Once again it has struck me down. The motorcycle bug. Having bought a new bike brought back the manic interest that had been kept dormant through the rigors of ordinary life. Not only have I been riding the new beauty, but I’ve also resurrected the Beast…
Despite the weather being much nicer than we are used to here in Sweden, I decided to make an effort to get the old CBR 600 running again. After all, we’ve spent a lot of time together and she deserves better than being forgotten in a garage somewhere.
First of all I drilled some holes in the headlight mounts to fit new turn signals. Not only did it work as planned but it came with the positive side effect that the headlight now stays in position which was a problem earlier when I used the turn signals as mounting bolts for the headlight. Then I went for a carb synchronization.
When I started the bike, she roared to life but immediately died when idling or giving gas. I did various tests, trying to increase the idle but she ran rough and died again and again. Having fixed the brakes earlier and done everything except making a new seat to be able to pass her through MOT inspection, this was quite the setback so I decided to do what I always do in this situation: tear down the carbs.
However, this time I decided to go deeper into the cleaning process than I have before, tearing them down completely including the jets. There I discovered that at least three of the four pilot jets were clogged in the center line going along the axis of the jet. No matter how hard I tried to get that out (without having access to compressed air), they remained clogged. I tried letting the jets remain in denatured gasoline for a while, I tried some carb cleaning product, I even went out and bought a small ultrasonic cleaner.
The cleaner obviously made some parts more shiny but what worked in the end was not any fancy technological advances but a good old fashioned “boil them in lemon juice”. That actually removed the clogs as well as get the jets bright and shiny again. Hopefully this will solve the problem of her running rough, and make it possible to do a proper carb sync later on.