pe reivers

Yes,
All you have to do is get rid of any glaze that is present.
BUT!!
Because of the typical wear pattern of the cylinder, make the hone shoes quite short, and do not hone the part where the ports are in using this hone.
So first, hone the complete cylinder, then shorten the stones to get the upper cylinder job done.

jack1933

My Feedback: (2)

Hello Capt, yes a brake hone will work, thats what I use.

Tired Old Man

My Feedback: (1)

Bowman rings are hand made, and are limited to small production run quantities to maintain tight tolerences. They are all hand lapped for proper fit. They are fit to the cylinder size, not sized to the piston. Check your end gaps for proper cylinder fit. .006" is a good starting point. File the ends square to obtain that measurement. It takes 2 to 4 hours of running time to fully break in a ring.

More oil absolutely equates to more power. Factors included are better heat transfer, less friction, combustibility of most oils. Some synthetics do not contribute to combustibility, but the decreased wear and reduced heat is a boon by itself. More oil does not equal more carbon if the carb needles are set for the mixture. Cold and rich running, along with hot and lean running, create more carbon with any quantity of oil but the types of carbon generated differ between the two causes.

Be careful honing small two stroke cylinders. The plating used in many is not what people think it to be and is quite thin. Well less than .003" Some of the manufacturers use a "flame coat" process. Cheapest of the cheap and any measurable wear in the plating renders the cylinder useless.

Iflyglow

My Feedback: (79)

If it is a chrome bore, you don't want to do that. You only do that with a steel liner. I am pretty comfident that the engine has either a Chrome or Nickelsil bore, therefore you can only install the ring and run it.

karolh

Sometime ago in chatting with Frank about fitting one of his rings in a glow engine he suggested deglazing the cylinder bore by gentle hand lapping using a 280 grade emery paper with oil.

Karol

togatoga

My Feedback: (42)

Decided to fit the second ring.Did a cursory inspection of the spe ring which was still relatively new and observed there is a a 1/16inch difference in length between it and the bowman.The bowman seems to seal better than the spe ring with little to no gap.Decide to use a another bowman ring for the second ring. Will post results once i run the engine.
I'm wondering why didn't spe provide a ring with less gap- could it be to cater for heat expansion?Then is the bowman ring in danger of overheating and greater wear at operating temp?

jack1933

My Feedback: (2)

This statement is not true, when you build engines, then you will know that honing is the ONLY way for the ring/rings to seat. Of course you are entitled to your opinion/theory, thats the problem with these forums, too many opinions without facts.

Tired Old Man

My Feedback: (1)

You must have some ring end gap to provide for expansion as the engine heats up. Installing a ring with zero end gap is a very quick way to sieze an engine. Check the end gap by installing the ring in the cylinder, right side up, without the piston.

pe reivers

The ring without end gap does not necessarily seize, if run in carefully. If the ring gets hotter, so will the cylinder. The ring is cast iron, with low expansion and the cylinder is aluminum with high thermal expansion. This would increase the gap.
If the ring should expand more, it bears very hard on the cylinder wall, and wears quickly until it again runs without end gap in the hot engine. Rings without end gap seal better, and I see no reason to doubt Frank's theorem of fitting rings without end play.
I have done it in a glow Supertigre engine, and there was no seisure other than very much friction in the cold engine at first start attempts. Later on, the engine became smooth as silk.

captinjohn

I agree...I talked with Frank and he recomends a very small gap. When he sets them up ...he said he never had a engine sieze. The cyl will expand more than ring in most cases. capt,n

Iflyglow

My Feedback: (79)

Like you said, there are to many opinions. I have built engines, and with a hardened steel sleeve, honing is the way to go, but with a two stroke small engine most of the cylinders are chrome plated, and your idea will not work very well. If it was a steal sleeve (NON plated) like a Super Tiger ringed, OS with ring, or a large two stroke with a steel sleeve, I would agree with you, but I do not on a small engine like mentioned that has a plated sleeve.
Chrome or Nickelsil plated sleeves approch 70 and sometimes 80 rockwell.[sm=idea.gif]

jack1933

My Feedback: (2)

I think we need to be refering to the same thing, which in this case is a 26 cc engine, I never said a word about small two stroke engines. All the engines I built had nika-sil plating on the bores, not chrome. And if one does not crosshatch these type cylinders, the rings may never seat. This is not some bs opinion, as you stated, but a fact based on years of experience.

