Hi folks,
Went to Robinsons for MOT on the GT380B this morning. Not for the 1st time, I broke down, though thats pretty rare, maybe 3 times in 30+ years. For the 1st time though, I couldn't fix it by the roadside! Symptoms were complete and sudden ignition failure. Fuse and all power OK. Pushed it the last mile.
Points cover off and there's the problem - points cam not turning as motor turned over. I guess its the break cam driven (nylon) gear, or the woodruff key, or the pin. It went during a nice bit of very brisk acceleration :-))
Anyone experienced this before, and what did you find?
The bike's at Robinsons and they'll van it back to me later this week. Looking forward to having that clutch cover off.
Cheers!
Mike
Points cam not turning - GT380
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yeadon_m
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astrax
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Re: Points cam not turning - GT380
Hi Mike
Sorry to hear about your probs, typical at the most inconvenient times.
Not familiar with the 380's but hopefully not too big a job.
Looking at a diagram, the drive gear #31 on the shaft, is that the nylon one, I wouldn't think there is too much resistance turning the shaft, were you giving it a bit of welly.
Does the points cam shaft now freely turn with a spanner on the end, either way cover off.
Sorry to hear about your probs, typical at the most inconvenient times.
Not familiar with the 380's but hopefully not too big a job.
Looking at a diagram, the drive gear #31 on the shaft, is that the nylon one, I wouldn't think there is too much resistance turning the shaft, were you giving it a bit of welly.
Does the points cam shaft now freely turn with a spanner on the end, either way cover off.
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grand tourer
Re: Points cam not turning - GT380
Hi Mike
My money is on the nylon gear, this component was a renowned culprit of sudden ignition failure on the GT380.
Andy
My money is on the nylon gear, this component was a renowned culprit of sudden ignition failure on the GT380.
Andy
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oldjapanesebikes
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Re: Points cam not turning - GT380
Add another vote to Andy's.grand tourer wrote:My money is on the nylon gear, this component was a renowned culprit of sudden ignition failure on the GT380.
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wardy
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Re: Points cam not turning - GT380
Mike; when you said you "broke down"at the MOT, I thought that it had reduced you to tears!
if it's the nylon gear, I'll have a spare if you cannot get one.
cheers Andy
if it's the nylon gear, I'll have a spare if you cannot get one.
cheers Andy
Andy;
1976 gt750A; 86 FZ750
1977gt380A
1982 z400j
1981 z650f.....1988 Sufolk punch 14"
"look;it's my bike; when you own it ,you can paint it any colour you like!"
(I once painted my Z650 PINK and had the pink panther logo on the tailpiece)
1976 gt750A; 86 FZ750
1977gt380A
1982 z400j
1981 z650f.....1988 Sufolk punch 14"
"look;it's my bike; when you own it ,you can paint it any colour you like!"
(I once painted my Z650 PINK and had the pink panther logo on the tailpiece)
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yeadon_m
- Posts: 7401
- Joined: Sat Jan 02, 2010 7:10 am
- Location: Canterbury Kent
Re: Points cam not turning - GT380
Ian,
I didn't try turning the points cam, once I spotted it wasn't turning with the engine, I felt relieved that I knew more or less what had happened and just left it for its MOT (and investigation/repair at home later). I know they're not supposed to do the MOT unless they can hear it running, but the same tester has done my MOT last 7 years so he's willing to do it!
I knew the failure wasn't anything I'd had before, because there isn't anything electrical that could result in the symptoms I had. Obviously the kill switch if it failed could, but I knew it was fine, because the neutral light still dimmed slightly as it always does, due to coil current draw when the switch was toggled. A six block coil connector or 3 block points connector cannot all fail at once, while leaving every other power supply intact. I didn't think point cam gear until I reached the workshop, then it came in a flash!
Andy, Ian,
Relieved to hear its most likely that nylon gear, although pricey they do seem to be available. Thanks Andy, I will be in touch if thats what it is and if not available new. I did worry overnight, what if its that the end of the crankshaft thats snapped off? but it cannot be, because I tried coasting and letting the clutch out downhill for a dozen yards and it sounded smooth and quiet...just not running.
