[Amac]

I rejetted the street & track SVs this winter. I went with the following on both bikes:

142.5 mains
17.5 pilots
2.5 turns a/f mixture
2 shims on needles.


I haven't had a chance to get the track bike out yet, but it seems like the street bike is a bit more abrupt coming from off throttle back onto the gas.

I.E. after turn-in on a corner, when I go to pick up maintenance throttle, the engine picks up abruptlyl and surges.

Now, some of (or most) of this could be the nut behind the bars being a bit rusty, but if it is a carb tuning issue, does anyone know where I should start? The one thing niether bike has had as long as I've owned them is a carb sync.

 

[RichDesmond]

I rejetted the street & track SVs this winter. I went with the following on both bikes:

142.5 mains
17.5 pilots
2.5 turns a/f mixture
2 shims on needles.


I haven't had a chance to get the track bike out yet, but it seems like the street bike is a bit more abrupt coming from off throttle back onto the gas.

I.E. after turn-in on a corner, when I go to pick up maintenance throttle, the engine picks up abruptlyl and surges.

Now, some of (or most) of this could be the nut behind the bars being a bit rusty, but if it is a carb tuning issue, does anyone know where I should start? The one thing niether bike has had as long as I've owned them is a carb sync.

I'd start with the carb sync, and maybe turn the idle up a little. You're jetting is very close to what I run and mine's nice and smooth.
I do have the Factory Pro needles, IMO they're worth the price of the jet kit.

 

[.RJ]

You could also richen up the air screws a touch, mine are 2.5 turns out and throttle response is great. I'm also running larger mains (152.5) - M4 full exhaust and BMC air filter.

 

[Amac]

Does anyone have any suggestions for where to pick up a decent carb sync tool that won't break the bank? I have 2 SVs a clymer and the factory service manual, I suspect I can buy the tool for less than having them both done by the shop.

 

[Amac]

UPDATE: Abrupt On/Off Throttle.

Update:

Well, I got both bikes balanced. I used the Carbtune and it works great!. I ended up using vacuum hose from a parts store down the road to connect to the front cylinders, and straight 1/4" to 1/4" connectors with no valves. I just used the vacuum caps to cap each hose and added a small ziptie for peace of mind.

Since I've got full fairings on both bikes, the hose really didn't bother me anyway, but I ended tucking the loose tubing between the frame and the coolant reservoir and keeping it in place with a long ziptie. If you go that route, be careful not to get in the way of your throttle cables.

Both bikes needed a little tweaking but in retrospect, I think my jerky, snatchy chain was the main culprit. I'll never know for sure. That's what I get for changing 2 variables at teh same time!

I had also dropped one shim on the street bike, (It has a full hindle exhaust system with little to no packing - I need to take care of that too!) but it was burping & backfiring a bit when I shut down the throttle so I added one shim back. Haven't had a chance to test ride her yet.

 

[nokturnal]

did you cure the abrupt on/off? I am having the same issue, but with the factory pro needles, exactly the same jetting/screw.

my chain is adjusted fine though.