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A A A A Author Topic: Erratic revs  (Read 1820 times)

CX PHREAK

Re: Erratic revs
« Reply #50 on: 23-Jun-21, 13:22 »
My best guess as to the bending of the valves would be a valve strike on the piston at some point.

This may have been caused by a worn out camchain allied to an over rev.

Due to the placement of the tensioner the cam timing on these motors retards as the chain wears. Bad cam timing can cause valve strike.

While this is a full set it's likely your most cost effective option for guide replacement. A machine shop can do the job and it is best to have the seats recut at the same time and the new valves ground in.

https://www.ebay.com.au/itm/303547277819?hash=item46acd3e1fb:g:pocAAOSw0vJcHXQa

Or you could source another head which may or may not have its own issues.

gm

Re: Erratic revs
« Reply #51 on: 23-Jun-21, 14:15 »
thanks again
CXPHREAK
I'll let you know how it goes

RAM

Re: Erratic revs
« Reply #52 on: 28-Jun-21, 16:00 »
Has there been sticking of the valves in the guides caused by burning oil/worn rings?
Do you use a top end lubricant in place of leaded fuel?
How did the bore look at BDC?

gm

Re: Erratic revs
« Reply #53 on: 21-Jul-21, 17:51 »
Hello Gurus
I hope you are all well and coping with the current COVID restrictions.

In response to RAM
I’m not sure if the valves were sticking but some shafts had discolouration that might indicate overheating.  I had been using a lead replacement additive in the fuel but I think I may have been a bit remiss in recent times (bad on me).  The bore looks clean and smooth. 

One item that might not be right is that the rocker has a sticking point for both the right- and left-hand sides.  I am not sure if this is normal or if it is likely to affect the operation.  I couldn’t figure out how to remove the rocker shaft.

On reflection of the situation, I had some doubts as to how to proceed. I removed the Right-Hand Side (RHS) head and although it was not as bad as the Left Hand Side (LHS) it wasn’t a pretty sight. I also double checked the LHS stats.
Briefly the stats for both sides are:
•   springs range from 48.9 to 50.55mm mostly around the 49area,
•   shaft diameters range from 6.52 to 6.58mm mostly around the 6.55,
•   runout of the shafts was all good at 0mm,
•   runout of the valve heads range from  .06 to 1.04mm,
•   valve contact surfaces range from 1.87 to 2.4.
While the gasket looked ok in the photo, they both began delaminating on removal.
There was some valve slop in two of the guides and a couple had cupping on the contact surface.

I was not sure if the removal and replacement of the guides was easy or difficult
I noted that the faces of the heads were scratched see photo
And I noted some corrosion in the water pipe from the head to the thermostat see photo.
I think I should purchase new valves, springs and guides and either do the replacement myself or take them to the engineers shop and get them to do it.

I seek your opinion
Should I have a crack at installing the guides or send it to the engineers?
Should I replace the water pipe, or will the O ring compensate for the poor surface of the pipe?
Should the surface of the heads be shaved?
If the rocker arm should be a smooth operation?
Anything else I may have missed?

Thanks again and hope to hear from you
gm

CX PHREAK

Re: Erratic revs
« Reply #54 on: 25-Jul-21, 15:08 »
The discolouration on the shafts may be indicative of overheating or is simply baked oil.

The sticking point on your rockers is wear to the rocker shafts. It is not usually an issue.

The shafts can be swapped inlet for exhaust so that the current bearing surface is moved to the top and the unworn top side moved to the bottom where the thrust is taken.

Have you given the valves a test lap to check their seating? Don't use coarser than medium compound. Aside from being to coarse for the job generally coarse has large enough lumps of abrasive to roll on the low spots, cleaning them and making it appear there is more contact between valve and valve seat than there really is.

The sloppy valves were exhausts?

If going the route of guide and seat replacements I'd put it into a workshop capable of the work if you can afford it. You'll never have to look at them again then.

The coolant pipe is fine.


gm

Re: Erratic revs
« Reply #55 on: 26-Jul-21, 15:24 »
thanks CXPHREAK
Not sure what you mean by swapping the valves.  The inlet valves have a head diameter of about 31.9 and the exhaust are about 21.9. I hope this is normal for the 650E.  The exhaust valve heads are bent out about a millimeter. I can't imagine they will ever form a seal again.
Yes it  is the exhaust valves that are sloppy.
What did you think of the scratches on the surface of the head?
GM


CX PHREAK

Re: Erratic revs
« Reply #56 on: 26-Jul-21, 15:29 »
As for the swapping - I meant the rocker shafts and not the valves.

I expected the exhaust valves would be the sloppy ones as intakes are generally OK.

The head gasket should handle the scratches in the head face but personally I would face them out. If you'll be putting the heads in to a workshop to be done maybe they can also give the gasket faces a quick reface.


gm

Re: Erratic revs
« Reply #57 on: 26-Jul-21, 22:53 »
Thanks again CXPHREAK
I will need to wait untill Sydney's lock down is over before I can get to the workshop.
I will let you know how it goes.
GM

RAM

Re: Erratic revs
« Reply #58 on: 30-Jul-21, 13:50 »
Should I have a crack at installing the guides or send it to the engineers?
Should I replace the water pipe, or will the O ring compensate for the poor surface of the pipe?
Should the surface of the heads be shaved?
If the rocker arm should be a smooth operation?


