Detonation Symptoms

• Detonation Symptoms
  Posted by Kreidy818 on 17 Feb, 2013 21:02
• what are the symptoms for pre detonation. my motor was breaking up on top today at the races and I am trying to figure out if it is jetting or something else. I just changed to a aaen pipe and a K&N filter this week and it started to do it in my main event. went back and bumped up the main jet from a 195 to a 200 and it still did it in the other main. didnt seem to do it much in the heats though
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• #1 Reply
  Posted by Hotbutta on 17 Feb, 2013 21:44
• 200 sounds big even for the AAEN, but I havent ran my Keihin in a long time. What pipe did you run before and what mods do you have?
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• #2 Reply
  Posted by WestTexasKing on 17 Feb, 2013 22:11
• Check plug for signs of detonation.
  I'd suspect jetting before detonation.
  It's not always easy to distinguish detonation from other problems just by the way it runs.
  However, if you want to try something else...buy yourself a few gallons of abnormally high octane fuel and see if the problem persists.
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• #3 Reply
  Posted by Iceracer on 18 Feb, 2013 04:09
• Kreidy you the third one who was there that has seen that issue. Try running again somewhere else before you get too carried away. Ill give you my # so we can talk, It may not be jetting, but we need to rule out some other possibilities.
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• #4 Reply
  Posted by Kreidy818 on 18 Feb, 2013 05:55
• gonna drop the main to a 190 and make a couple of runs up the street today. Now that I think of it, it was worse in the second main event.  the carb is a Duncan pre jetted Kehein pwk 39. The engine is 540 ported,squished and o ringed. was running a FMF pipe and Uni air filter, just switched to a K&N and the AAEN pipe.
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• #5 Reply
  Posted by Hotbutta on 18 Feb, 2013 07:00
• What fuel are you using and what cc or ocatne is the head cut for? What kind and condition of reeds? I hope it's not the Duncan pyramids.
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• #6 Reply
  Posted by Kreidy818 on 18 Feb, 2013 08:10
• Sunoco 110 leaded with maxima 927, v force reeds #3, Dont know anything about the squish, Motor was bought used
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• #7 Reply
  Posted by Stpltn250r on 18 Feb, 2013 08:41
• I would definetly cc the head installed. always a good thing to know. curious to who built the motor. iceracer is a good dude.
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• #8 Reply
  Posted by Iceracer on 18 Feb, 2013 11:26
• Did you have an outer wear on the filter?
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• #9 Reply
  Posted by Kreidy818 on 18 Feb, 2013 12:00
• no outwear
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• #10 Reply
  Posted by Kreidy818 on 18 Feb, 2013 14:23
• So I put in a 190 main and ran it up the road and same thing happens falls on it face blubbering on the top end. Still need to check the plug but was too disgusted and just put it away
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• #11 Reply
  Posted by Hotbutta on 18 Feb, 2013 14:32
• I think it's still fat. Show a plug chop.
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• #12 Reply
  Posted by Gillio on 18 Feb, 2013 14:56
• Pull a fuel sample from the fuel line and let it settle out, See if that 927 seperated. I had problems with that a couple weeks ago.
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• #13 Reply
  Posted by BadMoonRacing500 on 18 Feb, 2013 16:44
• Quote from: Gillio on 18 Feb, 2013 14:56

  Pull a fuel sample from the fuel line and let it settle out, See if that 927 separated. I had problems with that a couple weeks ago.
  

  This, i've had it happen too. Lower specific gravity fuels and low temps the 927 will seperate. It is common with Fuels having a specific gravity of .750 or less. 100LL is around .750 as are some lower grade racing fuels. If it gets cold enough it will separate from almost all fuels. If you look at the bottle of 927 it has a warning about separating at low temps.
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• #14 Reply
  Posted by Kreidy818 on 18 Feb, 2013 20:58
• I think I am gonna change the fuel that is in it. I will get some more sunoco and use honda hp2 (always had good luck with that) Might drop the needle one spot also. When I do a plug chop Ikeep the throttle open after killing the ignition if I remember correctly???
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• #15 Reply
  Posted by Gillio on 18 Feb, 2013 21:03
• Alot of those guys run super M and love it. I might change over in the future.
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• #16 Reply
  Posted by QuadMan8 on 18 Feb, 2013 21:17
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  I run the super m when its cold or when I am really lugging it trail crawling high high high up in the Rockies.  I run 927 in summer and at dunes.
  
  I read a post from Jerry Hall that mixing a little pump gas with your racing gas when its cold will help prevent separation. I don't remember what ratio pump to race fuel.
  
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• #17 Reply
  Posted by Kreidy818 on 23 Feb, 2013 15:47
• So after I fanally got to work on the bike today, I checked the plug (it was brown) changed to a resistor plug, and drained the fuel for new gas and different oil. Then I found sand in the tank! Drained it flushed it and all I have to say is...Damn!!
  That thing hauls ass. Now I just have to get it to handle in the corners.
  
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• #18 Reply
  Posted by Nopick on 23 Feb, 2013 16:07
• Motorgeek says it sounds like this.
  
  http://www.suzukiquadracerhq.com/video-u-tube/just-for-fun-name-that-malfunction!/
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• #19 Reply
  Posted by WestTexasKing on 23 Feb, 2013 19:31
• That's the problem, unless you're there in person listening to the engine and someone says it's detonating, you're probably not going to be able to identify it later on when it happens to yours.
  Video compression and less than stellar camera mics also change the way an engine sounds...
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• #20 Reply
  Posted by Hotbutta on 23 Feb, 2013 20:46
• I'm glad, because I could not tell the difference between the two videos.
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• #21 Reply
  Posted by Nopick on 23 Feb, 2013 20:50
• And I couldn't tell the difference when I was riding it.
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• #22 Reply
  Posted by Hotbutta on 23 Feb, 2013 21:40
• The RS250 was blessed to have a deto counter fitted by HRC. We should have been so lucky.
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