Changed the starter motor from the spare bike. Hot cranking problem appears to be fixed. I hadn't balanced the carbies since buying the bike and rebuilding them. Thought I would have a go and make my own device. Worked a treat. The carbs were way out. It now idles and no more flat spots. For those interested, I used a an old car vaccuum gauge, plastic tubing, and joiners from a wrecked 80s model Mercedes. Photos attached. The wingnuts crush the tubing to seal. Loosen the nut on the carb your testing.
Photos from Keith Williams's post
so gauges r 4 seting the idle?
I bought a carbtune pro, and the principles are the same. Just fancy plastic instead of good handiwork.
And then the test ride.....
quite a clever set up Keith thanks for sharing your ingenuity NICE!
Forgot to mention, you may need to restrict the tube going to the vaccuum gauge to stop fluctuation and get an accurate reading. I just bent the tube until the guage was nearly steady.
was there too much variation among carbs Keith and what could you mend using this method other than idle speed
Fernando, when I had refurbished the carbies, ie. new needles and seats, set the float levels, unblocked some jets and checked all the diaphragms were in good condition, I then set the butterfly's by eye to the same opening. The problem with this is the carbies are held with metal bars but in the process of installing them back into the manifold rubbers they can twist slightly, altering the set up of the butterfly's. Using the device I made, I followed the FJ manual and adjusted the screw between carby 1 and 2 until they gave me the same vacuum reading. Then I set carby 3 and 4 to the same vacuum reading. (you may have to alter the idle screw during this process to keep the correct engine speed) Then you adjust the screw between carby 2 and 3 to get all 4 reading the same vacuum. I had to repeat this step a few times to fine tune the setting. Providing mixture screws and other parts of the carbies are ok, all 4 cylinders should be receiving the same fuel / air volume. This should give you a smooth idle and better throttle response from idle.
thanks for such complete explanation now I'm expecting no troubles doing mine (lets hope)
when i first got my fj,i striped carbs,cleaned n fitted,i couldnt get her over 4 rpm,i striped carbs again n found the jets in the bowls,i had 4 goton to tighten them,i was amazed it even reved to 4g,now she reves to redline:),just gota sink them,great advice guys keep it up.....rite:)