Gen1 Head removal

[Johnwhatsisname]

I need to replace the cooling water spigot pipe from the top of the rear heads. The original has corroded and just disintegrated.
Do need to remove the engine for this?

 

[one2dmax]

No though getting them out can suck. You may need to remove the valve cover to get access to the top to push out out from that side. I would suggest to put something in there to catch anything that might chip away from it as you try and get it removed.

 

[Johnwhatsisname]

OK. The engine is out. A struggle but not too bad.
I have not removed anything yet but have just run a compression test and attach the results.
We are at about 4500ft agl (Similar to Denver). Can anyone tell me what I should be seeing so I can establish the amount I need to worry or not?

VMAX 1200 Compression Test
Done 24 October 2022
All plugs out. Engine turned over with battery, no carbs
	Dry Test	Test with oil in cylinder
	PSI	Bar	PSI	Bar
Cylinder 1	145	10	157	11
Cylinder 2	125	8.5	160	11
Cylinder 3	130	9	160	11
Cylinder 4	110	7.5	160	11

 

[Fire-medic]

Looks like the right-rear (cyl #4) is low by comparison. I think the chart is going to throw people off as the 'test with oil in cyl' should be over columns 3 and 4, where 'dry test PSI' is column #1. As cyl #4 recorded value comes up to the others, and cyl's 2 and 3 also rise, it seems your rings aren't sealing well. Removing the pistons/rods to see what the cylinders & rings look like would appear to be the next step.

 

[Johnwhatsisname]

I agree with the deviation on No 4. I am reluctant to delve too deep here as the bike was running ok. The problem with these bikes is that they are cheap to buy and run and believe me, I am a fan. However, when you start buying spares then no so cheap. There are probably better bikes available
Please correct me if I am wrong here:
I understand the standard compression ratio on these Gen1 is 10.5:1. So, If I am at sea level and Std pressure is 14.7 psi I should see a pressure reading of 10.5 x 14.7 = 154psi.
I now need to de-rate this for altitude so about 15% less gives 130 psi. No too far out. Except for #4. I don't know how standard this bike is as I have not owned it since new.
Am I missing something here?
Any feedback would be very welcome

While I am on a roll. Both spigot pipes on the head outlets are completely corroded so will need to be replaced. So is the other thingy with the valve on the front. Has anyone tried a different metal replacement? I am thinking stainless steel or even marine grade aluminium? When this done and complete I am planning demineralised water in 50% with Glycol as coolant. Any suggestions here also welcome.

 

[MaxMidnight]

The reason the spigots corroded is probably due to the lack of corrosion inhibitor. Provided this is maintained at the correct levels then IMO the OE material is fit for purpose.
Interested to hear how you intend to affect a repair - not read of it being done before.

 

[Stephan]

The compression ratio is the ratio between the volume of the cylinder and combustion chamber in an internal combustion engine at their maximum and minimum values says Wikipedia. It is not a measurement of pressure.

Here is what the Yamaha manual says about measuring compression pressure and the specifications. (Sorry the bottom picture did not align).

You can adjust these psi values for your elevation.

Unfortunately it appears that cylinder 4 is out of specification simply because it is so different than the other three cylinders.

If it was me I would take off the heads, regrind the valves and recheck.

Good luck!

 

[Mac Max]

You may want to look into performing a leak down test to help you pin point the source of the compression loss before tearing into it. In the absence of an actual leak down gauge you could also induct compressed air into the cylinder via the spark plug hole and listen for leak by at the intake and exhaust ports to help diagnose improperly seating valve. Worth a shot, maybe?

 

[Johnwhatsisname]

Thank you to all for the feedback.
@Mac Max: You are correct on the leak down test but unfortunately I'm too late as the heads are now off. Now that they are off I will re-seat the valves anyway.

@Stephan: Thats what I was looking for. If I de-rate the Std/Max/Min psi values for altitude then I am not way out. In fact between Std and Min. for #4.

This water jacket pipe seems very under-engineered. What is it, plastic, fibre glass? I am going to investigate getting something turned from the appropriate grade aluminium. Maybe with an extraction screw. Any comments on this?

 

[MaxMidnight]

This water jacket pipe seems very under-engineered. What is it, plastic, fibre glass? I am going to investigate getting something turned from the appropriate grade aluminium. Maybe with an extraction screw. Any comments on this?

As it has corroded it is a ferrous metal and a mild steel?

'Fraid I have to disagree re the design - mine is 23 years old and is still as good as new....but then I've always made sure that the anti-freeze/ corrosion inhibitor was at the recommended level.

 

[Johnwhatsisname]

I agree with you but I don't know what happened before owned the bike.
The part I was referring to is this

Joint 1 26H-12469-01-00
Its a water joint between the cylinders. The above part number should be a hot link.

 

[Stephan]

Thank you to all for the feedback.
@Mac Max: You are correct on the leak down test but unfortunately I'm too late as the heads are now off. Now that they are off I will re-seat the valves anyway.

@Stephan: Thats what I was looking for. If I de-rate the Std/Max/Min psi values for altitude then I am not way out. In fact between Std and Min. for #4.

This water jacket pipe seems very under-engineered. What is it, plastic, fibre glass? I am going to investigate getting something turned from the appropriate grade aluminium. Maybe with an extraction screw. Any comments on this?

Part number 26H 12469 01 is plastic. Not that strong but all it does is convey water. Trouble is it is in an awkward place to get out and to fit and this two activities tend to damage it!

 

[MaxMidnight]

The only issue that I can recall is the (very, very) occasional weep from it and even that is rarer than a rare thing of which there aren't many.
As Stephan suggests, uless there is good reason, leave it alone.

 

[Fire-medic]

Part #15

 

[Johnwhatsisname]

Unless I have missed a removable link in the cam chain, I have to remove this in order to get the heads off.
So now its done and plastic pipe broken. Oh well...
Now I can concentrate on really why I started the job in the first place.

 

[one2dmax]

You can knock in one side (center) wall of the spigot and it will pull right out. It's just a pressed in sleeve. Then make a custom sleeve and press it back in. I need to make a driving tool and a few spares since I have one to do the same thing here with.

 

[Johnwhatsisname]

For those who may be interested I have now had the heads cleaned up but more importantly had a brass pipe made and inserted for the coolant spigot.
I am now awaiting parts which should be here end Jan.
Can someone help here: I have decided to install the heads complete so will need to break the timing chains. Does anyone know of a good break and make chain tool for this?

 

[gentsvmax]

OK. The engine is out. A struggle but not too bad.
I have not removed anything yet but have just run a compression test and attach the results.
We are at about 4500ft agl (Similar to Denver). Can anyone tell me what I should be seeing so I can establish the amount I need to worry or not?

VMAX 1200 Compression Test
Done 24 October 2022
All plugs out. Engine turned over with battery, no carbs
	Dry Test	Test with oil in cylinder
	PSI	Bar	PSI	Bar
Cylinder 1	145	10	157	11
Cylinder 2	125	8.5	160	11
Cylinder 3	130	9	160	11
Cylinder 4	110	7.5	160	11

OK, keep the light's dim and noise to a minimum.
It's close to Christmas! Best chain down the mod monkey$

 

[Johnwhatsisname]

?? You have lost me.

 

[RempageR1]

Can someone help here: I have decided to install the heads complete so will need to break the timing chains. Does anyone know of a good break and make chain tool for this?

I`m not sure this chain can be broken and then put back together again. Haven't seen anyone do that before and I`ve read quite a number of threads here.