I was riding home from work yesterday, cruising around 65 mph on the interstate when I lost all power. I tried turning to reserve thinking I was out of gas but quickly realized that wasn't the issue and pulled to the shoulder of the busy highway.
I tried to start the bike but all I got was a clack clack lack. Hand over the exhaust pipe showed a little bit of compressions.
I used my AMA roadside assistance to tow the bike 50 miles home. I now don't recommend AMA's roadside assistance it since it took them 2 hours to get a tow truck to me while I sat in the dark on the side of the interstate in cold and windy 38 degree weather.
This morning I went out to the bike and noticed the cam chain tensioner was sitting on top of the starter motor cover!
So I'm assuming the tensioner came loose and then the bike instantly jumped timing and bent both valves to oblivion. Does sound seem like a relatively simple top end rebuild or could I have done more catastrophic damage?
The bike had a top end rebuild done by a shop 2 or 3 years ago. They were the last ones to install that cam chain tensioner and I feel like they didn't torque the screws down enough. Why else would the whole thing just pop out? I left a message with the shop to see if they warranty their work but I won't hold my breath.
Oh, that sucks.
OMG, yea, they'd flake out cos its 2+ yrs ago. An auto transmission shop did that same nonsense to me and he was referred by a friend. And in my case, I had that car wrecked and just needed to submit a receipt to get some more $$ from insurance. He couldn't be bothered to find the receipt from ~2 yrs ago.
But Hope we see your progress.
Cool.
Buddha.
I took the valve cover off. The first damage I see is the small cam chain guide that sits above the tensioner is shredded. Pieces of it all over the engine. So I'll definitely have to remove the cams to replace that piece.
What diagnosis would you run? Can I check the valve clearance to determine if the valves are bent? Or do I need to buy a compression tester?
I'll check the timing next to see if its off and how far.
Quote from: Bluesmudge on November 09, 2022, 04:29:45 PM
I took the valve cover off. The first damage I see is the small cam chain guide that sits above the tensioner is shredded. Pieces of it all over the engine. So I'll definitely have to remove the cams to replace that piece.
What diagnosis would you run? Can I check the valve clearance to determine if the valves are bent? Or do I need to buy a compression tester?
I'll check the timing next to see if its off and how far.
Valve clearance will help. So would the shining light in the intake and exhaust port trick.
And yes check what's happened to the timing. However the shining light is far more effective as is the valve clearance. It will be very very high - unless its broken a valve. In that case that valve will be 0.
Cool.
Buddha.
Ok, so for "shining light in the intake and exhaust port trick" do I shine a light down the spark plug hole when the cam lobe isn't touching the shim/valve and then look in the corresponding exhaust port/intake port for light? Seeing any light would mean bent valve, right?
For checking the valve clearances, should I re-install the cam chain tensioner before checking?
Yeah, look at the top of the pistons through the spark plug hole, you do have one of these " cameras on a wire " endoscope things, dont you?
Sorry about the problem!!
The light trick is you make sure all the valves are closed - CCT should be re-installed and the valves timed properly if you're turning the motor over - which you may have to. Unless you removed the camshafts. So shine in intake port, look in spark plug hole and exhaust port. Shine in exhaust and look in spark plug and intake port. Shine in spark plug and look at the other 2. The brighter the light and the less ambient light the more likely it will be easier to see.
But anyway if you can - check the valve clearance of any valves that are closed right now - without touching anything. If that is huge like 10X the specs - you can guess the valves are bent. Even 1 bent valve = you are better off taking it apart not reassembling and setting timing etc etc. Then take off the cam shafts and do the light trick.
Cool.
Buddha.
Its too cold for me to work on the bike today, but I did quickly throw a feeler gauge on the 3 valves that are in position. Both intake valves are less than .15 mm so likely still in spec. Right exhaust valve is more than my largest feeler gauge at .50 mm so definitely bent. Maybe it's possible the timing jump ended up somewhere with interference with the exhaust valves but not the intake valves. Is that possible?
