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Cam chain tension

BSA

BSA

Joined Feb 2006
4 Posts | 0+
Unknown
How tight should the cam chain be? I am reassembling a'98 501 with a new chain (78 link Regina) and the chain is as tight as a bowstring; the old chain I removed was also super tight. The motor was disassebled due to a whining noise and in an attempt to cure that I have replaced the main and transmission bearings. The new 78 link Regina cam chain fits with so much tension that even with the 'post' of the chain tensioner fully retracted the tensioner body stands off from the cylinder about .100 and tightening its screws results in additional tension being applied to the cam chain. Any ideas?
 
Hi BSA,
The cam chain is of the correct length so your whine noise is more than likely the result of some incorrect parts or the mismatching of parts.First, did you purchase this bike with the noise present or did it appear while in your use? ....nsman
 
i would give dale lineaweaver a call or pm him , i would also recommend using one of his h/ duty cam chains .
 
OK, I'll be the one to ask the first stupid question here; BSA, did you actually count the links on your new chain? If not, you should do so. If that is correct, you've got a parts mismatch or defective tensioner. Good luck anyway, and I'm sure you'll get someone on UHE who's seen this particular problelm before. :) Corey C.
 
BSA said:
How tight should the cam chain be? I am reassembling a'98 501 with a new chain (78 link Regina) and the chain is as tight as a bowstring; the old chain I removed was also super tight. The motor was disassebled due to a whining noise and in an attempt to cure that I have replaced the main and transmission bearings. The new 78 link Regina cam chain fits with so much tension that even with the 'post' of the chain tensioner fully retracted the tensioner body stands off from the cylinder about .100 and tightening its screws results in additional tension being applied to the cam chain. Any ideas?
Click to expand...

Does your 501 have a cylinder base gasket installed?
 
Dale,

I don't see where you are going with this?

If he did have the gasket on, as he is supposed to, then the distance between the cam gear and the crank gear would be (X) distance.

If he did not have the gasket on, would that not make the distance between the cam gear and the crank gear (X) minus the thickness of the gasket making the cam chain have to much slack in it?

BSA says his chain is to taunt. In my mind I am thinking too thick of a gasket or two gaskets, no?

Please explain.

Regards,
 
sandskipper said:
Dale,

I don't see where you are going with this?

If he did have the gasket on, as he is supposed to, then the distance between the cam gear and the crank gear would be (X) distance.

If he did not have the gasket on, would that not make the distance between the cam gear and the crank gear (X) minus the thickness of the gasket making the cam chain have to much slack in it?

BSA says his chain is to taunt. In my mind I am thinking too thick of a gasket or two gaskets, no?

Please explain.

Regards,
Click to expand...

Hi Keith,

Husaberg increased the main case deck height and consequently eliminated the base gasket somewhere around 1998. No one knows for certain where the definitive line was drawn regarding production.

It is entirely possible that a base gasket was placed on a set of cases that were of the later tooling. You can get the chain on, however, it is very tight.

See why they keep me around? :D LOL

Best Regards,
Dale
 
LINEAWEAVER said:
sandskipper said:
Dale,

I don't see where you are going with this?

If he did have the gasket on, as he is supposed to, then the distance between the cam gear and the crank gear would be (X) distance.

If he did not have the gasket on, would that not make the distance between the cam gear and the crank gear (X) minus the thickness of the gasket making the cam chain have to much slack in it?

BSA says his chain is to taunt. In my mind I am thinking too thick of a gasket or two gaskets, no?

Please explain.

Regards,
Click to expand...

Hi Keith,

Husaberg increased the main case deck height and consequently eliminated the base gasket somewhere around 1998. No one knows for certain where the definitive line was drawn regarding production.

It is entirely possible that a base gasket was placed on a set of cases that were of the later tooling. You can get the chain on, however, it is very tight.

See why they keep me around? :D LOL

Best Regards,
Dale
Click to expand...

You sir are indeed a vast pool of knowledge :idea: . I remember reading the post husabutt included and everything started coming back to me :lol: , now it all makes sense to me :oops: .
Thanks for the clarification Dale, Im sure I will not forget this time :thumbup: .

Regards,
 
LINEAWEAVER said:
sandskipper said:
Dale,

I don't see where you are going with this?

