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Replacing the Cam Chain

  • Thread starter Thread starter WifeofDink
  • Start date Start date
W

WifeofDink

Guest
Okay guys I really need your help

I have to replace the cam chain on my 1980 GSX 250X. Yes I do know what and where the Cam chain is and what it does but this is a first time job for me I have some idea of what I need to do but I am hoping that some kind soul will give me details instructions

It also appears that the chain has jumped a tooth so I know I have to line all the timing marks up etc. is there anything else that I need to check while I am at it.
 
If it jumped a tooth while running there is a chance of bent valves.......... my timing chain recently snapped and I am putting it back together now, but i cheated> i Pushed the pin out of the new chain and attached it to old chain and ran it through. NOt sure if everyone woudl recommend this. But to do it the normal way, you have to take engine out and split case. Id recommend getting service manual and looking at what it fully takes to do it on your bike, then maybe ask waht you need to know or want more explanation on ........... just my thoughts, but i have been up 24 hours at this point and not sure on how complete i am in though.

later
ben
 
mine jumped twice over the years both time i ended up with bent valves but i believe it jumped more than one tooth.
 
What makes you think that the chain is bad? Can you see visible damage to the chain? It is the tensioner that keeps the chain in place and it has to malfunction in order for the chain to skip. Cam chains do not have a hard life (they are bathed in oil): my GS1000 cam chain went 80,000 miles before getting a little loose sounding, so I replaced it, just in case. What does Dink think?
 
Dink thinks the cam chain needs replacing, you can hear the chain when the motor is running and the tensioner is at full tension, Dink believes the chain is either stretched or worn from what he has said to me
 
It's still running thats good. Definately need to investage before any damage is done. I would check the tensioner first. Changing the chain can be done by removing a link pin. It is a common way used to replace the chain, Hook the new chain to the old one and pull the new chain thru the engine then reconnect with a chain press or a master link
 
Don Dink think the camchain DEFINITELY NEEDS replacement as the tensioner is at full travel the timing marks are not aligning as they should and the top end is noisy, all this I told Jean at the time and I believe she wishes to attempt to do it herself and therefore is after advice about how to do it . As both her and I know that if I try and help her I will "take over" and do it myself, obviously this is not what she wishes to happen with her bike. BTW no valves are bent as it appears thhat either the timing was incorrect when the previous owner assembled the motor or it has only jumped one tooth as instead of aligning to the "T" mark at TDC it is aligning to the "F" mark.
Dink
 
All that info sounds like a stretched can chain I think! Unfortunately I have packed all my manuals during the house move, but you can measure the distance between 20 links to see whether it is within limits.

The best advice I can give with cam chains is get the manual to be able to set the timing properly. To replace the chain get one with a master link, break the old one and feed it through using the old cam chain. Rivet the new chain properly otherwise you risk it breaking,,this is crucial!!!

The cam timing then has to be set properly..this is also crucial!!

If you get it wrong the engine has to be removed and split, gaskets etc. If the chain timing is wrong..well it is not a nice feeling as the rebuild is expensive...

If you don't know what breaking the chain and rivetting is..time to get someone to show you so YOU can do it next time!!! Like many things once you see it done it does not seem tooo bad.....
 
The Bathurst method of changing a chain. :-)

Order the new chain and ask the store to break the chain with their chain breaking tool. They will remove the pin from one side plate only.

Remove anything in the way, such as fuel tank etc.
Remove the tensioner.
Remove the timing cover, probably bottom right of motor.
Remove cam cover.
Remove cam shells. They should be marked A/B/C/D so you can fit them back in the right places.
Remove cams. Take note of how they sit in the head so you can put them back correctly. Note that the cams have arrows on the right side of the sprockets, two arrows for the exhaust and one for the inlet.

Support the cam chain with some wire so it doesn't fall into the case.
Pull the chain towards the front so you can work on it.
Cover the motor with a cloth.
Get a dremel style tool and grind off one of the link pins. Do not get stuff in the motor. Pull the pin enough the break the chain.

Link the new chain into the old one.
Pull the new chain through carefully. You need to turn the large nut in under timing cover to assist. The bike is in neutral, isn't it?

When you have the new chain fully through, rejoin the link. You do this by getting some multigrips, setting up the side plates in line with the pin, closing the multigrips over the pin, and squeezing it into place. It takes some effort.
When the pin is in place it will be flush with the side plate. You need to push it a little further to match the others. Do this by putting a small nut or a thick washer over the pin and squeezing the grips on it, pushing the pin into the nut or washer.

The link is now very tight. Loosen it by gripping the link and the adjoining link with two pairs of pliers, and working the joint until it loosens. When using a chain breaker to do this it is normal to push the pin slightly too far, then to bring it back to normal, and the pin is magically loose like new.

You now have the chain done.

Put the motor, cylinder 1, on TDC. There is mark on the timing plate, but you can also check it by removing the plugs and sitting a screwdriver carefully on the piston and seeing when it is fully at the top.

Replace the exhaust cam under the chain with one arrow pointing to the gasket surface of the head and the other arrow pointing upwards.
As you do this, pull the chain tight on the exhaust side of the motor.
You need to check how many link pins between the top exhaust arrow and the inlet arrow. Count out the links and put the inlet cam correctly into place.
Replace the cam shells. Tighten the bolts only to the set amount, they are easy to strip.

Now check that you have the motor still on TDC, and that the exhaust arrow is pointing to the gasket surface properly, and that you have the right number of pins to the inlet sprocket.

Fit the tensioner. Don't rotate the motor without the tensioner.

Rotate the motor with a spanner a few times and check the arrows again.
Now do it again.
Especially check the gasket surface arrow against TDC. It is easy for the chain to be one link out. Sometimes it looks OK when you assemble it, but as the cam shells are bolted down the cam sits lower and the arrow no longer lines up.

If you need to adjust it, remove the cam shells and tensioner so you can move the chain over the sprockets.

Check the shims while you have the top off.
Assemble the cam cover, fuel tank, timing cover etc.
Ride away.

Have fun,
Kim
 
Thanks Don Dink :roll: for explaining fully explaining what is happening I really must learn the right names for the thingys and doovas :D

Thanks everyone for your advice :D

Dink has a chain breaker and all the tools I will need to do this job as I have worked on bike motors before this shouldn't be too hard, I am determined that the bike will be running again very soon
 
make sure you follow kims advise about how not to drop the cam chain into the tunnel................I did that and I wasted four hours trying to get it out :cry: :cry: :cry:
 
Its not as hard as it might seem, just take time and be methodical. Is the tensioner the same as Dink's bikes? I cannot remember what the GSX250 looks like. If the bike has not gone that far the tensioner will need a good clean and grease, otherwise the new chain will wear more quickly than it should.

Good luck!
 
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