Stolen (now recovered) Bike FZ6N Conversion

[FinalImpact]

IMO a leak down test is more time consuming and because our hunch is the engine is out of time, now you have to position the crank at some unknown rotational degree TO CLOSE THE VALVES AND DO THE TEST!

Compression test:
What if the compression just happens to be above 150 psi, that would be good to know, yes? And if they are all equal, now we know a lot more than we did before 10min after the first test.

This is an interference engine and it's very likely that if one intake or exhaust valve is bent, all of the I or E's are bent. That said, with the valve cover off you check the lash when the lobe is away from the bucket (dont know where the crank is, it's out of time) but if it has some huge gap, the valve is bent and you know you have big issues.

Anyway there are countless ways to skin this.... fuel was added and it seemed to run. It has some compression.

Screwing a gauge in and pushing the button is pretty easy and that is the path I would take. Hopefully all the values are the same. If low, pull the cover and verify the marks are out of alignment, check the lash to confirm the valves have not kissed the pistons.

Lastly, this is not ours to do. These are simply options and the path I would follow using basic hand tools and a compression gauge. One could gather all the info they need to resolve this in an hour and a half.

Good luck.

 

[ajbuck68]

Good luck.

Thanks, I'm gonna need it. Haha

 

[TownsendsFJR1300]

No Randy, your completely missing my rational...

For his issue, you WANT the crank at TDC, compression stroke.


A compression test will show (for the OP, Very likely low), but not what the actual issue is.

As fast as it spins, we already KNOW the compression is LOW. The exact #, doesn't matter, it needs to be addressed..

If all the exhaust valves are open/leaking, you now KNOW the exhaust cam IS OUT OF TIME...NO guessing..


Agreed thou, that side cover and valve need to come off. Just a visual and maybe a feeler gauge will tell the story(bent valve?)..


As I recall, we had a member here with the chain off one and it didn't bend any valves (maybe a year ago?), ran crappy
but no damage.


.

 

[ajbuck68]

Hey guys,

It's been a while, but I finally had time to do some stuff to the bike. I was able to successfully complete both a fuel pressure test and a compression test. Unfortunately, it failed both.

Fuel pressure test:
5 psi while holding the ignition
7.5 psi just after letting off

Shop manual says to replace the pump. Is there anything I can do to try to clean/repair it? And what are you guys' thoughts on buying a used one off ebay? I really don't wanna drop $500 for a new one.

Compression test:
Cylinder #1 110 psi
Cylinder #2 120 psi
Cylinder #3 130 psi
Cylinder #4 125 psi

So I'm guessing this means the cam chain is off also. I didn't get around to pulling more. I'll have to schedule that for next time.

Thanks for all the help so far!

Sent from my HTC6545LVW using Tapatalk

 

[FinalImpact]

Re: Groggy engine, won't stay running

Thanks Cliff.
If I were to guess I'd say the Pressure Regulator in the pump is stuck open and you're not building proper pressure. The injectors need 36 psi.

Your starter fluid and co adjusts indicate plugs are firing and the engine can run if it has something to burn.

What you need to do is connect a fuel pressure gauge to the pumps output. A 0 - 100 PSI gauge will do. If below 36, pull the pump and remove and clean the P/R. Its a tiny valve with spring and seat. The pump is capable of 70+psi and uses that valve as a controlled leak so to speak.
Do you have an air compressor? It could be used to back flow the valve. Valve has a strap like clip with two locks on it.

^^^ this needs done. Pull the pump assembly, connect it to a 12v source with core wires as big as the those on the pump. Submerge pump in water with the gauge connected and pump outlet blocked. Read the pressure. If it reads 7.5 psi, block the pressure regulator (PR) outlet. Id guess the PR will be streaming a steady stream of water and when plugged your pressure will climb to 60+++ psi.

If all of this is true, clean the PR (it has debris in it and is stuck open and leaking) and your pump is fixed when the PR has the debris removed and it builds pressure.

Yes, low compression #'s support the high cranking speeds. You're going to have to dig in and pull the valve cover to verify what went wrong. You may need a new CCT too.

Do a search on fuel pump repairs (sticky in tech section) and checking/adjusting valves, a sticky in How To section. All the info is here...
Gokd luck.

Ps you can be basic psi gauge new or used for $15. You need a hose and fittings and its a one time expense.

 

[ajbuck68]

Re: Groggy engine, won't stay running

^^^ this needs done. Pull the pump assembly, connect it to a 12v source with core wires as big as the those on the pump. Submerge pump in water with the gauge connected and pump outlet blocked. Read the pressure. If it reads 7.5 psi, block the pressure regulator (PR) outlet. Id guess the PR will be streaming a steady stream of water and when plugged your pressure will climb to 60+++ psi.

If all of this is true, clean the PR (it has debris in it and is stuck open and leaking) and your pump is fixed when the PR has the debris removed and it builds pressure.

Yes, low compression #'s support the high cranking speeds. You're going to have to dig in and pull the valve cover to verify what went wrong. You may need a new CCT too.

Do a search on fuel pump repairs (sticky in tech section) and checking/adjusting valves, a sticky in How To section. All the info is here...
Gokd luck.

Ps you can be basic psi gauge new or used for $15. You need a hose and fittings and its a one time expense.

Thanks! I had forgotten about that post and the pressure regulator. I didn't go all the way back on the thread. I'll have to do that.

And I'm just doing a free loaner tool from auto zone for a fuel pressure test kit. I can keep it for up to 90 days for free, so I'll just stick with that.

Sent from my HTC6545LVW using Tapatalk

 

[FinalImpact]

Re: Groggy engine, won't stay running

Just confirm a couple things:
Fuel pressure was tested on a closed system. Meaning there was no exit for the fuel to go to. This is often referred to as a stall test. It is not a flow or volume test.

Engine cranking it typically takes about 2 to 3 complete compression cycles to build cylinder pressure. Guessing you would have all the plugs out, and press and hold the starter button about 3 to 4 seconds each. Does all that seem reasonable with the testing performed?

Also it is wise to install the removed spark plugs into caps and ground to reduce the risk of high energy (18 - 25,000 volts making its way into the wiring harness and potentially damaging the ECU or other electronics.
Or flip run switch off so the coils have no power, but I never use it. Not sure if it will still crank when off. lol

 

[TownsendsFJR1300]

Re: Groggy engine, won't stay running

It won't crank over with the RED kill switch switch OFF.

Most Yamaha Out Board engines will crank over with NO spark when the safety lanyard is pulled.


Re compression testing, holding the throttle WIDE OPEN gives a mu=ore accurate reading in addition to FI's post above.

Compression should be between 184 PSI and 234 PSI roughly...