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Post by Walms on Feb 22, 2014 8:07:22 GMT -5
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Post by zambia on Feb 22, 2014 8:11:54 GMT -5
...say that name 3 x quickly... |
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Post by JA-Moo on Feb 22, 2014 16:10:00 GMT -5
Most is standard knowledge, the rest is off in left field........
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Post by pipe welder on Feb 23, 2014 11:31:49 GMT -5
Well worth the read. I brought up the issue several years ago of modifying the combustion chamber design to a more modern shape on my stock engine. I had very mixed opinions on this from several people who knew what they were talking about. I also think it's worth noting that the unwelcome combustion processes that occur during engine operation don't always happen at a level that can be easily noticed. When this leads to engine failure we tend to wonder how the rider never notice a problem before she blew. With regards to detonation, Klemm says: “Detonation Always produces Audible Pinging” ….Wrong. There are “some” 2stroke race engines that do emit an audible “pinging” noise when they go into runaway detonation …. But that is the exception, not the rule. On top of that, virtually no 2stroke race motor makes an audible pinging of any kind, when experiencing the slightly elevated percentage of deto strikes that routinely deliver a seized piston. Thanks for posting Mr Walms |
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Post by JA-Moo on Feb 23, 2014 20:40:59 GMT -5
True, you can destroy a piston and not hear a thing. I also have a pile of plugs colored with 91 with ethanol. And jetting with race gas is foolish.
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paulh
3rd Gear
Adrenaline is brown
Posts: 528
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Post by paulh on Feb 23, 2014 22:54:54 GMT -5
Agreed! the way I see it...If you could jet/tune it with race gas, might as well just jet/tune it with pump gas.
But kinda the reverse happened to me as to klemms theory.
I always ran low octane on my S3 racer, On the way to the next races I decided to get an edge and purchased high octane from Sunoco. It ran sluggish after the first lap and then seized. after I got back to the pits it started up fine. I checked over everything, plugs looked a little suspicious but nothing had changed except for the fuel I used. Drained the tank and put low octane back in and it was fine for the rest of the weekend.
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Post by Walms on Feb 24, 2014 7:20:33 GMT -5
Well you need to take everything you read with a grain of salt BUT it's always good to get different perspectives.
I agree that it only makes sense to tune with the gas you plan to use, I've followed LC's recommendation to even try to always fill up at the same station to minimize fuel differences. I also believe anyone that was on the Huron tour will attest to the fact the gas seemed to vary with every fill up.
I didn't really like his explanation about taper angles either, it might have been easier to say the taper angle effects the transition from 1/4 to 3/4.... Does it go from lean to rich, rich to lean or stay consistent... Nothing more than that.
What I plan to do, because I'm starting from scratch (again) is to tune the bike to my best ability, then put it on a dyno with an exhaust probe to get it fine tuned.
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Post by pipe welder on Feb 24, 2014 14:37:46 GMT -5
You may not get anyone who will run the exhaust probe on the dyno for you as I was told the two stroke emissions cause the O2 sensor to fail and their not cheap. It will also only read one pipe.
I agree about your comment on how he describes certain issues like the taper but I think he's making assumptions that we have enough background to see his point. Your right on top of the partial throttle testing as I saw you do it before but his point on not using a set of the pant meter is valid. Repetitive accurate timing runs over a measured distance at "x" throttle is a very accurate real world dyno if you do it right.
I am assuming that his discussion about using high octane for jetting is simply to use it as an insurance. Meaning that if you are full loading at WOT on a long pull he states that even minor detonation (undetectable) may cause piston temp changes and could effect combustion wich may give you false impressions. So why not use high octane. (I could be wrong on that point)
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Post by Walms on Feb 24, 2014 14:52:29 GMT -5
I'm pretty sure Soup's bike had a probe in there when he had his bike dyno'd it's how Craig knew it was running lean.
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Post by Walms on Feb 24, 2014 15:05:07 GMT -5
It would make sense to use high octane of you are measuring the air fuel ratio on a dyno but if you jet like 98% of us, you are listening for the sweet spot between deto and burble and it's not like that is going to be more than 3 jet sizes.
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Post by pipe welder on Feb 24, 2014 18:26:41 GMT -5
I'm pretty sure Soup's bike had a probe in there when he had his bike dyno'd it's how Craig knew it was running lean. You could try this as he also says "most dyno places don't like hooking up their expensive O2 sensors to 2 strokes" Wideband Oxygen SensorAs for your comment " you are listening for the sweet spot between deto and burble" I think Kliemm's reference to “detonation management” says clearly - "Modern data gathering tools developed during the 1990s showed clearly that the best racing engine setups actually detonate 5-15% of total combustion strikes." Kevin Cameron ads in his article " If we hear it at all....." indicating that we often will not hear it. He goes on to state "When detonation begins even light deto this boundary layer is scoured off by the impacting shock waves, and heat transfer from hot gas to cool metal accelerates. In only a very few detonating cycles, piston temperatures rise dramatically, and the rest of the parts exposed to combustion gas aren't far behind." So the question you want to ask yourself is, will I hear the minor deto and if it's there is it affecting the combustion and messing up my plug readings? Interesting stuff! DETO by Kevin Cameron Klemm mentions: "Read Kevin’s piece on Turbulence, and engine builders please experiment with those squish bands! It should be done methodically on a repeatable dyno with copper tube connected to the engine to listen for knock. There’s surely hidden HP there! I don't think he would suggest the tube if you could hear the deto he's referring to which is not necessarily the loose bolts on the piston that you may be referring to. Here's some more reading to sort your tuning and keep ya busy. DynoTech Blog 2011My summary from some of this is that it seems some experts feel that deto (possibly considered mild or even "light") may occur without the tuner hearing it and it will change the combustion characteristic enough to effect peak measured Hp and possibly plug readings that the tuner is using to determine optimum jetting. Walms you have all the knowledge and the expertise to do it right on this new setup your doing. I think its going to work great for ya just the way you plan to do it. (This thread should go under Tuning) |
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Post by Walms on Feb 24, 2014 22:35:57 GMT -5
Thanks for the links Jim! Those scooter guys are pretty intense! I'm looking forward to the challenge of jetting this new setup!  |
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Post by Walms on Feb 24, 2014 22:37:17 GMT -5
Also, I'm not aware of a way to move a thread...
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Deleted
Deleted Member
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Post by Deleted on Mar 30, 2015 7:04:02 GMT -5
I'm pretty sure Soup's bike had a probe in there when he had his bike dyno'd ......... an assumption? I was there for the dyno run, no probes were inserted into the pipes. |
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Post by Soupdragon1957 on Mar 30, 2015 7:53:30 GMT -5
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