Not running on all four!! HELP!

[Fire-medic]

Vboost rubber and manifold cracked.

Here are some enlargements and I cannot see the 'manifold cracked.' It appears to be a casting mark to me, the 'crack' has no discernible depth to it. The VBoost rubber "at 5 o'clock' is so-blurry, that my admittedly Boomer eyes can't see any flaw in the rubber, nor much of anything else in that area, though the floor of the intake manifold is fairly in-focus. If someone could show me the rubber crack, I'd appreciate it.

When casting is done, the plug might be made of several parts, and that to me is the type of shape I see, where the multiple-piece casting plug is removed, and that type of mark is the parting line between the two adjacent pieces.

 

[99YAMAHAVMAX]

Here are some enlargements and I cannot see the 'manifold cracked.' It appears to be a casting mark to me, the 'crack' has no discernible depth to it. The VBoost rubber "at 5 o'clock' is so-blurry, that my admittedly Boomer eyes can't see any flaw in the rubber, nor much of anything else in that area, though the floor of the intake manifold is fairly in-focus. If someone could show me the rubber crack, I'd appreciate it.

When casting is done, the plug might be made of several parts, and that to me is the type of shape I see, where the multiple-piece casting plug is removed, and that type of mark is the parting line between the two adjacent pieces.

View attachment 89996View attachment 89997

Don't look on the manifold intake boot look at the single clamp on the VBOOST intake. Click on the photo then magnify it.

 

[MaxMidnight]

Thanks Mr Medic, I feel better now I know I wasn't the only one looking at the wrong part.
This is what Mr 99Yamahavmax is referring to



I don't disagree that it needs to be sorted but I doubt that one could say definitively it is split.
If it did allow air in it is most likely to cause a lean condition and unlikely to cause a misfire?
A plug chop would show if it was running lean. Do one at (say) 4K and you should see a lean condition on one plug, at (say) 7.5K on both plugs.

 

[maleko89]

While it's running, spray some brake cleaner around the manifolds and boots to see if idle changes.

 

[Fire-medic]

Don't look on the manifold intake boot look at the single clamp on the VBOOST intake. Click on the photo then magnify it.

Oh yes, thanks, I see what you mean. I suspect that tear isn't going to have much to do with causing a lean condition. The entire ~1/2" under the clamp is what's providing the sealing.

As a matter of fact, people who are fanatical about weight loss might go as far as to trim off any donut material outside of the clamp, like the 1960's factory racers for NHRA/AHRA where they dipped the bodies in acid to lighten the cars. The factories never intended for those cars to stay in the hands of the drag racers, they leased the racers those acid-dipped cars for something like a buck (yes, $1!) and at the end of the season, the cars were returned to the factories where they were crushed. Why? Because the acid-dipped bodies continued to deteriorate, no matter how they rinsed them. From the time they were 'born,' they had a final date with the crusher.

The cars were also 'sound-deadening/insulation delete' with no carpeting, but rubber mats like a taxicab/fleet order. Radio delete, wind-up windows (no PW/PDL, PS, PB, AC or other accessories which added weight). The drag racers would strip out the glass and replace it w/plexiglass, and remove the window crank mechanisms. The name of the game was lightness.

A comparable in the European roadracing world was the famous mid-1950's) Moto Guzzi V8, which was only campaigned by the factory. They didn't even bother to paint it, leaving it bare metal, because 'paint weighs something.'

 

[cyclejunkie]

Someone educate me. What is a COPs setup? It’s obviously something to do with the electrical system.

 

[99YAMAHAVMAX]

Someone educate me. What is a COPs setup? It’s obviously something to do with the electrical system.

Coil On Plug-replaces the coils and spark plug wires-the coil is built into the plug -2 generation Vmax's come with them-you can find ready made sets for the 1st generation at Exactrep in the UK or on Ebay in the US

 

[99YAMAHAVMAX]

Thanks Mr Medic, I feel better now I know I wasn't the only one looking at the wrong part.
This is what Mr 99Yamahavmax is referring to

View attachment 90001

I don't disagree that it needs to be sorted but I doubt that one could say definitively it is split.
If it did allow air in it is most likely to cause a lean condition and unlikely to cause a misfire?
A plug chop would show if it was running lean. Do one at (say) 4K and you should see a lean condition on one plug, at (say) 7.5K on both plugs. Don't assume I'm a Mr, Thank you

 

[MaxMidnight]

Someone educate me. What is a COPs setup? It’s obviously something to do with the electrical system.

