1971 CB350k3 Ignition/spark advance unit?

[Gyi2os]

I'm beginning to think my ignition/spark advance unit is a culprit to my bike being a finicky little bi8ch lately...

Timings always been a PITA, The bikes run 'good' for a few 100 miles at a time, then everything turns to hell (one cyl drops at various points in rpm range). I've replaced the points+plate already, idle timing is fine, pulls nice until about 5k rpm then stumbles the rest of the way up.

With a strobe, dynamic timing is set at LF and F respectively. When i get 'er around 3k rpm like the manual says, my R cyl. is maybe 1/4 inch behind my L cyl...

Took the points plate off, inspected it and one side seems a hair 'easier' than the other and seems to move a hair more freely.

Trouble is, i can't find a NOS part anywhere. Have any of you had any luck finding a seller for aNEW condition IAU?

Also, i bought a Dyna CDI a while back. Been to lazy/don't want to 'splce it in' unless i have to/kinda wanted to use it on my CL360 instead. Any thoughts on whether or not the CDI would remedy this issue?

 

[Rocan]

no point in a "cdi" on a bike with points...


look at the bore-tech electronic ignition... should cure problems your having but pricy. but HUGE upgrade for the cb350

 

[crazypj]

That's a points or coil problem, not ATD.
If it was points cam not advancing properly it would show up on both cylinders equally.
For only one cylinder to be advancing it has to be in the electrical system.
Check coil voltages when running and primary peak voltage at 3,000 rpm (need a PPV adapter for multimeter)
PPV will be somewhere around 80~150 volts but should be close to the same on each coil.
You also want to check the cam chain tension (and tensioner)
If cam bearings are worn the cam can 'float' chain starts flapping around it will alter timing depending on crank position

 

[Gyi2os]

Rocan, damn $369! that is pricey. That'll be my last resort. Thanks though.

PJ, I'll look into those things, thanks for the help. Will report back in a few days with what i find.
I'm assuming i can find a PPV adapter at most auto parts stores?
I'll re-check cam chain tension. Skrew it, i'll just do the whole 'tune up' again(for the third time) in my manual.
How can i tell if the cam bearings are worn, will i hear a certain sound at a certain speed?

 

[djelliott]

i noticed you mentioned adjusting your timing to the F and LF marks. Those are for setting points gap. You should adjust timing to T and LT. Also be sure you are setting this all up to TDC on the compression stroke. I do agree that it sounds like more then a timing issue though. I had a similar situation and it turned out to be the coils.

 

[teazer]

F and LF are FIRE ie teh time it sparks. T and LT are TDC.

For teh timing to change on one cylinder versus the other is probably a bad coil or connections or points floating on one side. Another odd possibility is a loose cam chain allowing the timning to vary from one side to the other. I'd adjust that first.

If you have a DYNA S set up, I'd fit that and forget points and condensers etc.

 

[Gyi2os]

Yeah, so went through a full tune up again... and a valve was a hair off, the timing wasn't PERFECt but close, cam chain reset properly.

bike was a hair better but not 'good'


Then i used my powers of deduction to step through all the shit i had done to the bike recently... Then i looked at my nice, freshly oiled K&N pods... It was after i cleaned and re-oiled them that the bike started getting pissy... how had i forgotten. Took the pods off... And the fackin' thang ROARS. it pulls great all the way through the power band... with just a slight 'burble?' at over 7 krpm

sorry for the false alarm, though i do still think i might i have an electrical issue just starting to show or it's just lean at te top end, though i did up my mains 10 and shimmed my needles 1 maybe another 5 up might fix it, i'll try that after i 'fix my over oiling of the pods if it still exists. I'll definitely use the above tips to get rid of the last gremlin if the jet increase doesn't do it.