Carb jetting

[3wheel_life]

Been having issues on my project 200x, hard starting, backfiring on deceleration, and seems to have a flat spot at certain Rpms. I'm 99 percent sure it is carb related. The trike has a supertrapp exhaust, uni filter and airbox lid removed. I pulled the carb to check the jetting because I know with those mods it definitely needed to be jetted up some. From what I can gather, the stock main jet is 108 (for a 1985 200x) and slow jet is 40. In my carb, the main jet is a 118 and the slow jet is still at 40. The needle clip was leaned out all the way (clip was at highest setting). Took the plug out and it definitely showed a lean condition. I moved the clip to the 3rd slot, turned the pilot screw to 2 and 1/4 turns out. Haven't started the trike yet to adjust idle. My question is, does a 118 main jet seem high? I'm not very knowledgable on jetting and have never really done it since I've never had a trike with any performance stuff on it.

[barnett468]

post a photo of your plug . if it is pure white or close to it, it is screamin lean and i would then try a 122 in your case.

the pilot may or may not be too small . you can tell to some degree by the way it starts . if it easily starts with no choke, it is likely not too small.



PREVIOUS KAWASAKI INTERNATIONAL R & D PROJECT ENGINEER AND ATV DEPARTMENT SUPERVISOR

[yaegerb]

Been having issues on my project 200x, hard starting, backfiring on deceleration, and seems to have a flat spot at certain Rpms. I'm 99 percent sure it is carb related. The trike has a supertrapp exhaust, uni filter and airbox lid removed. I pulled the carb to check the jetting because I know with those mods it definitely needed to be jetted up some. From what I can gather, the stock main jet is 108 (for a 1985 200x) and slow jet is 40. In my carb, the main jet is a 118 and the slow jet is still at 40. The needle clip was leaned out all the way (clip was at highest setting). Took the plug out and it definitely showed a lean condition. I moved the clip to the 3rd slot, turned the pilot screw to 2 and 1/4 turns out. Haven't started the trike yet to adjust idle. My question is, does a 118 main jet seem high? I'm not very knowledgable on jetting and have never really done it since I've never had a trike with any performance stuff on it.

only adjust 1 circuit/setting at a time when adjusting a carb....otherwise if you see improvements you don't know which change you benefited from.

With your mods, I would think you would need no more than a 112. Turn your pilot screw back to stock specifications, put your airbox lid back on and put your needle clip on the richest setting (bottom) and see how it responds.

also, have you thoroughly cleaned the carburetor and checked for intake leaks?

[3wheel_life]

post a photo of your plug . if it is pure white or close to it, it is screamin lean and i would then try a 122 in your case.

the pilot may or may not be too small . you can tell to some degree by the way it starts . if it easily starts with no choke, it is likely not too small.



PREVIOUS KAWASAKI INTERNATIONAL R & D PROJECT ENGINEER AND ATV DEPARTMENT SUPERVISOR

It does not start easily or stay running without feathering the throttle until it's warm. The plug is a brownish color, I'll post a pic when I pull it back out.

[3wheel_life]

only adjust 1 circuit/setting at a time when adjusting a carb....otherwise if you see improvements you don't know which change you benefited from.

With your mods, I would think you would need no more than a 112. Turn your pilot screw back to stock specifications, put your airbox lid back on and put your needle clip on the richest setting (bottom) and see how it responds.

also, have you thoroughly cleaned the carburetor and checked for intake leaks?

The only thing I've done so far is move the needle clip to the 3rd position and moved the pilot screw back to stock. I soaked the carb and cleaned and blew it out. Still will only start if I'm giving it a little throttle. I will put the airbox lid back on, see what happens. If no change, I will move needle to richest setting and report back.

[El Camexican]

As posted above your symptoms likely have nothing to do with your main jet, so put the stock one back in until the rest of the issues are solved.

