Carbon Deposits on Head

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Jeb
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Carbon Deposits on Head

Post by Jeb »

I swapped the head on my 220 with a race-gas cut RB-modded head that I'm chompin' at the bit to try (tomorrow) . . .

and I took a quick shot of the top of the piston (shown below). For running since February I guess it's not too bad. Most of this riding season I've ran the Amsoil Interceptor, but in fairness to the Amsoil I did run a bit rich until a few months ago and I did use run about 2 gallons of premix with cheap 2-stroke oil that I bought in a pinch. So what you see is not entirely the Interceptor.

Questions: I took the pic after I had lightly scraped at the deposit to see how easy it would come off. You'll see that the buildup is not thick. But note how the pattern shows a predominance of buildup on the intake side. What does that signify? Also note the two lobes that stretch out the most pointed to either side of one of the studs to the left rear of the cylinder. What does this mean? Finally, towards the exhaust side of the piston the buildup is not an even layer; rather, it's sort of a texture-patterned deposit. Again, what is the significance of this?

Would you be worried?

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Post by canyncarvr »

Re: 'What does this mean?'

I don't know.

...but I wouldn't be worried about it! :rolleyes:

Kewl how THAT works, 'eh?


The shape of the carbon is curious. Doesn't seem reasonable that a contained wavefront would look like that.

Was this a reused head gasket or new? It IS a Cometic? Torqued to what?

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Post by Jeb »

Reused head gasket from Moose Racing, nuts were torqued to 18 ft-lbs and rechecked after a little use after installation . . .

but "reused" here is better described as slightly used since I installed the gasket when I swapped the piston last Octoberish and had the original head modded in Februaryish.
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Post by IdahoCharley »

Apear to be running too rich to draw any conclusions based upon the top of the piston deposits. When your running that rich the deposits don't accurately reflect the flow (or combustion) of fuel within the engine. Also if the squish is not in the ball park the residual fuel pattern flow on the top of the piston is unreliable. Answer to your question - I would not be worried one bit.

Piston deposits can indicate intake port flows patterns to people familiar with porting design. i.e. indicate which ports are out of balance fuel supply wise: whether ports need to be redirected/enlarged or reduced in size to maximize the effeciency of the combustion within the engine. Again IMHO the engine was running too rich to draw any conclusions.

P.S. IMO - You took the first step in getting that engine to run correctly by installation of a better head. :grin:
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Post by canyncarvr »

IMO and all..but the more modified the engine, the more care need be taken on everything else. I wouldn't use re-use or slightly re-use a gasket with a head modified for combustion pressures you can reasonable expect to be encountered from use of a high-octane fuel.


A btw, sort of...

Banshees are overheaters. A stock Banshee engine overheats at the drop of a hat. Mr. Black modified my Banshee head...improved squish mostly..slightly increase static combustion pressures. It's not a severely cut race-gas piece. I still use pump 92 (and some toluene when I want a bit more fun). The result performance-wise was a pleasure...but an unexpected result was improved cooling. Well, that inferred from my Banshee not spitting anymore, even when it probably has reason to. More correctly, improved overheating I suppose. It doesn't cool better, it overheats less.

There are more advantages to thoughtful head engineering than just increased performance.

Let us know what fuel you use and how you like it!

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Post by Jeb »

Once again good stuff from the guys that understand these things much better than I - thanks IC and CC . . .

Just a BTW in case I didn't mention this: the head I swapped out - the one that now sits on the shelf - is also an RB-modified head, just NOT cut to race-gas specifications. So, IC . . . does your comment about a "first step" still stand? Just curious!

Just to eyeball it, the race-gas modded head had a slightly lower profile (of course) but appearances were that the angled portion on the head (closer to the outside) had a slightly different angle.

I do believe I'll swap out the gasket soon based on the comment (and thanks). I've got maybe 6 weeks of riding left before I go under the knife (and out of riding for a while) so not a bunch more on this gasket. 'Think I'll be alright? What would I look for to tell me that I wouldn't be - weeping or similar? I'll swap out gaskets when I pull things apart this winter for some preventive maintenance.

I picked up some VP 110 (107 motor octane . . . and PURPLE!) and mixed it 50/50 with premium pump (that's 92 in these parts). I come up with 99 octane, and I ran this by Ron when I sent in the head and he indicated this would be fine.

