Ninja EX500 carbs on an XS650?

[mrriggs]

If you stick it in gear and drag the clutch to bog the motor down, does the rpm stay down until you give it gas again or does it immediately shoot up when you pull the clutch in?

Stick a timing light on there and see what the advance is when it is idling slow and when it is idling fast.

If the initial advance is too low then you have to open the throttle plates more to get it to idle. When it's revved up the timing advances and the combination of more timing and higher throttle opening can make it "idle" at a high enough speed that the timing never retards.

 

[tbone1980]

mrriggs- Thanks for the suggestion. Timing is good. I got it running correctly after figuring out the carbs were set way to lean. I adjusted the needle position and mixture screw to run more rich. Now the bike runs like I have never felt before. Completely renews my interest in this bike. I have had the bike for 4 years and it is so nice to finally have it running like it is now. Thank you to all of you who have added their experience and tips with moving to this carb.

 

[j0hnnybmx]

just put 500ex carbs on my new build. 40 ilots 140 mains jjj needles on the center clip. WOT is pretty strong and idle is perfect... have a small sputter while cruising around 60-65mph.. prolly need to lean my needles out i think?

also, i might add. i got my carbs off of the 500ex.com forum off of the user "ducatiman" he ultrasonic cleaned the carbs, rebuilt them, adjusted the floats perfectly, and did a bench sync, for $120 shipped to my door, did it in a very timely manner also. very satisfied. if anyone is considering this swap i highly recommend it.

 

[ippytattoo]

That is a very good price. I have thought about offering something similar but also doing the jets and that was about the best price I was finding for donor carbs. You got a smokin' deal.

 

[scabber]

BMX I would try that you might be jetted rich. Try slot 2.

 

[j0hnnybmx]

yeah ill lean em out tomorrow and see what happens. its like a whole new bike with the carbs tho.

 

[rowdyrandy]

Hey guys just made this swap on scabbers suggestion, here's some quick numbers but I'm just getting started -

Also, I'm in Denver so put me at the generic 5,280ft - Bike is bored 4th over with emgo shortys on stock headers. Uni filters and JBM intake boots.

Pilots - 40
Needle - stock
Mains - 138
Mixture - 1 1/2 turns out

Upping the pilots surprised me the most considering the elevation, stock they came with 35's. I have not tinkered with the needle yet but have a pair of jjj and shims waiting. The bike runs pretty damn good for the little amount of work I had to do. Off idle it seems like it could be better, but was out on the freeway yesterday and no hiccups at wot or stuttering. Bike ran great just cruising.

Something to consider as well - I'm using the oem equavalent jets. Maybe that explains why my pilot is at 40 even up here at altitude, or this beat is just a thirsty one. Again, just getting started but I know there's always a lack of numbers for us up here at altitude.

More to come in the next week - suggestions are very welcome, if the info I gave provides any insight

ippy , riggs, and everyone else - thanks for the work so far, one of the best things I've done for this bike in awhile

 

[ippytattoo]

Rowdy once you get the jjj needles in there you may be rich in the lower midrange / upper pilot transition but I am running 40/gfh(2nd slot)/140 with good results at sea level

 

[pekka]

Be careful out there! I've been hearing this slight rattle sound when accelerating. I thought that it was the slides rattling (my CRF450R actually does that) but then it hit me. Could it be detonating/knocking/pinging (in Finland we say "nakuttaa")?!?! I checked the timing and it was little too advanced. Adjusted and tested. Rattle gone! Hope I did not do any permanent damage to my new piston set... At least now I know what pingin sounds like.

Also a question: how much does the float level affect mixture? I think my left carb has about 1mm lower fuel level than the right and the plug also looks "leaner". I've been trying to compensate by opening the mixture screw more on the left... I do not want to open the bowls because the carb kit I fitted had shitty gaskets that got swollen out of proportion and are a pain to put back on. Double:

Pekka

 

[j0hnnybmx]

here's my freshly (almost) finished scoot been running the bike with the ex500 carbs for about a week or so now, settled on 40 pilots 138 mains jjj needles bottom clip runs good all throttle positions, good idle good WOT. still need to sort something for the choke, but in due time.. need to get my seat finished asap.

