1976 XS650 restoration and rebuild, advice and help welcomed!

Hello everyone, after a month in or so a quick update. Funny story. By luck one day a few months back on a flight, I was exiting the plane in San Francisco. A guy tapped me on the shoulder. He had seen me reading 'Motorcyclist' magazine on the flight. Turns out, he is the publisher! So we exchanged cards. Turns out their office is coasting distance from my own. They were eager to learn about the old bike I was working on, and have been very gracious with some old back issues of Cycle World, featuring the XS650 back in the day!

Long story short, another gentleman from his group and I spent a little time syncing the carbs over the weekend. Big improvement, more top end, smoother idle, and rev up to speed. So the 76' is running pretty happy. Once she's warm...

Has anyone ever encountered this, or have a suggestion? This works everytime, so at least that;s good. From a 'cold' (65-70deg ambient temp) in order to start the bike, I need to turn the idle adjustment screw ~1.5-2 turns. The bike starts, and I back it back down to an idle speed of ~1200rpm.

My starting procedure:
1. Fuel on
2. Choke on
3. Turn Idle Screw in
4. Kick over the motor
5. Turn choke off
6. Starter button > Fire

2 things. Once the engine is warm, I can hit the starter and she goes right away. When on a cold start, the choke doesnt seem to have much function.

If there's any wisdom out there, I am all ears! Thank you all!
 
Let me see if I am understanding what you're saying. Are you saying that it is cold blooded and difficult to get running right when it's cold but after it warms up things improve?

If so, I can tell you that several of us are right now experimenting with different jetting to rectify a lean condition. You can read my experience here. Post #847 and #867

http://www.xs650.com/threads/my-60th-birthday-present.47639/page-43

PS. Who are the guys you met at Motorcyclist? I've been reading those mags forever
 
You shouldn't need to turn your idle speed up like that every time you go to cold start the bike. Here's how I cold start my '78 - choke on, hit the button, roll the throttle open a hair to keep it running once it starts. I actually hold it open a little and apply a couple small throttle blips at the same time. This seems to help get it going. Within a very short time on warm days, say 10 seconds or so, the motor will start "8 stroking" (running rough) and that's my cue to turn the choke off.

Finding the perfect idle speed setting for these (not too fast hot, not too slow cold) can be a bit of a chore. It's a shame to go and change that setting every time you cold start, and you shouldn't have to.
 
Let me see if I am understanding what you're saying. Are you saying that it is cold blooded and difficult to get running right when it's cold but after it warms up things improve?

If so, I can tell you that several of us are right now experimenting with different jetting to rectify a lean condition. You can read my experience here. Post #847 and #867

http://www.xs650.com/threads/my-60th-birthday-present.47639/page-43

PS. Who are the guys you met at Motorcyclist? I've been reading those mags forever
Thank you Mailman. Yes, youre correct. Fires up easily when warm, but cold is a bit more stubborn. I'm going to dive into your post on the lean condition... Much appreciated!

Initially I was thinking I could have an issue with the Enricher / Choke passages. (page 13 on the trusty Carb Guide).
 
Last edited:
You shouldn't need to turn your idle speed up like that every time you go to cold start the bike. Here's how I cold start my '78 - choke on, hit the button, roll the throttle open a hair to keep it running once it starts. I actually hold it open a little and apply a couple small throttle blips at the same time. This seems to help get it going. Within a very short time on warm days, say 10 seconds or so, the motor will start "8 stroking" (running rough) and that's my cue to turn the choke off.

Finding the perfect idle speed setting for these (not too fast hot, not too slow cold) can be a bit of a chore. It's a shame to go and change that setting every time you cold start, and you shouldn't have to.
Thank you 5twins, the procedure you've outlined feels pretty familiar. I think I had successfully done something similar unknowingly on occasion or two. I'll follow it to the letter and report back.

@robinc As for the link to Paul Sutton's tip. HOLY SMOKES that is brilliant!!!! Good grief, that is a slick way to skin the cat.
 
