Hey all,

I'm getting back into riding after a 10 year break, and picked up a tatty GS for my 16 mile round trip commute to my station. The bike was an ex-school bike - I was thinking that although the mileage was high (appx 46k), it would probably have been relatively well maintained. It was cheap - about £500, although I am aware of the false economy this can sometimes be lol.

I have a thread running about my sticky rear wheel. But I thought I'd post up some of the other things I've discovered about this bike...

Rippled Brake Disk
I am assuming that your brake disk, when running your finger along the flat side should be smooth? Mine has got some serious grooves in it. It feels rather 'wavey' as you run your finger from the edge of the disk to the axel.

Sticking throttle
Throttle response seemed pretty normal, albeit a bit gutless, for most of the ride. As I was approaching my home stretch, I noticed that the revs weren't dropping quickly as I dropped the throttle. I pulled over, and watched the revs rise up to about 2k... further twists of the throttle sent the revs up, with a very slow return. However after a while this issue went away. I am assuming I need to lube the throttle cable(s)...?

Poor throttle response
I sort of noticed this after the above incident. When pulling away from a standstill, I found that I needed to have the revs up vefore I engaged the gear. If I didn't do this, acceleration was pretty slow.

Engine Performance
After the above, I was heading up a mellow hill in 4th, and found I was struggling to get above 30mph. Dropping down helped, but was still pretty poor in terms of torque.


I was wondering if poor valve clearances might be responsible for the performance issues. But if anyone has any experience of these issue, I would be very grateful for your views.

Cheers guys
Alex

Not sure I can help on most problems but there is a few things you can do in the mean time,

Check spark plugs make sure they are getting good spark

Compression test

Check your float heights with the u tube method

All of these can cause problems like your experiencing

Roger Wilco mate, thanks for that...

One other thing I forgot to mention: When I took off the oil filter casing, there was some crud at the bottom of the cover... not sure if this is normal...

Cool

About the only thing you can do about the brake rotor is run a dial indicator on of to see if it is warped, and mic it for thickness. A hanging idle can be caused by a few things, but is most often a leak around the intake boots. Sometimes they are fine when cold, but as the engine warms up the cracks in the rubber let air slip past.

Seeing as this is a new to you bike, first thing, have the valve clearances checked. You don't know where they are at and the exhaust valve specs are too small anyway. Set them at .003 to .005 inches. You'll be chasing your tail if you don't start there. Even if PO said they have been checked, I'd check them myself to verify. So damn easy compared to other bikes.

My Yamaha Royal Star took hours just to get the valve covers off, then you have 16 valves instead of just 4 on these things!
You only check the valves on a Royal Star at 25K miles instead of 4K and mine were still in spec.

Also check your clutch cable adjustments, particularly if it seemed worse going uphill. I would do the full set up by starting under the engine cover and working out.  A GS500 should easily break the speed limit in 4th. I think if the disk is grooved slightly, not warped, that the pads will bed in and it should be fine as long as the disk is not below the minimum service spec. This can happen when pads were not changed soon enough.

In light of what you're experiencing, allow me to make a few suggestions: first, drain the gas tank; I mean EMPTY it completely. Condensation builds up inside the tank over time to the point where you could have a lot of water sitting in the bottom of the tank, diluting your gas and rusting the lowest sections of the tank, creating the notorious GS "crap pockets", which is why so many GSTwins members have to replace their gas tanks.

Let the container of old gas sit for ten to fifteen minutes; the water in the gas will settle to the bottom while the gas will float on top. Draining the tank is the best way to get the water (and assorted crud) out of it. You'll be able to do a good visual inspection of the tank to see how bad the rust is, so be sure to check the crap pockets, then use a SMALL mirror with a flashlight to check the top of the tank from the inside around the fuel filler neck. Feel free to post photos if you feel motivated...

Next, buy a bottle of the CHEAPEST carb cleaner / fuel injector cleaner you can find. Pour ONE OUNCE into the gas tank for each gallon of gas you have in there. Run the engine for a few minutes, then park it and let it sit overnight. The cleaner will help to soak the inside of the fuel system; any gum / varnish / residue it encounters will begin to soften. Follow the same procedure the next day; run the engine again, then let it sit overnight so the detergent will have time to work. Within a few days, you should notice a difference in how the engine performs.

If you use too much cleaner, you will smell it in the exhaust when the engine is running. If you use a LOT of cleaner, the engine won't start until you dilute the cleaner with fresh gasoline, or drain the tank and start over.

Good luck with this; let us know what you learn.