OK . . . all of this and now I get to describe first impressions as of just a little bit ago. Bottom line - yes, mo' power! After a good warm up I rode for several minutes in the back of our property. Not as earth-shattering of a change as the initial mods, but you can feel it . . .

here's where it really seems noticeable from what I could tell thus far:
  • I've been "practicing" getting better with all of my controls ( both brakes, throttle, clutch) and balance/body positioning by trying a twist on a routine suggested on Shane Watt's Dirt Wise. I get going in second and, while standing, come to a fairly quick stop using both brakes, clutch pulled in. Just as the bike stops I get her moving again, still standing with knees locked on. This is actually tricky when you first start trying it because you have to learn body positioning or the bike wants to get away from you (at least a 220 does :lol: ). I've gotten to the point over the last month where I can actually do this stop/start, stop/start in a much more aggressive fashion, sometimes getting the front wheel off the ground 2-3 times in a row ('not bragging, just lots of practicing cause I can do it at home). I tried it a bit ago - sitting down initially - and I could already tell the difference in low end. When I tried it standing up I did so but without the same aggression typical as of late and the bike now wants to be more aggressive on its own!! There's enough more lurch that the front wheel gets light and the momentum pulls harder than before. My grips try to pull out of my hands more easily, which translates to the throttle rolling open more, which translates to more momentum, which means more throttle . . . :blink:

    In the woods behind the house I like to get into third gear and get somewheres in the midrange, give it a fistful of throttle and blip the clutch for an somewhat exciting jolt forward. There's certainly a noticeable difference here as well - that jolt just got more pronounced, there's no doubt.
So that's from a little bit of motoring around. I'll have more gory detail after I get out this weekend and spend some quality time with my green gal and some fields, creeks, woods, etc . . .

but I can already preface what that report will be: hats off to another fine product from Mr. Ron Black. :grin:
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Post by Rick »

Monday would be a good day for a test......... :wink:
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Post by Jeb »

>|<>QBB<
Rick wrote:Monday would be a good day for a test......... :wink:
I'm gonna try . . .
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Post by IdahoCharley »

>|<>QBB<
Jeb wrote:Just a BTW in case I didn't mention this: the head I swapped out - the one that now sits on the shelf - is also an RB-modified head, just NOT cut to race-gas specifications. So, IC . . . does your comment about a "first step" still stand? Just curious!

:grin:
Nope!! Just get the jetting closer and your smile factor will increase and your piston deposits will move closer to the edge of the piston. A cleanly jetted bike is easier to ride (power everywhere) and is more predictable no matter what type of riding you do. Let us know how that race gas head treats you!
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Post by canyncarvr »

Re: 'the head I swapped out - the one that now sits on the shelf - is also an RB-modified head,'

BTW...I got that. Well..remembered it I guess. Thanks for making a point of it, 'cuz I wasn't sure about the 'first step' part.

The 'different angle' is the big deal, I'm convinced. And, there is more to be gained than power (which is why I brought up the heat issue).

IC wrote:A cleanly jetted bike is easier to ride (power everywhere) and is more predictable no matter what type of riding you do.
Truer words never spoken.

Well...excepting maybe what you said to yourself just before the last impact, 'This is gonna hurt!'

Another BTW...but this:
Jeb wrote:I picked up some VP 110 (107 motor octane . . . and PURPLE!) and mixed it 50/50 with premium pump (that's 92 in these parts). I come up with 99 octane...
I think is incorrect. Actually, I'm sure it is incorrect, but saying 'think' gives me an escape route when I'm proven wrong myself.

The 92 number you note of the pump crap is an average of motor and research octane. You need to use the same number for the VP fuel. If 107 is the motor number, there is a higher research number that you need to take into account to get the same 'flavor' of number as the 92.

I didn't look up VP anything...I don't know what the motor/research numbers are........

So..you're over 99.........

Not that the number matters.....I just like to draw attention to the inconsequential and matters of no matter.

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Post by Jeb »

CC - You're right about me being wrong. The (R+M)/2 of the VP110 is, well, 110 octane! Meaning that 50/50 mixture of the 110 and premium gives me 101 octane . . .

which is somewhat arbitrary (as implied) given my quest to optimize performance not being related to that number but rather in achieving enough octane to prevent detonation.

