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How can I "de-tune" my son's motocross bike?

06/25/2008 6:57 PM

I'm not a motor head and my 18 year old son just purchased a 2008 Honda CFR150 "R" motocross bike for his first motorcycle!

http://powersports.honda.com/motorcycles/motocross/model.asp?ModelName=CRF150R+Expert&ModelYear=2008&ModelId=CRF150RB8

I feel it needs to be governed down a little until he gets used to it but I'm not sure if I should mess with it.

Any ideas that are temporary and won't void the warranty?

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Anonymous Poster
#1

Re: How can I "de-tune" my son's motocross bike?

06/25/2008 7:07 PM

Cut in a restricter valve on the rubber fuel line or place a hard stop on the throttle cable.

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#2

Re: How can I "de-tune" my son's motocross bike?

06/25/2008 7:09 PM

There's nothing you can do.

Anything you do, he will undo.

He may, in fact, have some upgrades in mind already.

At one point or another I've had 3 18 yr olds. They were all smarter than me.

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#19
In reply to #2

Re: How can I "de-tune" my son's motocross bike?

06/27/2008 3:06 AM

Well then ask them what THEY would advise!

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#38
In reply to #2

Re: How can I "de-tune" my son's motocross bike?

06/28/2008 3:33 AM

Who poked that poor kid in the eye in your avatar?!

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#43
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Re: How can I "de-tune" my son's motocross bike?

06/29/2008 7:49 AM

That's my grandson saying grrrrrrrrrr, whilst making his pirate face.

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#3

Re: How can I "de-tune" my son's motocross bike?

06/25/2008 10:30 PM

Brick top is right. But there is a company called MSD that makes ignition controls. They sell ignition improvers that will add power, but incorporate a rev limiter. The limiter can be set to any rpm you choose, by means of a plug in module. A more knowledgeable poster than me will need to advise you what rpm to limit it to. Talk to MSD at www.msdpowersports.com They will tell you what product is right for your bike. Buy the kit. Install the kit, and then seal everything with silicone rubber, including the rpm module. Regularly check the silicone for signs of little fingers. The dealer should not object to a rev limiter on the bike. Your son and you might actually enjoy the project. There is the promise of more power when the rev limiter is brought up higher. Good luck, and let us know how it works out.

All you Honda experts out there, what should he limit the rpm to to help his son learn the bike?

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#4

Re: How can I "de-tune" my son's motocross bike?

06/26/2008 8:14 AM

My take from playing with dirt bikes since I was 5 or 6 to my current age of 39..don't try to tweak the fuel lines or change ignition. Probably the two easiest ways is to either put a throttle stop on or restrict the exhaust. For the throttle stop, you'll likely need to get a different throttle, drill and tap a stop screw to limit the cam/cable pull. You can probably restrict the exhaust with "washer" at the head pipe attachment. However, the new "performance" 4 strokes are somewhat finicky so it may run poorly. They especially don't like air leaks on the exhaust.

That bike's still pretty docile at low rpm's...

On this bike, if he's 18 and decent size, he'll probably scare himself a time or two but ready for all the power pretty quick.

For more info or suggestions, search and ck on forums like ThumperTalk, DirtRider, etc.

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#5
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Re: How can I "de-tune" my son's motocross bike?

06/26/2008 3:10 PM

Well considering my brother and I figured out how to undo the governor my dad put on our bikes by the time we were 10, I don't think you can do much to stop an 18 year old. The only thing that slowed us down was that he would stop buying the gas from time to time.

Sometimes you have to learn things the hard way. Tell him to be careful and take it easy for the first couple of rides. If he comes home hurt, tell him to be more careful next time. With dirt bikes, part of the learning is busting your butt a few hundred times. Most times its minor and worn as a badge of honor amongst your frinds. (Dude! Check this out!!! I totally busted my a$$!)

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#6

Re: How can I "de-tune" my son's motocross bike?

06/26/2008 3:43 PM

Thanks for all the tips, I'll have to check out the MSD link. I was actually going to talk it over with him first because he's making the payments.

