Ninja EX500 carbs on an XS650?

[Bjorn]

Thanks Gary! Tried it and they lift

 

[Bjorn]

In case anybody is wondering how much lighter the CKV's are:

Not a massive difference, but still 250grams..

 

[Bjorn]

I'm a club members now haha. Rebuild a set of carbs, ultrasonic cleaned, new o-rings, jet and needle recommendations from here. (MJ 138, PJ 38, JJJ needle (middle clip), float 0,5mm above the gasket, uni filters.

Some pictures of my XS throttle cable adapter. Shortened the OEM cable as mentioned somewhere in this topic, seems to work great!

Finished the rest of the carb swap today and tested them for the first time, super exciting!

It started right up, couldn't believe it. Had to set the idle a bit and sync the throttle bodies. Went out for a ride and was pleasantly surprised! They pull really strong from idle to the redline. No hick-ups or flat spots that I could notice.

Only the revs hang a bit when I blip the throttle at idle. Maybe open de mix screws beyond the current setting of 2 turns?

Thanks for this topic guys! Hope to add some more of my findings

 

[gggGary]

Careful you'll have me dusting off that set on the shelf!
Good job and thanks for the report.

 

[arcticXS]

I really like your bike and the mods you have done to it! It still looks just like it should, while having improved functionality and lower weight as well!

I just noticed a minor issue in your picture. The 2 threaded holes on each side, for the oem exhaust pipe bolt, at the bottom frame tubes seem to be open/empty. When I fitted a non-stock exhaust, I plugged these with 4 pcs short M10x1.25 Alloy bolts from Pro-Bolt. Just to protect the threads and keep dirt from accumulating. Short grub screws may be an even better solution for these holes.

 

[Bjorn]

Thanks arctic! Well the downside is that it's never done haha. Sometimes feels like it's leaning towards an obsession. Good idea about plugging these holes! It always seems to be oily around there anyway.

One downside of my pipes is it's hard to reach the left carb. Like switching a jet I always need to take the pipes of. Still like the looks but not always practical...

 

[Bjorn]

Question about the UNI filters: one filter keeps popping of when I try to tighten the clamp. I've tried every degreaser I've got but can't get it to hold....

Any tips? Maybe sand the flange on the carb or something

 

[arcticXS]

Question about the UNI filters: one filter keeps popping of when I try to tighten the clamp. I've tried every degreaser I've got but can't get it to hold....

Any tips? Maybe sand the flange on the carb or something

You could always machine short alloy "velocity stacks", and install them between filters and carbs. You have plenty of space, judging by the pics. A longer intake tract may even give you more mid range torque.
I have installed 70 mm long velocity stacks on my 34 mm flatslide carbs, and the largest K&N filters that I could fit. Posted a couple of pics in the "What did you do to your XS today" thread. (Post #10392 in that thread)

 

[Adamc]

There is nothing wrong with 34's. So easy to get them running good even a caveman can do it.

I am a caveman and I did it. Mine run great!

 

[ippytattoo]

I use the k&n filters so ymmv. I lost 2 filters off the left carb so I made up some wires to act as safeties. Pop riveted them to the chrome end cap and attached to 1 of the screws that hold the slide cover on. I used crimp on ring terminals (crimped, soldered and shrink wrapped) at each end.

 

[arcticXS]

It looks like the air filter connection stub on the carb is very short, while the UNI filters are designed to slide 15, maybe 20 mm over a pipe or similar. So making a machined filter adapter or velocity stack will also ensure a smoother transition between filter and carb, which in turn should help the carb function as intended.
If you still want to clamp the filters directly to the carbs, you could try a narrower hose clamp (jubilee clip) The clamp needs to be 1-2 mm narrower than the length of the stub on the carbs.

 

[Jim]

If you still want to clamp the filters directly to the carbs, you could try a narrower hose clamp (jubilee clip) The clamp needs to be 1-2 mm narrower than the length of the stub on the carbs.

1+ on the narrower clamp.
You can also take some sandpaper (180 - 220) and sand (scuff) around the carb opening. On my 34's, which were giving me the same problem, that gave just enough purchase for the filters to grab onto.

 

[Bjorn]

Just fitted the narrower clamps from my K&N's and sanded the flanges, seems to hold better.

 

[Bjorn]

Went out for a testride today, can't seem to dial in the idle. Running stock engine, semi open pipes, unis, 138/38/jjj 3rd clip, mix screws 3 turns open.

With the 3 turns the throttle doesn't hang anymore, and very quickly goes back to idle, throttle feels very responsive. Idle is around 1200. However after riding for about 30min, the idle is very low at around 900, riding away from a traffic light the bike sort of wants to stall. Opening the idle adjust screw raises the idle but now leaves the throttle "hanging" if a blip it at idle. Put the idle adjuster back and drove home.

Weird enough when I got home the bike was idling fine around 1100rpm. Tried to open de mix screws to 3,5 but it didn't increase the rpm.

Any ideas?

 

[jetmechmarty]

Went out for a testride today, can't seem to dial in the idle. Running stock engine, semi open pipes, unis, 138/38/jjj 3rd clip, mix screws 3 turns open.

With the 3 turns the throttle doesn't hang anymore, and very quickly goes back to idle, throttle feels very responsive. Idle is around 1200. However after riding for about 30min, the idle is very low at around 900, riding away from a traffic light the bike sort of wants to stall. Opening the idle adjust screw raises the idle but now leaves the throttle "hanging" if a blip it at idle. Put the idle adjuster back and drove home.

Weird enough when I got home the bike was idling fine around 1100rpm. Tried to open de mix screws to 3,5 but it didn't increase the rpm.

Any ideas?

Your pipes are huge! I'm going to fit mine from the get go.

http://www.xs650.com/threads/xs6502f-xs650sk-mash-up.58192/page-6
http://www.xs650.com/threads/xs6502f-xs650sk-mash-up.58192/page-7 Post #135

I have never tried to run big pipes. The information I've been picking up on these forums for years is that the XS650 will fall flat. Have a look at 650Central under exhaust, You may even want to give 3M a call. You'd be hard pressed to find someone who knows more about it.

 

[Bjorn]

Don't know what you would consider massive? I did my research and settled on 37mm ID or 1,45". Ran these pipes for years. Can't really see why this would affect my idle.

 

[jetmechmarty]

Don't know what you would consider massive? I did my research and settled on 37mm ID or 1,45". Ran these pipes for years. Can't really see why this would affect my idle.

They look even bigger. It was just a thought. As you were.

 

[gggGary]

remind me what ignition and advance you have?
Might try retarding the timing a smidge see what that does.

 

[Bjorn]

Vape system, moving the advance is not easy, would need to re-indicate the rotor for that.

Would going up in PJ help?

 

[gggGary]

That part of the vape (timing adjustment) is kind of an issue isn't it?
Guess you will have to experiment a bit.