CX500 GL500 650 Global

somebody please help as this issue is aggrivating me. I have a 1980 cx500c. at higher rpms (above 4,000rpm) there is a rattle/knocking sound. but it only happens when i put stress on the motor i.e. accelerating or climbing hills. when decelerating or on perfectly flat surfaces the noise subsides and goes away. The sound gets louder and worse the hotter the bike gets (the longer i ride it). ive adjusted the valves and cam chain and changed the oil to the proper weight of 10-40 as listed on the frame plate. It was very quiet for about a year and i didn't worry about it. but lately it just seems to be getting worse very quickly and i do not want to seize up the motor if it is a bearing. the bike has 39,000 miles on it and when i adjusted the valves, it was so clean in there, it looked like a brand new motor. so its hard for me to believe that there could be a problem with it. Any advice/help would be much appreciated.

It does not sound good.Drain oil and check for copper flecks.Copper in the oil is a sign of big-end bearing failure(Any metal in the oil is a bad sign

There wasn't any metal flakes at all when i just changed the oil. the oil filter didn't have any in it either when i replaced it. So maybe it's a bad cam chain tensioner?

Please put your year and model either in your signature or under you Avatar on the left hand side.Then I can direct you to parts better


It's a good sign that there's no metal in the oil.You may caught it in time.This is the single most common service point on these bikes when they have been run and then left/neglected and cause of ruined engines.It's time to get the engine out and change the Cam-chain and check the Cam chain tensioner and Guide.They are getting hard to get new so hopefully your old ones will be OK.
Once done the engines are usually good until the cam-chain needs replacing again after around 50,000 miles depending on how well the bike is looked after.
If you read this thread you will see what a well looked after CX/GL500 normally does/uses,
viewtopic.php?f=20&t=289

If when you do this job you can post some pictures of the tensioner and guide I can advise better at that point.

You will need at least,

New Cam-chain.
New Water Pump Oil seal,
Number 11 on here,
http://www.cmsnl.com/honda-cx500a-1980e ... t/E12.html
They get brittle with neglect and then fail when you re-fit the rear engine cover/case.They are cheap enough.

New rear engine cover gasket or make your own,
viewtopic.php?f=10&t=256
You CANNOT fit the rear engine cover without one as it will cause the engine to bind and can ruin the Stator.

You should also test the stator just to be safe,
viewtopic.php?f=8&t=30
If you had no charging problems you may be OK with the present one.Some -people change the stator having taken the engine out as a matter of course but that's your decision and depends on funds available.

Read this thread as well,

http://choppercharles.com/cs/forums/126 ... wPost.aspx

This is an old forum post so you cannot use that forum as there is now a new one,
http://cx500forum.com/

thank you so much. i'm probably going to park it until i get the money to fix it because i don't want any damage caused. and thanks for the tips as i'm new to this forum. so, I guess it's typical for the cam chain to need replacing around this amount of miles then?

Yes.They can last around 50k miles well looked after but then must be changed.Much the same as cam-belts in cars

thank you for all of your help. I love this bike and want to keep it for a very long time.

what about the oil pump chain? how long do those typically last?

They usually last a long long time.Even brand new they aren't much tighter than when you get the front cover off and see the one on the bike.They are getting harder to find new but David Silvers has them,

http://www.davidsilverspares.co.uk/CX50 ... rt_112652/

Superb International Supplier of parts.I've used them and Wemoto
http://www.wemoto.com/bikes/Honda/CX_500_A/79-80/

A lot.Even this week I bought some new Fork seals from Wemoto.Ordered them Tuesday night they were here the est afternoon.That's very fast for the UK postal service.

There should be some play in them.Download a manual from here,

http://coodie.com/cx/

So long as the links look OK and it's not close enough to slap the clutch basket they can usually be re-used.

You should really put your location in your signature as there are other suppliers around the world.

thank you so much for all of your advice. I will get working on this very soon.