QuestionI have a 1982 honda cb 750 engine in my chopper and I am wondering why it is so hard to start on cold days. If it isn't warm enough outside it just plain won't start. Is their anything I can do or is their an underlying problem with this. The engine is a stock engine the only difference being the Dyna 2000 electronic ignition and dyna coils I have added. Any advise would be greatly appreciated.
Thanks
Cole
AnswerCole, is this a correct DOHC 750 Honda engine from 1982? The carb rack has a choke function, of course, and sometimes the cable slips from its correct position and the engines don't get enough choke to fire up. Your mention of the Dyna ignition and coils puzzles me as the DOHC engines had a transistor ignition system, with magnetic pickups on the left end of the crankshaft.
If your ignition is on the right side, then it is a SOHC engine with a whole different set of carbs on it. Those carbs just have a choke lever on the left side, which connects all the choke plates together. You can look down the carb throats with the air filters off and watch the chokes open and close, to be sure that they are all closing at the same time. Of course, all the idle jets must be open and air/fuel passages clean. Current alcohol fuels tend to separate within a week or two, when sitting in the float bowls, which will aggravate the problem a lot.
In either case, even with a stock engine, you have an altered air filter and exhaust system, which generally means that you will need to rejet the carbs. You may have to bump up the idle jet sizes one step to compensate for the changes from the stock settings. Richen up the idle mixture settings about 1/4 turn and add a little to the main jet sizes. In some cases, the needle settings may have to be altered, which can be a challenging task on some styles of carbs.
SOHC engines were built from 1969-78. DOHC engines were made from 1979-82. They are worlds apart in design and details.
Non starting engines need to be checked for the basics.. Compression (check valve adjustment), spark at the correct time and air/fuel mixtures at correct proportions at all throttle settings.
Stay with stock spark plug heat range settings.
If the engine compression is low, they will be hard to start when cold, plus the other things to consider during idle/starting conditions.
I don't know where you are and how cold COLD is, in your current environment. If you are around freezing temps, air cooled engines get pretty cranky starting and warming up quickly.
If you don't know the history of the engine, there could be other issues, like cam timing incorrect, air intake manifold leaks, etc.
Bill Silver