Just to make this easier on you, I'll condense everything into a check list:

-Check/adjust valves
-Check spark plugs
-Check compression (easy, since the plugs will be out anyway)
-Check float height
-Clean carbs/fuel system (I'd recommend actually popping the carbs off and cleaning by hand. It's more work, but it's more thorough, and will get you more familiar with your machine, which is always good)
-Adjust and lube throttle/clutch cables (again, easy since you'll have everything apart)
-Check for any air leaks around the carb boots, or the vacuum lines

The hanging idle is most likely caused by the bike running too lean. Cleaning the carbs and fixing any air leaks will most likely solve this issue.

I'd also recommend just replacing the rotor and pads. Just start fresh. The pads are already mated to the warped rotor.

I think that's pretty much everything...

If you have a free day, this can all be done. I've taken almost everything apart, cleaned and adjusted, and put it back together in a matter of hours. These bikes are extremely easy to work on.

Edit: Oh! And if you do have to adjust the valve clearances, be sure to sync the carbs after. Otherwise, it'll still have slight issues.

Quote from: azbo on June 22, 2014, 03:03:24 PM..............I was heading up a mellow hill in 4th, and found I was struggling to get above 30mph. Dropping down helped, but was still pretty poor in terms of torque...............

Quote from: 89500inPA on June 23, 2014, 01:43:40 PM................A GS500 should easily break the speed limit in 4th.................

A stock geared GS500 would hit max HP at 80 mph in 4th and wouldn't redline until over 100 mph.  It's a great high speed passing gear but not really a hill climber at 30 mph.

Thank you all for your words of advice. This is all really great, I'm actually really looking forward to getting this bike running nice.

First job - oil change - done. Did I imagine this, or does the engine sound a helluva lot better with the new stuff inside?

I have a new air filter, new sparks and a used rear disk off ebay on it's way to me now. I know I could have made do (cleaning, decrusting etc, but I thought a fresh start would be in order, given I don't really know the history of the bike).

This weekend, my mission is to remove the rear wheel to change the rear disk. While I'm at it, I'll have a damn good clean out down there, it's pretty grim. I am reasonably confident in getting this done; I have pretty much zero mechanical experience, but I recon the GS is a great place to start. Nevertheless, I see even this simple task as a mission.

After that, I was going to replace the air filter, but I think while I'm at it, I'll have a go at checking the valve clearances. But, I think I need to do some more research before getting into this task.

I have to be honest, the thought of opening up an engine a few months back wouldn't have even been considered. Now, maybe it's not such a big deal, but I definately need to swat up on what I'm doing, and what I'm looking for. I assume I'll need some width measure tool things for the clearance check (sorry, I don't know the name of these gauges).

With regard to the compression test, is this something that is used often when getting into bike mechanics? If not, I might take it into my local garage, to get them to do it (hopefully saving me about £20).

Checking the float height looks easy too, but again, I need to understand a bit more about this before doing.

Cleaning the carbs? OK, this does make me a bit nervous. Well, more than a bit hahaha... I will do it, but I might have to build up some hands-on experience beforehand hehe.

I will post back with photos or maybe a vid if I can find my lens (I suspect one of my young-uns has had away with it lol).

Thank you all again for your words of wisdom, it really is appreciated.

Chars

Alex

Quote from: gsJack on June 23, 2014, 09:34:40 PM

Quote from: azbo on June 22, 2014, 03:03:24 PM..............I was heading up a mellow hill in 4th, and found I was struggling to get above 30mph. Dropping down helped, but was still pretty poor in terms of torque...............

Quote from: 89500inPA on June 23, 2014, 01:43:40 PM................A GS500 should easily break the speed limit in 4th.................

A stock geared GS500 would hit max HP at 80 mph in 4th and wouldn't redline until over 100 mph.  It's a great high speed passing gear but not really a hill climber at 30 mph.

YES!  I want to reemphasize Jack's words here... the latter two concerns from the original post sound like normal GS behaviour.  A stock GS won't do much until 3k rpm, and I wouldn't climb a hill at 3k rpm ever on a GS... more like 5k+

The 'sticking throttle' sounds like you may have a slight air leak - So I'd check the carb boots for leaks

It would be worth it to do some brake overhaul on an ex-school bike, they were probably used heavily... and since emergency braking is taught heavily in the classes, an uneven rotor would be likely.  I would definitely check brake pad wear, and rotor wear objectively, and replace as needed.  (Oh, I see now you have one on the way, but don't forget about the front brake too!)Also at a minimum, bleed brake fluid if not replace lines as well.



