RD400 Daytona Special - Ran Reverse

[KANDY]

Hi All,
My RD400 - 2R9 Daytona special was not running right, dont want to pass 4000 RPM or very sluggish when try going 4000 and above. And when I started today - it wanted to go reverse. I checked the timing with timing light and seems to be 2.0. I checked only left cylinder. Could you guys put some lights on what could be wrong. It has Yamaha Factory CDI ignition all originl parts. The Idle RPM I have to set it near 2000 for the bike to idle. When it was running fine few months ago, the idle was below 1500.
Best Regards

[m in sc]

kick it harder on startup. ive had that happen and it blew the Kickstarter right out of the motor. this was on an early mzb, now vape. also why they now have ramped and longer triggers on the flywheels. you -sure- the rotor didnt slip?

[SoCal250]

I've never heard of an OEM ignition starting in reverse, but I suppose it's possible with the right conditions. As Mark said, I would double check your ignition timing. Spec is 2.0mm BTDC

Why have you set the idle so high? The factory spec for the 3J7 is 1100-1200 rpm. But that's another issue and not related to your power loss or running in reverse.

[m in sc]

i think hes saying has to be at 2k or will die. ie: clogged pilot circuit (would be my guess)

[350GUY]

Check your timing.
It's too advance.....

[KANDY]

i think hes saying has to be at 2k or will die. ie: clogged pilot circuit (would be my guess)

Pilot checked, looks clean

[KANDY]

Check your timing.
It's too advance.....

That was the first guess. I looked few times. The mark on the stator match at the small line on the Rotor at 2.0BTDC(Left Cylinder),
that means once the line matches, Piston still go up 2.0 on Dial Indicator. Need to check again I guess. How do I make sure Right Cylinder also spark at 2.0 BTDC, since there is no mark on the rotor.

[SoCal250]

Why is the idle set at 2K? If it's because it won't idle below that, then you have a problem. How did you verify the pilots "looked clean"? If it's been sitting like you mentioned, it's highly likely that the carbs are a little gummed up.
I would suggest disassembling the carbs and thoroughly cleaning the jets (including removing the needle jet from the body) and all passages. Then make sure the floats are set at 21mm (+/- 1mm).
Then set your idle at ~1200 rpm.

Then focus on your possible timing issue (if you have one). Double check with a dial gauge that the static timing is set correctly at 2.0 BEFORE TDC. Once you've verified the timing marks are correct, then start it and using an inductive timing light verify the timing is correct while running using the marks.

[350GUY]

Check your timing.
It's too advance.....

That was the first guess. I looked few times. The mark on the stator match at the small line on the Rotor at 2.0BTDC(Left Cylinder),
that means once the line matches, Piston still go up 2.0 on Dial Indicator. Need to check again I guess. How do I make sure Right Cylinder also spark at 2.0 BTDC, since there is no mark on the rotor.

Your issue is with the ignition. Verify your timing with a timing light.
If your timing is spot on and still having the issue, then check your woodruff key. Also make sure your stator plate, pick-up coil etc. is properly tightened.

[KANDY]

The bike was running as it should a month ago and was not having any issue. It happened two days ago when a buyer tested the bike, I was devastated to find suddently this issue started. I took a round to show the bike but when he did a spin it stalled and then all the above issue mentioned started.
I dis assembled the carb, removed the pilot and checked today. My guess is the ignition only, I took the rotor out and put it back today, everything is tightened good. Is there any chance something happened to the crank that the right cylinder is firing too retarded which is preventing the idle to stay low.

[m in sc]

no ont he crank q.
check the ign w a timing light.

[KANDY]

Checked the timing again and again, 2.0. I tried 1.8 also still the issue persists.
It kicks back so hard that my right leg is in pain. This is what I observed, when I kick, the rotor going anti-clockwise as expected, but if it did not start, the rotor bounsing back clockwise enough to give a spark and start in backward. Any advise is much appreciated.

[scully]

Have you tried new spark plugs, I've seen where iffy plugs can fire late and even cause backfires... Just a thought.

[DesmoDrew]

  45 year old electronics are 'iffy' at best.  Stuff breaks down internally.  "Everything looks good":  what does an electric current 'look' like?  Swap out for a VAPE or HPI.  Put the original parts in a bag and sell with the bike.   
   Most Carb issues are really Ignition issues.

[1976RD400C]

Checked the timing again and again, 2.0. I tried 1.8 also still the issue persists.
It kicks back so hard that my right leg is in pain. This is what I observed, when I kick, the rotor going anti-clockwise as expected, but if it did not start, the rotor bounsing back clockwise enough to give a spark and start in backward. Any advise is much appreciated.

If it's doing that, it must be too advanced. Maybe the CDI is misfiring and sparking when it shouldn't???