Author Topic: Detonation Symptoms (Read 1296 times)

Kreidy818 · « **on:** February 17, 2013, 09:02:31 pm »

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

Hotbutta · « **Reply #1 on:** February 17, 2013, 09:44:39 pm »

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?

WestTexasKing · « **Reply #2 on:** February 17, 2013, 10:11:14 pm »

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.

Iceracer · « **Reply #3 on:** February 18, 2013, 04:09:44 am »

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.

Kreidy818 · « **Reply #4 on:** February 18, 2013, 05:55:29 am »

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.

Hotbutta · « **Reply #5 on:** February 18, 2013, 07:00:48 am »

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.

Kreidy818 · « **Reply #6 on:** February 18, 2013, 08:10:27 am »

Sunoco 110 leaded with maxima 927, v force reeds #3, Dont know anything about the squish, Motor was bought used

Stpltn250r · « **Reply #7 on:** February 18, 2013, 08:41:14 am »

I would definetly cc the head installed. always a good thing to know. curious to who built the motor. iceracer is a good dude.

Iceracer · « **Reply #8 on:** February 18, 2013, 11:26:19 am »

Did you have an outer wear on the filter?

Kreidy818 · « **Reply #9 on:** February 18, 2013, 12:00:41 pm »

no outwear

Kreidy818 · « **Reply #10 on:** February 18, 2013, 02:23:45 pm »

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

Hotbutta · « **Reply #11 on:** February 18, 2013, 02:32:24 pm »

I think it's still fat. Show a plug chop.

Gillio · « **Reply #12 on:** February 18, 2013, 02:56:02 pm »

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.

BadMoonRacing500 · « **Reply #13 on:** February 18, 2013, 04:44:31 pm »

Quote from: Gillio on February 18, 2013, 02:56:02 pm

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.

Kreidy818 · « **Reply #14 on:** February 18, 2013, 08:58:56 pm »

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???

Gillio · « **Reply #15 on:** February 18, 2013, 09:03:42 pm »

Alot of those guys run super M and love it. I might change over in the future.

QuadMan8 · « **Reply #16 on:** February 18, 2013, 09:17:15 pm »

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.

.

Kreidy818 · « **Reply #17 on:** February 23, 2013, 03:47:42 pm »

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.

Nopick · « **Reply #18 on:** February 23, 2013, 04:07:48 pm »

Motorgeek says it sounds like this.

http://www.suzukiquadracerhq.com/video-u-tube/just-for-fun-name-that-malfunction!/

WestTexasKing · « **Reply #19 on:** February 23, 2013, 07:31:15 pm »

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...

Hotbutta · « **Reply #20 on:** February 23, 2013, 08:46:21 pm »

I'm glad, because I could not tell the difference between the two videos.

Nopick · « **Reply #21 on:** February 23, 2013, 08:50:29 pm »

And I couldn't tell the difference when I was riding it.

Hotbutta · « **Reply #22 on:** February 23, 2013, 09:40:58 pm »

The RS250 was blessed to have a deto counter fitted by HRC. We should have been so lucky.

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Author Topic: Detonation Symptoms (Read 1296 times)

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