So after talking to lots of people and checking some things out myself (see my Does this sound like I need a valve adjustment? (http://gstwins.com/gsboard/index.php?topic=27684.0) thread), I decided to take the GS to the shop and have then diagnose it. They said that the awful awful noise is most likely a bent rod or a bad bearing (as had already been suggested here).
The estimate? = $840 for labor + $200 to $500 for parts. :o :o :laugh: :bs: :cry:
Luckily I've found a friend with an empty garage where I can work, so I'm going to do this job myself. I figure it's going to be a great learning experience, and hopefully waaaaay cheaper. I'm starting this weekend, so y'all can expect updates, pics and lots of questions. :thumb:
Quote from: WildBlue on July 27, 2006, 03:03:12 PM
The estimate? = $840 for labor + $200 to $500 for parts. :o :o :laugh: :bs: :cry:
??? ??? OMG.....you could buy half a dozen ratbikes for that! :cookoo: :laugh:
Good luck on the wrenching. It'll be a piece of cake for ya'! :thumb:
Go ahead and order a complete gasket set so you'll have it when you're ready to reassemble. You'll need a dial caliper, valve spring compressor, ring expander, torque wrench, cylinder hone, circlip pliers and gasket scraper as well as solvents and moly grease.
It's not difficult but it is time consuming. Work patiently and cleanly and you shouldn't have any problems.
-M
take pics for us
Go wild. For less moeny than what they wanted you can make a do it yourself race bike!
Good to hear those words " I'm going to do this job myself ", and you always have help right here at the GStwin.com GS500 Message Forum, 24/7/365 days a year. Happy wrenching. :cheers:
you can buy a used engine for less than the parts to rebuild
i know where 3-5 are in SC for 4-600 a piece
and the TIME you save.......... ;) is worth about 50 HRS LABOR
i second werase used motor way better and easier as well(even though i can build one in my sleep i've done it so many times)
What about the learning experience though? But what ever gets you back on the road. :cheers:
Quote from: werase643 on July 28, 2006, 04:51:08 PM
you can buy a used engine for less than the parts to rebuild
i know where 3-5 are in SC for 4-600 a piece
and the TIME you save.......... ;) is worth about 50 HRS LABOR
Not necessarily, it depends on what's broken really. For me, that hardest part of the job was getting the engine out of and back into the frame and you'll have to do that anyway if you replace it. Not to mention that the replacement might not be any better than the original.
-M
if it was top end...pistons/rings....about 120 a side plus 40-60 a side to bore....300
if valves....12 a piece plus head gasket 30-40 plus taking it to a machine shop to have the seats cut....and bronze valve guides....150-200ish
crank brgs....60-80
rod brgs....50-70
rod....100
crank....300-500
sh!t adds up quick
but hey have a ball
why take pics....they are in the book....it will look just like the ones in the book
if ya gunna take pics take pics of the screwed up parts
Well yea, but if he's just spun a rod bearing he won't need to spend much. The bike's only got <13k on it, the top end is probably fine. Deglazing the cylinders is a good idea but the rings / pistons won't need to be replaced unless there's obvious damage.
Really the best solution is to remove the engine and tear it down. Once you find the problem you can evaluate your options.
-M
Quote from: werase643 on July 28, 2006, 04:51:08 PM
you can buy a used engine for less than the parts to rebuild
...
and the TIME you save.......... ;) is worth about 50 HRS LABOR
Yeah, probably, but I'm really learning a lot, plus the part(s) that need(s) replacing might not be too expensive.
So I went ahead and got started over the weekend. Tank came off, followed by the air box, fuel valve and carbs. Then the valve cover, camshafts, cylinder head, cylinder block and finally the pistons off of the connecting rods. So at this point the whole top end is off, and so far I've found the following:
- There's a lot of carbon on the crowns of both pistons, my friend tells me this means I'm either running too rich or too cold...(?) :dunno_white: I didn't clean the carbon yet, and I also didn't inspect the cylinder head very carefully thus far. Close inspection of both pistons shows no apparent damage, although I suppose something could come up once the carbon gets removed.
- On inspecting the cylinder block I found a scratch on the left cylinder wall. It didn't look too deep but it does worry me that it's even there.
So before removing the top end it was the case that when rotating the crankshaft (from the signal generator end) it was generally smooth but got a little tougher to turn at some point (with the spark plugs removed), then smooth again. After removing the top end it's smooth all around. This, combined with the scratch on the left cylinder wall, leads me to suspect that it's NOT a bad bearing as I originally thought, but rather something wrong with the left rod-piston assembly -- perhaps a bent left rod (it does look a little off center to me on visual inspection, but I might just be paranoid). Of course, for a more conclusive diagnostic I'll have to remove the rest of the engine from the frame and take it apart, which is the goal for this week.
I'll try and post some pictures in the next couple of days. Questions so far:
1) What does the excessive carbon on the piston crowns indicate?
2) Should I have the cylinders rebored to remove that scratch on the left one? Actually when you rebore, does it have to be done on both cylinders at the same time, or can you do just the one side?
Quote from: WildBlue on July 31, 2006, 01:12:03 PM
Quote from: werase643 on July 28, 2006, 04:51:08 PM
you can buy a used engine for less than the parts to rebuild
...
and the TIME you save.......... ;) is worth about 50 HRS LABOR
Yeah, probably, but I'm really learning a lot, plus the part(s) that need(s) replacing might not be too expensive.
