Bike idles ok but dies as soon as i put it in gear (Help)

[stevetink]

Greetings from the UK

This is my first time on here so please be gentle

My 1987 FZ600 up until this morning ran first time every time for the past 4 years of my ownership, she has never given me any problems at all, starts on the button first press until this morning, yesterday i went for a ride and it performed to its usual standard (it is 25 yrs old) but today it would not start, much turning over and it fired, ok i thought, crap in the fuel and off i went, splut judder etc huge backfire then death! WTF!!! it would not start, ok i was 20 yards from the garage and back i pushed it, after a short while (cigarette and scratching of head) i tried again, choke on press starter fired up ok, nice, i let it warm up and took the choke off slowly until it was running choke free, i got on the bike put it in gear huge backfire and it died. back in to the garage, anyone got any ideas as to what might be the problem?
Last year it had a full carb rebuild and cleaning by a pro mechanic who also changed the fuel lines and fitted an in-line clear fuel filter, these i have checked and they look very clean

 

[ChevyFazer]

Does the bike have a kickstand cutoff switch? If it does then that could be the problem, it could have went out.

 

[Motogiro]

:welcome:to this great forum!

What Chev says is probably the problem. There's a kickstand safety switch on all late model bikes and yours is probably unplugged or defective.

 

[stevetink]

Thanks guys i will check it out

 

[TownsendsFJR1300]

I just checked the parts fisch for your bike:
( 1987 FZ600T Yamaha Motorcycle Parts ), you should have a side stand switch. It looks much different than the newer model FZ's so you may have to by-pass it should it not come apart for servicing.

+1 on a faulty sidestand swiitch if its cutting off when you try to go into gear. The bike thinks the sidestand is down and is killing the motor for safety reasons.



More importantly, you also mentioned it would not start UNTIL MUCH TURNING OVER. That's going to be a separate issue altogether.

As the bikes apparently been run everyday, I have to seriously doubt the fuel has gone bad but perhaps you got a dose of water in your last fill up...

If you can put a small can (tuna fish can works good) under each float bowl, loosen the drain screw on the lower end of the float bowl and catch what fuel comes out. You want to look closely for any water droplets or crap in general. Do that for all four carbs.

I looked and couldn't find if you have a vacuum operated fuel switch at the bottom of the fuel tank. You do if theres a separate smaller rubber line going to either a intake manifold or at the top, front of a carb. If this lines breaks or cracks with age, you'll loose vacuum and the petc0ck won't work and you'll literally run out of gas (even with a full tank). Check it closely for any cracks, etc..

If all pans out ok, your carbs may be beginning to build up crap in them over time clogging the jets. Find some good carb cleaner/fuel conditioner and run it. Hopefully, if there is a jet starting to clog, this will clean it out before you need someone to manually clean the idle/main jets...

PLEASE POST YOUR FINDINGS/RESULTS/FIX and welcome to the forum!!!

 

[stevetink]

I just checked the parts fisch for your bike:
( 1987 FZ600T Yamaha Motorcycle Parts ), you should have a side stand switch. It looks much different than the newer model FZ's so you may have to by-pass it should it not come apart for servicing.

+1 on a faulty sidestand swiitch if its cutting off when you try to go into gear. The bike thinks the sidestand is down and is killing the motor for safety reasons.



More importantly, you also mentioned it would not start UNTIL MUCH TURNING OVER. That's going to be a separate issue altogether.

As the bikes apparently been run everyday, I have to seriously doubt the fuel has gone bad but perhaps you got a dose of water in your last fill up...

If you can put a small can (tuna fish can works good) under each float bowl, loosen the drain screw on the lower end of the float bowl and catch what fuel comes out. You want to look closely for any water droplets or crap in general. Do that for all four carbs.

I looked and couldn't find if you have a vacuum operated fuel switch at the bottom of the fuel tank. You do if theres a separate smaller rubber line going to either a intake manifold or at the top, front of a carb. If this lines breaks or cracks with age, you'll loose vacuum and the petc0ck won't work and you'll literally run out of gas (even with a full tank). Check it closely for any cracks, etc..

If all pans out ok, your carbs may be beginning to build up crap in them over time clogging the jets. Find some good carb cleaner/fuel conditioner and run it. Hopefully, if there is a jet starting to clog, this will clean it out before you need someone to manually clean the idle/main jets...

PLEASE POST YOUR FINDINGS/RESULTS/FIX and welcome to the forum!!!

Thank you, it ran today like a dream, until i got 300yds from home then it just died, so i suspect Dirt in the carbs, i am not discounting the switch though, it is booked in to a mechanic on Tuesday, i have poured a very good fuel line cleaner (Redex) and i will give it another go tomorrow

 

[TownsendsFJR1300]

If YOU want to rule out the sidestand switch (and save some $) follow the harness from the sidestand switch up to the main harness.

Unplug it, then connect the two harness wires TOGETHER. If the bike goes into gear with the sidestand down AND KEEPS RUNNING, you by-passed it. Go for a ride and see what happens.

**I don't know if its wired to run disconnected or connected so you may have to check it with the wires tied together

In either case, it won't hurt anything to connect the main harness wires together.

I suspect if it ran great for 300 yards, then died, its not the carbs but that switch.

Please post your results in either case and good luck