I was going to offer my help while he got used to it but he'll probably say NO WAY! I would have.........

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#7
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Re: How can I "de-tune" my son's motocross bike?

06/26/2008 10:54 PM

Why not offer him paid lessons?

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#9
In reply to #7

Re: How can I "de-tune" my son's motocross bike?

06/26/2008 11:15 PM

This I got to see. The son is paying for the bike, and he is also going to pay his father to give him riding lessons. After his father castrates the bike.

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#10
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Re: How can I "de-tune" my son's motocross bike?

06/26/2008 11:25 PM

Strange interpretation.

This bike is probably more manageable than a 2 stroke. I would leave it as is.

Send the kid to a motocross club or course so he will learn in a ''controlled'' environnement.

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#13
In reply to #7

Re: How can I "de-tune" my son's motocross bike?

06/27/2008 12:24 AM

There is an ex-motocross bloke in america somehwere who runs courses on doing loops/backflips with motorbikes. Takes about a week to learn I think. Its all done with lots of foam and stuff so your kid will survive and be far better at handling his new toy in no time.

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#8

Re: How can I "de-tune" my son's motocross bike?

06/26/2008 10:58 PM

As far as MX bikes go, the 150 FOUR STROKE is not a real power house. The 150 you have is a mini bike with some good suspension and ergos to go with it.

An average 18 year old will be far past the potential of a 150R in short order. But learning to ride with a limited amount of power will make for a better, more efficient rider. Having all the power in the world allows you to get lazy and rely on that power instead of rider finesse.

Leave it stock or buy a pipe and cam kit, ride the wheels off it for a year and then get him a 450.

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#11

Re: How can I "de-tune" my son's motocross bike?

06/26/2008 11:47 PM

All I can say is, don't restrict the fuel flow, lean burning your mixtures will possibly do some engine/valve damage.

Add some extra heavy oil to the filter, or shove a sock in the air intake line, to choke the engine more.

Take him out and get him to learn how to ride resposably, best thing to do.

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#12

Re: How can I "de-tune" my son's motocross bike?

06/27/2008 12:06 AM

If the goal; is to reduce top speed there is one easy and full proof way.

Take the bike to the dealer after you figure what top speed you will be comfortable with. Have the dealer remove the front,rear or both sprockets and replace them with a combination of ratios that at red line hits your number.

Your son will have a lot of acceleration and feel like he his going fast because of the RPM's.

Do not alter the fuel lines.

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#30
In reply to #12

Re: How can I "de-tune" my son's motocross bike?

06/27/2008 12:18 PM

I agree 100% about changing the gearing to slow it down, dont mess with the intake or carb they are hard enough to dial in with elevation changes. It is a dirt bike, get him ALL of the proper gear, he will crash... and you should look into a bike and go with him there are few things in life that you will be able to enjoy together like this. Good clean fun. I have three boys 6, 9 and 10 and my 6 year old has been riding since 4 he can ride a 90 and is begging for a faster bike. He will either like it or not, he is paying for it so he already does. the 150 is a great bike for learning and then some. He doesnt have to go to a 450 as the 250f's will pull him any where he wants to go. Have fun and get your self some gear also. Knee/ shin, elbow, chest protector, gloves, goggles helmet, boots.....

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#14

Re: How can I "de-tune" my son's motocross bike?

06/27/2008 12:40 AM

It depends what you are really setting as the goal?

All new technology 4 strokes have rev limiters built into the magneto.

Increase the rear wheel sprocket, this will slow down the bike and increase torque if you are worried about top speed.

The other idea to limit the power band is to pull the carb and change the needle jet to richen the fuel mixture, the jet needs to be of smallest available size with small venturi, which means less fuel, then lower the needle (raising the clip setting), which will decrease the air mixture, like running with the choke on. The spark plug will get damp, perhaps some whiskers will occur. He'll not be able to run real fast.

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#16
In reply to #14

Re: How can I "de-tune" my son's motocross bike?

06/27/2008 1:01 AM

Guest you are correct but I assumed reliability was important. Your idea could cause stalling and fouled plugs.