For my '80 and '83, I have found the 5T method :

"Here's how I cold start my '78 - choke on, hit the button, roll the throttle open a hair to keep it running once it starts. I actually hold it open a little and apply a couple small throttle blips at the same time. "

to be effective every time. I believe that I found this out thru progressive experimentation.
 
Yes, the couple small throttle blips "nudge" the RPMs up a bit for you so it stays running, then holding the throttle cracked a hair after that keeps it that way. These are very small blips, just little "bumps" really. The bike won't take large throttle blips or openings when cold.

These bikes usually start pretty easily when cold - if your chokes are working. If not, they can be very difficult to start cold. Are you certain your choke jets are clean/clear? The chokes won't work if they're plugged. Here's how to check them .....

IzS1tsu.jpg
 
This method probably came naturally to me (old neural pathways becoming re-awakened), having to start my old VW bugs and Ghias in years past with that method. The chokes in those Solex carbs had a heater filament like a hair dryer in them, and they would often burn out or malfunction.
 
When I bought my 1978 SE XS650 about 10 years ago, I just started using the the same starting procedure, that I did back in the 1970s and 1980s. Back then I had a 1976 XS500C, which I had bought new. Same Mikuni carbs.
1) turn on petcocks
2) turn on choke
3) key ON
4) kill switch ON
5) push the black button
6) engine starts
7) about 10 seconds later I turn the choke off, and at the same time I turn the throttle speed screw up about 3 partial turns.
As I am putting my ear plugs in, coat on, opening garage door, etc. the engine rpm starts to rise toward 1500/1600, so I adjust the
speed screw to lower the rpm back to 1200.

I can drive away, and as the engine gets hotter, at the next intersection stop the rpm will be up to maybe 1400, so I will again adjust the speed screw to lower the rpm to 1200.

GeorgeOC.....................you don't want to turn up the idle speed screw before the engine starts, because that would make the starting mixture too lean which defeats the purpose of the choke. You must leave the choke ON as you start and for about the first 10 to 12 seconds. You need that rich mixture when starting a cold engine.
There should be no reason to kick over the engine prior to using the electric starter. Your bike never needed that done when it was new, so why would you need to do that now? If the electric starter seems weak, you need to identify the problem. Your starter motor is in fact a "load test". If the battery is old it may not have the capacity to put out the amps required. Also the large cables from the battery + and - must have clean metal to metal contact. The other reason could be that your charging system is never reaching 14.1 volts. If it never attains 14.1 volts then the battery will never be fully charged. A charging system that only gets up to 13.5 or 13.6 volts will leave the battery in a weak state.
 
RG, when is the best time to check that voltage? After a little ride, to see if the battery is left with adequate charge?

Thank you for the advice!
 
RG, when is the best time to check that voltage? After a little ride, to see if the battery is left with adequate charge?

Thank you for the advice!
Start your engine and wait maybe 3 minutes. Rev up to 3500 to 4000 rpm and you should see 14.1 to 14.5 volts. If your battery is presently not fully charged, then you should use a bench charger and charge it for 8 to 10 hours, prior to testing it on the bike.

Remember its of little value to measure voltage of the battery when the engine is shut off. The only way to know if a battery has reached fully charged is to do a "load test" where a large amp draw occurs. Also specific gravity can be measured on a wet lead/acid battery.
Places that sell batteries can do a load test using a high wattage resistor to simulate a heavy load. But our bikes have a built in load tester, its
called a starter motor. A strong fully charged battery (of the correct size) will crank and start your engine with no trouble at all.

Another simple test is to watch the battery voltage as you push the start PB. Connect your digital VOM across the two battery terminals, selected to the low voltage scale of 20 volts. Then carefully watch the voltage scale on your meter as you push the little black button. The battery voltage will quickly show a lower voltage, but it should not go below 10 volts. A failed battery might show 7 to 9 volts.
 
Back
Top