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GT 380 Fuse Blowing

Posted: Mon Dec 09, 2019 1:59 pm
by Woodpecker
Hello all more help needed
I have just finished a complete rebuild and with your help resolved some issues which I posted earlier.
Having sorted out the lack of charge due to a faulty regulator I have another electrical problem which is driving me mad. I have started and ran the bike for up th 10 minutes in the drive with no issues. Take it on a short ride to the end of the road (200yards) and back and the fuse blows! all within 5 minuess. So far have checked the earths and red wires and disconnected both regulator and rectifier and same problen on the drive OK on the road with me on it fuse blows. I connected a meter in line with the battery red wire next to the fuse and readings no more than 5amps. I have changed the original in line fuse holder to a new push and twist type.
Any suggestions?
Stu in Kent

Re: GT 380 Fuse Blowing

Posted: Mon Dec 09, 2019 3:01 pm
by barney01
Just to confirm you are using a 20amp fuse? If the fuse only blows after a short ride it must be linked to something that you are operating i.e. the brake light perhaps there is a short there. The other possibilty is perhaps a short or bare wire in the loom close to the forks that comes into contact with the frame when you turn the bars?

Re: GT 380 Fuse Blowing

Posted: Tue Dec 10, 2019 1:36 pm
by Woodpecker
Thanks, yes correct fuse and I disconnected the brake light. Still investigating the loom but not found anything significant yet. Just a thought I fitted 3 new sets of points but only 3 new condensers ( at the time only found 2 ) Wahat are the symptons of condenser failure?

Re: GT 380 Fuse Blowing

Posted: Tue Dec 10, 2019 2:14 pm
by canaletto5
Make sure there are no trapped wires in the handlebar switches causing a short

Re: GT 380 Fuse Blowing

Posted: Tue Dec 10, 2019 4:11 pm
by barney01
Condenser failure causes points to burn out dont think thats your problem if bike runs before being ridden.

Re: GT 380 Fuse Blowing

Posted: Tue Dec 10, 2019 4:37 pm
by KETTLE BOY
Woodpecker wrote:Hello all more help needed
I have just finished a complete rebuild and with your help resolved some issues which I posted earlier.
Having sorted out the lack of charge due to a faulty regulator I have another electrical problem which is driving me mad. I have started and ran the bike for up th 10 minutes in the drive with no issues. Take it on a short ride to the end of the road (200yards) and back and the fuse blows! all within 5 minuess. So far have checked the earths and red wires and disconnected both regulator and rectifier and same problen on the drive OK on the road with me on it fuse blows. I connected a meter in line with the battery red wire next to the fuse and readings no more than 5amps. I have changed the original in line fuse holder to a new push and twist type.
Any suggestions?
Stu in Kent
First, I would start the bike, and check the voltage. Then turn on the lights, check voltage.. then put on indicators check voltage.. and if I carry on working fine, with blowing the fuse, then its something your operating, calming the fuse to blow..

A loose wire, a kinked wire, wires rubbing against something sharp.. could be dodgy fuses... it a suck it and see thing.. if it's fine when not riding it, it could be something under the seat, tank, headlight... keep us informed to what it was when you do find out..

Re: GT 380 Fuse Blowing

Posted: Tue Dec 10, 2019 5:27 pm
by slosher
Woodpecker wrote: I have started and ran the bike for up th 10 minutes in the drive with no issues. Take it on a short ride to the end of the road (200yards) and back and the fuse blows! all within 5 minuess.
Had the same problem with my 550 years ago.I found that the bike ran fine but kept blowing fuses,checked all the wiring every thing seemed fine.I must have gone through 15 fuses but it was only when riding it.Noticed it was when i changed into 3rd gear when the fuse blew :? :? Anyhow it seems that i had connected the gear change indicator block connector incorrect so for some reason it did allow me to,fitted it with the correct coloured wires it has been fine aver since that was 18yrs ago Dunno may be the same problem

Cheers Dave

Re: GT 380 Fuse Blowing

Posted: Wed Dec 11, 2019 8:44 am
by Alan H
Check the wiring to the brake light, especially from the rear brake switch. Or just think what you did immediately before it blew. Use new fuses as old ones get 'tired'.

Re: GT 380 Fuse Blowing

Posted: Sat Dec 14, 2019 9:48 am
by Woodpecker
Thamks for the suggestions, I disconnected the brake light, removed both handlebar switches and checked the wires for damage, Checked the seat to see that the battery connections are clear of the seat base. current plan is I have unplugged everthing and connected the battery directly to the ignition circuit via the kill switch and intend to add circuits one at at a time! It seemed all right at the first attempt but stopped for a while due to other commitments and rain. Will report back later. Also did a recheck on the coils although I can't see how they will blow a fuse. The secondary coils were down on spec at 11-12 Kohms but prmary ok at 5 ohms.

Re: GT 380 Fuse Blowing

Posted: Mon Jan 06, 2020 12:23 pm
by Woodpecker
Hello again
Having cleaned lots of connections, replaced the fuse holder with a better design and checked most of the wireing all seems sorted! Well I have run the bike to the end of my road and back several times (about 200yds) and not have to push it back. Now I have breakdown recover in place I'm ready for a proper ride.
On a seperate matter has anyone run a 380 on synthetic two stroke oil I have some and was thinking of using it?
Thanks to you all for expert help and advice.
Stuart