So here's my next question: what exactly does "pinging" sound like? Dumb question maybe but I don't believe I've actually heard it (or felt the effects if there's any such indication). I'd like to be sure because the next move I'm considering (after refining the jetting as needed) is to advance timing a smidge and then follow that by slowly and incrementally reducing the 110.

BTW I don't believe that presently I have so much more octane than needed that throttle response has been reduced if my initial ride is any indication. Throttle response seemed OK. Comments?
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Post by canyncarvr »

My point is not to nit-pik..but maybe to clear up something cloudy from time to time. Myself..my brain is one big fogbank 95% of the time..

Ever hear Emotional Weather Forecast by Waites?

Anyway...

By the time you hear pinging...it's already too late. That's a good rule of thumb. That's why it's called, 'The Silent Killer'...'cuz it can make your engine dead and you won't hear a dang thing.

It sounds like..well...pinging. Surely you've heard it in some engine or other. Like marbles in a coffee can getting shaken up. You can often feel it, too..like a miniature stroke (clot..stoppage..brain fart).

Have you tried toluene? Now there's an octane boost that will get your attention!

What is it you expect to achieve with advanced timing, btw....

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Post by Jeb »

>|<>QBB<
canyncarvr wrote:
Have you tried toluene? Now there's an octane boost that will get your attention!

What is it you expect to achieve with advanced timing, btw....
Toluene - got some, just need to actually try it. I'm not sure how it figures into the "equation" now that I've got the xtra-sweet head and use the 110.

Advanced timing - a little more on top . . . perhaps (maybe?)
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Post by canyncarvr »

Uhhhh.... no.

Which is why I asked.

Advancing the timing will retard the top end of things.

ha ha ha...I'm so funny..........

If you retard ignition timing on a 2-smoke, you will increase the top end..at expense of the bottom.

...and vicey versa..advance=better bottom (that's why you see the 'Advance' brand hanging in the ladies unnie sections of stores.

Uh..you've seen 'em...right? Don't tell me I'm the only one shopping there.

Anyway..advance=better bottom..at the expense of the top.

Hhhmmm....I guess there's a linkage to brassieres here somewheres....

Retarding ignition timing will also give you a harder hit (more effective/responsive 'pipe-time'). Maybe on a 220, that won't be noticed much.

Advancing timing WILL likely get you more heat..and the 220 generally has its hands full when it comes to dealing with heat.

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Post by Jeb »

>|QBB<[/url]
canyncarvr wrote:Uhhhh.... no.

Which is why I asked.

Advancing the timing will retard the top end of things.

ha ha ha...I'm so funny..........

If you retard ignition timing on a 2-smoke, you will increase the top end..at expense of the bottom.

...and vicey versa..advance=better bottom (that's why you see the 'Advance' brand hanging in the ladies unnie sections of stores.

Uh..you've seen 'em...right? Don't tell me I'm the only one shopping there.

Anyway..advance=better bottom..at the expense of the top.

Hhhmmm....I guess there's a linkage to brassieres here somewheres....

Retarding ignition timing will also give you a harder hit (more effective/responsive 'pipe-time'). Maybe on a 220, that won't be noticed much.

Advancing timing WILL likely get you more heat..and the 220 generally has its hands full when it comes to dealing with heat.
Well now, this is an interesting thing to learn . . . about you and those unnies!

OK, so it's retarding that I need to try.

So, since I was wrong about what advancing the timing would do, 'might as well make sure about the direction to turn the stator plate: counterclockwise to retard, right? Referring to the pic below, how much of a move from the middle of the three marks next to the screw would one make before a change would likely be noticed?

Your comments are well appreciated . . .

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Post by canyncarvr »

That's a KDX stator? If it is...they've changed.
Jeb wrote:counterclockwise to retard, right?...
OF COURSE NOT!

Sheesh....

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OK...that simply smarta$$ to get your attention.


Yes. It is correct. The motor spins CCW, looking at the stator plate. The farther the spark point (placement of the coil) is moved in the direction of spin, the later it will happen.

Vicey versa.

The shown marks are generally considered the 'limits' of change..to be safe. So...move it to 'top' mark, see what happens.

It looks to be a bit 'tardo already..may be just parallaxis.

I gotta go....late for shopping!! :wink:

Just kidding. I AM late for a Bombay Sapphire and Schweppes, though.... :partyman:

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