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Discussion Starter · #1 ·
I just picked up a 2006 ex 500 that was garaged for the last 7 years. I’ve rebuilt the carbs, fuel petcock and replaced all the vacuum and fuel lines as they were all stiff and cracking. I also replaced the spark plugs and air filter and I can get her to fire up without a hassle. Idles okay but the engine dies if I go beyond 4K rpms. I’ve thoroughly cleaned the Jets and carb bodies a few times in an ultra sonic cleaner. They were pretty rough but even after all the cleaning and replacing the worn components I can’t get the bike to go past 4K rpm’s. Any ideas on what could be causing the issue? I’ve checked for vacuum leaks and everything checks out.
I did notice that once the bike warms up it doesn’t idle consistently, it will drop and jump between 1-2 rpms
 

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07 Ducati SS800 '95 Ducati 900SS/SP '19 Honda CBR650R
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these Keihin CV carbs require some special attention to truly clean, set up and get to run. You've failed to post mileage on the subject bike (as valve clearances may be an issue) Please tell me you flushed old fuel, using new in your start attempts.
 

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maintenance schedule calls for valve clearance check at 7500....public knowledge that valves have been known to tighten prior. Heck, I'd do them. Followed by another go at carbs, including synching and setting pilot screws. How many turns out are they currently set at? Did you set fuel levels (via floats)? Stock sized jets confirmed?
 

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Discussion Starter · #6 ·
@ducatiman I’ll def get them done thanks for the suggestion!
im currently at 2 1/2 turns out and set the floats to 17mm

@haybaler I removed the tops and inspected the diaphragms. They still looked good but were gummed up so I cleaned them and made sure they weren’t any tears and are moving smoothly. I replaced the float valves as they were jammed and not moving at all. I did have some challenges with the spring mechanism inside the diaphragm during reassembly. The spring somehow slipped out of place from the middle section. The top and bottom portions of the spring were both in place but the middle part of the spring was not in place and the diaphragm got stuck so I had to reassemble it again but other than that no issues.
 

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Any chance the diaphragm missed the groove?
The rubber tends to shrink over time, making it difficult to reassemble correctly;
just sayin' that might account for the lack of higher rpm's if the slides are not raising properly.

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Did you clean the mouse nest out of the airbox? Mice prefer lower RPMs.
 

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Discussion Starter · #9 ·
@haybaler no, the diaphragms looked really great and were on the notch but Im going to take another look and make sure the springs didn’t pop out of place again.

@po18guy yeah, i cleaned out the air box and replaced the air filter. I checked for vacuum leaks and made sure everything is sealed properly.
Although now that I think about it I can’t say I confirmed the jets were stock because im not sure what the stock specs for jets are on these.
What size jets should be in there?
 

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IIRC - 122s or 126s. I think 126 is stock, but you can go smaller with a good air filter. Do you have vacuum gauges? Check vacuum at idle. If it's OPK, then what's left except cam timing? Are you sure it's an '06 engine? Almost sounds like an '87-'93 engine was swapped in and the timing has jumped.

Also make sure the throttle cable is not looped over the carb vent, thus preventing full throttle.
 

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07 Ducati SS800 '95 Ducati 900SS/SP '19 Honda CBR650R
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and N36N needles as well, OEM only, assure no jet "kit" copycat components installed
 

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stock jet sizes #130 mains #35 pilots.
Ah, yes. Thank you. My Dynojet kit recommended 126s and they work just fine with richer jets. Stock is lean on the needle and fat on the jets. Since the jet companies do not have to meet emission standards, they essentially undo what the EPA did.
 
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DJ 126's ARE richer, equal to 135 OEM Keihins. Too many (unknown as to OP setup) exhaust/intake variables to suggest specific changes here. Until such a time that he achieves throttle response past 4K as is, after finding out his specific in/ex setup and internal carb setup, I'll refrain from jetting suggestions, other than stock internals.

Note Dynojet instructions also call for drilling of the slide lift hole, thus permanently modding slides.
 

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Discussion Starter · #16 ·
Thanks for all the info guys! I have my next steps planned as such:
Check valve clearances
Confirm stock components are in carb
One more ultra sonic bath for carb body and component
Confirm throttle cable isn’t impeding carb functionality
Let me know if there is anything else I missed. I’ll post a follow up on what I find!
 

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Been 20 years since I jetted my '87 carbs, so I honestly cnanot remember. What is missing here? Does the bike not rev over 4K in neutral or will it not pull above 4K in gear?
IMO, it is something basic.
 

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Discussion Starter · #19 ·
Alright I’m back in the garage and looked up a bunch of posts on how to do the valves but I am a bit confused. One “how to” posted by FOG says to turn the flywheel clockwise until you see the “c” mark in the viewport and that the “IN” and “EX” marks should line up along the cam case but another post has a picture of the manual and this same position has the label TDC for piston 2. So what’s TDC for piston 1 and piston 2? Appreciate all the help gents.
 
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