pateli

My 1981 CB750 DOHC is running with the No.Cyl much cooler than others.New plug fitted Carbs Cleaned and balanced. There is a good spark with the plug removed and earthed.Any suggestions re checks appreciated. I am new to Jap bikes due to non kick starting right leg. I am still hav.ing problems with this bike. I have done a compression test all 4 cyls 125 to 150 psi.I have replaced the Ign coils. Tried to tune carbs using a colortune and found 3 of the pilot screws seized and 2 botched the jet body broken and filler repaired they are beyond repair.The Carbs on the bike are VB52A with Primary jet 68 secondry 75.I have been given a set of VB42A carbs Pri 68 Sec 102 (With Accel pump not on VB52A supposedly off a running bike) I fitted them as I got them but the bike would not run properly, spitting and Backfiring.Could I rejet them as the 52A is P68 Sec75 or should I canabalise the 42 and replace the damaged 52s. Any suggestions will help as I am missing out on some lovely runs. On Checking Valve Timing I find that With the dots on Cam sprockets lined up with cyl head and Cams facing Plugs the F in ATU is lined up not tht T as specified in the manual any easy way to reset

smiff95

Is the compression similar across all the cylinders?

pateli

Sorry for delay I was involved in other Things. The compression is between 120/150psi. I have decided to start from scratch so off came the Rocker cover The Valve clearances were good but I find when checking Valve Timing that with the Dots on cam sprockets the timing mark in the ATU is at F not at T as Manual says I reckon that I am out a tooth or two How can I reset them to Spec.

pateli

correction Wit Dots lined up with Cyl Head surface the Timing mark is at F not T