1:11

Part 3 of 3 videos on how to jet your 2 stroke MX dirt bike.
Links mentioned in the video are the following...
Introduction to the Keihin carb PWK38S • 1:11 Jetting Technique...
Introduction to the Mikuni carb TMX • 1:11 Jetting Technique...
Two Smoker Oil Ratios! • 1:11 Two Smoker Oil Ra...
Ordering OEM parts and jets • 1:11 Ordering OEM & Af...
Download Yamaha manuals for free library.ymcapps.net/library/o...
Pro Circuit jetting charts www.procircuit.com/jettingspe...
Donate Race Fuel link... www.paypal.com/donate/?hosted...
Thanks for watching!
[e-mail]

[@ode4492]

I’m surprised your videos are JUST NOW coming into my algorithm. For years I’ve scoured YT for the exact topics you’re discussing on your channel and you’re by far the easiest to listen to and the most informative. Perfect blend of knowing what you’re talking about but delivering it in a non-technical manner that easy to understand. Wish I’d found you sooner. Keep it up either way! Cheers.

[@MasterMotoTv]

Absolutely amazing video!! Thank you for the help and knowledge brother

[@MasterMotoTv]

do you go to Croom?

[@UpAllNight91]

@@MasterMotoTv Thanks! Yes sir, I get out to Croom from time to time. Been riding there since like 1997. I also try to camp out there about once a year. Love that place!

[@MasterMotoTv]

@@UpAllNight91 well I just blew up the top end this weekend trying to tune my bike. New top end will be in tomorrow. Are you near Brandon FL? I’d like to take my bike to you and maybe learn a thing or two.

[@UpAllNight91]

@@MasterMotoTv Hello. I'm located in Parrish which is right up the road. Bummer on the bike blowing up, that sucks. If you need any work done you can reach me at [e-mail]

[@theREAL9er]

I have an 09 yz125, your channels an amazing resource! Thank you

[@UpAllNight91]

Your welcome! Glad to hear that!

[@nastysoda9212]

Gave me all the info I need to get going on tuning my yz250. Thank you so much!

[@UpAllNight91]

Right on! Glad it was of help!

[@chris929rr7]

@@UpAllNight91 upallnite's channel - yz125\250 2t ex race team mechanic

[@sambuvca22]

great sound effects bud lol! i got a really clean 98 yz250 and i installed a lectron carb that just works awesome. i couldnt jet that bike to save my life. think the stock carb was just worn. your vids are great. keep up the good work

[@UpAllNight91]

Thanks man! Yeah I have run into a few carbs that just cant get right and I gotta write them off as age. 1998 YZ250, cool bike

[@bobberbear4622]

excellent video sir!

[@UpAllNight91]

Thank you!

[@71novatoomuch]

Pretty common sense breakdown. Great video!

[@UpAllNight91]

Thanks!

[@1176hambone]

I'm learning the feel. Rich feels thicker/juicier in midrange, stiff on top, kinda like a clogged catalytic converter. lean feels tinny, thin,hollow in the handlebars. My TC250 was so punchy in midrange for my Vet butt, lowered clip and its more linear, helps me control and roll on throttle easier.

[@UpAllNight91]

Right on. Sounds like you got a good grasp of it. Using it to tune in the type of the power you are looking for as well. It was kinda hard to make this video because its more of a hands on thats needed to learn the feel and sound. Good job!

[@dougw585]

Thank you, another great one!!

[@UpAllNight91]

Thanks! And thanks for watching!

[@ethanmartin2781]

i’m not surprised to see that the main jet on the keihin carb has effects at all throttle ranges. i have noticed changes in idling after changing main jet sizes on my ktm.

[@UpAllNight91]

For sure. I also notice the pilot effects the full throttle as well.

[@barkeep25]

I like that you mentioned that its also rider preference and that they can be tuned like the tuner app on the f's. People get way too caught up trying to find the magic combo or spark plug color.. lol i know i was one of em. Ditched all that. Just go by feel. Love a meaty midrange especially coming out of corners is really important to me so maybe a tad fat in the mid but main still revs out clean. So mines less linear, more punchy. But i freaking love that fealing, im addicted lol. So perfect for more me.

[@barkeep25]

Also cutting the head the way you did, woke up the bike so much and made jetting considerably easier. Obviously setting the squish isn't mandatory but does make jetting way easier

[@UpAllNight91]

I can understand that. My YZ125 I actually prefer the ever slightly rich needle used in the 2011 to 2021 over the slightly leaner 2005 to 2010 needle. It gives more throttle control.

[@UpAllNight91]

Yes getting the head right surely sharpens up the jetting, I agree with that

[@watts4200]

sick bike bro!!! 👌🤌

[@UpAllNight91]

Thanks!😁

[@250ridr2]

I'm getting "pipe bangs" stock reeds new top end 178main 50 pilot i'm at 850 ft 65° fmf exhaust system. Never had this before with the old top end kinda confused. Ive been letting it warm up for the heat cycles. And taking it easy, i was 1.5 turn out on air screw. I think the idle screw might need adjusted lower?

[@UpAllNight91]

I would check the power valve, make sure its closing at low RPM's

[@koby.s550]

hey man im having issues with my 2019 kx250f spitting and sputtering and then shutting off while im riding. i got it on my gopro if you have something i can send it to. i just need some guidance on what it could be!

[@UpAllNight91]

Hello. Sure. You can email it to [e-mail]

[@Liliros]

Hello, a question that you would recommend for a Yamaha YZ 250 2t 2023, I am waiting for a fmf factory fatty and shorty, it is carbureted as standard with a main jet 178, do you recommend that when I put the exhaust, I raise the jet to 180 or 182, thanks in advance, regards

[@UpAllNight91]

Hello. Usually aftermarket performance pipes seem to like about a main jet size leaner than the stock pipe.

[@marioguzman9290]

I recommend JD jetting Kitt

[@tuckerprestridge559]

Im.chasing an issue. 172 main jet fmf fatty kiehin carb 99 yz250.. set float hieght. Still having issues bikes not responive feel rich and slow. New reeds

[@UpAllNight91]

Hello. I would start with new reeds if they are old. However I am in the process of replacing my wifes YZ125 (317 hours on bike) carburetor. I thought it only needed a new jet block gasket, replaced that and it still runs a little rich on tip in. Nothing I could do to fix it, even jetting would only mask it and cause other jetting issues in other throttle ranges. So I installed my YZ125 carb (120 hours on bike) on her bike and it instantly ran like a brand new bike. Long story short, these carbs needle can wear into the hole the needle goes into (atomizer) after many hours of use. It will cause a richness. And this part is not replaceable, the only fix is a new carb. Not saying thats what you need, just sharing what I'm facing and what I found the fix was. About to do a video on this actually.

[@benjaminsanabria5212]

I put a new carburetor for my bike did what FMF said but when I run the fuel out of the carburetor it rev super high what should I be looking at

[@UpAllNight91]

Hello. When you say "run the fuel out" do you mean shutting the gas off and running the carb dry?

[@cliffordmcgraw8740]

I run 173 main 40pj 43 pilot on 110 with vforce3 reads apex head cx dome and read spacer. Im at 1090 ft elevation you think thats about correct. Also 32:1 on fuel. Stock exhaust

[@UpAllNight91]

Hello. Considering the elevation that sounds fairly close.maybe a little lean on the pilot but not too bad.

[@sethmacgillivary1281]

Does the transmition oil u put in ur motor lube ur crankshaft or does the oil u mix with ur gas lube ur crankshaft

[@UpAllNight91]

The transmission oil on a 2 stroke bik only lubes the trans and clutch. The premix in the gas lubes the crank and piston.

