Cam Chain -125cc, single cylinder, 4-stroke...

[Ted]

Hi, The cam chain on my Gilera Coguar 125cc (a cruiser made by a moped company!!!) is a tad slack, and the auto-tensioner if adjusted as far as it can go, so I guess its time for a new chain.

The main problem is that I cannot get a decent manual for it, Haynes never produced one, and I can only find service manuals for it.

How difficult is it going to be to do? I'm working on the assumption that it is an 'engine out' senario, which I have no problem with, but I don't know much about changing cam chains!

I was going to take it to my local bike garage, but he is fully booked with repairs at the moment, and won't 'delete' any of his MoT slots! (I guess people want the work done in the shite weather when they're using the car!) And the other local guy dosen't like touching Gileras (don't blame him...).

To take it to a Gilera Authorised Repairer would probably involve a 100 mile ride, a couple of days off work, and alot more money than I can afford!

So basically; How difficult would this be for someone with a general idea of engines, but with lack of practical experience?

Cheers in advance, Ed.M

[finpos]

It's not the kind of thing I'd try without a manual, but here are some thoughts:

Firstly, I don't know that engine, but the thought of the tensioner running out of adjustment any time before the whole engine is about to self destruct through wear seems unlikely. How exactly have you been adjusting it? Some engines have notoriously weak tensioners and it's actually that part that needs replacing.

Secondly, you'll often find that cam chains have a slack bit and a tight bit depending on the position of the cams. You need to be sure you've adjusted it in the right place.

Finally, if you do want to put a new chain in it, you can usually do it from the top by carefully breaking the old chain, linking the new one to it and using it to feed the new one under the crank. But you better be sure you know where all your timing marks are.

f.

[Ted]

I've not been adjusting it manually... its one of those spring tensioners... the automatic ones. From what I understand by other engines, there is some form of 'shoe' that gets pressed against the chain? Not sure if it is just this that needs replacing.

The whole engine could be knackered; after all it is a 125, and has been thrashed not only by me but also by the previous owner. I think it has had 5 previous owners... not sure without looking at the logbook...

If the previous owner was truthful its probably done about 15k? Not sure as odometer packed up!

And I was REALLY hoping that no-one would mention timing marks....

[TheShaggyDA]

A number of pages are showing it as having a Honda engine, so with a bit of luck we might be able to identify it and start from there.
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[Ted]

I know there is a lot of rumours about it being identical to the Honda CX125 engine, but I have my doubts. I agree they are VERY similar looking at them from the ouside...

[Ted]

This is the engine:
https://img.photobucket.com/albums/v474/EAM-Enterprises/other/left.jpg https://img.photobucket.com/albums/v474/EAM-Enterprises/other/right.jpg

And this is what gave me the doubt about the engine being the same as the Honda:

[finpos]

Looks like a cg125 engine in which case....

It's a push rod engine and so doesn't have a cam chain

f.

[Kickstart]

Hi

Speak to Bob Wright (Weston Super Mare) and see if he can supply you with a manual.

It has the same bore and stroke (I think) as various 125 4 stroke Hondas, but being an OHC engine it isn't going to be the same as a CG125.

Being a single the cam chain should be pretty easy to change.

All the best

Keith
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[Ted]

Hmmm... cheers finpos, but it MUST have a cam chain... as it has a cam chain tensioner... at least I'm sure its a cam chain tensioner...

Aha... The Oracle has appeared, cheers dude!

I emailed Bob Wright a while ago, asking if he can get hold of a workshop manual, but I never got a reply, which is a bit unusual for him! On the site he has a service manual listed for sale, but I already have one on CD... and being a service manual it dosen't cover anything as involved as this...

How hard is the whole timing thing? What tools am I likely to need?

[Kickstart]

Hi

Likely to be a case of setting the engine to TDC on a particular stroke, take off ignition system, remove cam chain tensioner, possibly remove sprocket on cam, with now enough slack take off the chain, put on new chain, check cam hasn't moved, put tensioner back in (having reset it), check timing is still right, turn engine over by hand, check timing is still right and then put the ignition back on.

This assumes the ignition lives in the engine oil and has the cam chain hiding underneath it.

All the best

Keith
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[Ted]

TDC? ...I'm sure I should know that one, but its escaped me right now!

What do I have to take off of the engine?

Assuming I have to take the engine out of the bike...

