1990 rm250 starting probs - Motorcycle-Journal Forums

aussie rm · 11-01-2004, 09:42 PM

hey guys, i have just rebuilt the top end on 1990 rm 250.the bike was bought with a holed piston. after trying to fire it up it started first kick and reved right out due to a dodgy throtle cable.now heres where the mind games behin.now i have no spark under compression. if i lay a plug on the cylinder it will pruduce a bright fat blue spark and even jump a 10mm gap on the spark gap tester. now keep the plug on the cylinder and screw in a plug into the cylinder ,ie motor under compression it will not fire spark or do anything for that matter. so off to the bike shop to get things tested.cdi, coil, stator, complete electrics were tested, on a growler and put under load. every thing tested fine. all earth points have been cleaned up , kill switch is working as it should.have i maybee over looked somthing, can some one please help has i am nearly about to push it over a cliff! cheers ash

92 RM 125 · 11-02-2004, 08:31 AM

i dont think the spark would die just from compression. if the bike is producing spark, it should also put spark into the engine, and having your local shop find nothing wrong with the electrical just adds to my theory. You probally have a different prodlem. are you sure the bike is getting fuel and air? Put the plug in the bike and then hold it wide open while kicking it over like 5 times. pull the plug out and look at it, if the plug is wet, you have gas. if not, put just a little bit of gasoline(or starter fluid) in the cylinder and then put the plug back in and see if it fires. if it starts and runs for a few seconds, that means you arent getting gas into the engine. if those dont work, try starting it with the airbox off.

aussie rm · 11-08-2004, 10:34 PM

i now have it sorted out .for some reason the air gap between the pick up coil and magneto was at about 2mm.buggered if i know how it moved as it is fixed on 2 posts.after carfully bending back down to 10 thou it now sparks like it should.and you no what it now starts 1st kick

11-01-2004, 09:42 PM	#1 (permalink)
aussie rm Newbie Joined: Nov 2004 Location: australia Posts: 4	1990 rm250 starting probs hey guys, i have just rebuilt the top end on 1990 rm 250.the bike was bought with a holed piston. after trying to fire it up it started first kick and reved right out due to a dodgy throtle cable.now heres where the mind games behin.now i have no spark under compression. if i lay a plug on the cylinder it will pruduce a bright fat blue spark and even jump a 10mm gap on the spark gap tester. now keep the plug on the cylinder and screw in a plug into the cylinder ,ie motor under compression it will not fire spark or do anything for that matter. so off to the bike shop to get things tested.cdi, coil, stator, complete electrics were tested, on a growler and put under load. every thing tested fine. all earth points have been cleaned up , kill switch is working as it should.have i maybee over looked somthing, can some one please help has i am nearly about to push it over a cliff! cheers ash __________________ baybe i should use it as bbq

11-08-2004, 10:34 PM	#3 (permalink)
aussie rm Newbie Joined: Nov 2004 Location: australia Posts: 4	i now have it sorted out .for some reason the air gap between the pick up coil and magneto was at about 2mm.buggered if i know how it moved as it is fixed on 2 posts.after carfully bending back down to 10 thou it now sparks like it should.and you no what it now starts 1st kick __________________ baybe i should use it as bbq

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
'01 Gixxer 600 has probs warm starting	GixxerFanboi	Mechanics Corner	4	11-10-2005 07:06 AM
1990 rm250 vs 2005 rm250?	cwdhunter	Dirt Bikes & ATV's	2	10-01-2005 12:31 AM
Rm250 1990 2-stroke Many Questions?	cwdhunter	Dirt Bikes & ATV's	4	07-12-2005 03:09 AM
Trouble Starting RM250	jimcam1	Dirt Bikes & ATV's	7	06-04-2004 10:04 PM
84 RM250 idle probs	Tink	Dirt Bikes & ATV's	1	01-06-2004 01:53 AM

11-02-2004, 08:31 AM	#2 (permalink)
92 RM 125 Seat Tester Joined: Sep 2004 Location: Burrillville RI Posts: 79	i dont think the spark would die just from compression. if the bike is producing spark, it should also put spark into the engine, and having your local shop find nothing wrong with the electrical just adds to my theory. You probally have a different prodlem. are you sure the bike is getting fuel and air? Put the plug in the bike and then hold it wide open while kicking it over like 5 times. pull the plug out and look at it, if the plug is wet, you have gas. if not, put just a little bit of gasoline(or starter fluid) in the cylinder and then put the plug back in and see if it fires. if it starts and runs for a few seconds, that means you arent getting gas into the engine. if those dont work, try starting it with the airbox off.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)