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SuzukiSavage.com
/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> PISTON NOISE /cgi-bin/YaBB.pl?num=1251606164 Message started by MMRanch on 08/29/09 at 21:22:44 |
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Title: PISTON NOISE Post by MMRanch on 08/29/09 at 21:22:44 ANYBODY EVER HAVE A CRACKED PISTON? i BEEN GETTING A THRODLE RELATED WACK OUT OF THE HEAD OR TOP OF THE BLOCK FOR THE LAST COUPLE OF THOUSAND MILES. SOUNDS ALMOST LIKE THE PISTON PIN AREA IS CRACKED AND GIVING WAY UNDER LOAD. IS THIS A COMMON (NATURE OF THE BEAST) THING OR SHOULD I LOOK DEEPER INTO IT? THANKS |
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Title: Re: PISTON NOISE Post by verslagen1 on 08/29/09 at 22:46:56 look for the "I hear you knockin' " and redux threads |
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Title: Re: PISTON NOISE Post by justin_o_guy2 on 08/29/09 at 23:30:30 You might give some thought to poking that caplocks button. |
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Title: Re: PISTON NOISE Post by verslagen1 on 08/29/09 at 23:38:34 yes, before he pushes your mute button. :o |
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Title: Re: PISTON NOISE Post by Oldfeller on 08/30/09 at 02:26:13 We have a history of eating up piston skirts and making some slap noise on the bikes that have been run right hard -- yours might fit into that category from what we saw at the Dragon run this past summer. |
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Title: Re: PISTON NOISE Post by bill67 on 08/30/09 at 05:19:23 Over size tires is hard on the little 650 motor. |
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Title: Re: PISTON NOISE Post by justin_o_guy2 on 08/30/09 at 05:19:42 How does a guy figure out if his engine noise is that of a healthy thumper or that of one needing a new piston? |
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Title: Re: PISTON NOISE Post by Toymaker on 08/30/09 at 07:43:14 yeah?...I wanna know too. :) |
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Title: Re: PISTON NOISE Post by Boule’tard on 08/30/09 at 08:56:29 <blind stab> Make sure you're not lugging the engine in too high a gear or running tainted gas. Switch to a different brand, premium gas for a couple of tankfuls, and pay attention to the noise as it relates to engine RPM and throttle position. If the noise only occurs with the cheap gas or under open throttle/low RPM conditions.. like the doctor said to the patient with the elbow.. don't do that :) </blind stab> Otherwise, get in there and replace the piston, rings, and hone the cylinder. Might be a good opportunity for some hop-ups ;) Sorry if these suggestions are too basic and you already tried them.. just checking. |
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Title: Re: PISTON NOISE Post by MMRanch on 08/30/09 at 20:13:31 Thanks for all the ideas . Anybody know what burnt valves sound like ? I've taken it apart and nothing looks or feel loose or scared, I'm seating the valves while its down, the seats look black (notice no capital lettler.....ha! ) |
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Title: Re: PISTON NOISE Post by Trippah on 08/30/09 at 21:12:38 Boule'tard..I never understood why people suggest running a premium gas..if by premium you mean higher octane. Unless MMRanch has modified the compression, regular swill is more than sufficient. He could drain the tank and add fresh gas but if the sound has been for the past several thousand miles, that's at least ten tankfuls so unless it's all from the same fuel storage tank, it can't be a culprit. By throttle related I suspect he is saying the sound becomes more frequent as RPM's increase, or gets louder. Might want to check valve clearance unless the sound is too low in frequency (Hertz) not of occurrance. Curious about nr of miles on the engine also. Oldfeller's suggestion on piston slap seems right. Let us know what you find. |
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Title: Re: PISTON NOISE Post by Phelonius on 08/31/09 at 10:19:13 4A584A58554649444F070 wrote:
Do a compression test. That will expose burnt valves. Phelonius |
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Title: Re: PISTON NOISE Post by Boule’tard on 08/31/09 at 11:04:00 5A7C677E7E6F660E0 wrote:
It is, and I've never gotten any noise running 87 octane gas. But I can't help but think the higher octane reduces spark-knock under high load/low RPMs even at the stock compression ratio. Quote:
