Tight cam chain

[Biker bob 16h]

Hi new to the forum I have a 1979 jota
I had a oil leak from rocker cover so decided to change the gasket cover off I thought I’d check the valve settings but noticed the cam chain was very tight so backed off the chain tensioner still very tight no up or down movement the chain is a regina with no link just peaned over so bought a new chain ewis
Fitted the new one and found it to be to tight same as the old one checked it was fitted correctly over the crank sprocket ok
It has c4 cams are there different lengths of chains I have ridden over 400 miles like this and feel lucky the chain didn’t let go
Anybody else had this problem any help much appreciated
Bob

 

[motoddrob]

Strange.
First thing I'd do is remove the tensioner blade then the tensioner mechanism itself. Then see what the chain does.

 

[Biker bob 16h]

Hi have taken the tension blade right out been told could be over sized base and head gasket but both look ok to me

 

[The Sock]

This may help.


Apologies for the orientation, for some weird reason it'll only put them in this way.

 

[Biker bob 16h]

Hi thanks for that when I fitted the new chain I had the complete adjustment assembly out and the blade
Someone had fitted a new blade and when I removed it not a mark on so it was that tight the blade was no where near it and adjuster wound fully out

 

[Biker bob 16h]

Just checked laverda paradise book says c4 cams have a different chain

 

[Biker bob 16h]

O

 

[The Sock]

Just checked laverda paradise book says c4 cams have a different chain

If it does, then it's wrong.

 

[Biker bob 16h]

Sorry it’s upside down

 

[andre g]

​

It is written you need different gears, te gears are generally the same but the orientation regarding the timing is different. The translation in English is wrong.

 

[Biker bob 16h]

Thanks for clearing that up

 

[Paul Marx]

Sorry it’s upside down

Badly translated into English, French is okay.
Different cam gears.
Paul

 

[Laverdian]

Not too many possibilities but if the head and base gaskets are correct then I suspect that someone may have fitted the front cam chain slipper upside down.

 

[Biker bob 16h]

Thanks how can I check if it’s fitted wrong cheers could well be the problem

 

[rocketonarail]

Whenever I fitted a new cam chain ..... the Mirage got through fourteen during the time I had it , replaced each time with Regina with a split connecting link ....... I always found the tension on the tight side of correct without even having to bring the tensioner into play .......

I would wind in the tensioner so that it just came into contact with the blade , but no more ....... in effect there was no need for the chain to be tensioned with the adjuster at all .

Bear in mind the chain tension between the sprockets should be just 5mm up , and 5mm down ......... which could be interpreted as bugger all really , and may give the impression of being overtight , when in fact it is actually ok .

After a few hundred miles , the new chain will " run in" anyway , and whilst maintaining the five up and five down tension when being measured at the correct position , will eventually develop fairly substantial slack at one or two other points further down the line ...... ( that`s what I found , anyway ... ) ...........

Replace every 12,000 miles ...........

 

[Biker bob 16h]

Thanks the old was so tight I couldn’t even move up or down and try to fit the new one really was hard about one link to short was going to buy another chain and split and add another link but don’t fancy two links in the chain will check front chain slipper

 

[Laverdian]

Thanks how can I check if it’s fitted wrong cheers could well be the problem

Bob, this is the last option as you’d need to lift the head.
One thing to add, when you check and adjust the tension in the chain, you must rotate the crank to the point that there is minimal action of the cam followers/springs on the cam lobes. With the tensioner removed it will be obvious when this position is reached as there will be noticeable slack in the chain.

 

[The Sock]

One thing to add, when you check and adjust the tension in the chain, you must rotate the crank to the point that there is minimal action of the cam followers/springs on the cam lobes.

Fig. 14 in the Handbook pages above.

 

[rocketonarail]

Dunno if this helps ....... it really helps to have been born with three hands ............

As it says in the notes , I would make sure the pistons were in the mid position whilst initially rotating the cams so the valves wouldn`t suddenly be brought into contact with the pistons by cam movement ...... once the cams were in their positions where the markings were closest to their twelve o`clock position , I would then move the outer pistons to TDC .... and then the fun could begin .........

I always held the exhaust cam in the correct position with a ring spanner on one of the cam chainwheel bolts with my left hand , having previously positioned the inlet cam correctly ... ( it would just about stay in place on it`s own ) ........ the cam chain would be draped over the inlet cam with it`s cam wheel marking at twelve o`clock ........ the exhaust cam would then be brought into it`s correct twelve o`clock position using the ring spanner with my left hand ....... the other end of the cam chain would then be draped over the exhaust cam with my right hand , each tweak of the ring spanner bringing it closer and closer to the end of the chain positioned on the inlet cam wheel , praying that would stay in place ..........
.......... the connecting link would then be placed into the inlet end of the chain with my right hand , whilst maintaining the death grip on the spanner in my left hand ......... then with my right hand pull the connecting link into place and slotting it into the exhaust end of the chain ...... ( that`s where the other hand would have come in handy ) ........


Eventually ....... chainwheel marks at twelve o`clock , link in place , rags stuffed everywhere to prevent anything falling into the crankcase , outer pistons still at TDC , and massive sighs of relief all round ........

This is when you now check the tension .

As mentioned earlier , I went through this routine fourteen bloody times ......

Happy days .............

 

[Biker bob 16h]

Made sure both cams were resting ie not on lobes have lifted the head front slipper looks in the right place can’t remove head till I can get the engine out trying to get a couple of friends to help trouble is my friends are old like me bad backs weak arms dodgy knees weak hearts no fun getting old this problem is doing my head in