Yamaha FZR600 '91 Engine trouble (i think?)

[ajordan9]

Hey BCF,

So I'm gonna give as much info to help you help me and really appreciate any advice/suggestions.

So I got the bike for cheap (non-runner but suspected dead battery) last year, I knew I wasnt gonna get round to fixing it for a while so flushed all oil, petrol and coolant.

Got round to doing it recently. New oil filer, oil, petrol, coolant. I had an old but new battery sitting around intended for my old Honda CB125 (maybe 2 years ago). It was a Yuasa YB9-B. They sent me two by accident so this one was unused. I charged it up, tested it and read 12V. I stuck it in the bike. It fired up after a little jump start down the garden. Was absolutely fine, passed its MOT ran it on/off for 2 weeks.

With work picking up didnt get round to using it for a few weeks, it sat in the heat and in some light rain. When it did start really raining it was mostly covered, though did get a little wet. Shouldnt be a big deal.

So i went to ride it after 2/3 weeks and it started fine got 1/2 mile away from home. Suddenly the whole machine dies and there is NO power at all. Luckily at the top of a hill I coast it all the way home with no power, just 2 wheels lol.

Open it up and I see this: https://ibb.co/TH8RVrk
And so the battery cable is obvs disconnected and I later notice some of the acid is missing, maybe its half way now between +/-.

Great. Get a new battery, this time recommended for the bike by Yuasa, YB12AL-A2. Pop it in. Bike turns on.
Electric start not working.
Indicators not working.
DIPPED headlight not working.
Brake lights or rear light not working.

Highbeam WORKING.
Horn is strong and WORKING.

Maybe a fuse? I replaced all the accessory fuses and main fuse today.

The bikes electric start is now working but it hasn't fixed the other issues. And whilst it does work the bike doesnt continue to run, it cuts out and sounds VERY clunky in what i assume is the engine. (Tried with/out choke)

Also if i keep the throttle engaged it wont die but when I put it into gear and tried to ride it in 1st gear it died straight away.

Again this bike was working fine before, no engine issues, clean MOT e.t.c.

Heres a video of where the bike is at: https://youtu.be/kYQP5cJX7y0

Any help or suggestions would be great!

[R1stu]

Maybe a wire in the harness has melted as well? or CDI issue
____________________
Carbon closet tart! https://www.bikepics.com/members/r6stuk/02r6/
Stolen bike. 2000 R1: https://www.bikepics.com/members/r6stuk/00r1/
Current bike 1991 Honda ST1100 Pan European, 1986 Honda cb350sg (Finished)

[Pukka]

Does the bike have an original voltage rectifier (looks like image below) located under the left hand rear fairing. They tend to fail quite regularly and i suspect its most likely caused damage to either the wiring or various electrical components as the battery terminal melted!


https://ae01.alicdn.com/kf/HTB1yMg0JVXXXXXhXFXXq6xXFXXX4/Voltage-Regulator-Rectifier-For-Yamaha-FZR600-FZR500-1989-1993-1990-1991-1992-XV250-XT600-FZR250-FZX250.jpg

I would start by having a quick check over all the electrical connectors and checking for any damage or melted parts first.

I can recommend the website fzronline.com. The forum is pretty much dead at this point but it still has a lot of useful information available. Has a useful conversion guide for an improved rectifier from an r6 here https://fzronline.com/wiki/doku.php?id=r6_voltage_regulator_conversion
____________________
'98 Honda CB500S, '89 Yamaha FZR600 (Ongoing project)

[Robby]

It's been a long time since I heard of a regulator/rectifier failing so that it fails to regulate the voltage but still allows electricity through. Usually these days they just brick themselves.

That said, my first thought here is that the reg/rec is no longer regulating - so instead of feeding ~14V into the battery (and the rest of the bike) it's feeding ~60V. This will boil the battery and blow bulbs.

If it was running, the test would be to start the bike and get a multimeter across the battery terminals set to DV volts. It should be showing 13-15V. If it's showing move like 11V, it isn't charging and total reg/rec failure is most likely. If it's showing 20-60V, partial reg/rec failure is likely.

