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Crf 150f jetting and simple power mod easy and inexpensive

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So i have never posted on here yet but wanted to share some valuable info that hopefully can help someone struggling as i was to get some more performance out of my 2014 crf 150f. This is a simple easy upgrade that will cost about $250 or less and the the power and torque difference is huge. 

 

So here is what you will need.

 

115 main jet

42 pilot jet

K&N filter

50 tooth rear aluminum sprocket. ( I used a JT sprocket) (no need to change front sprocket the stock will do just fine)

New Roller chain (the stock chain fits fine and is long enough however it is restrictive and robs you of power to your wheels) you can see forums on roller vs o ring chains (this is optional)

BBR rev box 

3 unifilter uv-6 inserts

 New exhaust is optional...or you can remove the baffle from the stock exhaust. (i used a Two Brothers full exhaust)

 

all these are available from CRF'S ONLY or on AMAZON  

 

So the process is simple First start by gaining access to your air box (you will need to take off the seat to gain access to the top of the box as well take out the old filter and remove the rubber snorkel from the top of the box. Then remove the mesh screen in front of the filter going into the intake. It is on there good so it will take some work. However it is worth it because it is three mesh layers and is very restrictive. Be sure to get all the mesh off. Now you will need more airflow so install the three uni filters in the top of the air box by drilling the appropriate size holes for them. Install the new air filter. So we have now solved our air problem. Next we will need to re jet the carburetor using the new 115 and 42 jets in the carb. I wont go into details on how to do that but it must be done or it will run very lean or not at all. 

 

So now we install our rev box which eliminates the factory rev limiter and create a better curve through the rpm range. Follow the instructions for this install it is plug and play and located behind the number plate on the front bars right side. 

 

Finally either install a performance exhaust or simply remove the baffle from the stock muffler. This is important because we have more air coming in and we need to allow it to flow. As i stated i replaced the exhaust with a Two Brothers full exhaust it was the best bang for the buck and it sounds great as well, The advantage is not only better airflow but it weighs a lot less as well. However you can get good results just removing the baffle.

 

I found a huge difference in power and performance. It is like having a new bike. I had done a lot of research on this and found this combination is the simple way of achieving results. Plus if you ever make the next step to a big bore kit most of the work is already done. 

 

I know some will doubt this or have different ways but i am simply saying what worked for me and has proven results. I am now able to pull the front end up easily and there is no sacrifice in top end from changing the sprocket because of the power difference. Most of the items i changed or modified are things that Honda had to do to meet emissions while producing these models. So all you are doing is allowing the engine to breathe better and rev a little higher. 

 

I hope this helps some of you in your quest for power.

 

 

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115 to big unless your riding in Death Valley (below sea level) and outside air temp is below 40d a 110 main jet at sea level at 70d air temp will make more power than a 115 any day of the week.

BBR CDI Box will not add one single ounce of HP on a stock, properly jetted 150f but will allow the engine to scream at 10,000 rpm for no reason, causing premature/abnormal wear. You will be spending money for nothing when you should be spending $ on suspension improvements instead.

There is no power to be gained on a stock properly jetted 150f buy changing the air filter to a different brand and especially by drilling holes in the air box.

You can completely remove both sides of the air box by cutting them off with a saw and leave both # plates off of the bike . There will be absolutely no more power made by removing the backfire screen either. Of course if your purchasing extra filters (K & N filters are bad for your dirt bike unless it's a street only bike) to change them out when they get dirty, then that is wise.

Another very wise thing that you have done to your 150f is to gear it down to decrease the bikes top speed.

The stock suspension is so poor that your taking less of a chance of hurting yourself by over riding your suspension. So good call there.

Edited by adnohguy
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Oh yes.  I forgot about the backfire screens.

 

Mike Coe leaves the screens in.

 

Frank Nye takes the screens out.

 

Since these tiny engines move so little air I can not see how removing it could make much difference.

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Oh yes. I forgot about the backfire screens.

Mike Coe leaves the screens in.

Frank Nye takes the screens out.

Since these tiny engines move so little air I can not see how removing it could make much difference.

When you charge $ for removing the screens, and get paid for it, then it's good, correct? Can't hurt anyway.

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Ok so let me start by saying that a 112  jet did not work for me it bogged at higher rpms. If using a stock exhaust the 112 will be fine. The 115 gave me best results.

 

Next you are correct the rev box adds no horsepower at all. It allows the spark curve to advance and allows more rpm at the top. It is always argued about if it damages the engine because of the higher rpm and it does not. It is limited from the factory for emissions restrictions and due to the airflow restrictions from the stock setup. (all emissions)

 

Now as far as the exhaust. You are correct removing the baffle (not talking spark arester) is only a cost effective way to get slightly better airflow and most to get sound. (That is why i recommended a performance exhaust.)

 

K&N is not the greatest for filtering and you are correct however if used with a prefilter it will allow the airflow you need, ( it is a matter of choice any high performance filter will give better results. (once again works with my setup) 

 

As far as drilling the air box and adding uni filters being a bad idea. i disagree with your statement simply removing the snorkel still restricts air flow. I bogged down and when i added the three holes that went away. So i made my statement on results not speculation or impulse.

