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Allison's 81 "Ole Paint"
- Thread starter gggGary
- Start date
With the stock airboxes back on it's running as good as it gets on an XS650. Smooth steady idle and then all the way to redline no burbles or flat spots. Funny how the factory seems to have had things tuned pretty well. The only change from stock in the carbs now is up from 132.5 to 135 mains. It'll slip the clutch hitting 5 grand going hard up a hill but don't need to worry about that either for now. Gotta try the ippytattoo 8 plate conversion one of these days. Some sidecover grommets and I'm done. Put one those handlebar voltmeter, usb ports on and it's idling at almost break even about 12.6 volts and a steady 14.7 once moving. stock electronic regulator, etc. May check that H4 bulb to see what wattage it is. It was idling for 15 20 minutes while tuning this morning with no problems.
Luv that rotor swap - very innovative! Strip the black paint off that caliper to really show it off - you'll be surprised how much it "lightens" the look!
Gary quote:
" Funny how the factory seems to have had things tuned pretty well"
I find it completely normal that these bikes run really well, when using stock air box, stock jetting, stock exhaust, stock alternator, etc.
Compare that to all the threads on here, in which pod filters, after market exhausts, larger jets, and PMAs are installed, and the result is months and months of attempts to tune the engine, and some never succeed at getting a smooth running engine.
I think the Yamaha engineers knew a lot more about engine combustion air flow and tuning than the average biker on this site.
14.7 volts is a little too high. It will boil out the battery electrolyte over time. Yes, you could try a higher wattage head light to lower that voltage. 14.1 volts is where it should be in a perfect world.
" Funny how the factory seems to have had things tuned pretty well"
I find it completely normal that these bikes run really well, when using stock air box, stock jetting, stock exhaust, stock alternator, etc.
Compare that to all the threads on here, in which pod filters, after market exhausts, larger jets, and PMAs are installed, and the result is months and months of attempts to tune the engine, and some never succeed at getting a smooth running engine.
I think the Yamaha engineers knew a lot more about engine combustion air flow and tuning than the average biker on this site.
14.7 volts is a little too high. It will boil out the battery electrolyte over time. Yes, you could try a higher wattage head light to lower that voltage. 14.1 volts is where it should be in a perfect world.
Yup H4 bulb in the retro headlight is an automotive 55/60 watt, stock is 40/50 will replace it with a lower wattage MC bulb, that should help with the low reading at idle. Thinking I will check and maybe parrallel the VR sensor (hot) wire so that the VR sees "true" battery voltage. Basically look to see what wire has what voltage when it's running. Then the usual ground checks etc.. Some component wires and plugs are pretty sketchy yet.
I still have the plugs in my pilot screw holes, which I'm pretty smug about. The factory spec charging voltage is 14.5 +/- 0.5v .
I would not be concerned with 12.6 volts at idle. These bikes have no need to charge at idle, or have voltage higher than 12.6.
Its that 14.7 volts that needs to be lowered, so lowering head light wattage would be the wrong way to go IMHO.
Its that 14.7 volts that needs to be lowered, so lowering head light wattage would be the wrong way to go IMHO.
Hey xj.......................I like a man that is a contrarian! Congrats on shunning the view point that the metal plug must be removed, and staying with the stock mixture screw setting.
That factory spec of 14.5 +/- 0.5 volts is wrong. The engineers at that time in history may have believed it, but its wrong.
14.1 volts is the target to aim for. 14.5 volts would be the upper most limit, and even 14.5 volts is hard on batteries.
I'm going to be contrarian about the charging voltage too 
But if you're compelled to lower it... dragging it down is the wrong way to go; if successful it has to be a strain on the charging system. Best thing to do would be change the voltage being sensed by the reg/rec. Probably put a trim pot wired like a voltage divider somewhere. Output is higher the lower the green wire is. I have a high wattage headlight that doesn't seem to affect the voltage. P.S. I know 14.6v is correct for cars. If you don't see that, something is wrong. Often a jammed up brush.
But if you're compelled to lower it... dragging it down is the wrong way to go; if successful it has to be a strain on the charging system. Best thing to do would be change the voltage being sensed by the reg/rec. Probably put a trim pot wired like a voltage divider somewhere. Output is higher the lower the green wire is. I have a high wattage headlight that doesn't seem to affect the voltage. P.S. I know 14.6v is correct for cars. If you don't see that, something is wrong. Often a jammed up brush.