RTK

My Feedback: (1)

Don't you need a diamond hone to make a dent in Nikasil??

pe reivers

No, you don't. But just breaking the shine in the bore, or milling the port edges is extremely hard on your tools. Making a cross hatch is one thing I never aimed for. Just breaking the surface without removing any material was as much as I ever hoped for. However, I too believe it should be done to give a new ring a fighting chance. It's the cylinder that wears the ring first to proper sealing, before the ring starts to wear the cylinder. David against Goliath it is.

Antique

My Feedback: (4)

Letter 1671
Where is the Nikasil?
The WORD on Nikasil

I am searching for a supplier of "Nikasil" plating chemistry, specifically interested in finding a solution operable in a "brush" or selective plating environment.

The coating is being widely used in the manufacture of motorcycle engine components (i.e, cylinder bores, pistons, piston rings) and the restoration of engine cylinder bores.

Robin M [last name deleted for privacy due to age of posting]
- Sears, MI



Nikisil® is a proprietary product of Mahle. If you desire information you should contact Mahle.

Dennis McCallister
Morristown TN



Although Nikisil® is a trademark of Mahle Corporation, our company has engaged in nickel silicon-carbide plating and diamond honing in the United States since the mid 1960s. We are presently one of the largest such companies in the world. We have found that by far the greatest demand for nickel silicon-carbide has been for aluminum cylinder bores, and the market still appears to be growing. We have no method of "brush plating" this coating.

Scott Z. Reath
U.S. Chrome Corporation of Wisconsin - Fond du Lac, WI
8 June 1998

My company has been offering a Nickel/Silicon Carbide coating service on aluminum cylinders for many years both here in Alabama and at our original facility in England, and have a throughput of several thousand cylinders each year. Like them too, we are not aware of any brush plating technique that offers good results and a quick survey of our associated companies around the world yields the same response, but I suspect that one could be developed given sufficient demand.

Geoff Slater
Auburn, AL

8 June 98

My electroless nickel reference indicates that Elnisil is a galvanically deposited dispersion coating of carbide, presumably carbide in nickel. Brush plating of this process may be less problematic than Kanisil or Nikasil, although the abrasion resistance is less for Elnisil.

See Metzger, W. et al. galvanotechnik 61 (1970) 12, 998


Tom Pullizzi
finishing.com - Brick, NJ



We need to put up a plant for Ni Sic plating for plating the bore of our new engine. As the Volumes are not very big (around 30,000 engines per year) we are looking for a cost effective solution.

Can we modify an existing electroplating plant for Ni & Cr for this process. Can I set up a pilot plant before mass production. Would be grateful for replies

Kumar R [last name deleted for privacy due to age of posting]
Jakarta Indonesia



I would like to know whether any one has any experience in coating Nikasil or similar composition on Graphite rods.

Venky C [last name deleted for privacy due to age of posting]
- Illinois

-

I am rebuilding a Porsche 911 engine which uses removable cast iron cylinders. Can anyone recommend the most cost effective method for plating the cylinders to restore them to their original dimensions?

Ben M [last name deleted for privacy due to age of posting]

.

I am a student in Istanbul Technical University. I am interested in Nikasil and Alusil. Which one of these gives better performance on pistons (especially cars).I study Metallurgical and Materials Engineering and this subject is my final work. Could you please send me any documents about this subject or offer books, magazines etc...

Thank you.

Ozgur O [last name deleted for privacy due to age of posting]
- Istanbul,TURKEY

Ed. note: letters 551, 2723, and 2858 address a similar topic.

.

I have a few questions. Can nikisil® cylinders be honed once or twice to clean them up? I've got a very low mileage 4-cycle engine in which the pistons dry-seized to the cylinder wall during long, improper storage. With steel sleeves I'd simply have a machinist perform a very light hone to clean up the cylinders.

How critical is the matching of pistons, rings, and cylinders in nikisil® set-ups? I've got a feeling it is a good thing, but necessarily critical. The question developed because I've seen suppliers selling piston, ring, and nikisil® cylinder sets. Two rings on one of the aforementioned engine are stuck in the grooves and must be replaced for engine reassembly. I would like to clean all parts, hone the cylinders, replace all rings, and reassemble the engine.

