Bike misfires then dies
Discussion
My bright idea of a cheap commuter is turning out to be more trouble that it was worth.
When I first took the bike out it was hesitant and terribly snatchy at slow speed. I think it was only running on 3 cylinders at times too.
Took the carbs apart and checked for any blockages - all looked pretty clean but the mixture screw on one of the cylinders was a turn further out than the other three. Set all four at 2.5 turns out and matched up the butterflies as close as I could off the bike.
Changed filters and spark plugs too.
Started it up and it ran much better so put it all back together again.
Decided to give it a run out today and when first trying to start it made a clunk and then nothing.
Tried starting again and it fired up and seemed to run well.
Ran for about 10mins in town, so low revs, then came to nsl road so opened it up a bit more.
At that point it hesitated again, misfiring twice before cutting out. Now no electrics so something has blown.
Apologies for the long winded post but wanted to give background on situation. Bike is 97 zzr600.
Any ideas?
When I first took the bike out it was hesitant and terribly snatchy at slow speed. I think it was only running on 3 cylinders at times too.
Took the carbs apart and checked for any blockages - all looked pretty clean but the mixture screw on one of the cylinders was a turn further out than the other three. Set all four at 2.5 turns out and matched up the butterflies as close as I could off the bike.
Changed filters and spark plugs too.
Started it up and it ran much better so put it all back together again.
Decided to give it a run out today and when first trying to start it made a clunk and then nothing.
Tried starting again and it fired up and seemed to run well.
Ran for about 10mins in town, so low revs, then came to nsl road so opened it up a bit more.
At that point it hesitated again, misfiring twice before cutting out. Now no electrics so something has blown.
Apologies for the long winded post but wanted to give background on situation. Bike is 97 zzr600.
Any ideas?
Yes, easily. Reg/Rec's are quite a crude instrument on bikes, the older ones essentially short the AC generated by each phase of the alternator as it spins. Newer mosfet ones go open circuit repeatedly, so that the voltage at the battery sits at 14.4v.
So, if they go wrong, you can end up with 80-100V AC at the battery terminals, which will boil the acid out of the cells in a very short order. Or cause a fire. Well worth checking the output at the battery terminals, and if the reg/reg is as old as the bike, consider getting a replacement.
On the subject of the carbs, you really want to check the float heights to make sure they're all in spec and even, then balance them with vacuum gauges; a bench sync will get you started, but you can't account for slightly different flow rates through the venturi/jet of each carb.
So, if they go wrong, you can end up with 80-100V AC at the battery terminals, which will boil the acid out of the cells in a very short order. Or cause a fire. Well worth checking the output at the battery terminals, and if the reg/reg is as old as the bike, consider getting a replacement.
On the subject of the carbs, you really want to check the float heights to make sure they're all in spec and even, then balance them with vacuum gauges; a bench sync will get you started, but you can't account for slightly different flow rates through the venturi/jet of each carb.
bgunn said:
Yes, easily. Reg/Rec's are quite a crude instrument on bikes, the older ones essentially short the AC generated by each phase of the alternator as it spins. Newer mosfet ones go open circuit repeatedly, so that the voltage at the battery sits at 14.4v.
The MOSFET regulators shunt the stator output just like the older SCR versions, but have a much lower resistance so dissipate less heat when switched on. Series regulators are very uncommon, at least on Japanese and European bikes.OPs intermittant faults and fuse blowing could be caused by a chaffed wiring shorting on the frame.
Bgunn, thanks for the info regarding the carbs. My intention is to get the bike stripped down once my garage is built and I can get my other bike out of storage. It needs a few things tidied up so I just wanted it running better than it was to get me to work and back for a few months.
With the reg/rec, I’ve had a quick search and found replacements that state they are MOSFET ones, where as many do not have much of a description.
I take it some that are for sale will still be the old style unless stated otherwise?
With the reg/rec, I’ve had a quick search and found replacements that state they are MOSFET ones, where as many do not have much of a description.
I take it some that are for sale will still be the old style unless stated otherwise?
http://www.roadstercycle.com FH020AAs work great, I chucked one on my Yammie Thundercat as a matter of course, not a huge re-wiring job, but a much better regulator.
As said, check the wiring all over thoroughly before condemning the regulator, but you can quickly test to see that charging system works as it should.
As said, check the wiring all over thoroughly before condemning the regulator, but you can quickly test to see that charging system works as it should.
bgunn said:
http://www.roadstercycle.com FH020AAs work great, I chucked one on my Yammie Thundercat as a matter of course, not a huge re-wiring job, but a much better regulator.
As said, check the wiring all over thoroughly before condemning the regulator, but you can quickly test to see that charging system works as it should.
I was looking at this one:As said, check the wiring all over thoroughly before condemning the regulator, but you can quickly test to see that charging system works as it should.
http://www.electrexworld.co.uk/acatalog/RR26_-_Reg...
Checked the fuses and all are intact.
I also took the kill switch apart in case I disturbed something when loosening the throttle cables but everything looks in order there too.
I haven’t been able to take the whole thing apart to check all the wiring but couldn’t see anything obvious.
Checked the battery voltage using my fisher price multimeter that gave a voltage of 13v so I assume that’s around the 12.6v mark
I also took the kill switch apart in case I disturbed something when loosening the throttle cables but everything looks in order there too.
I haven’t been able to take the whole thing apart to check all the wiring but couldn’t see anything obvious.
Checked the battery voltage using my fisher price multimeter that gave a voltage of 13v so I assume that’s around the 12.6v mark
Definitely do an all over electric systems check.
I had a really weird one on an old suzuki where it lost all power after hitting a slight bump in the road, it wasn't until I pushed it two miles home and started working on it I realised the CDI unit had vibrated the 1 remaining screw holding it on it's bracket out, and the jolt had allowed the clip to be pulled out of the CDI enough to cut power.
Gut feeling from your post says it isn't reg/rec and it certainly doesn't fail in the way you suggest (I have had 2 fail)
I had a really weird one on an old suzuki where it lost all power after hitting a slight bump in the road, it wasn't until I pushed it two miles home and started working on it I realised the CDI unit had vibrated the 1 remaining screw holding it on it's bracket out, and the jolt had allowed the clip to be pulled out of the CDI enough to cut power.
Gut feeling from your post says it isn't reg/rec and it certainly doesn't fail in the way you suggest (I have had 2 fail)
bgunn said:
You've checked the main fuse?
Was there any indication the bike behaved like this before? (Perhaps that's why it was sold...)
You could be right - buy cheap, buy....sWas there any indication the bike behaved like this before? (Perhaps that's why it was sold...)
teMain fuse is intact.
I guess it’s going to be take everything off it and check all the wiring then, sounds like that is the main suspect
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