Cam chain question?

[luke4130]

Alright, I've got to change the cam chain on a 85' slabby750. Is it as simple a pulling the old chain out and replacing it with the new one or by that will i f%*k up the timing? Some help needed thanks! (I'll be putting a manual cam tensioner while i'm at it also)

Luke.

[luke4130]

I was told to change it cos a mechanic said the chain was making a ticking noise (it is but only slightly, i just don't want a busted engine). Other than that the motor is running fine. Would the manual tensioner on it's own solve the prob? Luke.

Remove tensioner, remove cams, break chain and link new one to it, thread through (remove plugs so engine turns over more easily), unlink old chain and join new chain, replace cams (making sure you align them according to manual), install tensioner. Done.

Get yourself a decent chain breaker if you can afford it, otherwise you can use a grinder, just make damned sure you cover the motor with rags THOROUGHLY, you don't wanted bits of metal falling into the motor or plug wells.

When joinng chain you'll have to peen over the end of the joining link rods, a panel beaters dolly is handy here.

quote:Originally posted by luke4130

I was told to change it cos a mechanic said the chain was making a ticking noise (it is but only slightly, i just don't want a busted engine). Other than that the motor is running fine. Would the manual tensioner on it's own solve the prob? Luke.


The manual should give yoou the specs for the cam chain wear limit, normally a case of measuring the distance between a certain number of links at a coupl of places around the chain.
You could just try installing the new tensioner, doing it up correctly and seeing if there is still any noise coming from it. Auto tensioners are notoriously unreliable so I would suggets you try this before purchasing a replacement chain. What's the motor/mods?

[Hillsy]

Well said Chalky. Also a good idea to familiarise yourself with top dead centre and the way the cams sit before you start. Take off the rocker cover and RHS crank cover. Spin the crank with a spanner until the TDC mark comes around and the lines on the cam sprockets are horizontal (might need a few turns). The lines on the cam sprockets should be on opposite sides of the sprockets, and in line with the surface of the head.

Thanks Hillsy

[Hillsy]

BTW - you will KNOW when it's time to replace the camchain. They will get unbearably noisy before they get anywhere near breaking point.

[Docktor]

And dont stress if ya fuck it up any way, drop ya side cover n sus ya crank timin marks and line em all up.Wack a clip or summin on where ya join the chains so the dont slip off mid sump. Coz that will suck.

Doc

[shift1313]

be very careful not to drop the end of your chain into your case, that will be a fun job fishing that out!!!.

And usually manual cam chain tensioners are louder then the auto ones but they dont slack off on hard decel which is where the auto ones blow up your motor. On interference motors if you get enough slack in your chain your cams will be out of sync and might push a valve into a piston, kaboom. I run mcct's on two of my bikes, one i made, one i purchased. It is very important that you dont over tighten them or try to get rid of the timing chain noise or you will prematurely wear internals.

quote:Originally posted by shift1313

be very careful not to drop the end of your chain into your case, that will be a fun job fishing that out!!!.

And usually manual cam chain tensioners are louder then the auto ones but they dont slack off on hard decel which is where the auto ones blow up your motor. On interference motors if you get enough slack in your chain your cams will be out of sync and might push a valve into a piston, kaboom. I run mcct's on two of my bikes, one i made, one i purchased. It is very important that you dont over tighten them or try to get rid of the timing chain noise or you will prematurely wear internals.


What's an 'interference motor' Shift?

[shift1313]

Interference is where your valves protrude into the space your piston occupies at top dead center. Since your valves arent open at this time its not a problem but if your cams were to get out of time it causes problems. For instance a friend had a turbo diesel jetta he was running on peanut oil, the oil clogged his belt driven fuel pump which locked it up, broke the belt(which was the timing belt as well) so it sent his piston and valves into a love hate relationship.

Most high compression motors are interference by nature. Also when you look at American V8's that have valve reliefs cut into the tops of the pistons this is because of clearance issues.

did that answer it?

[luke4130]

Great stuff! Thanks guys, This saves me a lot of headaches as this topic isn't covered in the Haynes GSXR "Bible". Hope this comes in handy for other members out there. Thanks again.

[devo]

Luke as Chalk says tensioners are pretty shit house an after market
manual tensioner is the go.
But we generally used to take off the pick-up cover, turn the crank forward to take up slack at the front of the chain.
From there undo the large bolt at the rear of the tensioner remove the spring and put a a t-piece inside the hole and push the rachet in
atleast two clicks(listen carfully)when done put the spring and bolt
back in the tensioner, put your pickup cover back on taking note that the allen bolt with the sealing washer goes back in the right hole. Top up your oil if nessesary and Bobs your Uncle.
Now thats the first thing I would do before replacing anything. Remember GSXR engines have always been a little noisy.
If the noise still persists buy a loud can and whack that on or a good stereo and just turn it wright up :D;)

[luke4130]

Ah but mate, she already gots a LOUD can! Its actually louder than the cut down yoshi i have on the other bike... I like that :D

[devo]

:D:D:D;)

quote:Originally posted by shift1313

Interference is where your valves protrude into the space your piston occupies at top dead center. Since your valves arent open at this time its not a problem but if your cams were to get out of time it causes problems. For instance a friend had a turbo diesel jetta he was running on peanut oil, the oil clogged his belt driven fuel pump which locked it up, broke the belt(which was the timing belt as well) so it sent his piston and valves into a love hate relationship.

Most high compression motors are interference by nature. Also when you look at American V8's that have valve reliefs cut into the tops of the pistons this is because of clearance issues.

did that answer it?


Got ya mate ;)

Knew about the valve/piston overlap, but hadn't heard the expression before (probably because I'm just another back yard mechanic)

[shift1313]

might just be what we call it in the states, never know.

[rockape76]

might be a good idea to have a digi camera handy take photos as you go ,its amazing how quickly you can forget how something goes together .....the photos make a great reference