If he did have the gasket on, as he is supposed to, then the distance between the cam gear and the crank gear would be (X) distance.

If he did not have the gasket on, would that not make the distance between the cam gear and the crank gear (X) minus the thickness of the gasket making the cam chain have to much slack in it?

BSA says his chain is to taunt. In my mind I am thinking too thick of a gasket or two gaskets, no?

Please explain.

Regards,
Click to expand...

Hi Keith,

Husaberg increased the main case deck height and consequently eliminated the base gasket somewhere around 1998. No one knows for certain where the definitive line was drawn regarding production.

It is entirely possible that a base gasket was placed on a set of cases that were of the later tooling. You can get the chain on, however, it is very tight.

See why they keep me around? :D LOL

Best Regards,
Dale
Click to expand...
As the guru said to the young pupil as they sat upon the mountain," How can I teach you the meaning of life if you continue to cry "********" after every word I say?" :roll:
 
Purchased this bike about 4 years ago and it has been fine, no noise, until the last ride when I first noticed the whine which got progressively louder thru the day. The bike has never had a cylinder base gasket. The new (and old) cam chain both have 78 pitches. The piston at tdc is about .015 short of being even with the top of the barrel. The head gasket is .055 thick. Do I need to shorten the barrel? Could wear on the aluminum cam sprocket be a problem? There is a slight variation in cam chain tension as the engine is rotated. Note: I also run a '02 501 which has been trouble free except for the cam followers and a electric starter which usually doesn't.
 
Compressed head gasket thickness is most often .045" - .050".
Optimal safe deck clearance being roughly .040".

Given your gasket thickness and piston recession you may indeed remove .020" or so from the cylinder base. Such should provide for improved performance in addition to acceptable cam chain slack.

Squish clearance reduction and a slight retarding of the camshaft shall provide the boost.

If one should choose to be particular the cam sprocket may be slotted and the camshaft timing altered to tailor said engines power characteristics.

Note:
Do not remove material from the cylinder top as the plated bore will be inclined to chip.

Best Regards,
Dale
 
One thing is for sure....you need to upgrade to the steel camshaft sprocket ASAP.
 
Hi BSA,
It is unlikely that your old cam chain tightened up in use,it may be that shorting the barrel will alleviate this problem but I do not expect that the tight chain is the cause of your whine problem.I would be looking for a case where the gear mesh has changed suddenly.My best quess would be that the bush in and/or the drive gear behind your clutch basket has worn causing a gear mesh change and resultant gear whine.
 
nsman said:
Hi BSA,
It is unlikely that your old cam chain tightened up in use,it may be that shorting the barrel will alleviate this problem but I do not expect that the tight chain is the cause of your whine problem.I would be looking for a case where the gear mesh has changed suddenly.My best quess would be that the bush in and/or the drive gear behind your clutch basket has worn causing a gear mesh change and resultant gear whine.
Click to expand...

Hi Nsman,
From the initial post I am under the impression said engine has whined since BSA has had it. If both old and new chains are tight said engine will indeed "whine".

I have had to shave a few Husaberg cylinders in my day. :lol:

Hope you are doing well.

Sincerely,
Dale
 
BSA said:
Purchased this bike about 4 years ago and it has been fine, no noise, until the last ride when I first noticed the whine which got progressively louder thru the day. The bike has never had a cylinder base gasket. The new (and old) cam chain both have 78 pitches.
Click to expand...
 
nsman said:
BSA said:
Purchased this bike about 4 years ago and it has been fine, "no noise, until the last ride" when I first noticed the whine which got progressively louder thru the day. The bike has never had a cylinder base gasket. The new (and old) cam chain both have 78 pitches.
Click to expand...
Click to expand...

Guess I should have put my glasses on. :lol: LOL
 
Thanks to everyone for their input. I took .015 off the bottom of the barrel so that the piston is now flush with the top of the cylinder. That solved the tension problem. As I said I replaced trans. and main bearings which were a little rough. The engine started first kick and now runs quitely and more smoothly than before; at least while idling in the garage. Hopefully I'll find out more this weekend. Thanks again.
 
Did you inspect the rocker arm cam follower bearings? We don't need a repeat of Nevada Dirtbikers adventure so soon :)
 
Yes, inspected every bearing in the engine. Replaced the cam follower bearings.
 

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