OzVMX Forum

Clubroom => Tech Talk => Topic started by: FireKwaka on June 01, 2013, 08:53:38 pm

Title: Minibike won't go !!!
Post by: FireKwaka on June 01, 2013, 08:53:38 pm

Yamaha MX80, ran like a beauty before we parked it, Daughter  keen for a ride at a dirt track rec day I am helping with. Weak and inconsistent spark, dohh. Tested with the plug sitting on the head with all clean connections.

Cleaned the plug, checked the lead had a good connection at the cap, checked all electrical connections, checked and cleaned all earth connections,  lite file of the points and push started but only fired a few times then dead.

Prior to parking it for several months it had new rings, new plug, new points, wiring pruned and a carby kit . It had the same  inconsistent problem prior to the tune up, ran sweet after the tune up but now got this incosistant spark !!!!

Any tips to get the little Yamy going would be greatly appreciated by both my daughter and I.

(http://i1305.photobucket.com/albums/s558/Firekwaka1/P1010392_zpsda7436bf.jpg) (http://s1305.photobucket.com/user/Firekwaka1/media/P1010392_zpsda7436bf.jpg.html)

Title: Re: Minibike won't go !!!
Post by: SON on June 01, 2013, 09:12:46 pm

Try starting with a 6 plug, warm it up, then run it on the 8
Goggles on your daughter at all times,
Eyes don't grow back.

Title: Re: Minibike won't go !!!
Post by: Montynut on June 01, 2013, 09:19:02 pm

Condenser needs replacing most likely. Capacitors do not like sitting for long periods. The condenser not only protects the points from burning its main role is to create a much stronger spark by collapsing the coil primary field much faster by sinking the reverse voltage coming from the coil.

Title: Re: Minibike won't go !!!
Post by: 80-85 husky on June 01, 2013, 09:35:08 pm

get her some long sleeves too :o

Title: Re: Minibike won't go !!!
Post by: FireKwaka on June 02, 2013, 08:10:06 am

Thanks Guys, Running a 7 plug atm. Good tip Montynut I'll try a new condenser, yes guys she has some more safety gear now.

Title: Re: Minibike won't go !!!
Post by: 80-85 husky on June 03, 2013, 06:56:30 pm

Ive still got the elbow scars from riding in t shirts, always ends in tears!!

those points are a nightmare, got lots of contact cleaner on them and set right. I rode an old xl 250 motospurt and it was the same, going like a dream, next day no start :o fiddle with points, away she would go... no method or rhythm to it...

Title: Re: Minibike won't go !!!
Post by: frostype400 on June 03, 2013, 08:49:56 pm

Have had dodgy coils too on mx80 and a mx100 I had.

Title: Re: Minibike won't go !!!
Post by: FireKwaka on June 03, 2013, 08:55:52 pm

The condenser looks difficult to get to!! Is there any way to test any of these possible faults apart from replacing and hoping?

Title: Re: Minibike won't go !!!
Post by: TT5 Matt on June 03, 2013, 09:21:35 pm

a victa lawnmower condenser will do the job or better still wip the points/condenser out and put a victa spark module in and have a way fatter spark which will suit todays shite fuel.want to know more pm me