron cylinder on a car or bike.

You know worst case scenario here is you take a piston from a new engine, and just give it a real light outer hone, and then you got that whole cross hatch thing going for you, and maybe a more free and easy piston fit, which is not a bad thing on a race engine (shorter break in time), so I suppose it's not a bad way to go, sounds like it could be worth a try to me...

Hmm, now of course there is thoughts of a proper tool for this, say a reverse hone tool, sprung in rather than sprung out...
You didn't see yet sleeve chromed amd ground with perfect mirror surface, it doesn't mean it is not exist. I can provide you sleeve for our engine even .049 size with perfect mirror and 1.5 micron non-roundness. I can provide you hundreds of them and all of them will be the same. So statment, that is not possible it ijust came from lack of knowlodge.
Please no hard feeleings. Just want to tell you, there is exist something that can't be realy done.
All my expirirnce in hobby we made sleeve on althe, mill ports, chrome plated, ground outside, ground inside, polished inside and only last step is ground piston to fit ( individualy). It is much more expencive process then honning, but if use just a litte immagination, you can understand that kind of set will last at list 30-40 % longer. It will have less friction etc.
Just no hard feeling, it is not real motorcycle, it is Rc engines, size 12 and they work at 40-45 K not 8-9 K.
Please no hard feeling
Just look Palmaris racing engine tread please. there are pics of 21 sleeve I made, if you live in LA area, I would love to show personaly.
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Old 06-04-2004, 11:09 PM   #44
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Actually, I think you partly misunderstood me, most plated liners are just fine, I'm only talking a small percentage that may not be "true" round, I know that most are just fine, but it depends on the process used to plate them, and then finish them off.

Likewise, I know plated liners are not usually perfectly shiny, it's just that my point was that unlike other liners, they have no crosshatch for oil retention and anti friction/wear benefits, meaning they do not lubricate as well as a iron liner, but then they are of a much harder material meaning they get longer life that way.

Yes, Plated liners can be ground and then polished, but not honed, I do understand that also, motorcycle engine basics are not that far removed from RC engine basics, your working from the same basic principles, particular with some of the latest advances in motorcycle cylinder plating technology.
And motorbikes have been revving well past 9K for some time now...

All your really saying is you can get more engine life by applying basic blue printing principles to RC engines, which is not really that new, in any form of motor sport.
The part I found interesting was the use of a lapped, or really crosshatched honed method to the outside of the piston, which in reality has the same effect as if you did it to a cylinder wall, and that is to help retain oil on the piston walls to aid lubrication and help slow engine wear.

Unless I'm missing something, it's all fairly straight forward stuff right?
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Old 06-05-2004, 12:13 AM   #45
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I think here is some missunderstanding. Lapping isn't the solution to make cross scratching and make more traps for oil. Lapping is step to make toooooo tight fitting to normal, withut run in ( xtra stress etc). If piston initialy ground to right fitting, I will never do or sugest lap piston. The oil film specialy castor is that strong, so our fitting will not brake it ( otherwise any engine will bluw up just after it start). So that scratches aren't nessecary, more then that from our theory they are very good trap for brasive which creating during the engine run and it start working as unwanted lapping tool ( it is apply to harin cuts on the top f piston) We never do them.
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