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#18
In reply to #14

Re: How can I "de-tune" my son's motocross bike?

06/27/2008 1:22 AM

OEM's spend a lot of time and energy to get the carburation right on this type of bike. Small displacement and a 4 stroke to boot, not the easiest thing in the world to jet correctly the first time around.

Don't fool with the carb. If you really don't want the 18 year old man to ride the minibike, take it away from him and give him back the schwinn.

Markar, I do not want to offend you, but you son is 18 years old and making the payments on the bike. Talk to him and offer a Rider Awareness Class.

I have been riding for years both on and off-road. Last year my wife wanted to learn and get her endorsement also, so she signed up for a RAC. I watched all three days, and I learned a lot also.

She passed with flying colors and now has her endorsement. We ride together and on separate bike now.

Now we have a 77 GT550 Triple Two Stroke, 05 V-Strom 650 and an 03 DRZ400S.

Hey, why don't you get a 150R also and you both can share some quality time on two wheels.

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#15

Re: How can I "de-tune" my son's motocross bike?

06/27/2008 1:00 AM

Hey listen, the best thing is, just let him learn on his own. Give him some courses to learn from, or let him go free. Hes a kid, he will learn it. I started out on a 750 crotch rocket when i bought my first bike. That was stupid, but i learned to control it. You didnt "de-tune" his first bicycle did you? Hes going to wipe out, hurt himself, and probably go to the hospital for some broken bones. But think about like this... its not a 450!

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#17

Re: How can I "de-tune" my son's motocross bike?

06/27/2008 1:07 AM

Just be thankful he didn't purchase an ATV, and leave ot at that.

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#20

Re: How can I "de-tune" my son's motocross bike?

06/27/2008 4:15 AM

I am sure your 18 year olds will appreciate your Fatherly "Love"

Instruction and trust is beter than restriction and distrust

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#21

Re: How can I "de-tune" my son's motocross bike?

06/27/2008 5:24 AM

Put a restrictor in the inlet air duct somewhere.

The hole should be about 60% of the diameter of the duct at that point, cutting off about two thirds of the air flow through the vena contracta effect. It has negligible effect on low speed torque but it will make it wheeze at higher revs.

I have played with one to three carburettors on a 6 cylinder engine and the difference in high speed revs/power is very noticeable.

Try breathing through a small diameter tube and you will see what I mean.

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#32
In reply to #21

Re: How can I "de-tune" my son's motocross bike?

06/27/2008 2:16 PM

I agree the restrictor plate is the way to go - it works quite well to limit top speed in auto racing. Ed

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#44
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Re: How can I "de-tune" my son's motocross bike?

06/29/2008 11:23 PM

There are ways around the usage of restrictor plates, and its found mostly in racing.

Fly cutting the heads/cylinders and using a higher octane fuel then linishing the intake runners to "hide" the welded intake runners.

moving the air intake into the airflow so the engine is doing less "sucking" to get air thru the restrictor plate as there is more of a +ve pressure upstream (much easier to suck air thru the plate when its being pushed in the other end)

Toyota once "Cheated" and were busted for it after a time, they manufactured a ingenius mechanism that when the intake tube was removed and the port inspected and found to be correct, the intake tube reinstalled and the hose clamp tightened auxiliary port openings sprung open and allowed for bypassing the restrictor plate, ok, a bit expensive, but what a piece of work ;o)

If this 18yo wants to experiment, he may get a source of Methanol and add to the fuel, gives it a extra kick, been there done that, dropped the bike in the process, or actually didn't drop the bike, it took off from underneath me. That was on my 4-stroke Honda XL-250

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#22

Re: How can I "de-tune" my son's motocross bike?

06/27/2008 6:58 AM

Take, and hide, the keys.

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#23

Re: How can I "de-tune" my son's motocross bike?

06/27/2008 7:06 AM

I think that it should be pretty obvious by now, detuning the bike is a bad idea. When I was 18, I had already rebuilt and swapped half a dozen engines, as well as tuned them pretty hot. I garantee that there is nothing, short of destroying the bike(and even then), that you can do to it, that he could not undue relatively easily. At 18 I was extremely arrogant and rebelliuous. If my father detuned my bike, I would modify it to be even faster, just for spite.

