[Jakup]

I bought this bike for my girlfriend and have done a little jetting before this bike. It is a fun bike but mostly midway though throttle pulling up hills it falls on its face. Keeps running but sounds like crap and will not accelerate. It mooatly happend with altitude. We can start in the desert at 2500 at the beginning of the day and end up near 6000 within a couple hours. Referee to the stock jetting chart. And said to lean out the main and change needle. Had stock jetting so I went down to 135 like manual says. Went up in pilot just to see if could feel anything down low. Ran the same. Kept main at 135 and dropped pilot down as well to 35 from the 40 I had just installed. Ran the same again. Adjusting fuel screw each time from cracked open to full 2 turns out and never feel any difference.

Bike has stage 1 cam
Stock repacked exhaust can and omg end cap for sparkies


What is your elevation ?? ______2500-6000________

What type of riding are you doing ?? ________desert/mountain___________

What is your Fuel Screw set at ?? _______1.5-2_____

What jets are in it (Pilot/Main) ?? __38____/___135___

What is the Needle Clip Position ?? (IE: 3rd from top , etc.) ______3rd______

Was the bike running fine then just started doing this ?? , or was it like this when you bought it , or after sitting for a extended period ?? ____________ran like this when purchased__________________________________________________________________________________

Have you actually pulled the carb and cleaned it (removing all the rubber parts like Fuel Screw O-Ring , Slide , Floating Slide Plate O-Ring , gaskets , jets , and flushed everything with carb cleaner and blown out with air) ??? __________________yesss_____________

Do you have a Manual ??? (Yes/No) ___yesss__/_____

Have you lifted the subframe and airbox , and looked down the throat of the carb and twisted the throttle to see if the accelerator pump is squirting ?? , and if it just barely misses the slide and does not hit it ??? ________________________yesss__________________

When/if you took the carb apart , did you note which way the floating plate is on the slide ?? , was the hole at the bottom ?? , or the Top ?? , it needs to be at the bottom .. __________bottom__________

Did you drain and flush the tank and put FRESH Premium in ?? ____________yes______

Was the bike sitting for a long time (over 3 months with gas in it , if so see above last 2 questions) ?? __________no__________

If the bike was recently purchased , was the prior owner up front and explained the issues with the bike ?? , and if it was recently purchased how long have you had the bike , and were the issues present then ?? ______________no issue_________

[Bryan’s crfs]

I bought new a 2016 & 2017 crf150r. I saw the dealer prep guy ride both bikes in the lot so I figured they were good to go..1st trip out went to gorman in California. Altitude around 3500ft. Air temp was 43deg. Both bikes ran very lean. Ok power on the flat land, stalled and bogged on hills. Stock jetting is 138 main 38 pilot. Had a lot of bogging issues and idle problems...got the bikes home. Tore both carbs apart.. found black plastic shavings inside the carbs..carbs were dirty and pilots had residue inside...was told that Honda 150r are jetted lean from the factory for emissions. I installed R&D air screw for easy access.. 1 bike I went to a 40 pilot...other I went to a 42 pilot..between the 2 I should be able to adjust the tune with the air screw to find what jet works best..main and needle were left stock. Bikes have FMF power core 4 slip on muffler with spark arrestor.. so that kind of chokes up things compared to stock muffler... taking the bikes out this week to see how they run...also going to try using VP T4 fuel...want to eliminate the issue of bad gas. Right now at sea level. Both bikes idle good and very good throttle response....I was told if bogging continues... try going to a smaller leak jet size..it will reduce the amount of fuel coming in from the accelerator pump..

[Bryan’s crfs]

Recap after I took both crf 150r back out to gorman. Air temp was 55deg. Altitude was 3470ft..did use vp t4 fuel... turned the fuel on. Gave 3 twist of the throttle... bikes would not start on the choke..turned the choke off. 2nd kick it started..idle was good.. throttle response was slight boggy until fully warmed up..both bikes ran very good.. no adjustments made on air screws.. waiting to get home so I can pull the spark plug and read how they both fired...

[Back2-2]

My suspicion would be that you have to large of a pilot jet or the pilot is adjusted to far out. At 55F and 3500 ft the engine should require enrichment to start. One try would be to find the setting you have presently on the fuel/air screw. Then adjust it in [CW] from that setting and see if they begin to act and start as they should. Start at 1/2 to 3/4 turn in to see if it has a significant difference.
Second, that FMF is going to have much less restriction then the OEM stock muffler. Even with the FMF spark arrestor.
At 3500K alt. you may need a step up in main jet but the stock pilot should be fine with maybe minor adjustment.

[xxwarbirdxx]

I have a 2012 CRF 150RB. I replaced the stock exhaust with a T6 Pro Circuit Full Exhaust system and stepped up the main pilot to 45.
The bike has excellent acceleration until the rpm's rev up to the point where I need to shift...

Does anyone have any advice on what adjustment I need to make in order to get the bogg from occurring at the top of each gear?

An added note, I added a larger rear sprocket that added 4 teeth.

Thanks!

[Back2-2]

If you are getting a bog at the top of the rpm range that is usually an indication of over fueling / to large of a main jet.
You can confirm that by slightly backing off the throttle while in the bog condition and if the bike accelerates and rpm increase - you are to large on the main jet. Make sure you are not hitting the rev limiter and confusing that with a fuel issue.