Replacing guides also requires valve seat cutting. A job for the engineers.
A soft new O ring and rubber grease should seal OK.
Shave heads if they are warped otherwise light clean with a smooth block with medium grade wet & dry and kero.
Hylomar sprayed on gasket is another option.
Rocker arm operation should be as smooth as possible. Clean and polish shafts.
I hope you can solve all problems easily.

gm

Re: Erratic revs
« Reply #59 on: 30-Jul-21, 15:17 »
thanks RAM
I'll let you know how it goes
gm

gm

Re: Erratic revs
« Reply #60 on: 05-Aug-21, 17:33 »
Hello again Gurus
I hope all is well and to all those in lockdown I bring you more puzzles.
I'm sure others have walked a similar path but it seems that each time that light at the end of the tunnel appears someone or something turns it off.
I became concerned about the not so smooth operation of the rocker arms so while I was waiting for the new exhaust valves and guides to arrive, I had a quick look.
The really bad things seem to be the grind marks on the Left hand exhaust rocker shaft and the chip off the Right hand exhaust rocker arm what do you think??
how could this happen?
and do you think the chip is fixable?
gm

Seagrass

Re: Erratic revs
« Reply #61 on: 05-Aug-21, 18:03 »
I don’t think that chip is worth worrying about as long as there are no fragments floating around.

If those shafts are around 8 to 10mm diameter I have a supply of them.

Seagrass

nodrog

Re: Erratic revs
« Reply #62 on: 05-Aug-21, 21:15 »
I can check see if I have a spare rocker. Should have seeing as I have a complete head that's beyond repair.

gm

Re: Erratic revs
« Reply #63 on: 06-Aug-21, 13:20 »
thanks Seagrass and Nodrog
much appreciated
I measured the diameter of the shaft and the bore and they both measured around 14.98.  the manual indicates they should be max 14.05 bore and shaft.
I measured a few times and have a witness to make sure I did it right.
does this seem odd??
gm

nodrog

Re: Erratic revs
« Reply #64 on: 06-Aug-21, 19:55 »
Iv'e just looked at a manual for the 650 Turbo, It specs a rocker arm shaft of 15mm. Perhaps all the 650 have a larger Rocker Arm shaft. I'm pretty new to this myself, but can say the spares i have are all of 500's. I think you need a Guru to help you sort this one out.

Seagrass

Re: Erratic revs
« Reply #65 on: 06-Aug-21, 21:30 »
Graham I have eight brand new shafts here and they measure 14.98mm.

We had these made some years ago as Honda no longer has them.

I ended up buying the leftover ones from CX Phreak at I think around $13 each but I will need to try and find my records of actual cost.

Seagrass

CX PHREAK

Re: Erratic revs
« Reply #66 on: 06-Aug-21, 22:51 »
N/A rocker pins are the same diameter whether 500 or 650 but the 650 pin has 2 oil anulars and the 500 one.

I have 650 pattern pins in a few 500 motors.

Seagrass

Re: Erratic revs
« Reply #67 on: 07-Aug-21, 08:33 »
CX Phreak those are the ones I have too.

Seagrass

gm

Re: Erratic revs
« Reply #68 on: 07-Aug-21, 18:00 »
Nodrog
I believe the rockers on the 500 and 650 are interchangeable.
Seagrass tell me if I got this wrong?
isn't this fun
gm

Seagrass

Re: Erratic revs
« Reply #69 on: 07-Aug-21, 18:34 »
They are interchangeable so no problem.

The CX650 Turbo nodrog is referring to may be different but I have not checked that part number.

Seagrass

nodrog

Re: Erratic revs
« Reply #70 on: 08-Aug-21, 22:40 »
I'm a bit confused (This happens with age) as the manual for the 500 states a shaft diameter of 13.98mm, where as you explain your shaft is 14.98mm. When you say the Rockers are interchangeable I'm guessing you mean the complete assembly is interchangeable.
I should have a complete assy somewhere, not certain of condition and not able to measure mine yet as I am still waiting on delivery of a suitable Bore gauge. Happy to part with an assembly if you need one.

Thought i'd add Nodrog is just Gordon backwards.

gm

Re: Erratic revs
« Reply #71 on: 09-Aug-21, 18:15 »
Thanks Nodrog
I'm as much in the dark as you. My manual said 13.something was the correct size of the shaft and bore yet it is clearly 14.89.
Are you able to look at the shafts? and measure please don't worry if you can't or if it is a hassle
(I figured the Gordon bit.) would you prefer to be addressed as Gordon?

gm

Seagrass

Re: Erratic revs
« Reply #72 on: 09-Aug-21, 21:58 »
I will go through the parts lists and work out if they are the same part and therefore same size.

Watch this space!

Seagrass

Onetrack

Re: Erratic revs
« Reply #73 on: 10-Aug-21, 08:10 »
The Haynes manual states on page 47
"Spindle OD
All 500 models except CX500 E-C ...13.982-14.000mm
Service limit................................. 13.960mm
All other models ............................14.966 - 14.984mm
Service limit..................................14.950mm"

Part number
14450-415-000
Suits models
CX400 E
CX500 1978 USA
CX500 1979 (Z) USA
CX500C 1982 (C) CANADA
CX500C CUSTOM 1979 (Z) USA
CX500C CUSTOM 1980 (A) USA
CX500C CUSTOM 1981 (B) USA
CX500C CUSTOM 1982 (C) USA
CX500D DELUXE 1979 (Z) USA
CX500D DELUXE 1980 (A) USA

14450-ME2-000
CX650-ED
The clue is the central part code

Seagrass

Re: Erratic revs
« Reply #74 on: 10-Aug-21, 09:23 »
Thanks Les.

My checking of the workshop manuals shows the same thing.

The larger 14.98 diameter rocker shaft suits the 500-EC, 650-ED, 500-TC Turbo and 650 Turbo models

Seagrass

 


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