Topic: Engine noise under load

[jilespalcock]

Hi all,

I did use the search engine (the Google one) to look for this first, so apologies if this is already covered, and please direct me to it.  However...

I have a CB500 4 K1 (1975 registered).  I have rebuilt it twice (second time was due to crud destroying the main bearings, but that's another story). 

I am getting a noise that sounds like chain noise coming from the engine under load (when I set off and slip the clutch in etc.).  There is NO chain noise at idle and under no load (i.e. revving it up or coasting along under steady throttle).  I have new plates in the clutch and convinced it is not that.  The primary and cam chains are both brand new.

Any thoughts or suggestions?

A confused amateur bike mechanic!

[strynboen]

have you the can thain tensioner korrekt in the groove..dovn in the bottom(the rear tensioner)...damed easy to put it vrong inn.(.Photo is a vrong mounted one)

[jilespalcock]

Many thanks for replying.  are you saying that the bottom of the cam chain tensioner could be in the wrong place?  I thought it just dropped into place and was bolted into location, but I am new to these engines.  I just want to be sure before I take the head off (again!!)

[robvangulik]

Did you put it on the main stand and listen if the secundary chain to the rear wheel makes the noise?

[jilespalcock]

I checked that one, and it doesn't seem to be the final drive chain.  The noise comes in when the engine is put under load.  I did this by applying the front brake and slipping the clutch in a little.  That makes the noise happen (as well as setting off up the road).  Listening carefully to the noise, it does seem to be coming from the front end of the engine. 

I think I will drop the sump off and have a poke up inside to see.  An endoscope will probably be a good idea!

[dave500]

heres a clearer picture of a tensioner mis-cued,this didn't make a sound.if your slipping the clutch to cause the noise is it not a clutch noise?

[jilespalcock]

Many thanks for the picture.  I will certainly look at the tensioner next.  I did take the clutch to pieces to check it out.  No signs of damage or wear.  It all seemed in order and was operating correctly.

[Deltarider]

coming from the engine under load (when I set off and slip the clutch in etc.).  There is NO chain noise at idle and under no load (i.e. revving it up or coasting along under steady throttle).

Hm. Are you sure it's not knocking/pinging?

[thep1pe]

Had a noise under load on my 550. Turned out to be exhaust header leak at flange gasket.

[strynboen]

Loose engine bolts..or thain rubbing metal//chain fender(..senter stand..as the chain get Loose at the bottom at acceleration(i think)

[jilespalcock]

coming from the engine under load (when I set off and slip the clutch in etc.).  There is NO chain noise at idle and under no load (i.e. revving it up or coasting along under steady throttle).

Hm. Are you sure it's not knocking/pinging?

Actually, I'm not.  Thanks, I'll look into that as well.

[uksparky]

If the noise is half engine speed its coming from top end..just guessing ..   i agree with Deltarider  timing too far advanced ping ping..........can you post video //

[jilespalcock]

well, I have removed the sump and looked.  The tensioner is indeed in the wrong place, so will fix that.  Worse though (and this is my fault entirely) there is lateral movement of the starter clutch and primary chain on the primary shaft.  I must have missed out a spacer when I rebuilt it.  Time to remove the shaft and check what is missing.  I think this may be the problem... hopefully.

Will report back when those things are done this weekend.

[dave500]

if that shaft can move sideways much the beefy square hyvo chain or the cam chain wont like it.

[strynboen]

you can remove the shaft vitin the engine(or is that the kickstarter)or both...

[Little_Phil]

I've removed the primary shaft without splitting the cases to renew the starter clutch. You could possibly do it with the engine in the frame, especially as you are only sliding it out, checking spacer/thrust washer and replacing. But I took the engine out as I was doing the starter clutch and that is really tricky. (even with a worn primary). The new primary chain may make it all a bit tight.

[dave500]

you can do starter clutch in frame,i posted a how to years ago here,but with photobucket shutting all the free stuff down its useless.

[Little_Phil]

Seems excessive. If that shiny bit on the shaft is a spacer. Shouldn't it be the other side of the starter gear between the gear and starter clutch. There is only a thin thrust washer that side.
https://www.cmsnl.com/honda-cb500k1-four-england_model14660/partslist/E15.html#results

[jilespalcock]

Ahem.

I have a bit of advice for the forum:  Never rebuild an engine when you are distracted by a divorce.

I rather stupidly failed to put the left hand side primary shaft bearing in when I rebuilt it.  So, the shaft was working fine under no load, but when load was applied, it started to whorl and clash and hence the noise and the excessive lateral movement of the starter clutch assembly.  A little bit of wear occurred on the casing at the end of the shaft but nothing fatal.  I managed to take out the starter clutch and rebuild, even with a new (hence tight) primary chain.  Thanks for all the advice.  The engine is now running sweetly.  I still have a few snags to iron out - the battery isn't charging, and the kick starter sometimes doesn't engage.  Need to investigate those more.  I understand the circlip on the kick starter shaft can be a little wimpy and the groove needs deepening to put a beefier circlip on.

For information regarding the starter clutch that I discovered:

• It is easier if you lay the bike over on its left hand side (I used an old car tyre to rest the bike on) once the primary shaft is removed.  Obviously remove ALL spillable fluids first, including the battery.  Everything is stacked nicely without gravity fighting you.
• Separating the gear from the clutch body first gives you plenty of room for manoeuvre, however on rebuild you need to use a small mirror and a wire hook to get the gear lug past the clutch spring loaded dowels (fiddly but much easier than trying to wrestle the whole assembly in).
• Withdraw the starter motor, as it makes it easier to slide the jockey wheel into place behind the clutch gear.  This bit was very fiddly.

[dave500]

well done jiles,on the centre stand your not fighting the sideways gravity though,still fiddly but better than splitting the cases!

[jilespalcock]

Thanks!  You are correct, but I also had better access and relatively more comfort!  I'm only in my 40's but I'm already not as supple as I was!

[dave500]

#$%* im 60 this year and no where near as supple as you used to be!

[PeWe]

Women are always a distraction, bad and for worse That's how they works, "by design".

[dave500]

women don't distract me at all,well not since the last time I walked through a plate glass door.