 

Remember to meet EPA standards they restrict everything for emissions. Just like any bike car or truck racing, trail, street  it doesn't matter what are the  first upgrades? Exhaust and intake..

 

Once again this worked for me. There are allays skeptics who seem to know it all. I will simply say there is no one setup that is the best it is trial and error. I played with jetting and ways to get the engine breathing better to get to this point. Each bike will be different. Luckily jets are cheap and easily replaced. I went from a 110 all the way to a 125 before i settled on the 115 being correct for my setup. 

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But at least the stock suspension is working as designed, correct?

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No....Forgot to mention that in my reply. I have made suspension upgrades. You are correct the stock suspension is scary. Good for trail riding but dont get to crazy. I have installed a new rear link. New springs front and rear triple tree and a few other goodies. 

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Very interesting.  Our 2004 CRF150F came with a BBR CDI, 115 main jet, and backfire screen already removed.  The 115 was too rich and after verifying float level externally we installed a 110 main.  Much better from high-mid to top.

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I have no issues with the 115. tried 110 and 112 bogged on high end. went to 115 no issues. Dont forget i am using a two brothers full exhaust not just a modified stock exhaust. Also the difference between an 04 and 14 can be it as well. 

 

whatever works. 

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I've noticed that if you set the float level on the 150 to the manual spec's of 12.5mm the fuel level itself seems low as compared to other carbs I've worked on, their fuel levels in the bowl are more like what you get if you setup the 150 by using the clear hose on the bowl drain spigot method, it's only a difference of about 3mm but it could make a big difference to the main jet that's needed, so what I'm getting at is, if the float setting is at factory spec's you may need a bigger jet than what is needed if you set up the float up to where other carbs normally have their floats set(talking 150 only) maybe the 150 is designed to run with a lower fuel level in the carb :excuseme:  :excuseme:

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No....Forgot to mention that in my reply. I have made suspension upgrades. You are correct the stock suspension is scary. Good for trail riding but dont get to crazy. I have installed a new rear link. New springs front and rear triple tree and a few other goodies.

No mention of how many 3mm flat washers you placed under the clip of the needle. Or verifying float level settings, proper valve adjustment or if you adjusted the idle mixture screw for the fastest idle speed before setting the base idle speed where you like it...

Believe it or not, we are trying to help you get the biggest bang for your buck.... You stated that you are a first Time poster here on TT.

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No....Forgot to mention that in my reply. I have made suspension upgrades. You are correct the stock suspension is scary. Good for trail riding but dont get to crazy. I have installed a new rear link. New springs front and rear triple tree and a few other goodies.

I take it that you had the rear shock re-valved properly or replaced it with one that actually works like a rear shock is supposed to?

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Yes dont post much, and this is why. Everyone always has a better way. . It is actually not helping it is like someone trying to show off and belittle someone for trying to help the community get a little out of there bike. Let me say that you dont always need to give every detail and spec. sorry i didnt put 5k into a 3k bike. If i wanted a 150r i would buy one. 

 

Needless to say i am not stupid and to be belittled in that manner is offensive. I guess i will leave this post by saying you are the expert no one knows as much as you and you are correct in everything you say. 

 

You win your advise is the best and you know it all. no one will ever do it as good as you. Your way is the best way. I should have used all the products you used. Damm i feel like an idiot sorry i ever questioned you. Should of checked in with you before i made my purchases. When i grow up i want to be just like you and know everything and. 

 

So in closing if you feel that my way is wrong than why does it work? I guess i should do it your way and have my bike run like crap because thats what you did? If a 110 112 or anything else doesnt work why would i do it? I have been there it does not work on my application. That is what you fail to realize. I have a 150f not a race bike it will never be that. I simply gave a guideline of success i had. It may work for some but not others. You need to stop the way of thinking that you are the authority on how to do everything. This forum is for people to give suggestions and success stories. Should i tell the person who lowers there bike its a mistake? Or the person who likes a different tire that it is wrong? 

 

Help is one thing criticism is is another. Closed minded is the worst of all. 

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As I have always freely stated on TT many, many times, I enjoy learning something new here every day.

Some days I have to admit, that I don't learn any new stuff at all.

In fact, many regulars here on TT do there best to save new Posters some $ on setups that are not cost effective, conjecture, non productive and just plain bad or hearsay advice.

Most people that post here don't have liquid cash laying around to blow,

Some people obviously do.

Thats fine, every one has there own way of doing things.

Take it or leave it, learning the hard way is how I learned also. Some times, for some it seems, that the learning curve can be very steep.

Edited by adnohguy

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I have no issues with the 115. tried 110 and 112 bogged on high end. went to 115 no issues. Dont forget i am using a two brothers full exhaust not just a modified stock exhaust. Also the difference between an 04 and 14 can be it as well. 

 

whatever works. 

