Sometimes weak or no spark

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Sometimes weak or no spark

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CBR Forum >> Past CBR Models >> CBR 600F >> Sometimes weak or no spark

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Sometimes weak or no spark - 10/4/2008 1:09:31 AM

4tune8

Posts: 13
Joined: 10/4/2008
Status: offline

Hi all

New here, first post.

I thought that I was done riding 30 years ago and now I''''m riding my son''s 1989 CBR600F,... and I like it!

He picked this bike up several weeks ago and it was running great. Then one morning it wouldn''t start. I''''m an auto mechanic and I''ve worked on my bikes years ago so I''''m not totally out of the loop. I did search the forum and found nothing that offered any hope.

It had power at the coils, but no spark. I started by checking all the connections. I figured pulse generators or spark unit. The manual I downloaded says 450 - 550 ohms at the pulse generator connects. I have 510 on one and 350 on the other. My thoughts are if one isn''t working, then it should still fire on 2 cylinders. No spark on any. I picked up a used spark unit, still no spark. While I was plugging in the old spark unit I pressed the connectors in very tight,... it started. I thought it was fixed until it suddenly quit after a few minutes of riding. After sitting for about 20 minutes it started. Remember it first wouldn''t start cold, so I don''''t think it''''s temperature related. Now it runs for a few days with no problem. Then one day a cold no start. Try it again the next day, starts! I have been over all the wires and connectors while it''''s been running and not a hiccup.

Now the symptoms have changed. I get an intermittent weak/no spark. It will sometimes try to start after it quits.

When it runs, it runs real strong with good throttle response. No it seems to run for a shorter time before it dies.

My gut tells me pulse generators, but I can''''t help but think it should still try to fire the other 2 cylinders. Is their any other way I can determine if I''m getting a signal to the spark unit???

Thanks for any advice you can offer, looks like my self or my son will be regulars here.

< Message edited by 4tune8 -- 10/4/2008 1:26:53 AM >

Post #: 1

RE: Sometimes weak or no spark - 10/4/2008 6:07:05 AM

tds94probe

Posts: 266
Joined: 10/18/2007
Status: offline

Hmmm, very odd. Did you try cleaning the connections on the bike? IE CDI Connectors, coil connectors, ect ect. These bikes are known for corroding the connections, so thats where id start. From what you said, it almost seems like it could be the plug for the cdi itself being corroded.....also are you using the kill switch to shut it off? My 600 has a faulty kill switch that sometimes if i use it it wont allow me to restart the bike with it in the run position, now i just use the key to shut it off and leave the kill switch in the run position.

_____________________________

''''87 CBR 600F - K&N Filter, Drilled Airbox, FP Config 3.0 Jets, FP Ignition Advancer, Hindle CF Super Sport Slip On, JT -1 Front Sprocket, CF Race Mirrors, CF Tank Pad, Shaved Rear Fender, Shaved Front Fender, Nokya Ultra White 5000K Headlight Bulb

(in reply to 4tune8)

Post #: 2

RE: Sometimes weak or no spark - 10/4/2008 6:26:38 AM

Hurricane rider

Posts: 624
Joined: 8/23/2008
Status: offline

weak- no spark makes me think plug wires are at fault. replace them with OEM wires, not that automotive crap they sell at autozone or whatever store is nearby. the true copper cored wire is what I think works best for SOLID connection.

(in reply to tds94probe)

Post #: 3

RE: Sometimes weak or no spark - 10/4/2008 8:20:08 AM

tripicana

Posts: 108
Joined: 11/16/2007
Status: offline

check the resistance of the plug wires. check and clean all the connectors up by the fuse panel. and like tds94probe said, it could be a bad kill switch, might take it apart and clean the connections in the switch. make sure battery has over 12 volts.

(in reply to Hurricane rider)

Post #: 4

RE: Sometimes weak or no spark - 10/4/2008 10:14:51 AM

4tune8

Posts: 13
Joined: 10/4/2008
Status: offline

Hi Guys

I did check all the connections. This bike has been fair weather ridden, garage kept. All the connections are bright, shiny and tight. No corrosion anywhere.

The kill switch kills the power to the CDI & coils. The bike always has full battery power at the CDI & coils when it won''t start.

I wouldn''t think the wires would be the cause as the spark is either good and strong on all 4 wires, or it''s weak and intermittent on all 4 wires.

But thanks for the help guys, I''m needing all I can get! Keep it coming!

< Message edited by 4tune8 -- 10/4/2008 10:16:28 AM >

(in reply to tripicana)

Post #: 5

RE: Sometimes weak or no spark - 10/4/2008 12:24:30 PM

tds94probe

Posts: 266
Joined: 10/18/2007
Status: offline

hmmmm.........worn ignition rotor or rotor contact points??

_____________________________

''''87 CBR 600F - K&N Filter, Drilled Airbox, FP Config 3.0 Jets, FP Ignition Advancer, Hindle CF Super Sport Slip On, JT -1 Front Sprocket, CF Race Mirrors, CF Tank Pad, Shaved Rear Fender, Shaved Front Fender, Nokya Ultra White 5000K Headlight Bulb

(in reply to 4tune8)

Post #: 6

RE: Sometimes weak or no spark - 10/4/2008 4:51:02 PM

4tune8

Posts: 13
Joined: 10/4/2008
Status: offline

Out of gas!!!

I can''t believe it! My son filled it up the day before and hadn''t ridden it more than 150 KMs. He DID switch it to reserve before he called me to rescue him.

My experience with automotive "sparks" is that it can jump a 3/4 inch with a snap. This had trouble making a 1/4 inch and no snap. I''m feeling a bit sheepish getting tripped up on this. I was taking the tank off to check the wiring again and it was feeling very light. A peek inside revealed about a 1/2 liter of fuel. I squirted some fuel down the carbs and it started right up.

So today he went riding with me following. He road for over an hour with no problems. Appears that was it. I know that we DID have a "no spark" issue in the beginning as after I pushed the connector together tightly it ran all the next day without adding fuel.

So I thank you all for taking the time to offer some help to this old biker; never too late to learn something about not checking the basics.

Cheers

(in reply to tds94probe)

Post #: 7

RE: Sometimes weak or no spark - 10/4/2008 5:48:08 PM

Hurricane rider

Posts: 624
Joined: 8/23/2008
Status: offline

thats kinda funny how a SIMPLE thing tripped you up. glad it was an easy fix.

(in reply to 4tune8)

Post #: 8

RE: Sometimes weak or no spark - 10/4/2008 6:09:15 PM

tds94probe

Posts: 266
Joined: 10/18/2007
Status: offline

lol I do that so much!!!!! I overlook the simple things because you never think that would be the problem.

_____________________________

''''87 CBR 600F - K&N Filter, Drilled Airbox, FP Config 3.0 Jets, FP Ignition Advancer, Hindle CF Super Sport Slip On, JT -1 Front Sprocket, CF Race Mirrors, CF Tank Pad, Shaved Rear Fender, Shaved Front Fender, Nokya Ultra White 5000K Headlight Bulb

(in reply to Hurricane rider)

Post #: 9