I'll keep updating as I dig into it more.
Yes, it depends on the direction and position the valve was when it was hit by the other valve. Say the exhaust was well open and the opening intake valve hits the back side of the open exhaust valve. That resulting leverage will deliver the exhaust valve a good shear and bending force while on the intake valve it may be mostly compression and a little bit of bending.
This bike is valve to valve interference not valve to piston. BTW they should have just made it non interference - like it has any performance illusions.
Cool.
Buddha.
Quote from: The Buddha on November 14, 2022, 08:20:52 AM
This bike is valve to valve interference not valve to piston.
I did not know that! This whole time I was assuming valve to piston interference. In a way, that's a good a good thing because I know there are probably no piston/lower end repercussions of all this.
I remembered I have a full head in the attic of my garage with only 5,000 miles on it. I think I'm just going to order new cylinder and base gaskets and copper washers, maybe new rings, and swap the whole extra top end over. I think that will be much faster and cheaper in the short term than doing all new valves and cam chain guides. Then I can take my time refreshing my old head since I've never replaced valves before.
Does sound like the easiest way. I've also got a spare head stashed away that I refurbished (actually my original head) ;-)
Hoping to do some traveling around Switzerland next summer to use up the bike a bit. Not doing nearly enough since my daughter arrived (8 years ago now ...YIPES..)
You didn't break a valve. You should be fine. Ofcourse you're gonna remove the head - so you will see the state of the piston. You basically lose nothing if I'm wrong about the valve-valve interference (which I am not, Dgyver and Werase643 have confirmed it in ancient posts on here). Good call on the spare head swap. Enjoy swapping.
BTW I'll go over everything the shop did a few yrs ago. TBH, how do you torque down something that it lasts several 1000 miles and 2 yrs. When I leave shaZam! loose it gives up with in the first 5 miles. That took some special talent.
Cool.
Buddha.
I finally got around to ordering all the gaskets and other random parts, plus a cylinder hone. I'm assuming Partzilla will take a few weeks to get everything to me.
I purchased a new cam chain tensioner as well. I had been running a manual version for the last ~25,000 miles but I want to go back to the automatic adjuster. I was never 100% confident in whatever tension I would set and I figure a brand new tensioner should last a good long time.
Quote from: Bluesmudge on March 30, 2023, 04:24:04 PMI finally got around to ordering all the gaskets and other random parts, plus a cylinder hone. I'm assuming Partzilla will take a few weeks to get everything to me.
I purchased a new cam chain tensioner as well. I had been running a manual version for the last ~25,000 miles but I want to go back to the automatic adjuster. I was never 100% confident in whatever tension I would set and I figure a brand new tensioner should last a good long time.
Good luck with the repair. Question on replacing the tensioner....does it require more than removing and replacing? Will the timing shift?
Quote from: HPP8140 on March 31, 2023, 03:23:17 PMGood luck with the repair. Question on replacing the tensioner....does it require more than removing and replacing? Will the timing shift?
The timing shouldn't shift, so long as you don't turn the engine over at all while the tensioner is out.
The hard part is that you have to wind it in, then while holding the tension figure out how to tighten the two mounting bolts (the bolts that backed out and caused my whole issue in the first place) and then once its mounted you can release the screw used to wind it and the tensioner will snap out and put tension on the timing chain. The whole process really requires a third hand and/or removing the carburetors. That was part of the reason I switched to the manual tensioner...with the manual APE tensioner I was able to replace a leaking tensioner gasket without removing the carbs.
Bluesmudge, you mentioned earlier that the sprocket on the cam had disintegrated, I wonder if all those metal shards have got all around your engine? Maybe take off the sump and try to wash down everything with kerosene and let it drain out?