And the weakest link, deliberately, is that gear. Two perhaps pertinent facts. One, when I rebuilt the motor at 40K miles, I didn't renew that gear, so its 44K miles and at least 35 years old by now! Two, I had a near hydraulic lock event earlier this year (leaking fuel cock, leaking float valve) and it did make a scary sounding thump when it started, and spat fuel out of the left pipe, but luckily ran like a swiss watch afterwards, including more than 100miles of vigorous riding. I wonder whether a violent back and forth event chipped a tooth on the gear in that moment and my brio acceleration yesterday after 5miles of nice steady running was the last straw!
Breaking down - if I'd been many miles from the workshop, I might have been reduced to tears! as it is, so long as isn't something really nasty, it'll be a bit of an adventure :-)
I'll keep you posted.
Cheers,
Mike
I didn't try turning the points cam, once I spotted it wasn't turning with the engine, I felt relieved that I knew more or less what had happened and just left it for its MOT (and investigation/repair at home later). I know they're not supposed to do the MOT unless they can hear it running, but the same tester has done my MOT last 7 years so he's willing to do it!
I knew the failure wasn't anything I'd had before, because there isn't anything electrical that could result in the symptoms I had. Obviously the kill switch if it failed could, but I knew it was fine, because the neutral light still dimmed slightly as it always does, due to coil current draw when the switch was toggled. A six block coil connector or 3 block points connector cannot all fail at once, while leaving every other power supply intact. I didn't think point cam gear until I reached the workshop, then it came in a flash!
Andy, Ian,
Relieved to hear its most likely that nylon gear, although pricey they do seem to be available. Thanks Andy, I will be in touch if thats what it is and if not available new. I did worry overnight, what if its that the end of the crankshaft thats snapped off? but it cannot be, because I tried coasting and letting the clutch out downhill for a dozen yards and it sounded smooth and quiet...just not running.
And the weakest link, deliberately, is that gear. Two perhaps pertinent facts. One, when I rebuilt the motor at 40K miles, I didn't renew that gear, so its 44K miles and at least 35 years old by now! Two, I had a near hydraulic lock event earlier this year (leaking fuel cock, leaking float valve) and it did make a scary sounding thump when it started, and spat fuel out of the left pipe, but luckily ran like a swiss watch afterwards, including more than 100miles of vigorous riding. I wonder whether a violent back and forth event chipped a tooth on the gear in that moment and my brio acceleration yesterday after 5miles of nice steady running was the last straw!
Breaking down - if I'd been many miles from the workshop, I might have been reduced to tears! as it is, so long as isn't something really nasty, it'll be a bit of an adventure :-)
I'll keep you posted.
Cheers,
Mike
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yeadon_m
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Re: Points cam not turning - GT380
Well folks,
Finally got around to taking it apart to see whats what. Thank heavens for impact drivers. The two cheesy screws under the points plate that hold the clutch cover on where right &*%^$$ ! One came out OK, but the other had been hacked previously by some total idiot (ahem....that was me, way back in the 1980s!). They are inset about 3 inches deep making it hard to get at 'em. Two taps with the impact driver and alls well. New allen bolts to be installed.
As expected, it was points cam gear thats shattered - pics attached. As you might be able to see, there was a flaw in it all those years - a bubble in the plastic, and I am sure it fractured there first, for I can see witness marks on the pieces either side of the bubble break. Interesting information I thought - my wife didn't :-)
Parts on order from Reiner - getting a new bearing, bushing, circlip and seals with the gear. Its possible a worn bearing or bushing contributed to the failure, and as the parts other than the gear are cheap, I'm not taking chances, but most likely it was just bubble magic!
Cheers,
Mike
Finally got around to taking it apart to see whats what. Thank heavens for impact drivers. The two cheesy screws under the points plate that hold the clutch cover on where right &*%^$$ ! One came out OK, but the other had been hacked previously by some total idiot (ahem....that was me, way back in the 1980s!). They are inset about 3 inches deep making it hard to get at 'em. Two taps with the impact driver and alls well. New allen bolts to be installed.