He is an adult(legally at least), treat him like one. Talk to him, tell him that you would like him to take a class for riding technique, even offer to pay for it. Put the ball in his court, he will respect you for respecting him. On top of easing you mind, it will make him a much more proficcient and safe rider.

You get more flies with honey than vinegar.

Just a thought from a fellow father, who used to be a lot wilder.

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#45
In reply to #23

Re: How can I "de-tune" my son's motocross bike?

06/29/2008 11:26 PM

"You get more flies with honey than vinegar"

Dunno where this saying comes from, but I have never seen a fly get even interested in Honey, Bees and European Wasps yes, father spilt about 5 litres of that golden stuff, within 1/2 Hr, there was a moving mass of bees and wasps trying to fight their way to get their fill..

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#24

Re: How can I "de-tune" my son's motocross bike?

06/27/2008 7:53 AM

Dude, the guy is 18. That makes him an adult. If by the time he is 18, he doesn't have enough sense to ride sensibly and watch out for himself, he needs to ditch it a few hundred times to teach him a few things. He will learn things like "Gee, my actions do have consequences!" "Gosh, that was a really dumb thing to do!" all by himself. Gravity has a way to teach these things.

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#25

Re: How can I "de-tune" my son's motocross bike?

06/27/2008 8:05 AM

Take it to a reputable dealer....

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#26

Re: How can I "de-tune" my son's motocross bike?

06/27/2008 8:39 AM

I started riding a motorcycle when I was around 18 (I wanted one sooner, but Mom said no!). This was after 18 or so years of insane bicycle riding. I say insane, because I was invincible and would attempt to jump anything. My experience on the motorcycle was that it was very intimidating. It took me at least until I was familiar with the bike before I would do anything daring. I'd say his experience will probably be similar otherwise he might not need a bike.

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#27

Re: How can I "de-tune" my son's motocross bike?

06/27/2008 8:47 AM

Like the guys are saying, if YOU haven't taught him by now, it's now down to him.

This bike is quite tame and a good first timer.

He'll soon discover that if it's too fast, to close the throttle and apply the brake. And if it hurts too much he'll park it up. At 18, the body hurts more when it gets bumped badly, than it did a couple of years ago.

If you really get worried get him a good looking girl with other interests, he'll ditch the bike in a flash.

Stu.

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#28

Re: How can I "de-tune" my son's motocross bike?

06/27/2008 9:04 AM

Go here:

Honda Riders Club

If you got the bike new from a dealer you probably got a complimentary year membership for free.

Read everything, study the recommendations, review the training course offerings, events, races, etc.

I wouldn't cripple a 150. One could kill themselves just as easily on a bicycle.

Hooker <--- a prior trail/moto rider who now just enjoys his Honda Aero cruiser

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#29

Re: How can I "de-tune" my son's motocross bike?

06/27/2008 9:14 AM

I wouldn't be so concerned with adjusting the performance. The CRF150 is a pretty potent motorcycle, but it is a good motorcycle for an 18 year old to learn to ride motocross. My best suggestion is to invest in the appropriate safety gear, helmet, boots, goggles, gloves, chest protector and last but not least, neck protection. Given the number of catastrophic neck injuries that have occurred in motocross, I believe that an investment in a good neck brace like the Leatt is not optional - I won't let my kids, nor will I ride without our Leatt's.

Another thing, invest in a proper riding school - I believe that even the Motorcycle Safety Foundation offers an offroad course - if not in your area, then there are schools that offer excellent riding schools. The investment in proper instruction will pay off two fold, not only will your son have a good foundation in the fundamentals, but he will also enjoy riding a lot more. Learning to ride and doing it wrong can be painful - been there, done that.

Finally, if you don't already have a motorcycle, go out and buy one. Riding together as a family is one of the best experiences that a dad can have. The best memories I have of my dad of when were riding and racing together and I know that some of my best experiences with my kids have happened on our motorcycles. Plus, if you are riding with your son, you can help him realize not to ride beyond his skill level. Just because the kids on an 80cc mini is jumping that triple doesn't mean he has to do the same thing.