So I went ahead and got started over the weekend. Tank came off, followed by the air box, fuel valve and carbs. Then the valve cover, camshafts, cylinder head, cylinder block and finally the pistons off of the connecting rods. So at this point the whole top end is off, and so far I've found the following:
- There's a lot of carbon on the crowns of both pistons, my friend tells me this means I'm either running too rich or too cold...(?) :dunno_white: I didn't clean the carbon yet, and I also didn't inspect the cylinder head very carefully thus far. Close inspection of both pistons shows no apparent damage, although I suppose something could come up once the carbon gets removed.
- On inspecting the cylinder block I found a scratch on the left cylinder wall. It didn't look too deep but it does worry me that it's even there.
So before removing the top end it was the case that when rotating the crankshaft (from the signal generator end) it was generally smooth but got a little tougher to turn at some point (with the spark plugs removed), then smooth again. After removing the top end it's smooth all around. This, combined with the scratch on the left cylinder wall, leads me to suspect that it's NOT a bad bearing as I originally thought, but rather something wrong with the left rod-piston assembly -- perhaps a bent left rod (it does look a little off center to me on visual inspection, but I might just be paranoid). Of course, for a more conclusive diagnostic I'll have to remove the rest of the engine from the frame and take it apart, which is the goal for this week.
I'll try and post some pictures in the next couple of days. Questions so far:
1) What does the excessive carbon on the piston crowns indicate?
2) Should I have the cylinders rebored to remove that scratch on the left one? Actually when you rebore, does it have to be done on both cylinders at the same time, or can you do just the one side?
When you bore you'll have to do them both. typically its a 1mm overbore (about .039 inches) Saw a set of standard compression 1mm over pistons on e-bay last night might check it out to see if you can get em cheap (search on Suzuki gs500). All pistons build up carbon on the piston tops. An old school trick is to run water through your carbs with the engine running to steam clean the valves and pistons. Since your gonna need new pistons and rings and maybe rods does JE or Wiseco make a higher compression piston like a 11:0 to 1?
damn dude for that price you can get a used engine and be on the road for 400$
w/out pictures it's impossible to say whether the carbon buildup is excessive or not. I would guess probably not; my engine had <8k on it and it had quite a bit.
The lack of resistance you're feeling when you turn the crank is completely normal. With the top end installed you're working against the force of the valve springs pressing against the cam lobes; remove that resistance and it should rotate smoothly.
Can you get pics of the scratch in your cylinder? You might want to consult w/ an automotive machine shop on that one. They could offer suggestions on the best way to deal with it based on how deep it is and its orientation.
Go ahead and split the cases and check out those bearings. Check the oil pan for telltale chunks of metal. Your repair manual will list the tolerances you need to check and what kind of damage to look for.
-M
Well, here they be:
Left piston:
(http://www.gstwins.com/photogallery/albums/userpics/14737/LeftPiston.jpg)
Right piston:
(http://www.gstwins.com/photogallery/albums/userpics/14737/RightPiston.jpg)
Left cylinder (front half):
(http://www.gstwins.com/photogallery/albums/userpics/14737/LeftFrontCyl.jpg)
Left cylinder (rear half):
(http://www.gstwins.com/photogallery/albums/userpics/14737/LeftRearCyl.jpg)
Right cylinder (front half):
(http://www.gstwins.com/photogallery/albums/userpics/14737/RightFrontCyl.jpg)
Right cylinder (rear half):
(http://www.gstwins.com/photogallery/albums/userpics/14737/RightRearCyl.jpg)
So as you can see there are two scratches on the left cylinder surface that bother me, one on the front and one on the rear. Also that seems like a lot of carbon on the pistons, but I don't know if it's more or less average (@12,000 miles). :dunno_white:
Today I finally got the engine off the frame, now the bottom half is sitting on some 2x4's waiting for me to open it up. One quick question -- I was trying earlier to remove the signal generator rotor but it's not wanting to go anywhere. There's that one bolt that goes through the center of it and into the crankshaft, which I removed, and at that point both the Clymer and Haynes just say "remove signal generator rotor, noting how the pin on the crankshaft aligns with the rotor", as if it's just a matter of pulling with your fingers. Do you guys think I need a puller to get it out? Is it pressure-fit onto the crankshaft?
the bores seem to have normal wear to me (if it had 20k plus)
looks as if it had over heated at some point and then scratched the bore, or oil level got low and the heat and no lube did it.
Carbon always builds up in a engine and the amount up in your case does not seem excessive to me. There is an equal amount on each piston its hard and dry which indicates its not burning a huge amount of oil. The scratches may have been caused by a broken piston ring, check them carefully and make sure there are no burrs, particularly on the ring-ends where they join. The bores need to be carefully measured and checked for taper and ovality, this is best left to a specialist whith the right equipment. Its not good practise to rebore just one cylinder, the replacement piston will be larger and hence heavier than the the original and may lead to vibration problems.
Quote from: rangerbrown on August 01, 2006, 06:58:47 PM
looks as if it had over heated at some point and then scratched the bore, or oil level got low and the heat and no lube did it.
I've kept the oil level always within specs, but I guess it's possible the previous owner didn't at some point...
Quote from: sledge on August 02, 2006, 06:54:01 AM
The scratches may have been caused by a broken piston ring, check them carefully and make sure there are no burrs, particularly on the ring-ends where they join.
Hmmm, I'll have to go back and check them. On initial inspection they didn't seem to be damaged, but it's worth checking again.
Good to know that the carbon deposit seems normal. The spark plugs also show normal wear, so I don't think I'm running hot or cold. I'm going to go ahead and open up the crankcase in the next few days, hopefully that'll reveal the source of the knocking. If not, one of my friends was saying "It wouldn't be the first bike that was taken apart and put back together and that fixed the problem without ever knowing what it was. :dunno_white:". :laugh: