Top Speed?

D

DozerDan

XS650 Enthusiast
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How fast does your stock 650 go?

I just recently got the bike running well enough and with good enough tires to take her out on the highway for a distance ride.

I have no problem going 55-65, but much above that it seems like its topped out.

Not looking for a race bike here, but just wondering what the bike should do stock. Around here if the speed limit is 65 you best be doing 75 or risk getting mowed down!!

So far I mainly just keep to the back roads. But would be nice to be able to take the bike places without only doing back roads.
 
>How fast does your stock 650 go?

If you do some searching, about 115 mph for stock. 130 mph or more with mods.

As for me, I'm a chicken. I've gone as high as 95 mph. I don't ride on freeways much, but when I do, 75 - 80 mph on my stock 78 xs650 and 79 modded bobber.
 
DozerDan said:
Not looking for a race bike here, but just wondering what the bike should do stock. Around here if the speed limit is 65 you best be doing 75 or risk getting mowed down!!

So far I mainly just keep to the back roads. But would be nice to be able to take the bike places without only doing back roads.
Click to expand...


I immediately thought, "wow sounds like Jersey." Sure, enough...

Anyway, I have done 65 and never pushed it past that. However, it feels like it has a bit left to go at that point. My engine was also recently rebuilt and isn't tuned 100% yet.
 
These bikes will easily do the Ton. Heck, even my XS500C would do the Ton.

I've had mine up to 90 mph, before good judgement and thoughts of a speeding ticket made be back off.:)

If you can only do 65 mph, you have carb problems (maybe diaphrams not lifting) .................ignition problems................voltage problems....................maybe a little of all 3.
 
retiredgentleman said:
These bikes will easily do the Ton. Heck, even my XS500C would do the Ton.

I've had mine up to 90 mph, before good judgement and thoughts of a speeding ticket made be back off.:)

If you can only do 65 mph, you have carb problems (maybe diaphrams not lifting) .................ignition problems................voltage problems....................maybe a little of all 3.
Click to expand...

New rotor, new coil, new plugs/wires. Carb was just gone through and did the 650 central needles and 42.5 primaries, left the 132.5 mains in. Diaphragms looked good, all passage ways in the carbs are clean and clear.
 
DozerDan said:
New rotor, new coil, new plugs/wires. Carb was just gone through and did the 650 central needles and 42.5 primaries, left the 132.5 mains in. Diaphragms looked good, all passage ways in the carbs are clean and clear.
Click to expand...

Are your air filters clean? If they are plugged up with dirt, it can choke the engine.
 
retiredgentleman said:
Are your air filters clean? If they are plugged up with dirt, it can choke the engine.
Click to expand...

Brand new oem style K&N filters


On a long straight away I did get it to 70 but it was not happy about getting there


How would they not be synced? they are directly connected, both are opening at the same time.
 
DozerDan said:
...
How would they not be synced? they are directly connected, both are opening at the same time.
Click to expand...

That they do. It's the amount that can be different.

There's a screw between them that opens one more or less than the other. They need to open the same amount at the same time, otherwise all kinds of weird things will happen, among the mildest probably some nasty vibrations at speed.
 
Maurice said:
That they do. It's the amount that can be different.

There's a screw between them that opens one more or less than the other. They need to open the same amount at the same time, otherwise all kinds of weird things will happen, among the mildest probably some nasty vibrations at speed.
Click to expand...

Def builds up some vibes in the 65 range.

I did not measure them but upon visual they appeared to be opening at the same time and amount.

Other than the top end (now that I know it should do more) the bike seems runs great since the new parts.
 
I think 75 mph is about 5000 rpm. I'm sure it goes faster than that, but I don't care to. At that speed it's kind of like holding onto the blades of a really large blender, which as we all know is one of its most endearing qualities. I think in the neighborhood of 120 is the actual top end.
 
Step into the wayback machine, mid `70s, when 106-108 octane gas was available, and 130 green avgas:

My stock XS1B would hit 110 mph, took awhile to get there though.
After chopping and 750 kit, would hit 125+, again took awhile, never found absolute top.

Weighed about 155 lbs back then, gasoline was better, roads smoother, less patrolled.

Ah, those were the days...
 
My bike (well, the engine at least) is neither totally stock nor much-modified: intake, carbs, exhaust, PAMCO... Having said that, the bike cruises at 80, and will go 90 while feeling like there's plenty more to go. Of course, I'll echo other previous commenters in saying that I have little or no reason/inclination to find the limit, and 80% of my riding is at 40-60mph.
 
I have run my 79 at 70 75MPH for a 100 or so miles a few times. Last week I found my crankshaft has loosened/twisted and the motor now has to come apart. Related? I don't know, but I am with the general consensus these should "easily" break 90 on the flat and they aren't all that happy doing it.
Compression test then cam chain and valve set, carb and ignition troubleshooting. don't bypass the parts that may take some extra effort or new tools.
 
Back in the day these bikes were said to top end at 104MPH. They all went faster. Any stock XS650 if correctly tuned and in good repair should be capable of 110MPH on unleaded high test straight from the pump. Change the gearing and do a few mods and 120 is not unheard of. Start boring, stroking and doing serious mods and you'll go in excess of 130.

I'm still running 650cc with stock cam and carbs and have no issues with 110MPH anytime I wish. But these things are really contrary and cantankerous and get something just the slightest little bit off and you can lose 20-30MPH off your top end real quick.

That's the main reason I'm considering switching to a single modern carb and dreaming of fuel injection... someday.....
 

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