[@emilysrosenburg9077]

I have a 98 cr 250 it will start and run it might run a minute or it might even go 15 minutes then it dies it’s like it runs out of gas any suggestions

[@UpAllNight91]

Be sure to check that the carb is getting a good flow of fuel and the carbs float bowl is getting filled up nicely. If thats good. I have seen stator coils that work fine when cold but fade away as it warms up and the bike dies. To test it run the bike till it dies. Quickly remove the spark plug and reduce the gap to about 0.012", install plug and see if it will run again and stay running. If it does then your stator is going out.

[@49684]

What’s considered winter in Florida? I’m living in SC last 4 years, but lived in MI most of my life.

[@UpAllNight91]

70 degress is winter here in Florida lol. But the cool air really doesnt start messing with our jetting till it gets close to and before 50 degrees.

[@andyhoms2001]

I like your decal kit. Where did you get it?

[@UpAllNight91]

decallab.com/ you can email them and ask for all their designs for your bike. Its like over 100, you will find it in there.

[@sethmacgillivary1281]

If I run my bike rich I know it wouldn’t run great, but would it harm anything besides fouling plugs?

[@UpAllNight91]

Depends on how rich. A little rich wont hurt anything but overly rich can wash the cylinder walls of lubrication and wear out the motor quicker.

[@Drakester55]

Question. I got a 03 yz250 making a trip to an Elevation is 0-2000ft. I am getting some spooge out the silencer. Plug is a little wet so I’m know I’m running a little rich. I got v force 3 reeds with Fmf factory pipe and turbine 2 silencer. Done some research and I’m seeing a lot of points to run a 175 main 48 pilot with stock needle 2 clip. I’m currently have stock 178/50 air/mix screw 1 turn out, jetting in at the moment. Any thoughts? Also, run 40.1 yamalube mix and do hill climbing/trail riding

[@UpAllNight91]

Hello. My wifes yz125 is jetted spot on while leaning towards the leaner side, running 40;1 and she also has spooge coming out of the silencer most of the time. I wont go any leaner because it would be too lean and I wont run less premix either as I don't want the motor to suffer. She just doesn't ride the bike hard enough to keep it cleaned out but its ok the way it is. The bike has 300 hours on the original crank and never fouls a plug. If you are not opening the motor up and keeping some good heat in her they will spooge, that's just how it is. Sure you can go too lean and run less oil but its not healthy for the motor. The spooge doesnt hurt a thing. I'm not saying your not opening her up enough but thought I would cover that just in case. a 175 and 48 with the stock needle on 2nd clip sounds fair to me, I don't see anything wrong with that jetting and sounds like a good starting point. As you go up in elevation you will also need to turn the air screw out to keep it nice and clean running at throttle tip in.

[@Drakester55]

@@UpAllNight91 okay, I’m going back to old riding spots and the bike ran good stock everything on it. Just thought on the Fmf pipe and vforce3 reeds on it now with getting stooge. Every thing I read about is everyone drops sizes when putting a pipe on. Just curious what your thoughts.

[@UpAllNight91]

@@Drakester55 Right on. The v force doesn't change jetting at all in my experience. PC and FMF pipes don't change the jetting much either but they seem respond better to slightly leaner main jets (usually one size leaner than the stock pipes preferred jetting) to bring out the extra top end performance they have to offer. These are just my experiences with these at least.

[@Drakester55]

@@UpAllNight91 hey, I replaced the mid body gasket on my YZ the other day and noticed the brass where the slide needle goes into the jet mid body is starting to chip/break/crack however to put it apart alittle. I have a picture of it but can’t send it on here. Just curious is that going to affect it at all. Just not seeing anywhere to buy a new jet mid body or how to replace the brass part of housing for the mid body. Any ideas?

[@UpAllNight91]

@@Drakester55 Hmm. Can you email the picture to [e-mail] . Sometimes the only fix is a new carb body but would like to see a pic.

[@againstmywill23]

Been struggling with mine for awhile. I’m at 6k ft and ride up to 10k ft. I’m gonna try some Suzuki needles.