 

Wow.  Somehow I missed the Two Brothers exhaust up there.  For sure an exhaust systems can impact your main jet selection.  My Engines Only Outlaw exhaust system only needs a 110 main jet as opposed to the 120 most use.  Frank did extensive dyno work and found that was the best main jet size for his system at sea level.

 

Very interesting that you had a bog at the top end.  That is something I have never experienced.  Usually just flat from being too lean or too rich.

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As I have always freely stated on TT many, many times, I enjoy learning something new here every day.

Some days I have to admit, that I don't learn any new stuff at all.

In fact, many regulars here on TT do there best to save new Posters some $ on setups that are not cost effective, conjecture, non productive and just plain bad or hearsay advice.

Most people that post here don't have liquid cash laying around to blow,

Some people obviously do.

Thats fine, every one has there own way of doing things.

Take it or leave it, learning the hard way is how I learned also. Some times, for some it seems, that the learning curve can be very steep.

See that is the thing you are still implying that my setup does not work and i am completely wrong. I am open minded and before i got a profile always read the TT feeds for advice or to see what works or didn't work. What baffles me is that you still imply that My setup is useless and a waste of money or time. Well i assure you if i change my jet it will take away performance. Also I assure you that valves and Float is set correctly. 

 

All I was simply sharing is something that worked for me. Think of this a Nascar stock car is the same however there are many different setups. What works for one may not work for all. All i shared once again is what my trial and error delivered the best results. I am no expert but not illiterate with engines. All i a asking you is to not try to cram something down someones throat because of the way you feel. You may not like any BBR products for example but John Doe lives by them.

 

This Forum is an information exchange. The best bikes are usually FrankinBuilds. I wont use every part from the same manufacturer ts about finding what works best for your application.Because your bike runs better on a 110 or 112 doesn't mean mine will or John Doe's will. I see posts ranging from 95 to 125 so are you saying that everyone who uses a different jet kit than you is wrong? If someone disagrees with you or had better luck with something else is wrong also? 

 

If that is the case then why should anyone else ever post we need to just check with you first. This is a forum to share the good the bad and the ugly. Believe me if asked i would recommend starting with a 110 or a 112 which i did and got that suggestion from a forum on TT that apparently worked for most. I also do see where people have run as high as a 125 did that 125 work for me? No but what is to say it didn't work for them. 

 

What I am saying is stop trying to say that other people are wrong unless they do it your way. Have an open mind and Listen to others. How did you learn? I am sure it was trial and error at times. 

 

I am not one of those who have money to burn. I have made bad decisions and some fails but the whole point was to share a success weather you believe it works or not every idea or setup is a baseline. Your information is great and i appreciate it. It is in fact where i started. It is where most should start.I simply wanted to share something for those who want a lower cost alternative to get a bit more pep out of there stock machine. However to be ridiculed and for you to attempt to make someone look like a fool is inappropriate. Have an open mind ask questions but don't lay someone else out because you disagree. 

 

I may be new to this site but not new to the game. As i stated not an expert but not a novice either. I reach out when in need and welcome advice and know how. What i do not welcome is flat out  belittling because someone else did something different than i would have. I would not do that to someone. 

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Wow.  Somehow I missed the Two Brothers exhaust up there.  For sure an exhaust systems can impact your main jet selection.  My Engines Only Outlaw exhaust system only needs a 110 main jet as opposed to the 120 most use.  Frank did extensive dyno work and found that was the best main jet size for his system at sea level.

 

Very interesting that you had a bog at the top end.  That is something I have never experienced.  Usually just flat from being too lean or too rich.

Thats what I am saying. My setup may vary. Someone could use the same exact setup and have a difference in jets. Carbs are so different right from the factory. You can have 2 identical stock bikes and the needle settings may be 1/4 to a turn difference between the two. As we all know jetting is on a case by case basis. These carbs are mass produced and in know way perfect. Direct form the dealer they have to set and tweak each bike before it leaves the showroom and each one comes from the factory with the same setting. So the variation is there. That is why when we change something we always have a variation of jets on hand  it is that small difference that can make a big impact. 

 

Thank you for a positive response and not bashing my choice. 

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Well I have to a admit, after rereading your very first post again, I have to admire you for thinking "outside the box"

Can't question your efforts on that.

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Thats what I am saying. My setup may vary. Someone could use the same exact setup and have a difference in jets. Carbs are so different right from the factory. You can have 2 identical stock bikes and the needle settings may be 1/4 to a turn difference between the two. As we all know jetting is on a case by case basis. These carbs are mass produced and in know way perfect. Direct form the dealer they have to set and tweak each bike before it leaves the showroom and each one comes from the factory with the same setting. So the variation is there. That is why when we change something we always have a variation of jets on hand  it is that small difference that can make a big impact. 

 

Thank you for a positive response and not bashing my choice. 

 

Trust me -- I understand very well.  You would not believe the number of people that posted there is no way my Engines Outlaw Outlaw exhaust system can be making more power with a smaller main jet.

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