Thank you.

Bill S [last name deleted for privacy due to age of posting]
- Concord, CA

.

The first thing to be aware of is that the Nikasil layer will probably be very thin, and so you should be prepared for that when considering any machining operation.

Typically, engine manufacturers using Nikasil and similar processes 20 years ago would have deposited a finish-machined thickness of about 0.10 mm (0.004"). More recently, we have noted that cylinders from several Japanese manufacturers have thinner coatings, sometimes as thin as 0.05 mm (0.002"), almost certainly as a result of improvements in the plating technology enabling a reduction in materials and processing times.

In normal use, it should be unnecessary to hone nikasil-type engine cylinders since the wear resistance and oil retention derives almost as much from the presence of the silicon carbide particles in the nickel matrix as from the original underlying honed surface finish. In Bill S's situation, it appears that there are marks on the bore which will need to be removed to avoid damaging new components during a re-build, and so honing will almost certainly be required. It is important that this be carried out using diamond honing tools of an appropriate grade, since the original surface finish can easily be "polished" by using conventional honing stones, and that may lead to a lack of adequate lubrication during the initial running of the engine.

One of the big performance advantages of nikasil-type bore over traditional cast iron sleeves (other than a major weight saving) is the ability to operate an engine with smaller piston to bore clearances since the piston and the cylinder will tend to expand a similar amount when heated. For that reason, it will be important for Bill S to accurately measure the bores after honing, then select pistons which will give him a clearance which satisfies the engine manufacturers specifications. Most normal piston ring materials work well with nikasil-type bores, but chrome faced rings (at least the compression rings) are by far the most commonly supplied by engine manufacturers. Close attention should be paid to the ring-end gap to ensure compliance with manufacturers specs.

Sorry the reply is so long, but I hope it answers Bill S's and some other questions at the same time.

Geoff Slater
Auburn, Alabama

.

I would like to thank Mr. Geoff Slater of Auburn, AL for the rapid and informative response to my engine rebuilding questions dated June .. In his response, George apologized for making a long reply. Apology accepted, however no apology was necessary. George provided a great bit of information in a very concise manner. Not only did I gain the confidence to rebuild the engine, but I was also provided with useful practical and factual information. Believe me, there are quite a few people claiming to be knowledgeable about engine coating and plating that make it up as they go.

One last item, Geoff. The subject engine has been reassembled and runs like a fine watch. The Italian motorcycle which this engine powers is a 1986 Moto Morini 350K2. This model was one of the last manufactured by Morini before they went out of business. The engine is a V-twin having 70 degree cylinder offset and Heron heads (flat head, combustion chambers in piston).

Thank you.

Bill S [last name deleted for privacy due to age of posting]
- Concord, CA

.

I am in the process of building some racing V-6 engines. These engines have a metal matrix composite engine block with Reynolds 390 series alloy as the base metal. The bore is 93 mm.

Alternatively, has anyone ever done this to the pistons instead of the block? My problem on this is that I have had to make forged pistons due to the boost pressures involved with this project so the aluminum on aluminum, won't cut it. I have exhausted all efforts to find a company that can do an iron plating so I have had to go the Nikasil route.

John C [last name deleted for privacy due to age of posting]
- L.A. CA USA

+

I've recently seized an engine on a 2000 YZ 125 dirt bike, and I realize this might not be the place to ask, but I only had a few quick questions :O). Since the 80's I believe the big four (Japanese) companies have used a thin Nikasil coating which is supposed to increase cylinder wear...etc...etc... I've been told that due to the thin layer provided, rehoning the cylinder is impossible (Or at least stupid) without having a new Nikasil coating added.

So my question is, if I only plan on having this bike for the next few months, and I've just installed a new piston, rings, crankshaft, and rod, will I be setting myself up for frequent engine failures and bad performance?

If anyone has any information on the costs involved in the process provided, I'd greatly appreciate it, Thanks.

