Ninja EX500 carbs on an XS650?

[derrickjeff]

thanks for that,got some jets from allans performance.bike starts and runs better now.just found out my permanent magnet system is only giving 10volts on tick over,any ideas as to why.

 

[mseriously]

So...anyone have the final word on this? Been sifting through this thread and it seems like I might take the plunge. Not having much luck tuning out a dead spot in my mikuni 34's...

 

[mrriggs]

Final word? If you read through the whole thread you will see a lot of guys satisfied with these carbs and nobody going back to stock carbs.

I put them on just to see how they would work. I still haven't done anything with the choke or shortened up my cables. Figured that could wait until the next time I had them off. So far there has been no reason to take them off. Been running them for over a year now and they just work, flawlessly, day-in and day-out. Crisp acceleration, seamless transitions, excellent mileage, and zero maintenance. What's not to like?

 

[troopthrowback]

Final word from me is that they're great. I've been running mine for a couple months now (my break in was a 300 mile dual sport rally where my 78 Yambler was the oldest bike entered) and they ran flawlessly. I've never done anything with the choke, I just hold it open with my hand till the motor catches, then it's no longer needed.

 

[56nomad]

The final word is 'it' as in 'just do it'.

 

[scabber]

They work better. No turning back to those old carbs once you try the PVK.

 

[Maurice]

It's a no-brainer, set-and-forget.

The last step for me was to adapt the CM400 throttle cable to the right controls (credit troopthrowback). Tuning is just about spot on with 40 pilots, 140 mains and JJJ needles in the middle groove, stock '78 exhaust and UNI pods.

Sold the BS38s (emphasis on BS) a long time ago.

 

[troopthrowback]

Thanks Maurice.

As an update on the cm400 cable, I realized a couple weeks ago that my housing cracked where I bored and threaded it for the Honda cable abutment. It's still holding fine, I think it cracked from over tightening, not from the boring process. Either way, do so carefully!

 

[XSLeo]

I use the CM400 throttle housing with both cables, works great. I had to do some rewiring to get the switches to work.
I might even swap out the left side controls so they match.
Leo

 

[pekka]

Couple of strange things happened: 1. Summer finally arrived and temperatures went from 15degC to 22degC an the humidity dropped a lot. 2. The milage of my XS jumped from 45 to 55 mpg! 3. Now sometime (not all the time...) when cruising at steady throttle, say at 50 mph the engine feels like it stops pulling. Like running out of gas. Give it more throttle and all is good. This happened over night. Any ideas? Rich because temps went up?

pj 40, mj 140, hkj needle@4th, pods, open pipes, battery ok

Pekka

 

[jd750ace]

Could be a reversion issue with your open pipes. Your exhaust temp will be higher and have an effect on reversion frequency.

 

[pekka]

Good point Ace. And actually by open pipes I meant "free flowing" pipes with big mufflers. I checked the plugs and they show lean condition. I raised the needles one clip. Lets see if that helps.

 

[mrriggs]

Just keep massaging it, you will find the sweet spot.

I was running GJH needles on clip #5 and getting 55-56 mpg. It was on the ragged edge of too lean. Still rideable, not surging, but unnecessarily lean.

I switched to GFH needles on clip #3 (1.5 steps richer). It was noticably "fat", both sound and feel, and the mileage dropped as low as 52 mpg.

Changed to #2 with a shim, bit cleaner and gained one or two mpg.

Removed the shim so I'm on #2 now (still GFH needle). It sounds and feels very good but I haven't got a good measure of mileage yet.

I wish they made a GFJ needle since the "H" diameter isn't quite as crisp on tip-in as the "J" diameter. I tried ordering GFK needles from Jets-R-Us but they sent me the wrong ones and wouldn't correct their mistake unless I payed shipping to return the unusable needles.

 

[pekka]

I might order a GFH needle just to test. Today I rode 50km's with the new needle setting and the plugs still seem rather white. The left whiter than the right. Did not notice any surging though. Need to do some steady speed riding and see how it works. I would be happy with anything better than 47mpg (5l/100km). Hey, first summer with badly adjusted BS34's I got about 35 mpg

Pekka

 

[scabber]

pekka I'm still trying to grasp your 50MPH cruse condition stops pulling. The running out off gas feel. Does it loose speed the reason I'm asking is at cruising speed you aren't necessarily accelerating. At cruse I use very little throttle to maintain speed. White plugs doesn't necessarily indicate a lean condition. The smoke ring at the base of the insulator is what to look for. The GFH is a leaner needle than the HJK by the way. You might not have a carb problem.

 

[mrriggs]

The GFH is a leaner needle than the HJK by the way. You might not have a carb problem.

It is a leaner taper but you run it shorter (richer). The idea is to get a better balance across the range.

For me, the "J" taper needles felt too rich in the 3/4 range. The "H" taper felt better. Dropping them down improved acceleration but caused a lean surge while cruising. The "G" taper allowed me to lift them up to improve the cruise mixture without it being too rich on acceleration.

 

[troopthrowback]

I may be running a bit rich myself. GJH needles on the bottom (richest) clip setting. Jets at 138/38. I got right around 40mpg on the last tank I measured. That sounds quite a bit lower than most around here. That was some pretty aggressive riding, speeds 65-75mph.

Thoughts?

 

[pekka]

I think the angle of the right hands wrist plays a major role... My 55mpg was on a 500km trip cruisin mostly at about 95kmh (~58mph).

 

[pekka]

Ok. Needles at richest setting and bit more open on the mixture screws. 100km's of riding with higher speeds and revs than last try I'm at 52mpg. No ill behaviour. So I guess it's all good.

Also finally got the choke sorted with a generic Harley choke cable. Now that I can actually get the choke all the way open it starts with one kick instead of three when cold. Happy, happy.

Pekka

 

[tbone1980]

I installed my set of ex500 carbs this week and am having an issue with the throttle sticking when cracking the throttle above 2000 rpm. The idle will climb to 3000 and stay there. I have replaced my tired carb holders with JBM ones. I am running Unipods with a free flowing exhaust. I have 38 and 138 pilots with JJH needles. I have the Air mixture screws at 2 turns and the float height at 16mm. I am also using the plastic donuts from my old BS34's as a needle spacer. I have sprayed carb cleaner around the inlets and had no change in rpms so I am pretty confident I have no issues there. The carbs have been synced and it is idling really well. It also starts on the first or second kick without any issues. I should also mention that I have done a very good cleaning of the carbs as well as I run a in-line fuel filter. I have checked the routing of the throttle cable and it runs freely without any snags. I am scratching my head trying to figure out why the idle is sticking when I crack the throttle above 2000rpm's. Thanks for your help.