- Bboy

I'm gonna be a busy boy 

Quote from: azbo on June 24, 2014, 02:18:00 AM
Thank you allI know I could have made do (cleaning, decrusting etc, but I thought a fresh start would be in order, given I don't really know the history of the bike).

After that, I was going to replace the air filter, but I think while I'm at it, I'll have a go at checking the valve clearances. But, I think I need to do some more research before getting into this task.

This should be a priority or you could be chasing your tail if you have issues the way it runs, and you don't know how it's suppose to run if it's new to you.

azbo, do change your oil and filter and install your new plugs and air filter but no need to panic over a valve check or carb cleaning.  Good to get that dragging rear brake sorted out now too.

If you have cold compression and can't hear your tappets on a hot engine the valves are not an immediate problem.  A tight valve will affect idle smoothness cold but it will smooth out in a minute or two as the engine warms and the clearances increase.  Do get them checked and adjusted as soon as your ready though as it will affect the life of your exhaust valves if they don't have adequate clearance over the long run.

I'm not one to be rushing into carb cleaning either.  Bought my 97 new and my 02 with only 4k miles on it and never touched the carbs on either and they have provided me with over 180k miles of fun GS riding.  If a bike has set unused for a long time and the jets are actually plugged completely it is necessary to tear them apart for cleaning.  The 89-00 GSs with 2 circuit carbs really were too lean for winter riding without rejetting but I had an old CM400 I used for a winter bike to splash thru the salt water here in NE Ohio and that 97 GS screamed thru the twisties and down the interstates happily for me spring, summer, and fall stock all the way.  I've used my 02 with the 3 circuit carbs year around for 10 years now also stock all the way.

The GS is a good bike for you to start wrenching on but always keep in mind the GS500 is not rocket science, it's more like tractor science.  By the way somewhere between 70 and 80 I got very old and no longer ride like I use to so am not a threat to others on the local roads if your thinking that.   

Thanks again everyone for the flow of information, it's all sinking in. Time to put this new found knowledge into practice.

Here's the bike in question:

I was trying to get the rear wheel off, in advance of the new disc arriving hopefully tomorrow. I managed to get at the caliper before the light failed me.

With the two caliper frame bolts and the single lever arm bolt removed, I still couldn't get the damn thing off. I'm not sure if it's something I'm doing (or not doing), it seemed to be still attached in some way... I'll have another crack at it tomorrow night...



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Get an owners manual and Haynes or Clymer's manual before disassembling another bolt!!!

There is no reason to take off the caliper to get at the wheel. All you have to do is put the bike up on the center stand, then take out the rear axle. Over simplified, but that's really about all there is to it......but you'd know this if you had already referenced any of the materials referenced above.


Sent from my iPhone using Tapatalk

Agreed. Grab a manual. It's possibly one of the most important tools you'll ever own for that bike. For the time being, however, the gstwins wiki has a buttload of information. So you can get a jump start on how this beast works lol.

JAS6377, jdoorn14,

Thanks for that. I do actually have a Haynes manual. I am a nube, and I am listening to (and very grateful for) all advice here (this place is great). Just to clarify, the reason I was removing the calliper was to try to carry out an inspection, and carry out a clean. My thinking was it would be easier to work on it while loose.

The fact that I cannot simply lift the calliper off the rear disc has stumped me. Perhaps I need to try to push the pistons back into the housing slightly? IDK. If I tried to remove the wheel without removing the calliper, I would still (I think) have the problem of getting the disc away from the calliper (although maybe the weight of the wheel might do the job).

Re. the brake, having had a look under the cap, I'll need new pads (they're beyond cleaning I think, quite a bit of rust in there which I guess can't be good for a brake system), and while I'm at it, I'm tempted to drain and replace the fluid. Is this worth doing, or would a bleed do the job?   

I'll have another crack at it later tonight.

Thanks again peeps

azbo,
1.You can't get the caliper off cause you still have the axle in place. Goes right through it! (unless there are 2 side bolts, haven't had mine off)
2. Those brake pad look new, plenty of life left!
3. You don't drain brake fluid, you flush it out with new.
4. A little rust on the pads shouldn't be a problem, but pulling them out is easy to clean them. (see manual)

It is frequently very difficult to remove the caliper from the rotor if the rotor has some circumferential  grooving from wear.  Just grab the caliper in both hands and wiggle it back and forth to push the pistons back in the caliper a bit and free it.  Happens all the time unless rotors are like new.  The wheel can be removed and replaced without removing the caliper with a stock size rear tire but is very difficult at times with a 150 rear like I'm using right now.  I've just pulled the caliper right off to begin with because it's easier to get the wheel back in place and axle back in without the caliper in place.