Alternative test is to have a look at the bulbs that aren't working. If they are all blown, it means they have seen too much voltage.

Reg/rec replacement is likely to be necessary. Hopefully it hasn't taken out anything expensive.

[A100man]

From the video it sounds like it's only running on two cylinders.

That could mean a coil failure or wet/corroded plug caps. You can identify which two cylinder by heat from exhausts - don't burn yourself they get hot quick.

Less likely is a partially failed ignitor (TCI sometimes confusedly called CDIs or ECUs).

I don't think your melted battery is connected to the poor running. I think its the rain.
____________________
Now: A100, GT250A, XJ598, FZ750

Then: Fizz, RS200, KL250, XJ550, Laverda Alpina, XJ600, FZS600

[Pete.]

That bike is definitely not running on four cylinders. Get a damp cloth, start it up and use the cloth to see which pipes are getting warm.

No idea what's caused the melted terminal - never seen anything like that before. I would say perhaps loose connection but I don't see any of the usual black evidence of arcing. I would be checking the heavy wires for chafing and also check the output of the reg/rec.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Kentol750]

Why no new spark plugs?
____________________
Some bikes.

[jeffyjeff]

[Pete.]

I would not expect any bike alternator to have enough output amps to melt a big lead terminal like that, even on an under-sized battery.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[doggone]

A direct short with power from from the battery could do it in seconds though.
That could be something as simple a a spanner bridging to earth.

[ajordan9]

Sorry everyone! I never got any notifications of replies so thought it might have just slipped into the ether. But thanks for all your replies. I'll try get it started up tonight and test these theories.

You're right it doesn't sound likes its running on all cylinders or at least not running right. Just trying to think what might connect all these random things not working but might be a more complicated issue of many things now not working.

Ah well, not the main bike so guess its all fun and games (until I get hurt and/or frustrated).

Will report back by the end of the week!

[ajordan9]

sorry for the delay. work **** keeping me at bay.

So managed to have a look at it today a bit further.

Had a look at the regulator/rectifier as suggested by some members. I followed this video to test: https://www.youtube.com/watch?v=I7Iyi8w9U_o&list=LL&index=2

It seemed to show similar numbers (+/- 2) when testing with a multimeter so I think that might rule out a faulty regulator/rectifier unit? Can't see any burnt out cables or anything around the unit which might suggest there's been an electrical overcharge.

As I mentioned the indicators/rear light/ headlight aren't working either. But had a look at some of the indicator bulbs and look fine/not blown? So not sure why they aren't working.

The battery was still at 12.3v so keeping charge fine as it sits unused (will charge if drops).

Lastly I managed to get all the spark plugs out and this is what they looked like: https://ibb.co/qJGPjGK

I guess the dry black coating indicates carbon fouling? (this is what google tells me) So could this potentially be why the bike is misfiring?

I think I might replace all spark plugs and clean out the plug caps to ensure a good connection. Then at least that's one thing ruled out i won't need to check again.

Again, any thoughts or advice would be highly appreciated.

[A100man]

While you have your meter out measure teh resistance of teh plug caps - assuming they are resistor type then you should see 5000 or 10000 ohms depending on built in resistance . If they are not and you have resistor plugs then the ohms will be much lower. compare values among the the four.

My FZ750 had a single corroded plug cap that was enough to knock out both #1 and #4 cylinders it came to light after a downpour.. just saying.

EDIT: Spotted your plugs are the 'R' type with resistor built in. Should they be?
____________________
Now: A100, GT250A, XJ598, FZ750

Then: Fizz, RS200, KL250, XJ550, Laverda Alpina, XJ600, FZS600

[ajordan9]

So back at it again now work is quiet.

So to answer the spark plug type, I'm just using whatever was labelled in the Haynes manual so they should all be the right sort. They've all now been replaced.