They look like this and are ignition coil and spark plug cap combined. Using them also eliminates the HT leads. They can plug directly into the OE loom where the coil(s) connector would normally go and onto the spark plugs.

Attached is a list of suitable CoP's.
Note that the list is well old so there may be more recent CoP's that would work. If anyone has any more information I'll update the list.

 

[Fab333]

View attachment 90004
They look like this and are ignition coil and spark plug cap combined. Using them also eliminates the HT leads. They can plug directly into the OE loom where the coil(s) connector would normally go and onto the spark plugs.

Attached is a list of suitable CoP's.
Note that the list is well old so there may be more recent CoP's that would work. If anyone has any more information I'll update the list.

do you have to make brackets to hold the cop's down so they dont pop up .

 

[TK3333]

do you have to make brackets to hold the cop's down so they dont pop up .

Sean sells c.o.p. brackets. I have a set ready to be installed. I have never had one pop off in over 10 yrs. without the brackets though.

 

[99YAMAHAVMAX]

Thanks Mr Medic, I feel better now I know I wasn't the only one looking at the wrong part.
This is what Mr 99Yamahavmax is referring to

View attachment 90001

I don't disagree that it needs to be sorted but I doubt that one could say definitively it is split.
If it did allow air in it is most likely to cause a lean condition and unlikely to cause a misfire?
A plug chop would show if it was running lean. Do one at (say) 4K and you should see a lean condition on one plug, at (say) 7.5K on both plugs.

Mr.? 99Yamahavmax?

 

[Semi239]

I don't disagree that it needs to be sorted but I doubt that one could say definitively it is split.
If it did allow air in it is most likely to cause a lean condition and unlikely to cause a misfire?

Thank you for all of the thoughts on the boots. I can see where they could be an issue causing a lean condition but I also doubt they could cause cause completely dead cylinders.

A plug chop would show if it was running lean.

This is a neat concept, had to look it up to see what you meant by that. It's brilliant.

http://kawatriple.com/carb/plugchop.htm

 

[Semi239]

I think my issue is bigger than carb boots. I'm also confident I have a good spark. But when capping off the intake on the carbs only cly2 has a strong draw. I ran a compression test and had terrible results on all other cyl but 2(see results attached).

What could cause this poor of compression other than piston rings? Could there be a valve issue? timing?

On another note, I have a nagging coolant leak on cly3. images below

 

[maleko89]

When you tested compression, engine was warm and you opened throttle wide open when turning over correct?

To see why compression readings are low, you'll need a leak-down tester. Could be piston rings, worn cylinder bores, valves, head gasket.

 

[Radioguylogs]

In your original post, the bike was running fine, then it abruptly it wasn't running right.

It doesn't seem probable the valves would suddenly change.

However, I wonder how many miles have passed before the last valve shim. It's doubtful that the valve shim would cause the original problem, or fully explain the low compression, but it's part of the system.

 

[MaxMidnight]

I too am assuming the check was done with the throttle open.

In the absence of a leakage test, squirting some oil down the bores may help the rings to seal better. If the readings improve then that would indicate the compression loss is at the valves. If they stay the same then it still could be both contributing to the loss. If it was a piston ring or bore problem then you would expect to get excessive piston blow-by which may result in oil being sent into the air-box via the breather.
It's interesting that you say it is cylinders 2 & 3 that have the issue but 2 has the highest compression whereas 3 has the lowest...would that tend to rule out compression as the issue?
Unless there has been a mechanical breakage e.g. a piston ring or bore damage then poor valve seating, bore or piston ring wear would result in a gradual reduction in engine performance not the sudden loss you describe.

Valve, bore or ring issues are not something that I've read about over the many years I had my Max so whilst I couldn't rule it out IMO it unlikely to be the cause. That said the compression values still need to be addressed. Before tearing the motor down try some oil treatment e.g. one of these.

If we assume the ignition system is working as it should that would leave the carburation.
Have you checked the throttle slide rubbers for tears or perforations? When was the last time the fuel filter was changed and is the fuel tank breather clear?