Quote from: herennow on April 01, 2023, 03:01:40 AMBluesmudge, you mentioned earlier that the sprocket on the cam had disintegrated, I wonder if all those metal shards have got all around your engine? Maybe take off the sump and try to wash down everything with kerosene and let it drain out?
I don't think I ever said that the cam sprocket disintegrated. The cam sprockets look fine.
I did say that the moment the cam chain tensioner popped out the timing probably jumped and bent the valves to oblivion. But that was before I learned from the buddha that this engine is valve/valve interference, not valve/piston. So, the forces involved would be much less than I was originally imagining. It seems like my intake valves bent my exhaust valves since the intake clearances are still in spec and the exhaust clearances are massively out of spec.
It does look like some of the cam chain guides had chunks taken out of them, so I did order a new sump gasket so I can drop it and see what's in there. The spare head I have has all the cam chain guides in place so those will all get replaced with the head.
He said the top guide in the valve cover. That's basically a rubberized plastic. Just needs to be cleaned out. A little left here and there wont matter. Its a soft material.
Cool.
Buddha.
I got the easy part done! It's always easier to take it apart than put it back together.
The top end is off the bike and the parts have arrived!
The hardest part of disassembly is getting the exhaust bolts out and getting all the electrical connections out of the way to give the head enough clearance to come out of the frame.
I can pretty much confirm what Buddha said: Definitely valve to valve interference and not valve to piston. The timing was probably 5 or 6 teeth off when I first got the valve cover off. One I got the head off I confirmed that there was damage to the underside of all 4 valves. The intake valves still seem to seal fine but the exhaust valves are so bent I can see a giant gap with the naked eye. The top of the pistons look fine but are covered in a compressed goop made out of all the chunks of the cam chain guides.
My original plan of swapping in the low mileage head (with fresh rings, hone, and gaskets) just to get the bike running is probably still the best plan. Hopefully the valve stem seals are still good on that head. It might just work if I can remember how to put everything back together.
Nevermind...there was exhaust valve to piston interference. I just removed both pistons and they each have a decent gouge from the exhaust valves. Suzuki, in their infinite wisdom, cast a relief for the intake valve into the piston head but not for the exhaust valve. The damage looks like you sunk your fingernail into some clay. I don't want to risk running it as-is...seems like thats asking for a hot spot and more damage.
So now I'll be waiting for Partzilla again. At least my GS will have brand new pistons...that's kind of cool. Saves me from scrubbing the carbon off the old ones.
How much are new pistons going for in the us?
Quote from: herennow on May 18, 2023, 11:22:15 PMHow much are new pistons going for in the us?
$80 each. So $160 for the pair.
Things got even more complicated today as I tore into it more.
-I have 2 sets of cylinders. Both have some scoring that I can catch with my fingernail and one has a decent pit in it, so no good based on the little I know about engines. I had already ordered the standard size pistons and rings, so rather than move to the oversize Suzuki pistons and have the cylinders bored out, I sprang for a new set of cylinder jugs on eBay. Pretty expensive at $450, but still cheaper $200 than Partzilla charges and I figure I'm in so deep at this point I might as well have a "new engine." I'll have brand new cylinders with factory cross hatching to mesh with the new pistons/rings.
-But then things got more interesting. I should heave checked this first, but I hadn't noticed that the rear cam chain tensioner guide was very worn out and had a chunk missing from it. Of course this is the one guide that can't be replaced from the top end. So now I have to remove the engine and split the case to replace a $35 cam chain tensioner guide. I've never removed the GS engine before, or messed with the bottom end of any engine. I imagine removing the engine will be much easier since I already have the top end off. Then the question is...do I rebuild the top end off the bike, or return the bottom end to the bike and then build the top end there. I've seen/heard its pretty difficult to slide the full engine into the frame.
This is turning into way more of a project than I expected. At this point half the reason I'm fixing the engine is for the learning experience, since after buying all these parts I'm getting close to the price of a decent used eBay engine.
