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Hey guys, I'm nw here just got a GS - 350$ ebay buy, no title, no carbs. easy fix - 
(my last project was a 400+hp supra, present project is a hybrid equinox for challengex (hybrid vehicle competition), I am an electrical engr. student at the university, so I know my way around a soldering iron, but also know which end of the slide hammer to apply to some @$$hole's jaw... I mean... a dent...)
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About the GS.

It has fresh oil and filter, new plugs, and rebuilt (pilot jetted to 40) carbs, K&n replaced airbox.

I noticed a slight periodic noise coming from the left side of the crankcase. I'm thinking either something in the generator, or the starter sounds loose - the noise comes and goes. It creeps on and lasts about 4-8 seconds, and then fades out at idle. You can hear it above idle, but it seems to disappear (or be muffled by the sound of my open K&N and the exhaust) when you rev through the powerband.

The carbs are not tuned - power seems to die off about 7k,  but its definitely not the air metering slides for the main jet bouncing up and down, that is another distinct noise.
It doesnt sound like rods, because the noise is not accentuated when the RPMs are crested (accel2decel, decel2accel)
Its definitely not coming from the top end. I can even feel some of the vibration/knocking if i put my hand on the left crankcase.

Any good ideas? Ive been through the search, and come up with a variety of diseases, (none of which are bacterial,) but they dont seem to apply, at least I hope not.

Any suggestions what I should focus on? I am kind of hesitant to pull the crankcase off at this point - got other things on my to-do list.
I dont want to be kicking myself for contracting that disease - the one that causes the permanent magnets of the rotor to come flying apart...

Let me know what you think, and ps - great forum, loads of info. I look forward to contributing.

Lev

 :)Can you describe the noise.........Like I have a noise that comes from the calm chazin tensioner and its very loud at idle and dissapears whenb I open the throttle its...  kerdonk kerdonk kerdonk. Best still record it and put it up on the site.

Hey welcome to the the site!

First off make sure its IN the engine. I had a GS that had a rattle that I thought sounded like an engine noise but turned out to be a cracked case guard vibrating. Look around the bike with it running and touch (with gloves on) parts to see if they are loose or shaking. I would look for a loose exhaust or the removable frame section being loose.

If you eliminate external factors, its not very hard to remove the left (or right) engine side covers to take a look inside. If you are lucky you will even get the gasket off intact and can reuse it. When you are removing the sprocket cover, also pay attention to if it was loose or had a big rock in the bottom as that could be your culprit too.

Now is a good time to invest in the manual too.

good luck,
James

You indicated that you replaced the airbox with a K&N and that you put in 40 pilots - unless you also upped the main jet do not ride at more than about half throttle for  more than a few seconds - the bike will be extremely lean at full throttle - and that means hot and that means burned exhaust valves or holes in pistons.

34c

Quote from: mjm on March 14, 2006, 10:20:08 AM
You indicated that you replaced the airbox with a K&N and that you put in 40 pilots - unless you also upped the main jet do not ride at more than about half throttle for more than a few seconds - the bike will be extremely lean at full throttle - and that means hot and that means burned exhaust valves or holes in pistons.

um, yeah forgot to mention, the main jets are shimmed up 2 washers.

Quote from: Wrecent_Wryder on March 14, 2006, 12:33:06 PM
Well, he did say it seems to be non-bacterial...
I'm still wondering what an engine noise that is caused by bacteria sounds like....

it was in reference to shrinath's diseases, namely starwalt's, etc.
--------------------------
after changing my brake fluid today, i listened to the engine noise some more... it seems it might be coming from the head, maybe cam chain tensioner. would that noise come and go, or when that thing goes, tis pretty steady? I would think that would be noticeable at RPM cresting, but it only seems to happen at idle after revving the engine some...

theres plenty of oil, so i'm not starving the thing.

anybody else?

23

does it everynow and then kinda make a "CHug" type noise at idle that correspondes with a drop in rpm, almost like a misfire?

