K&B .28 piston scoring  
View related threads: (in this forum | in all forums)

Tower Hobbies
Enter up to 4 keywords or Tower stock numbers
Logged in as Guest



Users viewing this topic: none
  Printable Version
       


90 Degree Muffler Adapter
Seller:  RC Specialties
Details:   $17.95   |  7/13/2008   |  Classified Ad
We will rotate YOUR AD in this spot if you select "Forum Featured" when placing or editing your ad!

All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Glow Engines >> K&B .28 piston scoring
Page: [1]

Login
Message << Older Topic   Newer Topic >>
K&B .28 piston scoring - 5/10/2008 10:55:13 PM   
jeffie8696



Posts: 901
Joined: 5/10/2007
From: coralville, IA, USA
Status: offline 		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!! 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?

_____________________________

Castor, its like Vitamin C for glow engines.OK now that I have mastered the taking off part and the crashing part what next
       Post #: 1

RE: K&B .28 piston scoring - 5/11/2008 3:58:17 AM   
rcdude7


 

Posts: 939
Joined: 4/12/2003
From: Maryland
Status: offline 		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.

(in reply to jeffie8696)
       Post #: 2

RE: K&B .28 piston scoring - 5/11/2008 4:42:13 AM   
jeffie8696



Posts: 901
Joined: 5/10/2007
From: coralville, IA, USA
Status: offline 		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.

Attachments
Click to see fullsize image.
Click for fullsize


< Message edited by jeffie8696 -- 5/11/2008 4:46:50 AM >

_____________________________

Castor, its like Vitamin C for glow engines.OK now that I have mastered the taking off part and the crashing part what next

(in reply to rcdude7)
       Post #: 3

RE: K&B .28 piston scoring - 5/11/2008 5:41:51 AM   
rcdude7


 

Posts: 939
Joined: 4/12/2003
From: Maryland
Status: offline 		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.



Attachments
Click to see fullsize image.
Click for fullsize

(in reply to jeffie8696)
       Post #: 4

RE: K&B .28 piston scoring - 5/11/2008 5:50:19 AM   
proptop



Posts: 4426
Joined: 10/18/2002
From: Rome, NY, USA
Status: offline 		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 )

< Message edited by proptop -- 5/11/2008 5:51:04 AM >

_____________________________

It's bad luck to be superstitious...
Revver Bro #77

(in reply to rcdude7)
       Post #: 5

RE: K&B .28 piston scoring - 5/11/2008 5:59:06 AM   
jeffie8696



Posts: 901
Joined: 5/10/2007
From: coralville, IA, USA
Status: offline 		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.

_____________________________

Castor, its like Vitamin C for glow engines.OK now that I have mastered the taking off part and the crashing part what next

(in reply to proptop)
       Post #: 6

RE: K&B .28 piston scoring - 5/11/2008 10:15:46 AM   
XJet


 

Posts: 3217
Joined: 3/31/2003
From: Tokoroa, NEW ZEALAND
Status: offline
quote:

ORIGINAL: jeffie8696
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?

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.


_____________________________

When I'm not here, I'm at RCModelReviews

(in reply to jeffie8696)
       Post #: 7

RE: K&B .28 piston scoring - 5/11/2008 5:54:40 PM   
jeffie8696



Posts: 901
Joined: 5/10/2007
From: coralville, IA, USA
Status: offline 		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.

< Message edited by jeffie8696 -- 5/11/2008 6:20:50 PM >

_____________________________

Castor, its like Vitamin C for glow engines.OK now that I have mastered the taking off part and the crashing part what next

(in reply to XJet)
       Post #: 8

RE: K&B .28 piston scoring - 5/18/2008 5:22:21 PM   
MOTORMAN37



Posts: 2044
Joined: 10/26/2002
From: CLINTONVILLE, WI, USA
Status: offline 		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.

(in reply to jeffie8696)
       Post #: 9

RE: K&B .28 piston scoring - 5/18/2008 7:04:49 PM   
jeffie8696



Posts: 901
Joined: 5/10/2007
From: coralville, IA, USA
Status: offline 		Motorman according to the Mecoa website the Sportster series of engine has a hard chrome piston. http://www.mecoa.com/faq/abc/abc.htm

_____________________________

Castor, its like Vitamin C for glow engines.OK now that I have mastered the taking off part and the crashing part what next

(in reply to MOTORMAN37)
       Post #: 10

RE: K&B .28 piston scoring - 5/18/2008 7:54:09 PM   
MOTORMAN37



Posts: 2044
Joined: 10/26/2002
From: CLINTONVILLE, WI, USA
Status: offline 		Jeffie,
I guess I was wrong on the piston coating.

(in reply to jeffie8696)
       Post #: 11

RE: K&B .28 piston scoring - 5/18/2008 9:46:31 PM   
jeffie8696



Posts: 901
Joined: 5/10/2007
From: coralville, IA, USA
Status: offline 		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.

Attachments
Click to see fullsize image.
Click for fullsize


_____________________________

Castor, its like Vitamin C for glow engines.OK now that I have mastered the taking off part and the crashing part what next

(in reply to MOTORMAN37)
       Post #: 12

RE: K&B .28 piston scoring - 5/19/2008 1:14:14 AM   
MOTORMAN37



Posts: 2044
Joined: 10/26/2002
From: CLINTONVILLE, WI, USA
Status: offline
quote:

ORIGINAL: 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.



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. 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.

(in reply to jeffie8696)
       Post #: 13

RE: K&B .28 piston scoring - 5/19/2008 1:52:04 AM   
jeffie8696



Posts: 901
Joined: 5/10/2007
From: coralville, IA, USA
Status: offline 		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.

_____________________________

Castor, its like Vitamin C for glow engines.OK now that I have mastered the taking off part and the crashing part what next

(in reply to MOTORMAN37)
       Post #: 14

RE: K&B .28 piston scoring - 5/19/2008 2:00:38 AM   
MOTORMAN37



Posts: 2044
Joined: 10/26/2002
From: CLINTONVILLE, WI, USA
Status: offline 		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.

(in reply to jeffie8696)
       Post #: 15