71' R5350 Is Electrified

[R5HiFive]

Hi there,
This will be my first post on this forum - happy to be here.  I have a few questions that when answered should leave me with a pretty solid R5.  Pics to come for you fine folk.
I have a 71' mostly stock R5350 that recently I've starting running & riding again - the catch is that when the bike has warmed, after roughly 10 minutes of riding, it will cut out and struggle to start again.  Recently this has been paired with a pretty nasty shock when I touch the metal of the bike, for instance when reaching to turn off the fuel - hurts. 
Wonder if anyone might have some input on this grounding issues I seem to be having?  Overheating coils? 

More importantly, possibly, is that I am running premix with a oil pump deletion - I may be running to lean as I have stock carbs and now oil in gas.   Should I increase from the pilot jet #40 and main jet #110 I currently have?  I can't seem to find larger parts readily accessible.

Thanks a bunch,
I'm enjoying exploring the forums,
Cheers - Tommy

[1976RD400C]

The only thing I can think of with the shock from the petcock is one of the spark plug wires is shorting/arcing to the gas tank, up under the tank where the coils are. Since the tank is rubber mounted, it is still letting the spark plug spark, but when you touch the petcock, zap. That may have something to do with the stalling problem too. There shouldn't be a problem to find a bigger main jet if you want to try that to see how it runs.

[m in sc]

welcome!
yeah that shock from the petcock is.. unsettling to say the least. I'l be honest, these days i usually just change the coils and wires and caps to new ones on any new project. I agree, sounds like ones arcing out tot he tank.

are the coils stock? or are they aftermarket ones? this def needs to be addressed.  I foyu look at the tech section, the sv650 coil mod is an option, or new ones from john at economy cycle .

as far as jetting, you can go up to a 115~120 main. as far as the pilot, its fine.   I m going to assume the air filter setup is stock? if its not, then you definitely have to re-jet.

jet link at economy (use pulldown to choose size):

https://www.economycycle.com/shop/yamaha-rz-350/fuel-and-airintake-yamaha-rz-350/carburetor-rebuild-kits-parts-related-fuel-and-airintake-yamaha-rz-350/jets-yamaha-rz-350/jets-mains-sold-each-test-product-do-not-purchase/

coil & wire package (direct bolt in):

https://www.economycycle.com/shop/yamaha-rd250350400r5ds6ds7-parts/electrical-ignitions-lighting/ignition/replacement-ignition-coil-kit-rdr5yds67-coils-caps-wires-for-rdr5yds67/

[R5HiFive]

Thank you both very much! The links are helpful, m in sc.  The coils are aftermarket & have been sitting on the bike for years now without use.  I may find replacing the spark plug wires and plugs as being beneficial.   
The problem is definitely not present before the bike warms.  I thing recently I ran into a fuel issue as I tried a 20:1 premix ratio.  Maybe I'll stick to a thinner 32:1 or consider a larger pilot to see if that makes a difference. 

Thanks again,
-Tommy

[R5HiFive]

are the coils stock? or are they aftermarket ones? this def needs to be addressed.  I foyu look at the tech section, the sv650 coil mod is an option, or new ones from john at economy cycle .

coil & wire package (direct bolt in):

https://www.economycycle.com/shop/yamaha-rd250350400r5ds6ds7-parts/electrical-ignitions-lighting/ignition/replacement-ignition-coil-kit-rdr5yds67-coils-caps-wires-for-rdr5yds67/
[/quote]


I have a set of original coils with original wires and caps - Are those of the resistor type?   I have that aftermarket coil you linked; would matching those coils with stock spark plug wires pose an issue? (Assuming the wires are not defective)

[m in sc]

stock caps are resistor type, yet. however being as old as they are i'd never trust them.

if the aftermarket coils are the round style make sure the leads *& connectors arent arcing to the bottom of the tank.

32:1 is fine, even 40:1 is fine. 20:1 is a bit steep for a stockish street bike.

the 'after the bike warms' dying issue can also be electrical. how is the voltage when its running at the battery? check charging voltage at 2000 rpm.

[R5HiFive]

Voltage at 2000 is about 13.6 volts.  Doesn't exceed more than 13.8 when revved to 4000.  Stock rectifier/regulator.  I have an aftermarket combo that I've been meaning to slap on.  The wiring harness looks beautiful under the tank - will run the bike with an auxiliary tank and watch for arching.
I'll stick to 32:1.  That left my plugs looking pretty, pretty...pretty nice and tan! 

[m in sc]

perfect. thats good.

also verify the gas tank is venting air when its running thru the cap. if thats clogged will cause the motro to starve and die. unlikely, but it if was ever lined or sealed with a kit, and they didn't cover the inside of the fuel cap, this is likely. Easy to check.. just look at it.

Its rare, but ive seen it.