Ok so heres the story, I have a 1987 cbr 600f. I bought it about 3 months ago it ran great. I rode it with no problems for about 2 weeks, then one day I pull it out of the garage and all it does is turn over. Finally after about 15 mins of trying to start it it fires but the throttle is wide open and its only running at about 1100 rpms. I slowly back out of the throttle and it starts to rev. I get it revving good and all take off down the road it starts spitting and backfiring, going back to only running at WOT at around 1100 rpms. I let it sit for about 20 mins and try again its runs normal, so I rode it all day that day with no problems. I park it for like 3 days and now it wont start at all. I sprayed it with ether and it wouldnt fire so I went to checking the ignition. No spark at plugs, I bought coils off of ebay replaced them still nothing. I checked all my fuses including main fuse, ive checked all connections that I see. Ive checked the blue and white wire on the CDI and the one right below that one(cant remember its colors) I also checked the killswitch on the handlebar. I checked these with a test light is that sufficent? Sorry for such a long post I just wanted to give as much info as possible. Any help would be greatly appreciated.

Brandon

 

How is the battery? These issues could all stem from too low voltage. The voltage regulator/rectifier is a weak link on these old girls.

 

The battery was brand new when I got the bike (I put the acid in it myself) I hooked a booster to the battery to try to get some spark because I read that if the battery was low it would turn over but not fire. Is that enough to produce a spark or does the battery its self have to be at proper voltage also? The R/R is what actually keeps the battery charged? As in I have a bad R/R and the times it would start was times that the battery was still good and over time the battery run down from the R/R not charging? Im sorry for all the questions but I know nothing about electrical. Thank you thrasher for your reply I hope that we can trouble shoot this.




(waiting on the purists)

 

If the charging system is not functioning correctly, yes the battery will run down. The battery will supply the bike with enough power to allow it to run until the voltage drops too low. The regulator/rectifier is the component that changes the alternating current produced in the stator into direct current and limits the voltage to prevent the battery from being overcharged. Failures of this component can result in too much charge getting to the battery and cooking it or not enough and it allows the battery to run down.
The best bet is to get the battery on a charger. Fully charge it and make sure it will hold the charge. Measure the voltage...should be around 12.5 to 13.1. Start the bike and see what kind of voltage it is putting out. If it is charging the voltage should rise. Starting out with a dead battery is a great way to burn up the new R/R. Hope this helps.

 

Will do! I will keep you updated on my findings. Thank you.

Brandon

 

Ok so a buddy of mine took my coils to work with him and tested them. One has a short and the other one has no resistance(these were the ones I bought off ebay) He also to the coils that were one the bike to begin with both show having shorts in them. So with that being said im going to return them to the guy I bought them from and get my money back. Now I will try to find some more coils and see if that fixes my problem. Will post back when I get more in to see if they work.

Brandon

 

The normal resistance of the coil is 0.1 to 1.0 ohms. I hope your friend is not calling a reading in this range a short.

 

Thrasher572 is right on the mark. Unlikely that your coils just all of a sudden went bad. More likely that the R/R is toast or the connections/connectors. You have to remove the gas tank to get to the connectors.

 

Thanks Billistic the coils didnt all of a sudden go bad they were showing signs of going bad around 2 to 3 weeks after I bought it. And The guy that actually tested the coils has been doing working on cars and bikes for around fourty years so Im good with his judgement. In my first post i wrote of the symptoms that lead me to believe it was the coils. He tested both sets ,Both sets bad. so it wasnt really an all of a sudden thing it took about 3 weeks of me riding it after the first symptom. I will check and replace R/R if need be.The R/R is between the coils correct? Thank you for your reply billistic

Brandon
ps now that I read that back through it sounds kind of mean. No offense meant.

 

usualy coils are good or bad, no imbetween. you need to get a voltmeter and test the charging system. check the voltage with the bike off at the battery, you need a minimum of 12 volts. then check the battery with it running, it should rise to 13-14 volts as you rev it. this is the easiest thing to check first since all you need to do is pull the seat. the r/r is between the coils, but the electrical connectors for it are under the tank. you can unbolt it, and block it up with a peice of wood if you dont want to completly remove it.