Rough start

jasidok

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I'm attempting to upload my video. I bought new carbs. Brand new VM34's. everything is still stock from Sudco. It's trying real hard. I think it's super rich. It just keeps turning with no end, just regular. if i pull the choke on one or both of them, it will start puttering and then every so often backfire. and it makes this gurgling noise through the exhaust. I have spark. I have gas. I havent ever checked compression or the leaks or rotors.... what do you think? just really rich right? I will upload viodeo asap... camera is being weird... of course... trying to get this wrapped up today......:bike::bike::bike::boxing:
 
heres the video i took earlier. I am going to pull the carbs and see if i cant make it leaner. I am going to start with the float height and PJ. Although i want to hit all three... MJ float height and PJ.... But I'm taking it slow....

 
Have you taken the plugs out and verified the rich condition? Doing nothing open and then trying to light off on choke would seem to indicate it being too lean.
 
Just a small point, but I wouldn't crank for too long at one time. You could overheat the starter motor.

In my experience, if everything is good - an XS650 will light up right away. If it won't start quickly, you've got something yet to fix.

Pete
 
Holy moly.
 

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Yes. And I believe I’m just over 5k. Denver - 303! Not quite 5280 but close enough.


Hi. Ok. So this is very lean mixture then? I have the air mixture screw at 2.5 for the video. Should I adjust that or take a different route?


Max Pete... yea. Makes sense. I get a little overzealous. Thanks man.
 
New VM34s from Sudco could be either carbs with Sudco's proprietary jetting for the XS650 (very pricy) or cheaper carbs with Mikuni generic jetting (appropriate for 2-stroke motors only, way too rich for 4-stroke operation). Strip the carbs and post a jet list, otherwise I can't help you and neither can anyone else. Take the time to click the Tech button and find the link to the VM carb guide.

Edit: A "complete jet list" means slides, needle jets (AKA atomizers, AKA emulsion tubes), needles, pilot jets, main jets, and air jet (back of carb, it'll be either #2.0 or open hole).

Edit: The left plug looks carbon bridged. At least it's been firing.
 
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Hi so. I overlooked the intensely detailed manual/guide that inxs posted. (The very first thread in the carb section of tech) sooooo.... let me go through all of that. And I’ll let you know when that guide has fixed my issues. thanks again for your guidance!!!!
 
jasidok one thing about reading the plugs to see if rich or lean it needs to run. Not just idle but running as going for a ride to see how it is reacting to either lean or rich condition. Not too good to use starter that long either....bet the battery is run down some. Doesn't take than many rotations before she fires.
 
Yea. I actually have the charger right next to me for that purpose. But I’m learning these bikes are different and take more finesse and thought than I’m used to.

175 mains
15 pilots
2.0 air jets
2.0 slides
6F9 needles
159 P-6 needle jets.
 
Yea. I actually have the charger right next to me for that purpose. But I’m learning these bikes are different and take more finesse and thought than I’m used to.

175 mains
15 pilots
2.0 air jets
2.0 slides
6F9 needles
159 P-6 needle jets.
That falls pretty much in line with the carb guide starting point. A little light on the pilot... but that shouldn't prevent starting. 2 questions... how much fuel was in the bowls when you opened 'em? Seem about right... too much, not enough?
Second, did you try cracking the throttle... 1/4-1/2 open during start?
Also... you didn't mention where the clip is on the needles?
 
On starting if you don't hear it pop fire at least a little within a couple seconds save the wear and QUIT CRANKING!
Don't see you using the chokes?. 78 tank has vacuum petcocks, you turning them to prime to start it?
If I'm doing the cranking and get no fire, I'll slap my hand over a carb mouth for just a second. if it's fuel starved that'll cure it LOL
 
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