LO206 piston pop up check

steve baker

Moderator
Alternative method for checking LO206 piston pop up. Using a depth micrometer with center portion milled out to clear the carbon build up on the top of piston. This method eliminates the need to scrape all the carbon off top of piston. Only need to clean carbon off in 4 small patches on piston top.
This method is a common procedure for checking piston pop up in other racing organizations.

Steve
 

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Steve
Nice idea but doesn't the carbon lift the crossmember of the indicator?
 
Steve
Nice idea but doesn't the carbon lift the crossmember of the indicator?


Read my post carefully Jim.....................( with center portion milled out to clear the carbon build up on the top of piston. )
Its kind of hard to see in picture but if you look close you will see the .030 step on the bottom face of cross member. Double click on pic to make larger.........

Steve
 
Yep
I apologize I missed that part. I went right to the picture.
Since the cross member is long enough to go all the way across the bore why not machine the indicator to clear all the way across the piston and then just clean carbon from the center of the piston and measure it there.
 
My rulebook ( IKF) has a specific method of measuring pop up. It is measured parallel to the wrist pin with a bar across the piston. I understand your method with the carbon cleaned off the area above the wrist pin but why at the points 90 deg. to those marks? Any piston rock will negate those measurements.
 
Steve Baker wrote:

This method is a common procedure for checking piston pop up in other racing organizations.

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Do those organizations have a CC check on combustion chamber volume, unlike Briggs LO-206 Rules ??

I could see some people perceiving this as a way to decrease volume through carbon building up.
 
Checking the piston in one spot (the center) was VERY naive on my part.
In today's world it seems it's ok to lie and cheat to get what you want. I don't subscribe to that philosophy and i'm sure the majority of the people reading this don't either, but those people are out there.
Checking the piston at 4 places would help to identify if the deck had been angle or peak cut.
In fact checking with a bar parallel to the wrist pin won't find angle cut blocks either.
You would have to turn the bar 90* to the wrist pin and check it also.
 
I'm wondering; why is there so much carbon on the top of that piston in the first place? My two cycles, even with oil in the gas/alcohol, never had that much buildup on the piston!
 
Not uncommon on any engine today, fuel, oil, tune all combine to carbon build up. Also the LO206 is seldom dismantled that could be an engine with 4 seasons on it.
 
I had a guy that bought a used Comer engine from me. (I replace the one on my rental kart with a JR LO206)
He spent a LOT of money on having it rebuilt. Even after that it was still a dog so he ran it for hours with an overly rich oil ratio trying to build up carbon in the engine to make more compression. That didn't work either so he also bought a Jr LO 206 and lived happily ever after.
 
I was under the impression that the only carbon that can be removed is what can be readily wiped off with a rag. Scraping not allowed
 
Don
c. Deck gasket surface finish is not a tech item. Piston pop up can be .005
inches maximum. Piston pop-up to be checked with flat bar in center of
piston parallel to piston pin and then again checked 90 degrees to piston pin.
Tech Tool A25.
Angle milling or peak decking is not allowed.
d. Carbon build-up can be removed before pop-up is measured as long as
material is not removed from the piston. Exception – Competitors can deburr
the manufacturing part number/marks IF needed as long as:
− Removal does not extend beyond the defined script area.
− De-burring does not extend below the original piston surface area.
− The original part numbers and script are still clearly visible.

19. Cylinder Head
a. The ONLY head casting for the B&S 206 herein is the ‘RT-1’, cast into the
head just off the head gasket surface (towards the rear of the engine, PTO
side). The overall head minimum thickness is 2.430”.
b. Cylinder head must be “as cast”. Factory machining marks left on the head
gasket surface are a tech item.
c. Hard carbon may be scraped from head before measuring.
d. Depth of shallow area of combustion chamber must be .030 inch minimum.
This measurement to be taken with a depth gage on both the combustion side
and spark plug side of cylinder head.
e. Depth of the combustion chamber is .341 inch minimum.
f. Inspect retainers for alterations that would increase valve spring pressure -
.055 to .075 maximum flange thickness. Both intake and exhaust must have
OE stock B&S valve keepers.
g. Unaltered B&S part #555552 (exhaust) and #555551 (intake) can be checked
for appearance, weight, and dimensions. No machining, polishing, easing, or
alterations of any kind allowed. Valve surface must remain as factory, with
one single 45 degree face. No other additional angles allowed on any part of
the valve. Tech Tool A22.
h. Valve Guides: Replacement of valve guides with B&S part #555645
only is allowed. Maximum depth from the head gasket surface to the
intake valve guide is 1.255”.
i. Briggs & Stratton heat disperser, p/n 555690 can be installed in the
exhaust bolt boss per factory instructions.
 
