Timing chain oil feed question..

[tunnelrider]

Hello everyone, hope you are well!
After doing a 'timing chain job' I'm curious about the tube that feeds oil to the area, the tube with a spring in it..  Any tips on taking it off or testing the action behind it all? Or is it likely to always work considering it gets washed with hot oil? To take it off, looks like a stud in the engine case would have to come out to inspect the spring and piston.  There's not much info on this in manuals I've seen.. Cheers for any info.

[Barry]

It's the oil pressure relief valve set at 5 Bar (71 PSI). So the chain gets lubed on the assumption that the oil pump always produces more than that pressure.  The accepted wisdom is it doesn't get lubed at hot idle or very low revs.

I think it's safe to say the relief valve would always work on the assumption it's flowing clean oil.  The failure mode over time would be for the spring to get weaker thus lowering the pressure setting which would be the preferred direction for it to go in as far as the chain is concerned.

As for testing you could say at a simplistic level just measure the oil pressure.  While providing a benchmark that doesn't give an accurate reading as a relief valve would need infinite flow area to limit system oil pressure to the valve setting. The system pressure will therefore always be higher than the valve setting which is why you will read reports of oil pressure of 7 bar or more being measured.

It might seem a worry that the chain isn't getting a constant flow of oil at low revs. As I said that seems to be the accepted wisdom but I recall one person taking a different view. I can't remember the detail but I wonder if there is a small but constant leakage of oil through the relief valve.

[georgesgiralt]

Hello ,
I've exchanged the spring and the piston in this device.
First, you need to remove the stud (easy) and use a special tool with a 10 mm square end and another tubular end fitting above the tube. This part hold two set screws which are put in the tube holes to make a grip. Then you simply unscrew from the engine, remove the weaker spring and check if the piston needs attention or not.
To check if you have to mess with this, measure the engine oil pressure with the oil hot by replacing the oil sender unit by a gauge. Of course, you are using the correct weight oil for the temperature and the filter is properly sealed and the discharge ball is in it's proper place... Do another pressure check AFTER the intervention....
Your discharge tube seems to have been modified to accept a large screwdriver to remove it. Mine was not... Lucky you because very few dealers have the tool and none accept to rent it.....

[tunnelrider]

Thanks Barry and George for your good replies.  In the late hours of when I posted the question (it was way past my bed time, had just spent 6 hours in the garage in 7 deg C with a few mind warming beverages is my excuse) I was struggling to name the oil pressure relief valve!  So oil pressures up to 7 bar, that's pretty high.  Thanks George for your info on taking the pipe off and inspecting the spring and piston.  Seems a good opportunity and lucky I've got a mod so no special tool needed to take the pipe off.  Will read the pressure with a gauge as suggested. Thanks

[BPT]

I'm curious to hear about how the timing chain job went.  I asked about it here some time ago.

How was it and what do you consider your skill level to be?

[tunnelrider]

I'm curious to hear about how the timing chain job went.  I asked about it here some time ago.

How was it and what do you consider your skill level to be?

As long as you aren't rushed, I'd say it's a job most can can do when familiar with doing tune ups and basic maintenance.
Considering I've got sidetracked during the timing chain job into doing other bits of maintenance I'd say you want to set a bit of time aside for it. Apart from that, the trickiest part for me was deciding on how to install the crankshaft sprocket, the sprocket should be heated by a blow torch hot enough so it slides on, which I didn't do.  I tapped my one on using the old sprocket as a drift.  This was not hard or tricky to drift on but doing it again, I'd heat the sprocket with a blow torch, practice with the old sprocket first and have the knowledge it may not happen right first time but just pull it off and do it again. So that makes it a little more involved than tapping it on. The chain is easy to deal with.
I recommend using a repair manual as a guide if, like me, you are going in there for the first time. To get the timing cover off, the timing sensor, alternator and diode board have to come off so a bit of organisation is required to keep track of parts and marking wires/terminals.  My level is still pretty novice compared to a lot of people on here, mostly I've been doing things for the first time, rebuilt the top end a couple of times and a gearbox rebuild (except shim the cover) would be my biggest jobs before this.  Most timing chain jobs would be done after a certain amount of miles (seems like 50K-80K miles an accepted conservative amount) as a maintenance task but my one snapped, I didn't have much idea it was going to.

[BPT]

Thanks for the reply. I asked here a while back because my local shop told me it would be the first "big" thing I'd need to do.  They said I had a few thousand miles but there was some clattering that sounded like it could be that.