It's possible he's got excessive carbon buildup (which aggravates knocking) that has just become evident in the last couple thousand miles. The other advantage to premium gas is that they typically mix in a higher concentration of detergents, additives, "Techron" or whatever, that clean out the deposits. A good dose of SeaFoam might also help. Quote:
That could be the case. I was thinking the sound only occurs when he whacks the throttle open at too low an RPM, which would tend to induce spark-knock or piston slap. But yeah, if the noise increases with RPM (all other things being equal) it's time to bust out the tools. |
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Title: Re: PISTON NOISE Post by justin_o_guy2 on 08/31/09 at 11:16:11 Ive seen guys drop rice down the carb on cars when they thought there was a carbon buildup issue. IDK if it helped, I was just about 12. |
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Title: Re: PISTON NOISE Post by Oldfeller on 08/31/09 at 16:34:09 .... and is that how Rice Krispies were invented? Snap, crackle, pop .... Rice Krispies !! |
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Title: Re: PISTON NOISE Post by MMRanch on 08/31/09 at 18:46:20 If all else fails I'm "Going for the rice krispies" |
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Title: Re: PISTON NOISE Post by Boule’tard on 08/31/09 at 22:56:33 Careful, your bike will turn into a rice burner.. HUH HUh huh ;D ..oh. |
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Title: Re: PISTON NOISE Post by justin_o_guy2 on 08/31/09 at 22:58:00 It wasnt at an idle when they started feeding it the rice, it was rapped up tight enough to have been making 60 or so. |
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Title: Re: PISTON NOISE Post by Boule’tard on 08/31/09 at 23:05:51 Oh, a rice ROCKET, I got it :D Reminds me of that dude (or joke about the dude) that fed sand into the airbox of his BMW to "port the heads." |
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Title: Re: PISTON NOISE Post by verslagen1 on 09/01/09 at 09:04:14 So do you need an open exhaust for the rice trick? Or do you smell burnt rice till they're gone? |
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Title: Re: PISTON NOISE Post by T Mack 1 - FSO on 09/01/09 at 09:24:26 0B333E373435322E285B0 wrote:
Do a compression test. That will expose burnt valves. Phelonius [/quote] Compression check will also show rings on their last legs. And.... the Melted Piston syndrome. Which I am told would be a loud knocking noise. :( http://www.users.fast.net/~tommack/photos/100_1951.JPG |
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Title: Re: PISTON NOISE Post by Stimpy on 09/01/09 at 10:12:48 1) a flashlight, a small mirror and some ingenuity might help you to determine if your piston is cracked by physically looking at it through the sparkplug hole. (...and if you can get your hands on a miniature "snake-cam w/light" you are done! mechanics and doctors use those) 2) might help you to take a look at my recent engine rebuild thread w/ many findings and photos mainly regarding burnt exhaust valves and new ring install on an old piston Here: http://suzukisavage.com/cgi-bin/YaBB.pl?num=1246924611/0 Good luck RP |
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Title: Re: PISTON NOISE Post by Routy on 09/02/09 at 07:51:09 If its running good, it doesn't have any burnt valves. If it has piston slap, you won't find it w/o checking the clearance tween the piston skirt and cyl wall. If the piston is cracked, it is most common to be in the wrist pin/skirt area, which would be very hard to see thru the SP hole. Plain water thru the air intake, along w/ WOT is commonly used to rid piston/combustion chamber of carbon. If you do not have noise on cold startup, and at idle, I would not suspect any part of the piston to be at fault. Rich |
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Title: Re: PISTON NOISE Post by justin_o_guy2 on 09/02/09 at 09:43:30 Good points all, Routy. Be much easier to feed it H2O than rice. Would you want to do an oil change after that? |
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Title: Re: PISTON NOISE Post by Routy on 09/02/09 at 21:22:06 I and other mechs did it many times in the auto shops. We never saw any noticeable water get into crankcases, but an oil change can't hurt. Rich |
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