While I agree with you that an xs ran well from factory stock. Many people have successfully ran pods, rejetted carbs, changed up exhaust etc without months and months of troubles. You don't read about it because there aren't success story threads on here, just help needed threads. I'm only posting this for the passerby reader, it can be done with some research and know how.
^I haven't done this much, but mine runs as well with no filters as it does with stock filters. So if pods are between the two in flow I doubt they'd be a problem. I have not run it without exhaust pipes, so I can't say what exhaust is ok
xj quote:
"P.S. I know 14.6v is correct for cars."
I guess we'll have to agree to disagree. My Toyota Camry charges the battery at 14.1 volts during a short interval after starting the car to replenish the battery from the large current drain of starting, and then lowers the voltage to 13.5 to 13.7 volts on a longer trip. I've used a regular lead/acid battery and an AGM battery. They both work very well with this type of charging.
My XS650, controlled by a VR-115 regulator, is always at about 14.2 volts. The starter motor has always started the engine perfectly for 10 years now.
14.0 to 14.5 volts should work well for most people, but its best to stay in the 14.0 to 14.3 range.
"P.S. I know 14.6v is correct for cars."
I guess we'll have to agree to disagree. My Toyota Camry charges the battery at 14.1 volts during a short interval after starting the car to replenish the battery from the large current drain of starting, and then lowers the voltage to 13.5 to 13.7 volts on a longer trip. I've used a regular lead/acid battery and an AGM battery. They both work very well with this type of charging.
My XS650, controlled by a VR-115 regulator, is always at about 14.2 volts. The starter motor has always started the engine perfectly for 10 years now.
14.0 to 14.5 volts should work well for most people, but its best to stay in the 14.0 to 14.3 range.
How the floatbowls are vented is a factor.
Vented to the outside, or vented at the carb inlet...
Will need to do a bit of checking against this meter to see how it agrees with others, it for sure has some lag. Meter circuitry seems like it samples at a low rate or has a built in delay, perhaps some sort of stability algorithm. The meter voltage reading with the bike off and at low charge does seem to be spot on. Allison is not a distance rider most trips are to work and back a scant 4 miles 10 or 12 minutes each way with some city streets and idling, so 14.6-7 volts will not hurt for that use. I don' think I can change the higher engine RPM voltage by adding load without creating more problems than I solve. As mentioned a check that the VR and battery share ground and +12 on a common plane seems like good technique. My 79's with factory mechanical regulators that I can easily ADJUST as needed seem so elegant.....
Thought this looked neat.
poor pic, "chrome" 3d tuning fork from fleabay
http://www.ebay.com/itm/Motorcycle-...3D-Decal-Stickers-Set-For-Yamaha/252557166281
Thought this looked neat.
poor pic, "chrome" 3d tuning fork from fleabay
http://www.ebay.com/itm/Motorcycle-...3D-Decal-Stickers-Set-For-Yamaha/252557166281
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That is a nice little emblem, but I'd say that the chrome could use a little AutoSol polish and elbow grease Gary.
Hey, I can admit when I'm wrong (at least when nothing's at stake). My info came from an old owner at an auto electric shop, and it's possible he was talking about my model of car specifically. He was adamant about 14.6. Anyway, when then spec says 14-15 volts, I'd be satisfied with the spec personally. As we already concluded, after all this it's surprising how well factory spec works. If I was tweaking a charging system to remove a couple tenths of a volt I'd think something might be wrong with me.
Not my job..... and it's not her style...
With the final mods, the carburation passed the "Allison test" this morning with flying colors. Choke on, start, let go of throttle, choke in to 1st detent, walk away to "suit up", come back, choke to off, all without touching throttle again, helmet on, in gear, ride off, stop at end of driveway clutch in, NO throttle, wait til traffic passes and off she goes through the gears without a hiccup or burble. SWEET!
PS this gauge is wired directly to the battery, not tied into a stock wiring, after the ignition switch, down to the fuse box, back to the headlight bucket, sharing voltage with other loads.....
Gary, those 3D Yamaha decals would be great for adding a bit of extra style to seat and fairing plugs if you are into making your own fibreglass parts.