Unfortunately there are rarely any magic bullets in diagnosis and you often spend more time establishing what isn't the cause that what is which is frustrating.
Keep notes on what you have done and the results as it;s easy to forget. It also helps to write down exactly what it is you are trying to fix and the symptoms you are getting.
Don't discount the basics i.e. those items that are part of routine maintenance.

Regarding the coolant leak this looks like it is coming from the spigot/ hose joint? Have you taken the hose off to inspect the spigot surface and inside of the hose? If they are both OK and it still leaks then I'd try replacing the OE clip with a Jubilee one.

 

[Semi239]

When you tested compression, engine was warm and you opened throttle wide open when turning over correct?

Engine was warm, but I failed to test with open throttle, these figures are at idle. I will retest and report back.

To see why compression readings are low, you'll need a leak-down tester. Could be piston rings, worn cylinder bores, valves, head gasket.

I have a buddy with a leak-down tester. I will try that next. What should I be looking for? Ideally it would be no leakage correct? If it leaks quickly then valves and slowly would be rings?

It's interesting that you say it is cylinders 2 & 3 that have the issue but 2 has the highest compression whereas 3 has the lowest...would that tend to rule out compression as the issue?

I have misspoken, like you said cly2 is the strongest compression and seems to be carrying the weight of the other cylinders as when I unplug the coil, the motor dies, and the others will continue to idle.

Valve, bore or ring issues are not something that I've read about over the many years I had my Max so whilst I couldn't rule it out IMO it unlikely to be the cause

That's comforting to hear. I know Yamaha makes very reliable engines and these V4s can see 100k miles I've heard

However, I wonder how many miles have passed before the last valve shim. It's doubtful that the valve shim would cause the original problem, or fully explain the low compression, but it's part of the system.

It is due for a valve adjustment, On the rear cylinders there is a lot of valve and cam chain noise. That was on the docket as this bike has 39k miles. After the leak-down test and squinting oil into the cylinder I will pull the valve covers off and ensure the valve clearances are correct and the cam is trimmed properly.

Unfortunately there are rarely any magic bullets in diagnosis and you often spend more time establishing what isn't the cause that what is which is frustrating.
Keep notes on what you have done and the results as it;s easy to forget. It also helps to write down exactly what it is you are trying to fix and the symptoms you are getting.
Don't discount the basics i.e. those items that are part of routine maintenance.

Thank you for the advice Mr. Midnight, tracking all of my issues and attempts will help me keep on track to a solution

 

[Semi239]

Well I have a great update!

I retested the compression at WOT and scored wonderfully. 170psi+ on all cylinders. I am glad to have that ruled out.

I pulled the rear valve cover and found all valves in spec except for a single intake valve on cly3(1 thou tight). I also found an odd discoloration on the cams on cyl1. Has anyone seen this before? Mabe lacking oil? it's not on the other cams over cly3. see pics

Being that we got good compression I didn't do the leakdown test. I turned my attention back to the carbs. With the airbox off you can feel the strong vacuum on cyl2. But all the others have a very poor draw. Also, none of the needle slides are pulsing until I get the throttle close to wide open. While messing around with it by capping off the carb with my hand and taking it away I was able to get cyl 4 to draw well and saw a spark in rpms getting a bunch of fuel. But without my fiddling with it, the draw dwindled back down to nothing. It seems like there is so little air being moved thru the carbs that cyl3 isn't even getting enough fuel to fire and cyl1+4 are getting just enough to stay alive but are very very rich lean.

While I was there I shot brake clean at all of the boots and boost manifolds and found no cracks that drew in air enough to spike rpms. I will pull all of them and inspect them when I take the carbs off again.

What should I be looking for in these carbs? Obviously large debris blocking passages, but are there any problematic points in these carbs that should have special attention? I have had these carbs off 3 times(twice by me and once by a shop) and haven't found any glaring issues.

What do yall think?

 

[Bill Seward]

Poor draw through carbs would indicate a vacuum leak. My '85 had a bit of a leak and ran boots. really badly. Actually it was a huge leak, the right 2 carbs popped off the boots. Be certain you have the carbs fully seated on the boots, and make sure all the other clamps are tight.