Quote from: mjm on March 14, 2006, 10:20:08 AM
You indicated that you replaced the airbox with a K&N and that you put in 40 pilots - unless you also upped the main jet do not ride at more than about half throttle for  more than a few seconds - the bike will be extremely lean at full throttle - and that means hot and that means burned exhaust valves or holes in pistons.

I agree with mjm that you are risking serious damage to the engine; others have given you good advice about how to locate the noise you're hearing, but I am concerned that you are going to burn the exhaust valves (or worse) by running the engine in such a lean condition.

Your comment that "... forgot to mention, the main jets are shimmed up 2 washers..." does not decrease my concern. I realize that you're referring to shimming the NEEDLES with two washers, but that will not prevent damage to the engine if you continue to open the throttle with the engine running.

There was a recent post here from someone else (jason1080; I'll take a wild guess that he was born in October of 1980) who installed an aftermarket exhaust (V&H) with a K&N filter. He chose to ride without rejetting, and now faces the expense of a non-warranty repair; though we're all hoping things turn out well for him, he's probably not going to be happy when they hand him the bill for replacing the exhaust valves, and possibly even more work. Even worse, he's voided his warranty, so that is going to place an extra financial burden on him if something else breaks down. One major reason why people prefer to buy a new motorcycle rather than a used one is because they want the warranty; some even buy an extended warranty. Now, jason1080 has learned a hard lesson the expensive way (or an expensive lesson the hard way)...

This is your engine; maybe because you bought the GS for a low price, you think it is worth the risk to run the engine so lean, but I hope you'll reconsider and take the time to rejet the engine before bad things happen that could easily be avoided.

No one can force you to rejet the carbs properly, but the GS is notoriously lean straight from the assembly line, and that K&N filter isn't going to help matters.

Good luck resolving the noise issue; let us know how this turns out.

I just pulled off the head of a hybrid diesel we are building here on campus - one of the hybrid gas injectors leaked, knocked, and blew off the top land on #4 - mind you that is difficult to do on diesel pistons.

I'm quite aware of what lean a/f mixtures do to combustion temperature, as well as NOx emissions (if anyone cares). I think I solved (alleviated) the problem by taping a piece of cardboard on the top of the air filter - restricts airflow and enriches mixture, as far as I can tell.

There was another guy on the subaru impreza forums a couple of years ago when I was into boosted cars... he missed something about running high boost without backing it up with fuel. He faced some expensive non-warranty repairs after he blew both head gaskets and melted three pistons, after the dealership caught on.

I appreciate your concern on the carbs, but the noise is still there, and I'm really leaning towards valves, the bike has 26k on the clock, and I'm guessing noone ever touched the top end.

Looks like I might be selling the bike, though - got a good offer the other day...

Quote from: Wrecent_Wryder on March 14, 2006, 12:33:06 PM

Quote from: Smiley on March 14, 2006, 12:16:06 AM
:)Can you describe the noise.........

Well, he did say it seems to be non-bacterial...

I'm still wondering what an engine noise that is caused by bacteria sounds like....

Wrecent.......you know.....I'm still trying to figure you out,dude. Not easily made happy,huh

So if this thread ressurects itself to the top of the list, I apologize, its old, but I figure I should let the end of the noise come to light.

The bike sat all summer, while I interned in Michigan, driving preproduction cars 

While I was away, got to thinkin, and the more I thought about it, the more I couldn't let it live. I decided that I needed to track down that noise, so I yanked the cams off, and lo and behold, a worn down cam, rusty shim, and stuck bucket. I did a top end on it (reground the valves and seats), threw some ebay cams on it, reshimmed, and voila. Noise is gone. While I was in there, changed base gasket and threw a set of rings on it. Figured couldn't hurt.

Runs great, 4 months and 3000 miles later, not a tick from her. A slight oil leak from the base gasket surfaced, I shoulda siliconed that thing on.

Oh, and Cal Amari, I did rejet at the same time, and synced the carbs. But I must say, I ran lean for at least 2000 miles, and there was no visible damage to the exhaust valves when I pulled that sucker apart. Maybe I wasn't hard enough on it.

good news! You stuck with it and solved the problem. Thats great.

Show that engine bacteria who's boss!

-Turd.