When teching piston pop-up on the 206, are you checking it with a bar stock parallel to the wrist pin, or at front and back also like Steve's picture? For those of you teching front and back, how do you account for piston rock?

Now, as far as carbon clean-up -- you are having the competitor perform this work, right? I would not want to be responsible for scratching a combustion chamber or top of the piston and causing the competitor's engine to be illegal in the future as well. Are you requiring the piston be carbon free where the bar stock sits before teching, or simply clean a spot or two like Steve showed?

Next question: How are y'all teching for angle decking? Easy enough to detect peak decking, but angle decking? I'm real curious.
If you don't care to divulge trade secrets here, please feel free to PM me.

One key to this engine's success is the rules platform and consistent enforcement of said rules in the field. If individuals have their own methods of determining legality, then we've essentially created a gray area by using our own different techniques.


-----
Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
28 years of service to the karting industry
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
 
When teching piston pop-up on the 206, are you checking it with a bar stock parallel to the wrist pin, or at front and back also like Steve's picture? For those of you teching front and back, how do you account for piston rock?

Now, as far as carbon clean-up -- you are having the competitor perform this work, right? I would not want to be responsible for scratching a combustion chamber or top of the piston and causing the competitor's engine to be illegal in the future as well. Are you requiring the piston be carbon free where the bar stock sits before teching, or simply clean a spot or two like Steve showed?

Next question: How are y'all teching for angle decking? Easy enough to detect peak decking, but angle decking? I'm real curious.
If you don't care to divulge trade secrets here, please feel free to PM me.

One key to this engine's success is the rules platform and consistent enforcement of said rules in the field. If individuals have their own methods of determining legality, then we've essentially created a gray area by using our own different techniques.

Good questions Brian............that's why this needed to be posted and discussed! If i was a racer i certainly would not want a .010 + band of carbon scrapped off the top of my piston!( Ive already seen .018" thick carbon build up! ) Remember this engine program is being promoted as you can run it for years and years without replacing the short block. That could result in a huge amount of carbon build up on piston tops.

Steve
 
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Isn't it the racers responsibility to keep the engine legal? Shouldn't the engine be tecked as raced? If a piston has enough carbon buildup to seriously affect the compression ratio, and it's raced that way, doesn't that make it illegal, regardless?

How many serious racers would go four years without doing something to the engine? Nobody is going to race a full season (which it would take to make any kind of a serious buildup on the piston) let alone four seasons, without some sort of maintenance on the engine.

Let's see; a guy wins the race, his engine doesn't pass the CC check, doesn't that make him illegal, regardless of the reason why? And how long does it take to build up .005" carbon on top of the piston? It would take that much to make a .5 CC difference in compression ratio.
 
The LO206 engine rules do not specify a cc tech check. Al if your engineis performing comparable in a sealed class why must it be taken apart? Maybe the people that have adopted the LO206 are not serious racers in your opinion
 
The LO206 engine rules do not specify a cc tech check. Al if your engineis performing comparable in a sealed class why must it be taken apart? Maybe the people that have adopted the LO206 are not serious racers in your opinion
In my world, they're not. In my world, a "serious" racer wants to address all aspects of his racecar. I have nothing against people who want to do the L0206 class. It's just that they do not meet "my" definition of a "serious" racer. Now I understand everybody has their own definition of everything, I have mine and you have yours. I have no problem with the idea that we have different definitions of "serious racer".

In my world, getting peak performance out of both the kart, the engine and the driver, is what makes it fun. I understand that's not for everyone.

What has me wondering is; why just the engine, why not the kart and the tires?? Compared to the cost of a new kart and tires, the engine is cheap. What's more important to going fast, the engine? Not in a stock class!
 
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