Getting engine back in frame is easy if you know how. slide it in at 90 degrees to normal and then turn it forward once its almost in place. Ive got pictures somewhere, I know this was a revelation for me after struggling for hours.
I dont remember the bottom end7 gearbox being very hard to get back together. I'll double check my notes and post some pictures.
I remember that removing the heads and cylinders leads to gunk around the studs falling into the bottom end....
That rear cam guide is a dumb effing design. I've trashed many a motor at the sight of that damage.
Cool.
Buddha.
I have made some good progress on my rebuild.
I got as far as splitting the cases and replacing that cam chain tensioner guide. While I was in there I replaced the input and output shaft seals, the shift shaft seal, and put in a complete output shaft/bearing assembly from a lower mileage bike (16k vs 55k) because my output shaft splines were pretty worn from accidentally running a front sprocket with the shoulder faced the wrong way for a long time. I got it pretty cheap off ebay. I would have never replaced the output shaft otherwise, but since I'm there...
Started putting it back together. It took my a really long time to learn how the transmission works and to test to make sure I put it back together right and shift through all the gears. You can't really test it like you are used to on the bike until you get the shift assembly all back on. Then I couldn't find neutral and had to learn how the little wheel with removable pegs is the "neutral finder" and I had to move the neutral peg to where it now needed to be to engage neutral in the right spot between 1st and 2nd gear (something must have gotten out of alignment when I removed the output shaft so hopefully my neutral light still works after moving that little peg). I can now shift through all the gears as expected, including neutral.
The oil screen and sump cover is back on. Now its just oil pump, starter motor, clutch, and generator rotor to go back on and I can start rebuilding the top end like I originally intended. Or I might rebuild the top end off the bike and put those parts back on once the engine is in the frame since many of them require a lot of torque which could be hard to do with the engine on the bench.
good to hear, keep up the good work, some inspiration from my rebuild 10 k km ago...
last one, and here is the bastard cam chain guide....
Nice photos. That all looks too familiar now, although your engine looks much cleaner. Interesting that you didn't have to remove the starter clutch/generator assembly. The instructions said it was required but the instruction always to it the 'right' way and never the easy way.. Would have been nice to have one less thing to remove and re-install.
Did my description of the gear change neutral cog thing make sense? Does it sound like I did it right? I wasn't sure if it was okay to move those pegs to get neutral acting correctly. Its not described well in the Haynes manual, it just says to study how it works.
I didn't do the plastigauge thing since that wasn't the reason I was in the bottom end. If I was confident in my ability to assess and replace big end bearings, then I would have done it but I'm already way out of my depth here. I just wanted a cam chain tensioner guide that didn't look like a dog's chew toy. I'll be happy just to have a running back after all this is over.
Im sure it will work fine, I'm sorry I do not recall the neutral sensor.
I took a huge chance and just got new crank shell bearings and sized them based on plastigauge readings before and journal micrometer measurements. HAd a huge excel sheet, worked out in the end. Loved buying the japanese precision parts.
My old britbike parts really seem agricultural in comparison....
I just picked up my re-worked head from a local machinist. I gave him the low mileage head that came from a 2001 that ran out of oil and lost the bottom end. I figured it had 50,000 fewer miles and 4 good valves so it was worth risking the unknown history. He said everything look fine, like the top end had enough oil to survive. He cleaned everything up with a "multi angle valve job that's better than factory spec." New valve seats and viton seals that should survive better again ethanol gas. I blocked off the mechanical tach port since I'm putting this '01 head into my '06 bike.
New pistons, wrist pins, circlips, and rings are on the engine and looking good. Next up I'll drop in the new cylinders and assemble the top end and set the timing and valve clearances. I'll get this done eventually. And it might even run when I'm done.
Cool, getting there. Sounds like you are not far away.
I'm slowly building up an old triumph and it's taking its time also as life gets in the way. Hoping to hear it roar before winter though!
