How likely is it that my timing chain jumped? 1982 Gs550

[Guest]

My bike ran fine up till a week ago, then just had all these weird things happen all of a sudden. I found a few bad electrical connections and decided it was time for new spark plugs as well

Well the bike starts up and idled really rough and kept sputtering out. My friend told me to pull the valve cover and make sure all the cam lobes were within spec. So get the valce cover off, and i just happened to have the pickup coil cover with the timing mark off the bike. So i was curious and checked the timing, and sure enough when the timing mark was at tdc, numbers 1 2 and 3 werent where they were supposed to be.

It wpuld elxplain alot od the weird problems that happened all of a sudden, plus with my new plugs in there, plugs on cyl 1 and 4 fouled right away, and plugs on 2 and 3 still look brand new.

But how likey is it that the chain jist jumped? And is there anything special i can do to nake sure it doesnt happen again

[Steve]

Rotate the crank one full turn, see if the marks magically appear.

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[fieldmatt2]

I rotated it and lined up the tdc marks next to the 1 and 4 on the advancer, and on the exhuat cam sprocket 1 and 2 seemed to be 1 or 2 links off of where they should be

[Steve]

There are several marks near the 1-4 on the crank, make sure you are at the "T" mark.

If the #1 on the cam is not pointing toward the edge of the head, it needs to be adjusted. If it needs to be adjusted, you are probably in for a "fun" time.

You <might> try locking the tensioner in place (loosen the locknut, turn the setscrew in) before removing the cams, but I prefer removing the tensioner to verify its proper operation. The problem with that is that on your bike, you also need to remove the carbs to get access to the tensioner. Possible, but not fun or easy.

Once you have the tensioner either removed or locked in place, remove the intake cam. Then, remove the holders on the exhaust cam and rotate it as necessary to get the #1 to line up to the edge of the head. Put the holders back on the exhaust cam. Count pins carefully. Can't tell you how many times I did it wrong, so I emphasize this. The pin that is directly over the #2 arrow is PIN 1, not PIN 0. In other words, do not use that pin as a starting point and count the one next to it as PIN 1. Count out 20 pins, put the #3 mark on the intake cam under that pin. Put the holders on that cam. Here is the picture from the Suzuki manual that shows this process:



Install the tensioner if you removed it or release the setscrew if that's all you did, but make sure THAT part is done correctly, too. To be done correctly, the plunger needs to be fully retracted into the housing and locked in place. This can only be done with the tensioner off the bike. With the setscrew snugged down to prevent the plunger coming out, install the tensioner. When it is in place, loosen the setscrew to allow the plunger to extend. Turn the setscrew IN until it touches the plunger, then back it out 1/4 to 1/2 turn and use the locknut to secure it in that position. Now you can put your carbs back in (fun time) and finish the job.

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[hikermikem]

...plus with my new plugs in there, plugs on cyl 1 and 4 fouled right away, and plugs on 2 and 3 still look brand new.

This may be a coil issue, recheck your connections to the coils & your plug wires & caps too... Good time to replace your plug caps with some aftermarket NGK ones.

[fieldmatt2]

Followed the instructuons to reset the timing exactly, but the problem im having is that when i line up the TDC marks, i cant get #1 on the exhuast cam to sit flush with the edge of the head. Its either 1 link below or 1 link above being flush with the edge. Am i looking at a stretched timing chain?

[Steve]

If you are SURE that your crank mark is exactly right, and you are EXACTLY one link off on the exhaust cam, you will have to remove everything to get to the exhaust cam, move it ONE LINK and put it all back together.

Unless you have over 200,000 miles on the chain, you probably would not be able to mesure the "stretch" on the chain. Chains do not stretch. The pivot holes wear, making it look like the chain stretched.

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[fieldmatt2]

Well thats the thing, its not like its exactly 1 link off where i could just move it one link and have it right. Its more like its half of a link off. At TDC no matter what link im on, #1 is never flush with the block. #1 is either pointing slightly above the block, or slightly below the block. What should i do, go slightly above or below?

As for miles, it has 29k on it, but idk what the normal life expectancy of the timing chain is

[cowboyup3371]

How about a picture of what you are seeing so we can see it too? It might be just fine.

[JJ]

As for miles, it has 29k on it, but idk what the normal life expectancy of the timing chain is

I'm sorry, I can't help with the timing chain mechanicals. I have never done it; only read about it in the FSM.

I can, however, advise you on the normal life expectancy of the timing chain. Under normal operating conditions, the chain and gears should easily make it well over 100K miles.

[gwyon]

From what I've read here, a worn timing chain is rare, but it happens. I've got a '78 750, and I had to replace my timing chain. I bought the bike in 2015 with 19k miles on it. Lots of swapped parts on the bike, so I don't place much confidence in the odometer. Trying to set the cam shafts and do the valve timing, it was always a half tooth too far forward or a half tooth back. Turned out to be a worn timing chain. I used a Dremel tool to grind off a link and remove the old chain, and I bought a riveting tool to rivet the new chain in place. She lined up perfectly after that.
Your FSM should give you a measurement for allowable wear of the timing chain. Usually, you measure the distance between a certain number of links. With the camshafts removed, maybe you can straighten a portion of the chain and put a metric ruler on it. Then you'll know for sure.
Good luck.

[fieldmatt2]

From what I've read here, a worn timing chain is rare, but it happens. I've got a '78 750, and I had to replace my timing chain. I bought the bike in 2015 with 19k miles on it. Lots of swapped parts on the bike, so I don't place much confidence in the odometer. Trying to set the cam shafts and do the valve timing, it was always a half tooth too far forward or a half tooth back. Turned out to be a worn timing chain. I used a Dremel tool to grind off a link and remove the old chain, and I bought a riveting tool to rivet the new chain in place. She lined up perfectly after that.
Your FSM should give you a measurement for allowable wear of the timing chain. Usually, you measure the distance between a certain number of links. With the camshafts removed, maybe you can straighten a portion of the chain and put a metric ruler on it. Then you'll know for sure.
Good luck.

My problem sounds alot like yours.... but from what ive read id i were to replace the timing chain, id have to disassemble the lower end of the motor andtake the crankshaft out. What tool did you use and how did you do it exactly?

[cowboyup3371]

Matt, before going to that extreme please post a picture of what you are seeing so we can see it too.

[gwyon]

First, I'm nowhere near as knowledgeable as some of the guys here. Just want to be honest about that.
Second, I'm not saying my problem was the same as yours. Measuring your timing chain is the best idea.
With the old chain in place on the camshaft sprockets, I used a Dremel tool to grind off the ends of two posts on one link of the chain, and then removed the link. I took GREAT PAINS to make sure no metal filings or link parts fell into the open engine. I attached the new chain to the old chain (I think I used safety wire) and rotated the engine so the old chain was removed and the new chain was drawn down, around the crankshaft, and back up to the camshaft. Then I used a chain riveting tool to rivet the new master link in place. I used a D.I.D timing chain, and I followed their instructions to a tee. You don't want that rivet to fail.

[Cipher]

pics please...............My cams are a bit iffy in alignment but certainly not a tooth off.