Dean P [last name deleted for privacy due to age of posting]
- Aurora, Colorado, USA

++

There seem to be alternatives to Nikasil for the wear resistance improvement of aluminum cylinder bores. I've found companies that specialize in the ceramic coating of engine components; even worn out ones. Their claims seem to imply tremendous advantages. Check out their sites and see what you think. There are also coatings for "lubricity" using graphite and Molybdenum disulfide that are deposited on cylinders and pistons to reduce friction & galling. These are very high temperature coatings which ceramics seem ideally suited to and various process for deposition seem to be well worked out and not expensive. They have been used in racing vehicles for many years. It's a real eye opener what ceramics can do for an engine.

Good luck.

Peter K [last name deleted for privacy due to age of posting]
Freelance - Kelowna, BC, Canada

Dear Reader: please choose what you want to do.

I want to post a question or inquiry of my own.

I want to answer or follow-up on this question publicly (in non-commercial fashion).

pe reivers

Antique, I see you did your homework.
Indeed, diamond honing is the only way to get the hone stones and grinding wheels to last in mass production, but it is not the only way to schratch part of the shine off a surface when changing rings.
Carbide sanding paper will also work. Simple silicon sandpaper will not.
When bore restauration is required, the old NIKASIL is ground out, new NIKASIL applied, ground and honed to spec. This work is all done using diamond wheels and hones

Tired Old Man

My Feedback: (1)

Unfortunately a good many of the engines we use in R/C are not nikasil treated. We are led to believe that they are by the silence from the manufacturers regarding the plating used.

captinjohn

I have a question. I have seen quite a few cylinder bores that have some of the cross hatch marks somewhat there. Now the question is...would it be better not to hone or do anything but clean the bore when installing a Frank bowman piston ring? Seems like the ring is made to wear into the cylinder quite fast and give a good seal. That is the way it worked with my friends Webra 1.20 when I put a new ring in it. Capt,n

pe reivers

If the engine was mine, I would just use carbide sandpaper to slightly scratch the bore surface and round the port edges, fit the new ring and hope for the best. So far, it worked Ok.
Honing I think is done on new cylinders only. In used cylinders, the hone will not get into the topmost bore wear pattern wher the ring presses against the bore hardest.
In Nikasil bores I even doubt the need, because the tribological mechanisms (how things wear, or resist wearing) are quite different from iron or steel liners.

togatoga

My Feedback: (42)

Just ran in the engine with 2 bowman rings. These rings seat in fast with very little to no black gunk coming out of the exhaust. Things I've noticed- idling is better than the original rings , I could idle it down to 1800 and it just wouldn't die and I was able to tach 7450rpm peak on a 17x8 apc and this on 10 min running in! I reckon it might pick up some more as the ring continues to seat in.
This 26 has been my first foray into gas and it has been a good learning curve.

It has an OS160 muffler, an rcexl ignition, larger bore carb (11.1mm I think) and now 2 bowman rings. RPM is not much to write home about but that said, it started life with 6900rpm.

jack1933

My Feedback: (2)

Thanks, Pe, for answering my questions. as far as the procedure you suggested about the honing, I don't think all that stone changing is necessary. I try to stay away from the ports, but don't worry about it if they get deglazed/honed. Why would this be harmful?

pe reivers

I think you misunderstood that bit.
The stones can catch in the ports, and some engines have quite sharp port edges which I rather see rounded. That rounding cannot be done by a hone.

captinjohn

Just a idea...try a deferent exhaust or pipe? Capt,n

tkg

My Feedback: (1)

Pe's talking about "Blue Printing" an engine. Take it apart, clean everything, put it back together with as few + - as possible. Take 5 engines and built 4 perfect ones and have some spare parts.
This is the secret that RCI is always talking about when he talks about "stock" Zenoahs going 135mph in a T-6.
Buy the buy a careful break-in is almost as good as a blue print, but its way to boring for the average modeler to do.

Tired Old Man

My Feedback: (1)

Agreed!!

Even the Bowman rings don't break in that fast. They have a rather aggressive outer edge that takes a little longer to run in. I think the reason for the lack of "black goo" noted a bit earlier is because they haven't been completely through the break in process. 3 to 5 hours in moderated heat ranges is still 3 to 5 hours.

One thing that still troubles me is an earlier note about not having a "gap". Without an end gap rings will never break in. They can't because they can't expand during the heating process to seat propely against the cylinder. Seize the piston perhaps but not break in. Same thing happens when you run too tight of a piston fit in a cylinder. That one cost me an 80" Shovelhead a long time ago....