Thanks for following along. I'm posting mainly to keep myself sane as I slowly rebuild this engine and bike. I get to work on it at half hour or sometimes hour long intervals fit in between everything else life says is more important than my GS500 getting back on the road.
I snapped the oil pump gear while reinstalling the clutch basket. The instructions mention making sure the gears mesh with the crank cog's teeth but don't mention the less obvious oil pump gear that sits behind the clutch basket. there was a very loud cracking sound when it cracked as I was torquing then main clutch hub hit and I thought I had broken something serious. Luckily it's a pretty cheap part on eBay and I was able to get a low mileage one for $16. Another little bit of learning on this project and yet another part from some random salvage yard GS500 with far fewer miles than mine. At this point only the bottom end of of my engine is original to the bike and even that has a new used output shaft.
With the new oil pump cog I was able to get the clutch installed and button up the right side of the engine. A few days prior I put the top end on with a new cam chain tensioner and set all the valve clearances. Almost ready to go back in the frame!
A month later and I have the engine back in the frame and have officially started the bike! I was hoping this would be the end of this saga, but the bike runs like horrible sh!t. I was able to put a few miles on the bike, but it needs to be dialed in before it can be thought of as reliable transportation again. Seems like a carb/air issue, which is weird because the carbs were very dialed in before the bike broke down.
Starting cold with choke, the bike only revs to 1500 rpm instead of 4,000. Once warm it will hold 1200 rpm nicely with no choke. But the revs are slow to return to idle and I have a lot of flat spots, buzzing, and hollow sounding exhaust/intake note through the rev range. The revs drop below the idle point after a rev and then return to 1200. If I blip the throttle a few times in a row I sometimes get mild backfire through the carbs. At higher revs the tach needle seems to be jumping around as the bike is running rough/buzzy. Almost like it's running in one cylinder but both exhaust pipes get hot right away and the 2004+ bikes don't lose spark on one cylinder, it's both or nothing. Also both spark plugs look exactly the same: black/sooty except the curved electrode part which is ash white. This implies both cylinders are running and doing the same thing, because they look the same and both plugs were brand new. If one cylinder actually wasn't running that plug would look new. The sooty plugs make me think it's running rich, but I'm always skeptical of plug pulls to tell you much. But the idle drop after revs is also supposed to be rich running behavior.
The air mixture screws do almost nothing. It runs almost as well with them screwed all the way in as with them 4 turns out. Slightly better all the way in or .5 turns out than with more turns out. It does start to run bad after 4 turns out and it won't run with the mixture screw removed,. I confirmed the o-ring and washer and spring are in there, the mixture tip isn't damaged and the o-rings look plump. If I was tuning an old bike that was new to me this would make me think the pilot jets were too big, but I know this bike and the pilot jets are the stock size of 17.5, which was working great before the bike broke down (confirmed with a dyno run after the shop rebuilt the engine in 2020). This made me think that maybe there was an air or vacuum leak pulling too much air past the pilot and choke circuits, which also pulls more fuel to make it run rich? My ability to diagnose CV carbs is being stretched to its limit.
I checked the vacuum balance on both carbs, they were almost exactly the same already so required no balance adjustment. The valves were just set with the rebuild.
The carb to engine boots and o-rings are new.
I did a very general spray of wd40 and carb cleaner around everything and found no change in revs. Also tried pushing the carbs around and moving/squeezing the vacuum line to see if revs changed and there was none. That doesn't mean 100% there isn't a leak, but the carbs got fresh rubber bits in 2020 when the bike was rebuilt by the shop, so carb internals are only 3 years old. Fuel lines and half the vacuum line are brand new and the bike ran great before it broke down.
With the air filter removed I confirmed the action of both slides. They seemed to vibrate up and down when throttle was applied and the revs got choppy. Especially the right slide I don't know if that's normal with the air filter removed or indicative of the problem, like a vacuum leak I still haven't found.
