jeffie8696

I just tried to break in my NIB K&B .28 using Sig 5%nitro with 20% all castor and a 9X4 prop with the factory plug. I used the standard procedures , not too rich not too lean, let it run a few then let it cool, start over. When I got the engine it was particularly stiff at the pinch point so before I did anything I lubed the top end and bottom end and worked it over to get things real slippery. I just did a tear down inspection and I see the piston is deeply scored!! [X(] There is no problem with the cylinder that I can see which surprises me since the chrome plating on the piston should tear up the softer aluminum bore. It is almost as if the piston never got plated or something. Has anyone else had this problem?

rcdude7

My Feedback: (264)

Every new sporster engine I have run has needed to be cleaned out before running. The .65 I just bought had burrs in the carb and some small shavings in the crankcase left over from the mfg process. I had a .20 years ago and it was dirty also. The break in I have done with these engines is always very sloppy rich without leaning for quite some time because it would cause the engine to heat up and die anyway.

jeffie8696

I did open the crankcase and check it out. Didn't see any problems. I quess I should have removed the head and cleaned it out. I am very upset about it. My other 2 K&B Sporties are awesome. Here is a photo as you can see it didn't get hot. Must have been full of metal shavings.

rcdude7

My Feedback: (264)

This is the new 65 I cleaned out. I caught all the solvent and junk in a white cup, no picture of that though. I doubt there is even a step for cleaning before the engine is assembled at K&B, it was not good inside.

proptop

My Feedback: (8)

Does it still have compression? That looks like galling...maybe try cleaning the piston with some 1000 wet/dry paper and oil and if there is at least some compression, try it again? (after a good flushing out that is )

jeffie8696

I went ahead and ordered a new piston any cylinder from Mecoa. This piston is crap. I will take the utmost precautions with the new parts. I paid $50.00 for the NIB .28 plus $34.59 for a cyl and piston so that brings it up to about the price of a new one from Mecoa. Schtuff happens. Looks like I will be selling some of my other collection to pay for it.

XJet

Are you saying that these engines have a chrome plated piston and an unplated bore?

If the bore isn't anodized then that's crazy metalurgy.

Most AAC engines have a plated bore and unplated piston.

Some, like the Norvels, have a nickel-plated piston running in an anodized aluminum bore which is pretty good (and long-lasting).

Aluminum on aluminum will gall-up in no time unless one of the surfaces is anodized or plated in some way.

jeffie8696

Yes from what I have been able to learn they used a chrome plated piston, my other 2 Sportsters have very shiny piston skirts. That is what got me curious about it. What difference would itmake if the piston is plated instead of the bore? As long as one of them is.

Iflyglow

My Feedback: (79)

XJET,
The sportster line of engines had a High Silicon content aluminum case and bore all in one. The Piston was also aluminum (not plated). Chevy tried this years ago with the Vega with horible results. Briggs and straten has done it for years with the "Cool Bore" engines also.
The Damage I seen in the pictures also appears to be galling from lack of oil.

jeffie8696

Motorman according to the Mecoa website the Sportster series of engine has a hard chrome piston. http://www.mecoa.com/faq/abc/abc.htm

Iflyglow

My Feedback: (79)

Jeffie,
I guess I was wrong on the piston coating.

jeffie8696

Surprised me the first time I read it. Makes sense though. I believe Porsche also uses a similar system. And the Sportsters have no less than 5 intake ports. But according to my testing they are not high rpm runners as you would expect but rather low rpm grunt machines that just love big props and plenty of nitro. For example my K&B Sporty .20 makes 12,300 on a 10X5 Master Airscrew on Sig 15% nitro 20% castor. That is 4.32 lbs thrust at 58 mph. That should pull around my HOB Mustang well.

Iflyglow

My Feedback: (79)

I think if you check into it, you will find the Porsche does the samething as Mazda and Bmw are doing with there all aluminum engines. They run an aluminum piston in a Nickelsil plated aluminum block. That is the way my Mazda is done too. Every time I read it, I think of OS nickel flaking problems. But they are useing a much cheaper style of nickel plating.[X(] The only bad thing with this, is the fact that it is now in the case of the Mazda and BMW a non servicable block. If you score a cylinder, you buy a new block (boring and honeing is not possible with these). It could be a very expensive rebuild.

jeffie8696

Ouch no doubt!!$$$$ The only way I knew about the plating was a friend of mine is a Porsche 911 enthusiast and he mentioned the aluminum cylinder with a plated piston concept. Next time I see him I will get more specifics. I think my Mustang Mach1 is a better idea. All aluminum block with steel liners.

Iflyglow

My Feedback: (79)

That is heavier though. I agree, at least you can service the block, but there should never be a need with the other concept too, since the cylinder plating is harder than the rings or pistons. It just does not leave any room for a mechanical failure of any kind.

jeffie8696

I used to be a diesel mechanic, schtuff appens.

Broken Wings

My Feedback: (20)

Getting anything to stick evenly on the inside walls of a tube has got to be a pain. Plating the piston has got to be much easier.

I recently scored a Sportster .65 and it was perfect on the inside bore, the crank had a small problem.

jeffie8696

Hmmmm Florida. Yea that could explain a lot of the corrosion. Sporties are tough. My .28 will live again. I love the low rpm grunt they put out. A powerful engine turning a big prop with a lot of pitch is just cool to me. And my .45 will hand start at idle. I can't get any of my other engines to do that.

NM2K

My Feedback: (14)

You say that engine sat in the Everglades, submerged, for a few years? I've never seen a crankshaft in that condition before. Fortunately, they are still available. While you're at it, pick up a few crankcases with the bushings installed. That will save you some aggravation later on. I think I'll take my own advice and order a couple of .28 and one .65 sized crankcases myself.

I've been thinking of buying a couple of Davis Diesel conversion heads. That's why the concern for bushed crankcases.


Ed Cregger

Broken Wings

My Feedback: (20)

I bought it on Ebay for $9.99, it must have been in a flooded basement.

The crank cleaned up. The rest is soaking in antifreeze. I'm going to try Kmots parts dip on the cases and see if they'll come back to life.

I found some carburetor parts that I need on Ebay as well .99 cents.

proptop

My Feedback: (8)

I keep reading about the lack of a bushing in the case...makes me wonder if the .65 I got is really a bargain?
I bought what was advertised as a new, still in the plastic bag .45 for $32.95 (+ 6.95 shipping ) but when it arrived, discovered that it's a .65
That didn't bother me, because I just wanted to get a Sportster to add to my K&B collection...(it's the only one I have )

I'm thinking it must be a 'tweener because it has the later (modified ) head with shallower fins, but the early bushing-less case?

If I run it on a low nitro fuel with plenty of Castor, it should be o.k. though....(right?)

Jeff...sorry...don't wanna hijack your thread or nuthin'...just figured I'd ask while we were on the subject of Sportsters.

jeffie8696

Hijack away. My first Sporty is/was a .45 with the bushingless case and I think that with all the bearing surface of that huge diametr crankshaft it won't be a problem as long as I use goood all castor fuel. I am completely sold on Sig 20% all castor for everything now. I just measured the crankshafts of my beloved K&B .28 and a nice OS .25 FP. The K&B has a much larger bearing surface area so the bushing issue may be moot. I am getting .472" X 1.42" for the Sporty and only .432" X 1.12 for the OS. That is a substantial amount of bearing surfce. By the way, my Sporties ain't scared of lots of nitro.