From everything I've read and heard, it's that sprocket that is the real pain, just like you said.  Not something I'm looking forward to, either doing it myself or having to pay someone.

Thanks.

[tunnelrider]

The sprocket isn't that bad BPT, you'll deal with it ok when the time comes.
Perhaps an interesting end for me, if anyone's interested, put your Aircraft Accident Investigator hat on
On taking off the sump, the only part of the broken timing chain that made it's way to the sump was the undamaged master link fishclip (pics below).  Looking closely at it, the keepers that fit over the roller pins look worn.  Perhaps this came off leading to the chain coming apart..  I'm guessing if an official report had to be made (ha ha wtf?) it would be Suspect A!  But who knows really, it could have been forced off with a chain breakage.  Another interesting point on inspection was the chain tensioner piston wasn't working but this may have been a result of the chain bunching up against the tensioner on breakage.
Relax BPT, you are ok to be riding.  My symptoms before timing chain breakage: A rattly timing chain at idle but had been for a few years, an uneven idle that was hard to adjust to 1000-1100 rpm, it wanted to settle on 900rpm instead, which maybe accelerated the demise due to lack of oiling at idle.

[BPT]

As you said, the guy that told me about it said it wasn't urgent, that I had plenty of time. He was just telling me that would be the first "big" thing that would need to be done.  And was also going by the noise at idle although someone else recently told me they didn't hear anything unusual as far as that goes.

So yeah, I'm not too concerned about the being able to ride part, just getting mentally prepared for when it becomes necessary.

Thanks again for the report.

[Bob_Roller]

I had a timing chain failure three years ago .

Engine quit when I was at a stop sign about 300 feet, 100 m from work .

One of the pins on the masterlink broke at the groove for the retainer, the side plate came off and the chain was broken into 4 pieces .

Luckily the valves did not hit the piston, I pulled the heads and removed the valves for an inspection .

Got lucky, if it had happened a minute later, I would have been at 65 mph, 110 kph , I don't think I would have been so lucky with no engine damage .

One trick I have learned, is that when putting the master link in, I put the old link from the front to get the chain lined up, then installed the new link from the back side and pushed out the old link .

Saved a lot of time and hassle doing this .

[Justin B.]

Broken cam chains are no fun.  Years ago I broke the cam chain on my Honda CB450 at a little north of 10k RPM and trashed the head, jugs, and pistons.  But, the silver lining here, it gave me the excuse to bore out the gouged up jugs and put in a 500cc big-bore kit!  [smiley=mad.gif]

[Tony Smith]

Years ago I broke the cam chain on my Honda CB450. 

CB450T? If so I have VERY fond memories of a CB500T I owned. The fastest motorcycle of all time to set tappet clearances on - for a bet I once provided that I could set all four tappets in in under two minutes.

[Justin B.]

In the US the CB450 was the "street" version with exhaust running in the "BMW" position.  Thel also made it as a CL450 which was easier to get along with off-road with a brake pedal that didn't hang down so far and both pipes swept up on the L/H side for still more ground clearance, IIRC.  I put a helluva lot of miles on the 450 and when I got bored I raked it and put on 10" extended fork tubes.  Man, brings back memories...

[wilcom]

I had forgotten I once owned a Honda 450. I had bought it for resale with a rattly cam chain tensioner. As I remember it would just about break your back to ride the thing, extremely rough riding.   My main bike back then was a R50/2, cudda just been the comparison.

[Tony Smith]

  Thel also made it as a CL450 which was easier to get along with off-road with a brake pedal that didn't hang down so far and both pipes swept up on the L/H side for still more ground clearance, IIRC.  .

We tended not to get the "scrambler" versions of Japanese bikes in Australia - I have actually seen a CL450 that was an accidental mis-delivery to the then Honda dealer.

Apparently Honda were going to send a kit of parts to convert it to the CB variety but someone decided it was the bike for them as it was.

The CB500 I had was a good honest "workhorse" that did everything I asked of it (and more) I bought it originally as a spares-ship for a CB500T I was using as a motorcycle recovery sidecar outfit, but as is the way of things my "primary" bike developed a fault that put it off road and the CB still had registration left on it, so it was pressed into service.

I do recall that the brakes were fairly woeful even for the time and that the handling was on the ordinary side of the equation, but safely predictable. Just been doing the calculations and it was 37 years ago I owned it, so it was hardly in the first flush of youth when I got it as the last one was made in 1975 which means it was 5 years old as a minimum when I owned it.