Good luck and remember that riding motorcycles is supposed to be fun. It is a great way to exercise, and it is a great way to build friendships. It has been my experience that great people hang around motocross tracks and some of my best friends are people that I met while riding a motorcycle.

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#31

Re: How can I "de-tune" my son's motocross bike?

06/27/2008 1:58 PM

Based on my experience, and owning many dirt bikes since 13 YO, without any help at all from outside sources:

He will naturally find that the throttle is connected to his brain. No mechanical adjustments are required.

Let him fail, measure, adapt and overcome the problems on his own. A CR150 for a 18 YO is NOT that difficult to handle, unless he is so bloody out of his element that he should consider his choice to ride anything with an engine. Motorcycles may not be a good choice for his personal culture. Be sure he is doing this for the right reason, to have fun, and not to fulfill some manhood thing in the eyes of others.

He needs confidence, and that will come from failing and recovering with his own adjustments teaching him that HE and only HE is in control of the results.

Thanks for being a good dad.

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#33

Re: How can I "de-tune" my son's motocross bike?

06/27/2008 2:56 PM

Get a bike just like his and go riding with him.

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#34
In reply to #33

Re: How can I "de-tune" my son's motocross bike?

06/27/2008 5:10 PM

I agree with the other posters,suggesting you do nothing to the bike,a crf150 isn't that insane of a bike,and an 18 year old will soon ether decide he isn't the moto cross type or be bugging you for a 250f in about a month,the new 4 strokes are great bikes,but do take some special care,valves must be checks and kept adjusted ,and change the oil often,we change after every race day or every other practice,Our son who is 18 has won 3 championships in the last 5 years,started on an 80 when he was 13 went to the 250f 3 years ago,the absolutely best thing you can do is spend the money on good gear,not cheap stuff,worth every penny.Have fun its a great sport.

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#35

Re: How can I "de-tune" my son's motocross bike?

06/27/2008 9:04 PM

Your son has bought a very capable motocross bike, and your question is a fairly common one in my line of work. If he's going to ride this for fun, (not the x games or motocross competition) then there is a fairly inexpensive and relatively easy way to "de tune" the bike that will neither void the warranty nor be overly challenging. If you look at the parts fiche http://www.powersportseast.com/fiche_section_detail.asp

enter the make, year and model,(your son's bike is the crf150rb)

go to the hanldebar@switch@lever fiche and look at parts 11, 12 and 29 you'll see the throttle is just a cam with push/pull cables

now go back to the beginning of the fiche and select a kawasaki klx110-a8f go to the handlebar fiche and look at the parts group 32099 and 32099a as well as the associated parts(grip boots etc.

This throttle has two optional screws that can be used to limit throttle travel by turning them in to decrease travel or out to increase throttle travel.

substituting this throttle assembly will give you the ability to regulate the amount he can turn the throttle

HOWEVER this will be a single cable mechanism, unless you slip the throttle barrel from his bike into the kawasaki housing.. and modify the housing... a lot of work, yes. but it will do what you wanted until you feel more comfortable with his abilities.

IMHO your time and money would be better spent sending him to the MSF dirt rider school, which will give him the skills he needs to (relatively) safely operate a dirtbike and at least give him the basics.

hopefully this has helped..

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#36

Re: How can I "de-tune" my son's motocross bike?

06/28/2008 12:44 AM

Dude. Seriously, listen to me. The bike your son has purchased is not the "machine from hell!" Jeez, it's a 150cc dirt bike! Even if it falls on top of him, he won't be hurt very much. However, I do guarantee you that no matter what you do, he's still going to initially come home with some bumps and bruises, but NOT FROM SPEEDING!!! When I was first learning how to ride, I found out that the dirt is a very scary place and one tends to naturally throttle down a little while getting used to riding. This being said, my injuries NEVER CAME FROM SPEED!!! Instead, they came when I hit terrain that I did not know how to ride (even slowly). Let me explain...