Popping on deceleration and hard starting usually can be traced to a faulty choke circuit, lean fuel screw setting, a pilot (slow) jet that is too small or dirty, or a needle that is too lean.

I'd start by making sure your float height is property set and that your pilot jet has no obstructions before changing any jet sizes.

[El Camexican]

Might want to check valve lash and compression as well, a bad valve can cause hard starting and popping as well.

[3wheel_life]

As posted above your symptoms likely have nothing to do with your main jet, so put the stock one back in until the rest of the issues are solved.

Popping on deceleration and hard starting usually can be traced to a faulty choke circuit, lean fuel screw setting, a pilot (slow) jet that is too small or dirty, or a needle that is too lean.

I'd start by making sure your float height is property set and that your pilot jet has no obstructions before changing any jet sizes.

I didn't change the jets. The PO did and I do not have the stock jet.

[barnett468]

It does not start easily or stay running without feathering the throttle until it's warm. The plug is a brownish color, I'll post a pic when I pull it back out.

Is this with full choke?

Exactly what is your starting procedure?



PREVIOUS KAWASAKI INTERNATIONAL R & D PROJECT ENGINEER AND ATV DEPARTMENT SUPERVISOR

[El Camexican]

I didn't change the jets. The PO did and I do not have the stock jet.

Google Jetsrus.com and get what you need. If you're hesitant to mess with your carb there is a guy on here that goes by Flyingw. From what I've read he can make your carb like new again.

[3wheel_life]

Thanks for the site info. Not hesitant to mess with it at all, have rebuilt a lot of them but have never messed with jetting. I'm going to bring the carb back to stock jetting, replace the float, float needle and seat, and go from there.

[3wheel_life]

Is this with full choke?

Exactly what is your starting procedure

PREVIOUS KAWASAKI INTERNATIONAL R & D PROJECT ENGINEER AND ATV DEPARTMENT SUPERVISOR

I don't really have a starting procedure. I just keep kicking and trying different choke settings until it starts. But I usually always have to hold the throttle open some to get it to start

[barnett468]

I don't really have a starting procedure. I just keep kicking and trying different choke settings until it starts. But I usually always have to hold the throttle open some to get it to start

Waste of time time running a stock main jet with a Supertrapp unless it only has 1 disc in it . I would check the float level and try a 45 pilot before changing anything else . Also, if the carb is a Honda carb instead of a Chinese one, I would only use Honda jets because there can be a difference in flow between the same number size from different mfg's.

Also, make sure the plug is the correct heat range and gap.



PREVIOUS KAWASAKI INTERNATIONAL R & D PROJECT ENGINEER AND ATV DEPARTMENT SUPERVISOR
AND OWNER OF A TRI Z THAT ACTUALLY HAS A REAR SHOCK ON IT http://www.mustang.org.au/forum/Smileys/smilies/hysterical.gif

[3wheel_life]

Waste of time time running a stock main jet with a Supertrapp unless it only has 1 disc in it . I would check the float level and try a 45 pilot before changing anything else . Also, if the carb is a Honda carb instead of a Chinese one, I would only use Honda jets because there can be a difference in flow between the same number size from different mfg's.

Also, make sure the plug is the correct heat range and gap.



PREVIOUS KAWASAKI INTERNATIONAL R & D PROJECT ENGINEER AND ATV DEPARTMENT SUPERVISOR
AND OWNER OF A TRI Z THAT ACTUALLY HAS A REAR SHOCK ON IT http://www.mustang.org.au/forum/Smileys/smilies/hysterical.gif

I don't think there are any discs in it actually. Completely open at the end.

[El Camexican]

Someone please correct me if I'm wrong, but I believe that Keihin is, or was owned by the Honda corporation. If that is the case I would be very surprised if a genuine Keihin jet like the ones sold by Jetsrus werent a perfect match for your carburetor.

I recently had a guy bring me a "Honda" float needle to install in his XR. He paid $26 bucks for it!

