RZ350 tech query...

[pjmcburney]

Been trying to resurrect an '84 RZ350 with some difficulty.


Everything required to run the engine has been reassembled, but apart from a short period on the weekend, it steadfastly refuses to run, again.

Repeated kicking produces (apart from a sore leg) an occasional backfire, and I can hear and see a pop and a bit of smoke every now and then, but nothing to indicate a desire to run continuously.

Major-mechanicals and fuel-wise everything should be fine (as I've installed new pistons/rings and overhauled the carbs), but I'm unsure of the bike's electrical heritage.
Questions:
If the CDI is on the fritz, what are the likely symptoms?
How much spark should be present?
Does battery condition play a major part in how well it will run?
Is timing adjustable and would/could it be out significantly?
What spark-plugs are standard fitment and would new ones help?

As mentioned it did run quite well for ten or so minutes at one stage, which leads me to think I've got a dodgy connection somewhere.
It sounded quite ok actually, was running on two cylinders, revved well, idled ok, produced requisite clouds of blue smoke, and wasn't even leaking anything of consequence.

I can't seem to replicate this arrangement again though, and I'm now walking funny(er) as the kick-starting muscles in my right leg have packed up their bat and ball and gone home in protest .


Any thoughts/info greatly appreciated
Thanks
Paul

[tz375]

In no particular order:

Battery is not required for teh CDI ignition but it is for the power valves. If they happen to be stuck wide open (unusual but possible) that could be an issue

Dead CDI is usually a dead no spark thing. All or nothing as a rule

Timing is not adjustable as suck but the base plate can be slotted to get more or less advance.

Clean plugs are always a good idea but if you are testing for a spark, both plugs must be well grounded. If one is not, it can ground through the CDI and blow it out.

It used to run. Yeah mate. heard that one before.

Could the woodruff key inside the rotor have sheared by any chance? It almost sounds like timing is a mile out of place. Pull the cover and check the timing.

The fuel tap on mine is vacuum operated - no vacuum - no go. I'd pull the vacuum hose and check for leaks. Then I'd pull a fuel hose and apply vacuum to the vacuum port and see if the tap opens.

[pjmcburney]

In no particular order:

Battery is not required for teh CDI ignition but it is for the power valves. If they happen to be stuck wide open (unusual but possible) that could be an issue

Power valve cables aren't connected up at the moment - I've set them to fully closed for the moment.

Dead CDI is usually a dead no spark thing. All or nothing as a rule

Phew - I do have spark, not huge fat spark but spark nonetheless.

Timing is not adjustable as suck but the base plate can be slotted to get more or less advance.

I thought as much. It seems about right, magnets on flywheel pass the pickup just before TDC.

Clean plugs are always a good idea but if you are testing for a spark, both plugs must be well grounded. If one is not, it can ground through the CDI and blow it out.

I'll grab a couple of newies on the way home this afternoon.

It used to run. Yeah mate. heard that one before.

Well... it did go, honest, I was there at the time!

Could the woodruff key inside the rotor have sheared by any chance? It almost sounds like timing is a mile out of place. Pull the cover and check the timing.

Could have, but unlikely. I have no puller for the flywheel so that could be problematic to check.

The fuel tap on mine is vacuum operated - no vacuum - no go. I'd pull the vacuum hose and check for leaks. Then I'd pull a fuel hose and apply vacuum to the vacuum port and see if the tap opens.

Vacuum hose is blocked and tap set to prime.

Thanks TZ for the advice so far. I have some more investigating to do I reckon.


Cheers
Paul

[rngdng]

The 84 RZs are notorious for CDI failures. My 84 would run when ever it felt like it until I bought an 85 CDI box. I swear, it would run perfectly one minute, then die the next. Sometimes it would fire again in a few minutes, sometimes hours. There was a problem with the ignition circuit boards that cause the failure (the boards cracked), and (if that's your problem) it can be temporarily cured with a metal rod and a hose clamp (seriously). You can find articles on the web about it.



Lane

[pjmcburney]

The 84 RZs are notorious for CDI failures. My 84 would run when ever it felt like it until I bought an 85 CDI box. I swear, it would run perfectly one minute, then die the next. Sometimes it would fire again in a few minutes, sometimes hours. There was a problem with the ignition circuit boards that cause the failure (the boards cracked), and (if that's your problem) it can be temporarily cured with a metal rod and a hose clamp (seriously). You can find articles on the web about it.



Lane

Thanks Lane! I'll do a search on the interweb...

I have a known good RZ250 CDI that I could swap to check/confirm - is there a difference between the two?


Thanks
Paul