Bike has very little power (120km/h high speed on highway).I compression tested both cylinders. The left reaches 150 while the right stops at a measly 35ppi. I have never had a valve adjustment. Is a valve adjustment my first step or is there a quicker way to figure out the root of the problem? I'm considering simply replacing the top end(I have no garage and tinkering with the bike on the sidewalk may prove to be messy and bothersome).
Any input is appreciated.
P.S. plugs are fine, and both sides generate a spark..so I'm assuming the coils and electrical's are all fine.
Cheers!
The head would be the first thing to check. By your posts last October, you mention the problem slowly worsened. That could be a bad valve getting burnt more and more, causing you lose compression.
There could be other things, but nothing is going to be an easy quick fix.
If valves were out of adjustment and not closing, then the seats would be getting burnt. That means new valves and maybe a new head.
I think the head will have to come off to know what the real problem is. That's the only way to examine the valve seats.
If it is the rings, then the head still has to come off.
You could start with a valve adjustment and see if that helps!
Thank you!! yes I have been brushing this problem aside since last october. Now its time to get down and do this valve adjustment. I bought the shim tool..Time to get er done..I just hope it wont be a piston issue. I will update!
I opened up the top end and finally checked the valve clearances. Ok so both intake valves are not in spec. However I have a little concern. As I was hand cranking the engine I had constant tension, however at one point in the turn there was zero tension. It feels like if you are pushing against a door, and then the door opens and you fall through. This happens every revolution. Any ideas?
A 4-stroke engine has 4 strokes:
Intake
Compression
Power
Exhaust
Compression is just that. Compressing air fuel mix into a small space. Resistance should be felt. Normal.
Did you take out the plugs to assist?
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Quote from: jestercinti on March 18, 2013, 08:23:13 PM
A 4-stroke engine has 4 strokes:
Intake
Compression
Power
Exhaust
Compression is just that. Compressing air fuel mix into a small space. Resistance should be felt. Normal.
Did you take out the plugs to assist?
Sent from my iPhone using Tapatalk
lol. Don't forget to take out the spark plugs!!
Update! I checked the valve clearances with my feeler gauges and both the left and right exhaust valves didn't fit my feeler gauges from 0.02-0.09..however both intakes were fine (they both fit from 0.02-0.05/0.06). However when trying to remove both exhaust valve shims, I was unable to because the shim buckets were too tight to move around. Does anyone know how I can take out the shims without having the valve buckets loose..I'm unable to pry out the shim. Any help is appreciated.
One thing: Can you turn the exhaust buckets when in position to check clearance? If not, I expect that you will find a burnt valve.
Oh, one more thing: Have you watched the video on checking valve clearance?
Quote from: Paulcet on March 26, 2013, 06:06:37 PM
One thing: Can you turn the exhaust buckets when in position to check clearance? If not, I expect that you will find a burnt valve.
Oh, one more thing: Have you watched the video on checking valve clearance?
Firstly I have watched various videos on valve clearance checks, however none mention what to do if you can't rotate the buckets. Secondly, no I cannot turn the exhaust buckets when in position to check clearance. reason for my dilemma. I was expecting burnt valves anyways...question is now, what is my next step. Do I need to remove the engine from the frame to work on the valves? Or can I just remove the camshaft? Thanks paulcet.
You could loosen the exhaust journal caps just a little so the exhaust cam is a little loose. That can give you some room to turn the buckets and get the shims out.
You can work the whole top end without removing the engine.
If you remove the head, remember it is sort of stuck to the jugs. Lift the head and the jugs can come with it and a piston come out (don't ask how I know that, trust me I do know). You need to use a big ass screw driver and gently go around the space bwteen the jugs and the head to get the head loose from the jugs. Then you can take the head off. 2 people always work better: one can yell STOP while the jugs come up because you can't see that while lifting up the head.
Well, they don't mention what to do if you can't rotate the buckets because that should never happen. I would remove the head. I suppose you could roll the dice if you don't mind the extra work and pull the cam shaft to replace the shims. Be very careful with the cam caps.
You don't need to remove the engine from the frame to remove the head or cylinders.
Ok so what should I do first. loosen the exhaust journal caps, then change the shims to spec to see if it fixes anything?.Then if that doesn't fix anything I can take off the top end?
How would I go about loosening the cam caps?Would I need to remove the cam chain tensioner to do this? Do there happen to be any tutorials around youtube?
Thanks guys
You need a wrench - 12 or 14mm - to loosen them just a couple turns. just enough to turn the shim buckets. No need to loosen anything else. All you need is for them to have maybe 0.1mm space to turn the buckets.
When the shims are out, put in much thinner shims and tighten back down.
Now you should be able to do a valve adjustment by the book.
Wait, so you are saying that I need to put in much smaller shims, tighten it back down. Then I need to do the valve adjustment and put in another set of shims..Meaning 4 shims for the 2 exhaust valves??
Quote from: junk301 on March 26, 2013, 11:16:12 PM
Wait, so you are saying that I need to put in much smaller shims, tighten it back down. Then I need to do the valve adjustment and put in another set of shims..Meaning 4 shims for the 2 exhaust valves??
Basically yes. You need a set of shims in there to get a reading so you know if it needs adjusting. Since your valves are so tight and you can not get a reading at the moment you need to put a set of much thinner shims in than the ones that you will remove and recheck your clearances to see where you are at.
Ok great...how much thinner should I go? 10-15? Btw there wasn't even 0.02mm clearance. I need to get this done fast. Will update after new shims are in.
I would try .10 as a start. :thumb:
as in 2.10? that low??
Quote from: snOhio on March 27, 2013, 04:40:43 PM
a test shim will let you figure out exactly what you need to order. that way, instead of stepping down .05 and realizing you should have gone down .1, you can get it right the first time.