 

[timbeck]

J-BMX What are you using for a throttle and cable ?? thanks tim

 

[scabber]

Glad you got it sorted. The carbs look good on the bike. The bike looks great and should be a thrill a minute trying to get it to stop. Looks like a go machine anyway. Finish the seat and ride it like you stole it.

 

[j0hnnybmx]

J-BMX What are you using for a throttle and cable ?? thanks tim

lightly modified stock xs throttle cable, throttle tube is a biltwell whiskey throttle. (same as any stock single pull harley essentially)

Glad you got it sorted. The carbs look good on the bike. The bike looks great and should be a thrill a minute trying to get it to stop. Looks like a go machine anyway. Finish the seat and ride it like you stole it.

i knew i'd get some flack on here for no front brake... it stops too, don't worry. definitely better than most stock xs650's on the road i'd bet with the over weight unresponsive front disc, on worn out forks, dry rotten tire and basically useless rear drum!

and thanks, she loves to go as well

 

[scabber]

No flack on the front brake. The thrill a minute is from personal experience with no front brake. Had my hair stand on ends more than once sliding to a stop. After a bunch of near misses I put one on it. That is a nice rear brake you have and far superior than the push and pray setup 55 Harley drum on my old hardtail. Still a thrill to ride but it stopped a lot better with a front. If you ride it long enough a near miss is good.

 

[pekka]

Anyone experimented with drilling the slides? Seems to be the greatest fashion with other CVK users (new Triumphs, HD). Would larger holes give a bit more "snap" when whacking the throttle open? Or would they just ruin everything?

Pekka

 

[jd750ace]

Anyone experimented with drilling the slides? Seems to be the greatest fashion with other CVK users (new Triumphs, HD). Would larger holes give a bit more "snap" when whacking the throttle open? Or would they just ruin everything?

Pekka

What size is the hole now? drilling the slide lift hole can quicken the rate of slide lift, but too big a hole and you can get bogging and flutter. I plan on leaving mine alone. not much to gain there. On the 40mm and larger CVK carbs, the slide is a bit heavier than this series, and is less prone to flutter, so increasing the size up to 7/64" max is common. Since my 40MM Mikuni on the road star has 2 holes, we just leave those alone as well, although people have claimed to gain a little and lose nothing by increasing a single hole about 2 wire sizes. You're in an area that is typically only messed with on a flow bench, where the throat of the carb can be carefully observed. My advise, leave it be.

 

[pekka]

What size is the hole now? drilling the slide lift hole can quicken the rate of slide lift, but too big a hole and you can get bogging and flutter.

Not sure about the hole size now. Need to check next time I'm in there. Softer return spring apparently does more or less the same thing as a bigger hole. Or shorter spring (less preload).

Pekka

 

[jd750ace]

True. A softer spring you can swap. Start enlarging holes and clipping coils and backing up on a bad decision can get expensive. Tough to get data on original equipment springs too.

 

[pekka]

Just messed with the carbs. Turns out that the holes are 3mm already. And that's as big as you can drill without hitting the slide body. The Triumph guys are drilling to 3mm also. So that's it then...

Also re-checked my float levels. Left was about 1.5mm lower than the right. Now both are a bit over 1mm over the float bowl surface. I hope that evens out the plug colours and maybe gives better throttle response too.

Pekka

 

[rowdyrandy]

Anybody had issues with the bowls on these not filling fast enough? Got a problem with mine bogging at higher rpms and all signs seem to point to fuel starvation - It's pretty bad too, on the highway I can only get a few miles before having to pull over. My floats are set at 17mm right now - anybody else run into this? I have manual peacocks each running into a T then into a filter before reaching the carbs