Top Speed? Best performance upgrades?

warrenlevihursh

warrenlevihursh

XS650 Addict
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I feel like my 81 Café build is down on power after riding my buddies the other day. Granted, mine will do 80mph, but I have a feeling a correct running XS650 should do better then that. My bike is all stock, except with a shortened 2 into 1 exhaust and pod filters. What's the best bang for the buck when it comes to performance, and I don't mean rebuilding the motor or anything?

Also, will anyone's XS do a wheelie? Saw a Dime City picture of a CB550 Café doing a wheelie. I don't think mine would, even with a good first gear clutch pop!:laugh:
 
I was going to swap the exhaust sometime with my dual from my project bike to see if there is a difference. I heard the uni foam filters may help a lot, so I am planning on buying those next. Id have to check my notes for jet sizes, but I did go up a few sizes on both pilot and main.

The bike runs and starts great, it just feels like it has some flat spots in power. Plugs are on the lean side but not dangerously. I have the mixture screws out further then they should be I believe, like 4 turns? but it lean pops otherwise.

I will get the foam filters and mess with jetting some more this winter. I know this bike has a lot more power hidden somewhere!
 
warrenlevihursh said:
Also, will anyone's XS do a wheelie? Saw a Dime City picture of a CB550 Café doing a wheelie. I don't think mine would, even with a good first gear clutch pop!:laugh:
Click to expand...

My reasoning about all of these twisted cranks is a lot of them could have been done by, revving, dropping the clutch and trying to do wheelies
 
I think my jetting is close. I have a Pilot-45 and Main- 137.5 right now. Bs34 carbs, pods and 2-1 exhaust. No popping or stumbling. Is 4 turns out on the air screw too far? Does this mean i should go up on pilots and lean the mixture screw? What else can i adjust? There isnt a needle position to play with...
 

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Best bang for the buck:
700 JE piston set $288.00
Bored $150.00
Shell #1 cam ..$125.00
Want to pop wheelies, but large rear sprocket on or go smaller up front.
My 700 Shell frame flat tracker could pull 3rd on the street running 47 tooth on the
rear and still hit 90+ at the end of the straight away on a 1/2 mile track..

My last dyno was 57hp with the 700/shell.
 
Get rid of those filters. Unis work best. Might be choking you off a bit. I assume you meant bs34. Should be close with that jetting. I can tell you my 74 close to stock with bs34 carbs and kind of similar jetting has taken me around 145km/h and still felt like it had quite a bit more. Stock gearing too.
 
CDNTX650 said:
Get rid of those filters. Unis work best. Might be choking you off a bit. I assume you meant bs34. Should be close with that jetting. I can tell you my 74 close to stock with bs34 carbs and kind of similar jetting has taken me around 145km/h and still felt like it had quite a bit more. Stock gearing too.
Click to expand...

Yes i corrected it to 34s. I ordered the uni filters. So will these lean or richen things? Ill get those on before i buy bigger pilots. I cant believe i would need bigger. My bike is maxed around 80mph but im not sure about my sprocket ratio. Thanks.,
 
I did swap to the dual exhaust tonight off of my project bike. It was def much leaner. Popping and what not on decel, but i felt like the bike was a bit more responsive, so now im confused. Here is a pic of the dual short exhaust. I think its ugly though.
 

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You shouldn't need any bigger on pilots. You might need a 140 main. Might. I'm at a 140 and I run xs400 needles and the cdn bs34 needle jet with needle shimmed up half a step richer from the 2nd slot down from the top. With a 140 main the top end it perfect. But it was giving me a huge rich cut out if I'd whack on the throttle hard cruising around. So leaning the midrange really cleaned that up. Stock pilots seem okay for me. So far I'm the only one I have found on here with that cut out problem.
 
CDNTX650 said:
You shouldn't need any bigger on pilots. You might need a 140 main. Might. I'm at a 140 and I run xs400 needles and the cdn bs34 needle jet with needle shimmed up half a step richer from the 2nd slot down from the top. With a 140 main the top end it perfect. But it was giving me a huge rich cut out if I'd whack on the throttle hard cruising around. So leaning the midrange really cleaned that up. Stock pilots seem okay for me. So far I'm the only one I have found on here with that cut out problem.
Click to expand...

Ok cool. Thanks for the input. Ill try 140 next time the carbs are off the bike and see if it breaks up.
 
I was thinking that. My friends bike has that huge chopper exhaust, you know the kind that runs the entire length of the bike, well im pretty sure this is why his bike pulled so much better. I think the back pressure helps or something compared to the cut off junk i have.
 
When my bike was new and I was 24 years old, I had to see just how fast it would go. After break in, of course. With a couple of bigger chase bikes and my tach, we calculated my top speed at 112 mph. This was bone stock running flat out at sea level, chin down on the handlebar. That was pretty darn fast for a new bike that I bought for $1800!

Stock carburetors work very well with the stock airboxes. The stock exhaust isn't bad, either. The bike I refer to was my SK.
 
IMO, a shortened exhaust is your biggest problem, as well as the filters. Foam works way better. The pipes need to be in synch with the intake for everything to work it's best. I think mufflers are the way to go, straight pipes have crap for proper back pressure characteristics which really makes a difference in packing the fuel mixture in the cylinders.
 

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