[@UpAllNight91]

Oh man. Yeah. I'm sure at that altitude it can be very challenging. I don't personally have experience at them altitudes but I do remember hearing from guys who do that having the head rechambered with higher compression sure helps clean things up and makes the jetting easier

[@againstmywill23]

I’ll get it. I think your idea of learning what it feels like is smart. I know rich. A decent tune at 6k is crap at 9 or 10k. I can feel that. I did get a high altitude Apex head too.

[@UpAllNight91]

Ahh right on! I'm sure that head helps majorly. Down here in Florida we are at sea level and that makes it easier except when the summer humidity comes. It gets a little different in the high humidity to get them right on

[@aaaaaaaaaaaaaa4151]

Ive rebuilt a 83 RM250, it has a stock TM flat slide carb it dont run too good, Im thinking about replacing it with a PWK from a Yam YZ250 is that a good plan? ( The TM dont have an idle screw)

[@UpAllNight91]

Hello. Nothing wrong with using PWK. I would look for one from like a KTM 125sx (38mm) or a KTM 250sx (36mm) because they dont have the power jet. Since your bike doesnt have the electronics to run the power jet might as well get the PWK that does not have one in there. I dont know what size you are looking for but for some reason KTM used a smaller 36mm on the 250 and the larger 38 on the 125 and 150.

[@aaaaaaaaaaaaaa4151]

@@UpAllNight91 Any suggestion for the jets & needle? thanks for your help!!

[@UpAllNight91]

@@aaaaaaaaaaaaaa4151 Are you thinking of going with the 36 or 38?

[@aaaaaaaaaaaaaa4151]

@@UpAllNight91 38mm

[@UpAllNight91]

@@aaaaaaaaaaaaaa4151 ok, hmm. I dont have experience with a 83 RM250 but if I was to try and get a PWK 38 to work on it I would start with jetting found on other newer Rm250's with the PWK. Pro circuit has a jetting chart ( www.procircuit.com/jetting-specs.htm ), look at a Rm250's jetting with a PWK and start with that jetting. and then adjust from there,

[@sethmacgillivary1281]

How can I inspect the main bearings in my yz 125 without splitting cases just taking top end off

[@UpAllNight91]

You can check for play in the main crank bearings with the cylinder off. You can also just remove the stator cover and grab the flywheel and check the tightness of the crank bearings there.

[@sethmacgillivary1281]

@@UpAllNight91 will the flywheel have play if my clutch side main bearing is bad?

[@UpAllNight91]

If the bearing on the clutch side has up and down play you will be able to feel it on the flywheel as well. It will rock up and down as you try to move the flywheel up and down.

[@sethmacgillivary1281]

@@UpAllNight91 Ohhh ok have u ever had one go out on a yz 125 and feel it like that

[@sethmacgillivary1281]

@@UpAllNight91 if my flywheel has no play is it still possible my crank bearings are bad?

[@amello98]

Where’d you get them graphics?

[@UpAllNight91]

decallab.com/ if you email them and ask for all the graphics they have for your bike it will be in that list. Theres like over 100 in there lol

[@jonnyPizz]

Dyno tune it and save yourself the emotions of thinking is it perfect.

[@UpAllNight91]

Dynos are cool. I use them when I put a cars engine package together. On the dirt for me its more about how it feels and performs on the track than it is getting a good o2 reading and a nice curve that a dyno offers. Plus weather changes and its good to be able to jet it out yourself on the fly when it does.

[@MrHardbodies]

I should have just bought a TBI KTM fk meeeee. But I tell you what. I appreciate the information. I think you need waaaay more subs.

[@UpAllNight91]

Your welcome and Thanks man!

[@JackMacdonald-ih3ht]

How does weather change mess with jetting

[@UpAllNight91]

colder air is more dense, which that will lean the mixture. Which will require richer jetting.

[@JackMacdonald-ih3ht]

@@UpAllNight91 does dense mean thinner or thicker

[@UpAllNight91]

@@JackMacdonald-ih3ht Denser is thicker. More oxygen in the same volume of air.