[barnett468]

I don't think there are any discs in it actually. Completely open at the end.

ummm...alrighty then . I guess it's kinda loud.


PREVIOUS KAWASAKI INTERNATIONAL R & D PROJECT ENGINEER AND ATV DEPARTMENT SUPERVISOR
AND OWNER OF A TRI Z THAT ACTUALLY HAS A REAR SHOCK ON IT http://www.mustang.org.au/forum/Smileys/smilies/hysterical.gif

[3wheel_life]

ummm...alrighty then . I guess it's kinda loud.


PREVIOUS KAWASAKI INTERNATIONAL R & D PROJECT ENGINEER AND ATV DEPARTMENT SUPERVISOR
AND OWNER OF A TRI Z THAT ACTUALLY HAS A REAR SHOCK ON IT http://www.mustang.org.au/forum/Smileys/smilies/hysterical.gif

It's actually not insanely loud, but definitely loud. It was that way when I got it, this trike has been my winter project, and it definitely needs a lot.

[3wheel_life]

Pretty sure I'm just going to bring the trike back to a stock set up minus the uni filter. Can't imagine that I would be gaining a whole lot with the exhaust even when everything's dialed in right. Not racing this just want a good woods trike.

[Ranvier]

Find an end cap and some discs for the trapp. I think you can buy them from supertrapp.

[3wheel_life]

Had a little time tonight after work so got to tinkering with this some more. I decided that I couldn't get a good read from the plug since it wasn't new, had been run for a while and probably wasn't changed by the PO, so bought a few plugs. Gapped and installed the new plug, after about 20 or so kicks and trying different choke settings I got it to start, although it wouldn't stay running without feathering the throttle. As soon as I let off of would die. Moving the throttle stop screw seemed to do no good. I did have it idling for about 3 minutes, the idle was a little high, and tried to lower it by the throttle stop screw, as soon as I touched the screw it died. After about a total of 15 minutes run time (off and on as it would die and have to be restarted) I decided do check the plug. Definitely running rich. Plug was completely black.

239266

This was just an idle (or as close to as possible) check.

I pulled the carb back off disassembled it. Going to give it another soak and clean it out again. Also got my rebuild kit today. While I was taking it apart I noticed the washer and o ring missing from the throttle screw. Don't really know how big of a deal that is, but it's definitely something that's supposed to be there that wasn't.

I think my best option is to rebuild the carb, install the 110 stock main jet and new 40 pilot, set the mixture screw back to stock specs, and put the needle clip back to the 4th setting like the manual says for an '85, put the airbox lid back on and go from there. I also have a jet kit on the way for the exhaust/uni filter but I'd like to get it starting/idling right before I dive into that.

[3wheel_life]

Figured I'd come back to this and give an update. Got the trike starting, idling, and running beautifully now. It took a 112 main and 42 pilot. Took a lot of trial and error, one adjustment at a time like most of you said, and getting one curcuit at s time right helped a lot as well. It was running "good" with just the re-jetting, but still had some cut out at WOT. Slapped the airbox lid back on, now it's perfect. Big thanks to El Camexican, for recommending jetsRus, very knowledgable people and their jets are spot on. And another thanks to everyone else for your ideas.

[Dirtcrasher]

I have 15 discs in my 350X bored 1mm over and running a 37mm carburetor, 10.25:1. My pilot is a 60 or 65 and the main jet is a 185. That's from stock 350X carb which is around 38 and 142 ROUGHLY if I recall and I don't have my book in front of me.

I do not run an airbox lid ( I run the perimeter and chop out the very top so there is SOME water entry protection), and I make all the custom intakes to fit whatever model/size carburetor requires myself.

The new motor, (13:1 or so), will have an even larger carb and I'll start with that same pilot but about a 200 or so main jet for start.

Need a custom intake? I can make whatever anyone wants and I have most sizes of the tubing required in stock.

If not, I can have the tubing about 6 days after the order placement......