As expected, it was points cam gear thats shattered - pics attached. As you might be able to see, there was a flaw in it all those years - a bubble in the plastic, and I am sure it fractured there first, for I can see witness marks on the pieces either side of the bubble break. Interesting information I thought - my wife didn't :-)
Parts on order from Reiner - getting a new bearing, bushing, circlip and seals with the gear. Its possible a worn bearing or bushing contributed to the failure, and as the parts other than the gear are cheap, I'm not taking chances, but most likely it was just bubble magic!
Cheers,
Mike
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wardy
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Re: Points cam not turning - GT380
I wonder if it would be possible to get these remade in metal?
I can't see when they would break other than someone turning the engine over with the plugs in.
looks like a faulty gear as you say Mike; could have gone anytime over the years.
Andy
I can't see when they would break other than someone turning the engine over with the plugs in.
looks like a faulty gear as you say Mike; could have gone anytime over the years.
Andy
Andy;
1976 gt750A; 86 FZ750
1977gt380A
1982 z400j
1981 z650f.....1988 Sufolk punch 14"
"look;it's my bike; when you own it ,you can paint it any colour you like!"
(I once painted my Z650 PINK and had the pink panther logo on the tailpiece)
1976 gt750A; 86 FZ750
1977gt380A
1982 z400j
1981 z650f.....1988 Sufolk punch 14"
"look;it's my bike; when you own it ,you can paint it any colour you like!"
(I once painted my Z650 PINK and had the pink panther logo on the tailpiece)
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Roger Ackery
- Posts: 3693
- Joined: Wed Jul 20, 2011 3:40 am
- Location: Sydney NSW Australia
Re: Points cam not turning - GT380
Hi, Andy,have a mate that had a GT380 that did exactly the same thing as Mike's 3 years ago,apparently that part is designed to break first if there is a problem,sort of the weakest link,he had one machined up in brass,we will never know how long it will last, as he has since sold her on!! Cheers, Roger. GT750A.
Cheers.
Roger
GT750A.
Roger
GT750A.
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yeadon_m
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- Joined: Sat Jan 02, 2010 7:10 am
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Re: Points cam not turning - GT380
Andy,
You're right, if the gear is sound, it shouldn't break in normal service and I've never gone to it with a spanner on the cam. What I found though was a bubble in the moulding and it broke there. I now recall hearing it go (I keep crazily detailed notes) and in May this year after I'd not run it for 3months, when I started it, there was a light but distinct 'crack' noise from the right side of the motor that I'd never heard before. That was the occasion when I had found that my fuel tap was leaking and a lot of fuel spewed from the left pipe vent when it finally ran. I guess that the poor start it made that day banged the gear hard eg backlash and that was that. Mind you, it ran several hundred more miles before letting go (into three pieces!).
Reiner does sell steel gears but I once read that if this is installed, its noisy. I'll keep it in mind of the NOS one ever fails, which it probably won't.
Roger, do you know if your mate mentioned his metal gear being noisy at all?
Parts have been shipped from Reiner, so shouldn't be long before she's running again! Meanwhile, back to the laborious job of doing first-cut polishing on the better set of fork lowers for my GT550 project......fingers are getting smoother than the forks!!
Cheers,
Mike
You're right, if the gear is sound, it shouldn't break in normal service and I've never gone to it with a spanner on the cam. What I found though was a bubble in the moulding and it broke there. I now recall hearing it go (I keep crazily detailed notes) and in May this year after I'd not run it for 3months, when I started it, there was a light but distinct 'crack' noise from the right side of the motor that I'd never heard before. That was the occasion when I had found that my fuel tap was leaking and a lot of fuel spewed from the left pipe vent when it finally ran. I guess that the poor start it made that day banged the gear hard eg backlash and that was that. Mind you, it ran several hundred more miles before letting go (into three pieces!).
Reiner does sell steel gears but I once read that if this is installed, its noisy. I'll keep it in mind of the NOS one ever fails, which it probably won't.
Roger, do you know if your mate mentioned his metal gear being noisy at all?
Parts have been shipped from Reiner, so shouldn't be long before she's running again! Meanwhile, back to the laborious job of doing first-cut polishing on the better set of fork lowers for my GT550 project......fingers are getting smoother than the forks!!
Cheers,
Mike