[[email protected]]

I've had my 71 CB450 running and on the road for about 3 weeks now and could never seem to get it running perfectly. I've been tinkering with the timing and got it to run the best I can but got tired of the popping coming out the right exhaust and lack of power. A buddy of mine just did an intake and exhaust and power commander on is Grom and he's leaving me...... Just embarrassing, I know.

When I took the timing plate off the points and the stater cover off I began turning the engine over by wrench just to see when my spark was STARTING to hit. It hits about mid way through the compression stroke. I sat for about an hour trying to adjust and flip the advanced timing gear for craps and giggles, but nothing I can do at the points will let it FIRE when it's supposed to. The lobe starts OPENING the points at the point where I should be CLOSING the points. Like an idiot I forgot to snap a few pics of the points and advanced gear, but I do have my timing marks.

LT on my Stater: (dead on)

Timing Mark Exhaust Cam: (mark on the cam is slightly over the mark on the block)

Timing Mark Intake Cam: (mark on the cam is slightly under the mark on the block)

NOTE***** The advanced timing unit looks to be good. The marks all line up and I'm 100% sure it isn't 180* out.

If anyone can help, I would greatly appreciate it. Are you able to set timing without pulling the engine? Also, you're supposed to check timing at LTD at the end of your exhaust stroke and before the intake stroke correct?

 

[76TWIN]

Timing is checked at LF (Left Fire) and RF (Right Fire) not LT (Left Top dead center) or RT.

 

[76TWIN]

Also I can't really tell with the small pics but it looks like your cam timings are off by quite a bit. It doesn't take much for ignition timing to be all out of whack when your cam timing isn't spot on.

 

[[email protected]]

Timing is checked at LF (Left Fire) and RF (Right Fire) not LT (Left Top dead center) or RT.

engine timing. not ignition timing

 

[[email protected]]

pretty sure you use LT to make sure your cam chain and timing are good. I brought that up because the lobe for the ignition timing isn't lining up properly for spark. I know I use LF and F for ignition timing but that seems to be all out of wack. I don't think my tensioner is doing it's job and it skipped a tooth.

 

[76TWIN]

Did you recently do a top end rebuild? If so what cam chain did you use?
Have you checked your cam chain tensioner to see if it is indeed working?

 

[mike in idaho]

Not trying to be a wise-ass here, sort of reading between the lines, you do know the coil fires when the points OPEN, not close?

 

[[email protected]]

Did you recently do a top end rebuild? If so what cam chain did you use?
Have you checked your cam chain tensioner to see if it is indeed working?

Nah I haven't rebuilt it. It sat for 42 years and my grandpa quit riding it because he couldn't get it right either. He passed away 7 years ago so now that I'm older and know what questions to ask I'm pretty much stuck. I don't know what he did with it, all I know is what I've seen and fixed so far. Compression is good and spark is strong. Fuel is good too with me rebuilding both carbs, new lines, and treating the tank. I just have a problem getting the ignition firing just right. I do have Dynatec Coils and condenser. But my issue is at the points and them firing properly.

Not trying to be a wise-ass here, sort of reading between the lines, you do know the coil fires when the points OPEN, not close?

No, you're not don't worry. hahaha

My shop foreman told me they fire when they CLOSE. Like when the points touch. This is my first bike so I could be wrong about that or getting the terminology wrong. I'm no stranger to classics though. My 72 C10 had points and I threw them away and put an HEI in. Haven't seen people having too much good luck with that on this platform so I figured I'd keep the points.

Correct me if I'm wrong, but I thought the points worked as a "switch" to activate the coils to send spark. And for that to happen they need to close, or touch.

 

[FrankyV]

Nah I haven't rebuilt it. It sat for 42 years and my grandpa quit riding it because he couldn't get it right either. He passed away 7 years ago so now that I'm older and know what questions to ask I'm pretty much stuck. I don't know what he did with it, all I know is what I've seen and fixed so far. Compression is good and spark is strong. Fuel is good too with me rebuilding both carbs, new lines, and treating the tank. I just have a problem getting the ignition firing just right. I do have Dynatec Coils and condenser. But my issue is at the points and them firing properly.



Correct me if I'm wrong, but I thought the points worked as a "switch" to activate the coils to send spark. And for that to happen they need to close, or touch.

You are wrong, the opening of the points causes the coils to release their built up electrical charge and fire the spark plugs.

 

[mike in idaho]

I'm guessing your shop foreman probably grew up in the post points era and never had deal with them. They are a switch. The coil is charged up with the points closed, then the points open and a spark occurs when the electrical field collapses. Turn the engine over to where the points are closed, then push them open with the end of a screwdriver, you should see/hear a spark at the plug gap.

 

[[email protected]]

Thanks guys! Yea when I rebuilt my c10 my grandpa took the points out of my big block and said, "you'll never use these." So when I came across them on this bike.......

I thought they worked like on my truck. When they touch, the circuit is completed and sent to the plugs. So I had it backwards?

I still think I have a timing issue with the cams though. I pulled the tensioner off and I think it may be weak. My foreman told me you set the tensioner with the engine running, is that correct? I would have figured to make all your adjustments with the engine off.

 

[76TWIN]

Um no. You should NOT be adjusting the cam chain tensioner with the engine running. Time to get yourself a copy of the factory service manual and stop listening to your foreman,. I don't think he knows these bikes.

 

[76TWIN]

You can find a copy of the FSM here by the way

Manuals and Technical Documents

 

[[email protected]]

Thanks 76TWIN. Yea he told me he told me today that he was wrong and felt bad hahahaha. I had been chasing this for a few hours between jobs then got frustrated and called it quits for the day. I thought my points were the problem when it was my engine's timing.

I couldn't get the timing chain right on the bike so I'm pulling my engine tomorrow. I kept trying to get my cams straight and it would jump a tooth on the crank. Do these things jump time a lot? It's retarded on the exhaust about 2 teeth and on the intake about the same. I never thought to check that when I got the bike. My grandfather said he never could figure why it didn't "run right" so he parked it and it sat until I got hold of it 42 yrs later. I had always thought he had a carb issue, but found out I was wrong....

 

[[email protected]]

Pulled the engine and got it back in time. While I had it out I figured I'd paint the frame. I'm waiting for the paint to dry then I'll give the ignition timing another shot. Can I do the timing with the block and battery? I figured I'd gator-clip the positive to the wire on whichever point I'm adjusting then gator-clip the negative to the case.

 

[76TWIN]

Nope. You'd fry the points that way.

 

[[email protected]]

I'll just wait till I have the bike together then. This weekend I plan on getting it done.

 

[TOOLS1]

You can set the timing that way, you just need to have a light, or buzzer in the circuit to tell you when the points open.
TOOLS