NEW PLUGS BATTERY REPLACED CDI UNIT REPLACED . BIKE NOT FIRING ON CYLINDERS 1 AND 2.FIRING ORDER WAS 1234. WHEN I CHANGE LEADS TO FIRING ORDER 1243 CYLINDERS 1 AND 2 COME ON AND 3 AND 4 GO OFF!
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I have 2002 road star midnight. I lost completely spark on all 4 spark plugs. Before bike was running OK but sometimes on low RPM while idling would skip a firing on a at least one cylinder making spufff like sound. I put new spark plugs, and wiggled a little coil wires. Bike with new spurk plugs would not fire up at all. Checked for spark on all 4 spark plugs - no spark., not even an electrical I lost completely spark on all 4 spark plugs. Before bike was running OK but sometimes on low RPM while idling would skip a firing on a at least one cylinder making spufff like sound. I put new spark plugs, and wiggled a little coil wires. Bike with new spark plugs would not fire up at all. Checked for spark on all 4 spark plugs - no spark., not even an electrical charge going to spark plug. Went back to coils. Each coil (there 2 of them) has 2 spark plug wires and 2 ignition timing signal wires connected to them. I realized that these ignition timing wires contacts are corroded to the point they would not conduct a charge from the distributor to coil. CLEAN ALL THE TIMING WIRES Contacts on the coils. I did that and bike fired up right away and started running much better without sputtering or skipping a cylinder firing. SO DISCONNECT ALL THE COIL WIRES AND BRUSH THE CONTACTS WITH A SMALL METAL WIRE BRUSH.
The firing order for your bike seems to be a secret. I have just spent a quarter hour Googling it and found nothing except information about how the race engine was developed to have uneven firing intervals so it behaved more like a vee-4 engine.
It isn't difficult to discover the firing order for yourself if you don't mind getting dirty, though it could be easier to just ask a good Yamaha mechanic - probably by visiting a dealer.
Remove the spark plugs and turn the engine steadily in the normal direction of rotation. Traditionally the "front" of the engine or number 1 cylinder is at the generator or none-drive end but a few manufacturers do number from the drive end. The alternator rotor is often marked with valve timing information, namely a tdc mark and maybe others.
A hollow spark plug with some tubing glued into it will be a great help. Crypton used to supply one for your purpose with a whistle attached which was most useful. Any cylinder where the piston was moving up with the valves closed would create a whistling noise until the piston reached the top of its stroke.
This won't help decide which cylinder is the theoretical number 1 but detecting and noting the order of cylinders reaching the compression stroke will give an idea of the firing order. It is unlikely to be in cylinder order as that would be difficult to arrange and keep the engine in good balance and would mean making the crankshaft much stronger than it needs to be. Such firing orders as 1 3 4 2 or 1 2 4 3 are commonly used to limit torsional vibrations of the crankshaft.
Check your tank vent. Ride the bike until it stalls, pull over and pop open the gas tank lid. If you hear a "ffffwwwwwah" of air being sucked in when you open the tank, your air vent is blocked. The bike runs great when you start out, but as fuel is taken out of the tank no air can get in to replace it and the tank develops a vacuum.
i would actually replace the caps and leads on side not working, a bad connection may still spark when not under pressure, then test coil before i think about cdi
find a running sr 250 and swop his cdi unit with yours if the bike runs, fine. if not put his cdi back in and try again. if the good bike now starts it will indicate that your cdi is faulty. the cdi is located under the tank inside the frame. don't buy a second hand cdi unless you can test it on a working bike. they are very expensive and you don't want to buy a dud
Hi With Ignition switch off :- 1st Check for bad connections, broken/crushed wires, continuity & resistance between the cap, HT lead, coil, ignition coil primary wires 2nd Disconnect the CDI unit from its connector & check for the same between the loom side of the connector back to the coil 3rd Check coil is earthed
If all OK suspect the CDI unit but double check everything first( there are some more checks as well), as these are very expensive
Ride safe
Bike-Doc
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89 Katana uses two coils, one fires cylinders 1 and 4 together and the other fires 2 and 3 together. It's a waste spark system. So your firing order is either one coil or the other every revolution.
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