2016 Yamaha Raptor 90 Carb removal, cleaning, repair 

Yeah, sometimes the microfiche diagrams are not the best. They orient them different than they actually are. I appreciate you coming by and for commenting, glad it was helpful!

Glad to hear that! Thanks, I appreciate the feedback!

Absolutely!! Happy to help 👊 Happy New Year!

Thank you, I appreciate it! 👊

It is possible to put the throttle slide in backwards sometimes. Maybe that's what happened? The other thing you can do is get it running and spray carburetor cleaner around the carb and see if it chokes out to find if there is an air leak on the carb or intake boot.

It is a keihin factory carburetor from yamaha that comes on this machine. I do believe that it is a fuel screw. I remember at one point speaking with Yamaha about it and they said it is a fuel screw. On the motor side it's always a fuel screw and on the intake side it's an air screw. I do know these machines pretty well. I was a gold certified yamaha technician for 20 years. These carburetors come so lean, but usually adjusting the screw little by little helps. How long as it been doing this? Just wondering if you have checked the valve adjustment at all? The air filter is clean and lubed with air filter oil? I'm assuming it's a foam filter and not paper. Make sure the throttle cable is adjusted properly too. Just thinking of some stuff, you may have done all of these already 😆

@@wickedrepairs8527 since brand new. We will just live with it. It needs an accelerator pump ha. And the air screw thing on the backside isn't ALWAYS the case... I'll bet you five bucks that's an air screw lol. Even a gold 20 year mechanic can't know EVERYTHING.. especially when there's a thousand videos and websites out there saying that has to be a fuel screw. I've had this carburetor apart so many times it's not even funny i have carb kits from Arctic Cat, ebay, PZ19 carbs, like 12 throttle needles and every size jet 10 above 10 below, emulsion tubes with bigger/ more holes, electric choke, that's how I figured out the air screw fuel screw thing. Trying to troubleshoot why the hell this thing sputters when you crack the throttle. Ive traced the paths of every hole 17 times lol. Every video, except like 2, says that on that side it has to be a fuel screw, but it doesn't look like any fuel screws. It's just on the "suction" side instead of the other side- I know it's back assward, But there's a pilot air hole on the intake side and if you take the float bowl cover off and spray through you can see where everything goes, the screw doesn't contact any fuel or mixed air fuel. That is why it's not a needle and it's a flat blunt screw. The dealer had this thing for a whole month, it does have a new carb They threw on every part from another machine- I'm talking full main wiring harness, ignition coil, ais pump, pretty much everything and couldn't figure it out and just said these small carbs are finicky. It runs good until the automatic enricher shuts off, heck it always runs good if you just come to a stop wait 3 seconds and punch it fast it'll cough, sometimes die. and I have completely plugged off the enricher hole, but if I put richer jets in it just sputters at the top end. Also yes valve clearance is spot on, compression is 205 psi. I just put a uni filter in there and some uni extra vents on the cover. It's made by Kymco

I can find a carburetor manual online for a Honda CRF 50 with a similar Keihin carb, but it won't let me post it here lol. It's an air screw on the engine side of the slide. That's all I can find but alot of these factory Keihins are backwards. And you probably don't give a shit anyways lol.

@JrodBooya no. I do care 😆 Anything educational I'm all for! It definitely seems like an air screw, just doesn't make sense with the location. I am definitely going to check. I even thing I have a service manual for one. I have a ton of them. The first shop I worked at closed as the owner retired and I got a ton of manuals and tools from him.

@@wickedrepairs8527 the process is the same turning it until it idles highest its just backwards- in is rich. And they both change the mixture ratio lol I run it only 1/2 to 3/4 turns out so it idles rich. This helps with the lean bog when stabbing the throttle fast. Its a 2022 model its been almost 2 years since i crackheaded out on it trying to get it to run like it's EFI, so it's not fresh in my mind plus I'm burnt lol but I am 100% positive about the air screw thing. Its a Keihin PTE i believe, which as far as i found is just a name brand disposable carb for factory cheap machines. Keihin doesn't have it on any of their websites or parts for that model specifically. The extra UNI air box vents actually make it a little lean popping at 1/3 throttle now. I didn't think they would do anything but I'll probably try a bigger pilot again and lower the needle clip and see if either helps. The bigger pilots before would make it sound and run rich. It actually runs perfect the way it was stock, besides fast stabbing the throttle once in a while and bogging or dying out. Can't have it dying out if my kid is trying to cross a road! Ok I'm done being a chatty Cathy now 👍

Where is your idle/air mixture screw set to? I believe it should be at 3/4 turns out, but that is a guideline of course. You can adjust it wherever as needed, but if you adjust it a lot and make it real rich and/or lean you could foul a spark plug doing so (possibly). I am leaning more toward your throttle slide/needle though. Make sure it's installed properly and the throttle cable has free play. I'd start there anyhow

@@wickedrepairs8527 I started at 3/4 then 1 full tuen then 1 1/4. No change. Throttle seems to be free.

Is the jumper on the cdi box removed?

@@wickedrepairs8527 the jumper has been removed

I thought the throttle needles had multiple knotches for the clip like on dirt bikes.

I have the same issue. I’m about to clean carb but you and I could both have compression losss. Don’t need full compression for idle.

@@tru3sk1ll Cleaned and rebuilt carb 3 times. Runs like a top. I also adjusted the float.

Yes it would!

What about a 2018 Raptor 90?

Same process!

Thank plugs! 👊

What needle are you talking about? Just want to be sure. There's the needle valve for the float, or the throttle needle jet, or do you mean the air mixture screw with the spring?

I'm having the same issue. If I mess with the choke, it accelerates the 4wheeler. Almost like the choke and throttle are backwards

@apuente15 sounds like it may need to be adjusted. Maybe the idle is too high where it's getting a idle hang and the choke on makes it race up. How's the throttle cable, make sure it has about 2-4mm of free play.

@@wickedrepairs8527 throttle cable has zero tension.

@apuente15 zero tension as if it's not connected and raising the throttle slide? Of the throttle slide was in backwards it would Rev wide open when you start it.

If you're getting fuel coming into the air box, there is 2 things that could be happening, possibly even at the same time. The float needle valve is probably getting dirty and partially stuck, and/or the pilot jet is getting plugged and fuel is not burning fast enough. Most likely the bigger culprit is the needle valve

@@wickedrepairs8527ahh geez so now i gotta take it all apart an clean it haha. Whats us crazy is my raptor is 2023 and the fuel screw is actually covered by a piece of metal or aluminum.its not how yours is in the video. Probably like that from factory so ppl couldn’t mess with it.

⁠@@wickedrepairs8527i forgot to mention it runs smooth no bogging down its only when its in idle. I did notice every time i let off the throttle it start two stepping “ pop pop pop” im guessing its the needle screw

@mclovin_it8872 yeah, I would suspect the needle valve is leaking over a bit at idle. You can definitely try to adjust the air/fuel mixture screw and see if that helps.

@mclovin_it8872 yes its a plug that is there for emissions. Definitely drill that cap out! Very slowly, use a drill bit then drive a screw into the cap and pull it out. Be careful and go slowly, so that you don't drive the drill into the screw. It's so important, vital in fact to remove that screw when cleaning a carb

It is the stock carburetor that came with the machine. I wouldn't recommend getting anything other than a yamaha one. Aftermarket ones typically aren't jetted properly and/or simply don't work well. Yamaha is costly but worth it