You're on a dirt trail going along fine, then you go through a turn and suddenly you're on the ground, because you didn't have the knowledge to "read the dirt," and you went into the squirrelly part. Next, you go around a turn, and you're suddenly faced with a bunch of ruts that were made during the rainy season and now are as hard as concrete. OK. Your front wheel catches a rut, and suddenly, the bike is steering itself, and you're not, and with it suddenly whips to the side, you fall off - Ouch!!! It only takes a little experience to realize that you need to learn the finesse it takes to attack these terrain situations, and you also realize that a little slower might not hurt as much... I would even go so far as to say that the power is matched to the rest of the bikes handling capabilities - detune that, and you're potentially putting your son at even more risk, because power in the appropriate situation is how you get through the situation.

There is not one kid in a thousand that wants to try back flips on the first time out - if there is one, he needs to be in a mental institution! I have yet to meet the rider that didn't find dirt scary as hell, before they started to feel more comfortable riding there.

As the guy said previously, if you are this afraid of your son getting hurt, invest some of your money getting him riding lessons. Even if you do get him lessons, remember, he's still going to come home with boo-boos. It's the nature of dirt riding (and part of the fun).

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#37

Re: How can I "de-tune" my son's motocross bike?

06/28/2008 3:18 AM

DONT DO IT, he will loose the interest in the powerless bike, buy youself a bike and go with him, and spend more money in protective clothes than a detune set. 150 cc bike is nothing for a 18 yr old. and again it is better to have power to go over the hill than stopp in the hill and roll backwards. One guy riding a bike has to learn to control the speed. If he gets used to go full throtle all the time due to lack of power, he will go full throttle all the time when he gets a bigger bike, and then what? will dady detune his 1800cc Honda VTX ?

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#39

Re: How can I "de-tune" my son's motocross bike?

06/28/2008 9:07 AM

No need to bother, he had 3 days off work and rode all day each day with several of his friends that have been riding for years. He's getting pretty good and already talking about a 250 and looking into resale value in a year or so.

Thanks for all the tips.

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#40
In reply to #39

Re: How can I "de-tune" my son's motocross bike?

06/28/2008 2:15 PM

OK. so don't piss-your-pants over the 250cc! It's not that much more power, and is probably better suited for his weight. Where the 150cc will bog-out, the 250cc will get him through - and again, we're not talking speed, just the ability to pull him through the rough spots.

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#41
In reply to #40

Re: How can I "de-tune" my son's motocross bike?

06/28/2008 7:51 PM

How about this plan. You buy the 150, and enjoy your time with him. While he learns the 250, you get to learn the 150.

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#42
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Re: How can I "de-tune" my son's motocross bike?

06/29/2008 6:19 AM

Bob,

GA.

Stu.

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#46

Re: How can I "de-tune" my son's motocross bike?

07/01/2008 2:29 PM

Slip a split spacer onto the throttle cable at the carb to limit fuel to the engine. But of course the best strategy is to equip your son with proper riding gear, good advise and let him gain experience.

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#47
In reply to #46

Re: How can I "de-tune" my son's motocross bike?

07/01/2008 2:42 PM

...or why don't you just put sugar in his gas tank.

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#48
In reply to #47

Re: How can I "de-tune" my son's motocross bike?

07/01/2008 7:39 PM

take off the weels that realy slows things down :p

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#49
In reply to #48

Re: How can I "de-tune" my son's motocross bike?

07/01/2008 7:47 PM

Yeah. This whole thread has gotten too ridiculous! Either you raised him right to at least have some common sense or you blew it. It's a little late to be worrying about it now.

However, if he has no trust in his son, just tell him "No bike while you're living in my house!" I wonder when he let his son take the training wheels off his bicycle? When he started high school?!

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#50
In reply to #49

Re: How can I "de-tune" my son's motocross bike?

07/01/2008 8:45 PM

Exactly best way is to add a bomb like in that crappy movie Speed

if your son goes over 55miles the bike will blow up, that will teach a life lesson (or his last )

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