So now with the bike sitting dormant for a little while i've pulled out the old fuel and topped it back up with fresh fuel today. Charged the battery overnight and that was giving a good reading. Went to start it up and this is the reaction I got:

This is what I first got: https://youtu.be/10DmqaQ7t9k
The starter is clearly whirling but engine is dying out and the exhaust is coughing up a lung.

I left it for a little while, came back and it started once finally then it died out. And now all i seem to be getting is this: https://youtu.be/fdLJqtUicDk
Note that when I just hit the ignition switch it sounds grumbly, wanting to go. Then when I give it a tiny bit of throttle it dies and you can only hear the starter motor.

Not sure why its totally not starting how having replaced the spark plugs. I tested the end 2 plugs for spark so they're definitely working too.

Any ideas? Is it worth taking the petrol tank off and having a look at the carbs and fuel line?

Thanks so much in advance. I hate this bike as much as it hates me lol.

[R1stu]

can you hear the fuel pump when turning on the ignition?
____________________
Carbon closet tart! https://www.bikepics.com/members/r6stuk/02r6/
Stolen bike. 2000 R1: https://www.bikepics.com/members/r6stuk/00r1/
Current bike 1991 Honda ST1100 Pan European, 1986 Honda cb350sg (Finished)

[ajordan9]

hmm i'll have a listen for that. I'll find it in the Haynes manual and stick my ear to it.

Does it make a particular noise? I assume just a pumping sound?

[R1stu]

It's bolted to front of fuel tank next to the carbs. When you turn ignition innit will make a sliding scale drone sound. Lasts about 2 to 3 seconds
____________________
Carbon closet tart! https://www.bikepics.com/members/r6stuk/02r6/
Stolen bike. 2000 R1: https://www.bikepics.com/members/r6stuk/00r1/
Current bike 1991 Honda ST1100 Pan European, 1986 Honda cb350sg (Finished)

[ajordan9]

So had a listen and heard nothing! I think I remember the noise from a while ago when it first started because it sounded weird to me lol. I've removed the tank and the thing looks pretty old, I know I could test it but just decided to just replace it along with the petrol filter and will give it all a clean to ensure no clogged lines anywhere.

Did test the spark plugs again and seemed fine, I also tested the Spark plug caps (as suggested by a member) and got this reading at 200k OHMS:

1+4 32.8
2+3 31.4
Does this sound good?

No a clue what it means but watched a video on how to get the readings.

With the petrol tank out, do you think its worth just poking around the carbs to make sure there's nothing funky in there?

[R1stu]

May as well but if hear no noise then maybe that's the issue
. Stick a battery to pump see if kicks in

Should get this sort of sound for around 2 to 3 seconds.

https://youtu.be/-0U3BUeUphg
____________________
Carbon closet tart! https://www.bikepics.com/members/r6stuk/02r6/
Stolen bike. 2000 R1: https://www.bikepics.com/members/r6stuk/00r1/
Current bike 1991 Honda ST1100 Pan European, 1986 Honda cb350sg (Finished)

[ajordan9]

Hey,

So back again! I've now replaced the fuel tap (as it was leaking), fuel filter and fuel pump along with all the in-between fuel lines from tank to carbs.

I now have that preciously annoying fuel pump noise and the bike now fires up on what sounds like all 4 cylinders. Progress.

The problem I'm having now, is it takes maybe 10 times of turning the ignition and throttle (with choke) to get it fired up. But when it finally gets there the exhaust is popping and spluttering every 10secs or so AND the bike doesn't idle. The second I come off the throttle it dies completely. Almost instantly. There's no sign it's even trying to idle even after keeping it running for a minute on the throttle. This happens both with and without choke.

I've put in fresh petrol, checked the air filter which seems clear and reasonably clean but I'm thinking it could be the carbs? I haven't actually touched them yet or looked inside.

Any advice would be greatly appreciated as always!

[oilyrag]

If it's been sitting around for a long time it probably needs the carbs cleaned but you could try turning the idle adjuster in a few turns to bring the idle speed up.

[jeffyjeff]