I might have found the problem when I removed the air filter to look at the carb slides. The metal bottom of the foam uni filter had come partially unglued and was probably letting a lot of additional unfiltered air into the air box. I tried taping it back together while I wait for a replacement but that didn't seem to fix the problem, but I'm just going to wait for a new filter before trying to diagnose any further.
If a new air filter doesn't fix the issues I'll check fuel height. There was a moment when my temp fuel tank was off and the bike was running that the choke acted correctly by jumping up to 4,000 rpm instead of 1,500 rpm. So the bike seemed to like running low on fuel in the float bowls (again confirming that it's probably running rich for some reason). But I don't want to bandaid the problem by lowering the fuel level if that's not the actual problem, so if fuel height is correct then I'll start dismantling the carb for cleaning. I was hoping the carbs would work as good as the day the bike broke down because I'm pretty sure I drained the float bowls not long after the bike broke down and I also usually put in ethanol free gas but it's still possible there was some fuel in there to gum them up these last 8 months. I don't know carbs well enough: is it possible that a clog somewhere could make it run rich at idle and bad through the whole rev range? I'm pretty sure the only thing that effects all throttle positions is the fuel height and the float needle/valve. The carbs were stored upside down on the bike sometimes while I worked on it. I wonder if that could have messed up the float position or float valve function?
I got things pretty well dialed in now. I had broken one of the vacuum nipples on the white doohickeys on the carb tops on my 2006 carbs. I replaced both carb tops with ones from an '01/'02 bike (same as gen1 SV650). See my other post about it. It really cleans up the '04+ carbs and seems to have fixed a lot of my tuning issues. For a lot of the rev range the bike seems to be running better than ever.
The new carb tops plus a new OEM air filter seems to have fixed my issues. I just have a really big dead spot if I do a fast WOT roll on while cruising on the freeway. I hit a big dead spot around 6000 rpm with WOT. If I roll on slow using mid throttle it doesn't happen. I'm probably jetted way too rich for the OEM air filter since it was set up on a dyno for the Uni filter. I'm not sure if it's the main jet or the slide needles causing the issue.
I'll probably eventually try and tune it a little more by either going back to the Uni air filter or swapping out all the jets and needles back to OEM but for now it's nice to just finally be able to put some miles on the bike. 50 miles so far. I'll ride it another 50 and change the oil for the first time after the rebuild. The original Suzuki break in was 600 miles but that feels like a lot of miles after my fresh amateur rebuild. I want to get any metal shavings out of there.
The good news is that a lot of the secondary little things I fixed up while doing the rebuild has the bike really feeling fresh. New chain/sprockets. New clutch springs with a 3 point clutch adjustment. New rubber gaskets on the speedo/odometer. New output shaft so the front sprocket doesn't have excessive play anymore, new left handlebar control so my turn signal and horn controls don't stick anymore.
The bike still isn't running quite right. Its totally rideable but a little funny.
Choke only brings RPMs up to 1500 or so but it starts reliably. Choke has to stay on for awhile. Like 5 minutes. The bike used to only need choke for 30 seconds or so. I think its normal to need choke that long but the rpms should be up around 4,000 with full choke.
Once warmed up the idle will drop below 1200 rpm coming to a stop, implying the bike is rich. But adding any more turns to the mixture screw makes it run worse, implying its not. My Stainless Steel headers look a little bit blue which I think is new, implying its a little lean.
I have a very lightly hanging idle, which is also usually a lean condition. It feels like I have almost no engine breaking. Can't lower the idle any more or the bike will die coming to a stop. Mixture screw was already adjusted for highest and best idle.
I'm guessing I need to clean the carb. Maybe some small areas like the choke passage got gummed up before I drained them. That's the only thing that changed about the carbs, which were working great otherwise. I guess I'll order some o-rings and gaskets so I can freshen things up while I'm in there. So much for my pride in never having cleaned a set of GS500 carbs before.