Do I just start striping down from the top, or can I access the chain from the side?

[TUG]

[Ted]

[Kickstart]

Hi

As mentioned TDC = top dead centre.

I would hope that you can change the cam chain in a single like that without dropping the engine out or taking the top end off. Would hope that you just do it from the side.

However without looking at the engine I cannot really say.

All the best

Keith
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[finpos]

Ok, given that it's got a cam chain tensioner (why do you think it has? I'm 95% sure that's a cg engine clone), I'm still uncertain about it running out of travel if it's fully automatic...

So, there's automatic and there's automatic. On some types, at a certain service interval, you need to rotate the engine to a given point and release the bolt on the tensioner. That'll allow a spring to push the slipper into the chain and take up the slack. Then you do the bolt back up to lock it there.


f.

[lukamon]

count yourself lucky. my dna 125 cam hain SNAPPED while going along ive replaced the chain, put the engine near as i can get it at TDC and lined the marks up on the camshaft sprocket, but what i want to know is, does it have to be on one of the two turns for the engine to spark, or does it do it both turns? dont want to get it together and it doesnt start
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[cheekythomas]

Its a self adjusting tensioner on the Coguar 125.... so if its fully extended the chain needs replacing.

Theres 2 chain slippers fitted, both should be replaced as they will be worn as well.

If youve not done one before, triple check the timing marks before and after youve done it, and turn the engine over by hand first after youve fitted the new one to just make sure nothing hits.
Even if youve not done one before it will only take you just over an hour, its dead simple on them...

Engine doesnt need to be removed, all done in situ... once you can see the top and bottom sprocket (after cam inspection cover and side cover is off) make sure the timings marks are lined up, theres one on the cam sprocket and crank sprocket... remove the tensioner, undo the 2 bolts holding the cam sprocket on and drop the chain down and remove it from the bottom (a tip is to tie a bit of spring on to it first, that way you can use it to pull the new chain back up)

The front guide is simple push fit, so pull out and replace it. The rear guide that the tensioner pushes against has a bolt holding it in at the top... swap that one too.

Refit all removed bits, check the timing marks and refit the covers.

If you need the numbers to get the bits..

Tensioner gasket is 495452
Timing chain 495445
Front Guide 495454
Rear Guide 495449
Cam Inspection Cover O-ring 495644
Tappet Cover O-rings 495647 (Need 2)
Crankcase Gasket 495421
Crankcase Timing inspection O-Ring 495662

[Ted]

Cheers Tom! I'll order the bits when I get a chance!

Just checking here, and this is a noob question... ...but would it be the left side of the engine I get at it through? (the side in the left photo)

[Odie]

I have a manual for a coguar, genuine gilera one.

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[Ted]

If you mean the little red owners manual... then so do I... pretty much useless, I've got the service manual, a bit more rare, but dosen't help with this...

[Odie]

No.
I have the Gilera service staion manual.
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You are so ugly when you were born the doctor said "I?m gonna drop it, if it falls is a rat, if it flies is a bat."

[Ted]

yeah, got that on disk... I was hoping that it would give me more info than it does...

You've not got a Coguar tho have you?

[Odie]

My wife has one, beautifull little bike, i do all the servicing.
Never let her down in 4 years, used every day to travel to work, 9 miles each way + ride-outs most week-ends, rain or shine, sunny or snow.
Cannot fault the bike.
How many miles has yours done?
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You are so ugly when you were born the doctor said "I?m gonna drop it, if it falls is a rat, if it flies is a bat."

[Ted]

I'll agree that it never fails to start, and in all fairness it would be a good bike if it was treated right from new, and it is almost the best value for money vehicle I have ever bought!

But... when something does break, no mechanic wants to go near it, everything is made cheaply, but costs a fortune to buy replacement parts, the speedos tend to stop working, and they are well known for getting through fork seals...

Mine is a 2002, I'm guessing a minimum of 15k if the previous owner was telling the truth (the odometer and speedo broke before I bought it), but the previous guy knackered it... It was used in all weathers, it was stored outside, and he rounded off and over-tightened every nut and bolt on it!

[Ted]

Hold on... just read your sig... what CX bits you got for sale?

And what year/model are both the bikes?

I'm after a radiator (from a B, but I think an A would fit), rear foot pegs, and if you give me a while I can probably note down quite a list!