Yes, that was exactly my worry since I have to go and order the shims..Btw what exactly are test shims..do you happen to know where I can order them?
No "test shim" by name. It is just a shim that is known to be too small.
I could just buy one shim to test both right..replace, measure than replace the other exhaust valve the same way, measure, than buy the 2 new ones....Question. Does anyone know what shims come stock in the gs500 engine. I doubt a valve adjustment has ever been done on my bike before.
There is no stock shim size. There are ranges of sizes that are most common. I would guess that's 260 and 265 since I have so many of them. The slightest difference in machining will cause a different shim size.
Close to what adidas said, my 02 came with two 265 and two 258 shims. My 97 had a 265 and a 262 on the exhaust valves, never had the intake shims out to check them since they went 80k miles without a change.
http://www.gs500.net/gallery/data/500/GSvalvelogs.jpg
Update. Alright so its been a long time since my last update but here it is. To remove the old shims i tried loosening the cam journals to a clearance of 0.03. I could get the shims to rotate but not the buckets...I can only think that something is wrong with the buckets. Whats my next move. Taking off the cam shaft??
My bike had issues where only one cylinder was firing, then i found that one of the magnets on the signal generator was complete abliterated. so i replaced it and it worked
My 94 engine that I've just replaced was firing on one cylinder for a day, whole bottom end then blew shortly afterwards!
People above seem to have suggested good things to check for, so for now I'll leave my oar inside the boat!
thanks for the responses..But does anyone know if i need to take off the camshaft? I cant find any info on this. helps appreciated
Quote from: junk301 on April 16, 2013, 11:05:47 PM
Update. Alright so its been a long time since my last update but here it is. To remove the old shims i tried loosening the cam journals to a clearance of 0.03. I could get the shims to rotate but not the buckets...I can only think that something is wrong with the buckets. Whats my next move. Taking off the cam shaft??
Next move depends on what you want to do. Tight buckets are not good, very tight ones are even worse. I had a very tight one on my 02 GS, so tight it held an exhaust valve open when cold and there was no compression pop checking it with the thumb over the hole and cranking. I put a screwdriver in the bucket notch and hit it with a hammer trying to turn it and it wouldn't budge. Aluminum expands more and faster than steel when heated. Starting the bike it would run a bit rough at first but then smooth out in less than a minute and run like new the rest of the day. I decided to let it go until next check to see if it would wear in and loosen up but about 10k miles later I cranked it one freezing cold morning and bang. Valve stuck wide open and was broken off while cranking. I pulled the head to repair it with new valve and bucket and it's gone another 75k trouble free miles since.
That bucket was so tight I had to drive it out from inside with a long punch and heavy hammer. Your buckets must not be that tight since they don't stick open but are closed down to little or no clearance when cold. At this point I think I'd go ahead and change shims to get proper clearance first to see how it is, if you have a burnt valve it will be necessary to pull the head to replace it anyway. If compression is restored you might be OK as is. Your bike, your choice. Getting those tight buckets out to change them can be very difficult. You should be able to get the shims out by compressing the bucket with your tool. I just pick them out with tweezers at the notch but some here lift them out with a magnet, they are not tight.
junk301, your first consideration in your first post above might turn out being the best approach. Tight buckets are a pain in the butt! But if you have the test shim suggested in the following posts it might be worthwhile putting it in the right exhaust valve to recheck compression to see if valve is burnt before going ahead.
Quote from: junk301 on February 18, 2013, 06:46:26 PM
Bike has very little power (120km/h high speed on highway).I compression tested both cylinders. The left reaches 150 while the right stops at a measly 35ppi. I have never had a valve adjustment. Is a valve adjustment my first step or is there a quicker way to figure out the root of the problem? I'm considering simply replacing the top end(I have no garage and tinkering with the bike on the sidewalk may prove to be messy and bothersome).
Any input is appreciated.
P.S. plugs are fine, and both sides generate a spark..so I'm assuming the coils and electrical's are all fine.
Cheers!
Quote from: gsJack on April 20, 2013, 05:30:04 AM
junk301, your first consideration in your first post above might turn out being the best approach. Tight buckets are a pain in the butt! But if you have the test shim suggested in the following posts it might be worthwhile putting it in the right exhaust valve to recheck compression to see if valve is burnt before going ahead.
Quote from: junk301 on February 18, 2013, 06:46:26 PM
Bike has very little power (120km/h high speed on highway).I compression tested both cylinders. The left reaches 150 while the right stops at a measly 35ppi. I have never had a valve adjustment. Is a valve adjustment my first step or is there a quicker way to figure out the root of the problem? I'm considering simply replacing the top end(I have no garage and tinkering with the bike on the sidewalk may prove to be messy and bothersome).
Any input is appreciated.
P.S. plugs are fine, and both sides generate a spark..so I'm assuming the coils and electrical's are all fine.
Cheers!
Thank you so much for your post and very sorry for the late reply. Here is my question. Since I am working on the engine inside the frame I cannot get to the shim notch with a screwdriver. To take out the shim, would removing the camshaft be necessary? I dont mind doing this if it does not prove to be very time consuming. Like I mentioned earlier both exhaust buckets are tight in this way. For your info, I have garage space for the next month so I don't mind tinkering with the top end myself.
Mentioned above somewhere that I picked shims out with a tweezers at the notch but others just lift them out with a magnet in which case it wouldn't be necessary to turn the bucket to get at the notch. Need to compress the bucket enough to get the shim out with the valve tool or with a couple of screwdrivers.
I'd snug the cam caps back down and put in the smaller test shim and then if you have clearance recheck the compression before deciding whether or not to pull head. Make sure you stuff a rag in the cam chain slot in the center of the head so the shim doesn't end up in the sump when you pop it out. :icon_lol: