1986 fz 600 purgatory

[erburtt]

- It's not a good city bike. All the starts and stops will overheat this thing. I tend to ride later at night when the city is just a big, mostly empty race track.

I find it hard to believe Toronto is ever empty enough to ever resemble a race track!

I'd agree on the 07-09 FZ6 as your next bike, but obviously I have a bit of a conflict of interest

I hope you're truthful when you sell her to the new buyer, I've yet to be really burned, but my last project bike had quite a few little surprises

 

[James Crispy]

I find it hard to believe Toronto is ever empty enough to ever resemble a race track!

I'd agree on the 07-09 FZ6 as your next bike, but obviously I have a bit of a conflict of interest

I hope you're truthful when you sell her to the new buyer, I've yet to be really burned, but my last project bike had quite a few little surprises

Lake Shore / Gardiner west are very empty in the late hours

I would never put anybody through what I just went through. I think whoever buys this next is actually getting a bike that is ridable and is now in good working order. It's more of a project bike than a reliable commuter for sure !

Bike is looking good Townsend.

I'll have to test ride a FZ6 then !!



Thanks!

 

[The_Paragon]

Next Bike should be an 07-09 FZ6.

HMMMM... Back in 2012, I came on this forum for help with my '86 FZ600, and I SWEAR TO GOD someone said the same thing to me... Maybe it was Mr. TownsendsFJR1300 himself.

So anyway, I ended up buying a 2009 FZ6... Funny how that works.
25,000mi later, I still love the FZ6!!

 

[TownsendsFJR1300]

Took off the tank and tested the flow from the current fuel line / filter vs. a new fuel line. The new (clear) fuel line seemed to flow better so I installed that one.

View attachment 65106

Took a test drive. Early on there was a hint of the problem, but it went away. Did about 20k then sat near my place and let it idle. Took about 5 mins but yes, same story. Died.

Now that the fuel line is clear, I can see that fuel is just not flowing to the carbs after a certain point.

:

Either a vacuum leak to the fuel valve, it simply failed OR as noted earlier, the inner filter (inside the tank) is clogged.

You found the issue, NO FUEL flow after a certain amount of idling. The carbs are simply running out of gas...


I'd bet if you hooked up an auxiliary, (like a lawn lower gas tank) direct to the carbs it would idle fine. I'm sure you have vacuum at the carb for the fuel shut off valve, perhaps a hose is cracked, or again, its inside that valve...

With all you've done, a little more digging / investigating should solve this VERY minor issue (compared to what you've done)..


***Also, what IS the factory idle SUPPOSED to be? I know you have it at 1,000.

The newer bikes call for 1,300 or so.

It is very possible that if your idle is too low, your not pulling enough vacuum to keep the fuel valve OPEN. IE, its turning OFF the fuel as its designed to do..

 

[Hellgate]

I'm thinking dead float valves and/or the floats are not set to the correct height. Thoughts?

 

[James Crispy]

I'm thinking dead float valves and/or the floats are not set to the correct height. Thoughts?

The factory idle is supposed to be between 1150 - 1250 rpm.

Mine tends to hover between 1300 - 1200, or what seems like. I did make a small adjustment to the idle knob. Maybe I'll set it back as I didn't notice any difference at the time...hoses are all new.

I'll have to try the aux tank trick. Townsend maybe right with the not enough draw causing the petc0ck valve to close.

When I cleaned the carbs, the floats seemed fine / clean and I set them to the proper height. Man I hope it's not anything like that.

I'll start with the idle adjustment / petc0ck.


Paragon: Nice. Lots of FZ6 love up in here.

 

[Hellgate]

The factory idle is supposed to be between 1150 - 1250 rpm.

Mine tends to hover between 1300 - 1200, or what seems like. I did make a small adjustment to the idle knob. Maybe I'll set it back as I didn't notice any difference at the time...hoses are all new.

I'll have to try the aux tank trick. Townsend maybe right with the not enough draw causing the petc0ck valve to close.

When I cleaned the carbs, the floats seemed fine / clean and I set them to the proper height. Man I hope it's not anything like that.

I'll start with the idle adjustment / petc0ck.


Paragon: Nice. Lots of FZ6 love up in here.

I'm just trying to think of simple things that might be the cause as usually it's the little things, not the big ones.

 

[James Crispy]

I'm just trying to think of simple things that might be the cause as usually it's the little things, not the big ones.

Yea. Thanks !!

All on the list. If I have to take the carbs out again I'll def. check those valves

 

[TownsendsFJR1300]

Even if the float level adjustments were off, that further "down the line", especially when James is visually seeing fuel stop/slow flowing tells me that's not the issue.

If they were too high or too low, he shouldn't be able to get the higher RPM's out of the engine(he's getting fuel).

And if the float too low(not closing), fuel would be pouring out the carbs..

With the rust that was in the tank, it wouldn't take but a tiny piece to clog/slow things up.


James, if you have a fairly large, stationary floor fan(set on high), use that and an auxiliary tank and crank it up and jet let it sit for you 15 minutes, etc run time..
If your careful enough, simply strap your aux tank to the back bone and go for a ride. The issue pops up quick enough.


Does the fuel switch lever have 2 or 3 positions? Prime, (if you have it), should allow full flow ALL the time..

Again, if it has this setting, try it W/O the engine running(not hooked to the carbs, just a catch can), fuel should be readily flowing pretty quick...

 

[James Crispy]

Ok. So tonight I spent some time with the idle adjustment bolt.

That thing is

S.E.N.S.I.T.I.V.E.


However, there is a sweet spot. I seem to have found it after a few short trial runs.

Then I attempted a regular city ride and even did some errands. It was totally fine. Logged 64km this time. This has brought back a small amount of (dangerous?) confidence in the bike.

I did not do the sit and idle test. I just wanted at least one friggin day to just ride.

Let's see how the next few days go...

 

[James Crispy]

Also, Townsend, the petc0ck has 3 settings: Reserve, Prime and On.

I usually leave it on Reserve.

I dialed it to Prime before I started it and watched the fuel line into the carbs. It flowed. Bike started immediately.

 

[TownsendsFJR1300]

Does the fuel switch lever have 2 or 3 positions? Prime, (if you have it), should allow full flow ALL the time..

Can you flip that lever??

 

[James Crispy]

Does the fuel switch lever have 2 or 3 positions? Prime, (if you have it), should allow full flow ALL the time..

Can you flip that lever??

I can but the manual says not to ride with it in that position.

 

[TownsendsFJR1300]

I can but the manual says not to ride with it in that position.

That position is a permanent ON.

It does NOT need vacuum for fuel to come out. If running with it ON/Prime and that solves your problem, you NOW KNOW its the petc0ck or vacuum line preventing fuel flow.

BTW, as long as your floats are closing, no excess fuel coming out of the carb or flooding, it won't hurt anything.

***Now if a float stuck open, float needle didn't seal fully, yes you'll get fuel leaking out till the tank runs dry (fire hazard).

But for testing purposes, it'll likely rule the fuel switch yea or nay.. Make sense?

 

[James Crispy]

That position is a permanent ON.

It does NOT need vacuum for fuel to come out. If running with it ON/Prime and that solves your problem, you NOW KNOW its the petc0ck or vacuum line preventing fuel flow.

BTW, as long as your floats are closing, no excess fuel coming out of the carb or flooding, it won't hurt anything.

***Now if a float stuck open, float needle didn't seal fully, yes you'll get fuel leaking out till the tank runs dry (fire hazard).

But for testing purposes, it'll likely rule the fuel switch yea or nay.. Make sense?

Gotcha. :thumbup:

 

[TownsendsFJR1300]

Any updates?

 

[payneib]

Suspense is killing me.....

 

[James Crispy]

A few test runs tonight and the idle was fluctuating so I made a few adjustments. Seemed to be good.

However, the same idle death problem caught me a little way from home on a busy street. I don't stray too far these days.

I tried setting the gas tank to constantly on. No change.

Waited about 10 mins with the company of another rider who stopped to ask if I needed help. Matt. Good dude. I am impressed with how other riders check in like that. He waited until my bike started up and followed me home just to be sure. Thanks Matt !

I think I'm going to take apart the petc0ck (again). I really need to beat this thing.

:Flip: <---- directed at the bike.

 

[James Crispy]

There is no escape.

 

[FinalImpact]

Vapor lock is killing you.
I had a 140hp Chev Corvair, 4 1bbl carbs. Even with 9psi of fuel pressure, heat soak expands the fuel in the lines and float bowls and 9psi would not overcome it as the idle speed flows so little fuel that fuel would turn to vapor it starves. You have gravity only so spring pressure at the float bowl is very critical.

As in, a poor engineering effort leads to the incorrect spring rate on the float and you chase your tale...

When you had the float bowl needle and float in hand, was it directly coupled or did the needle have any kind of spring loading built into the needle?

Also, check the bowl vent lines. If plugged, pressure builds and fuel won't come in.

As for the vacuum petc0ck, with a vacuum gauge or vacuum pump, you could rule it out by monitoring or applying vacuum directly to it but the prime mode says its innocent. They suggest it NOT be ran that way as its safety feature to stop fuel spill should be on its side!

It may come down to thermaly insulating the fuel line and perhaps something under the carbs.