[@michaelgarland579]

I have yz125 2003 an it has 35 for pilot seems to small but bike running dam good so should i leave it alone??? My spark plug is black on one side every time ??? Why

[@UpAllNight91]

If its running good you can be good. But sometimes a little trial and error and you may find you like one better than the other. Maybe try a 37.5 just to see, and or try the leaner one too. I often cant leave good enough alone till I truly see what the other options have to offer lol

[@michaelgarland579]

@@UpAllNight91 im gonna try that when I get my bike back from my mechanic I like what u said im try 37.5 an IL try leaner one too see how it does il keep u updated bro.

[@UpAllNight91]

@@michaelgarland579 Yes Sir!👍

[@michaelgarland579]

My pilot is 63 an after a few rides its getting clogged I put a filter strainer in my gas tanks to help bike still runs good even if pilot clogged u have any suggestions

[@UpAllNight91]

@@michaelgarland579What are you finding clogging it? anything floating around the float bowl?

[@RadioReprised]

stock pwk on my RM 250 2003...runs great but will not idle and it loads up and dies after about 10 seconds at idle. Dropped from a 48 pilot all the way to a 38 and it still never leans out even with the air screw 3 turns out. Fresh top end and 185lbs of compression with new Boyesen reeds. 162 main, 6.5 slide, 50 PJ and stock needle on the 2nd clip. All circuits are clear, new midbody gasket, choke sealing the well. I can get it to idle for a little bit and put the choke on and it didn't effect the rpm at ALL?! Spits a lot of spooge out the pipe but runs amazing through the rev range....just will not idle.

[@UpAllNight91]

Hmm, does it have a nickle plated cylinder or a sleeve?

[@RadioReprised]

@@UpAllNight91 stock bore.

[@UpAllNight91]

@@RadioReprised Ok, I ask because cast iron sleeves can cause all kinda of issues when not installed correctly. Is the powervalve closing completely, center and side sub ports?

[@RadioReprised]

@@UpAllNight91 Yes, but I should say it's 90 to 100 degrees here. I am ordering a 32 and 35 pilot and will try again! Thanks for the thoughts!

[@UpAllNight91]

@@RadioReprised Oh yeah, hot here too

[@sethmacgillivary1281]

If I run my bike to rich can it cause problems?

[@UpAllNight91]

Depends on how rich. A little rich wont hurt anything but overly rich can wash the cylinder walls of lubrication and wear out the motor quicker.

[@sethmacgillivary1281]

@@UpAllNight91 would overly rich give cylinder more lubricant??

[@UpAllNight91]

@@sethmacgillivary1281 overly rich washes the lube off the cylinder wall. The fuel needs to be lean enough to vaporize or atomize to drop the lube out of it,

[@Soul_Popper]

I usually use JetsRus when I buy jets or carb parts. Might be worth checking out even as a quick reference since they have info like typical jet ranges.

[@UpAllNight91]

JetsRus, Will check it out! Thanks

[@johnbrass8910]

This is a pain to do, 2 strokes are so old school. Get a 4 stroke with EFI, you will be a happier rider. No wasted time on old carbs. Didn't anyone tell you carbs are bad? :>

[@UpAllNight91]

On a 4 stroke I agree, EFI is best. Owned many of them and wont own a 4 stroke carbed bike. But on a 2 stroke a carb can't be beat by EFI. The 1 HP lost in power due to the extra power pulled from the stator to run the fuel pump and extra electronics is not made up in the end and the motor doesn't even feel any better. They are two totally different animals

[@bobbysteffan2507]

Some of us mechanically minded people geek out and actually enjoy tinkering and tuning bikes til that 2 stroke absolutely barks!!!

[@UpAllNight91]

@@bobbysteffan2507 Yeah, I love knowing my bike runs as good as it does because I took the time to get it all dialed in.

[@andyhoms2001]

Yeah, lame. 😕 👎