I just picked up a crf150r expert last night from the local dealer and after my initial (parking lot) 5 minute test I have come to the following conclusion.
IT IS A BEAST!
This is not a bike for inexperienced or timid riders and probably not well suited for woods either. It is a handfull and it will try to put you on your ass any time you slam the throttle hard. The dreaded "Honda bog" is there making slow transitions hard and it is LOOOOUUUUDDDDD!
I would never though that I would be considering taking performance away for a motorcycle but this bike is intended to replace my wifes CRF150F and I know that I am going to have to tame this little rocket a bit.
Here are some of the mods that I am considering:
-Heaviest flywheel weight available (Stealthy does not make one yet)
-Restricting the intake( getting creative with the air filter or carb)
-Restricting the exhaust( corking it?, excessive blowby concerns me)
-Using low grade fuel (87 octane or other)
-Decreasing compression (by any available means, more blowby concerns)
-Messing with the timing or any kind of electronic modification
-Getting a lame cam
-Going to a heavy chain (520 kit) and changing ratios (sprokets)
I know that this is a subject that will be on the minds of many husbands and parents out there considering owning this bike so please put your 2 cents.

I would recommend quieting the exhaust, since that is a concern, and reducing the carb size. Having had quite a bit of experience with increasing performance by increasing carb size, I would think that you could limit the performance by reducing carb size. Reducing the carb size creates more drag on the intake, which limits how quickly the bike can rev.

Redrider305,

I'm going to post a little review on the bike as I just tested it.  To answer your question, however, you need weights on the flywheel.  That would be the first thing you'd HAVE TO do.

Either that, or you simply teach her to have some freaking throttle control. The bog can be fixed with the proper jetting.

ben

You could try and run an extra head gasket or 2 that will give you less compression.

I really think the best thing would be to use a FWW and maybe cork the exhaust.

ben

Hi guys and thanks for the posts.
Hey Ben, what is FWW?
Also I would like to say that going with a heavier head gasket was a very creative idea. I guess the thing on "detuning" is to think on reverse. One of my first impulses was corking this puppy but I am concerned that added back pressure could bring valve issues or excessive blowby. Oh what the hell, I am cancelling any emissions I see and instaling a breather anyway, just havent got there yet.

redrider305 said:

Not sure but I would guess:
FWW = Fly Wheel Weight

Yep, Fly Wheel Weight. It will basically make the motor rev slower and be less likely to stall because of the added mass to the rotation of the crank.

ben

Crower cams makes a G1 cam that is all about bottom end.  FWW for sure, and quiet exhaust.  Once people start making controllable ignitions (vortex) they should make a setting for woods.  520 chain is also a great idea, and gear it low.  If your riding in the woods, you don't need to go 65 mph.  With all of the above, i think you will be pleased.

In addition to good ideas above, Rekluse will surely come out with an auto clutch - that would be a super addition for a 150R modded for the woods/trails.

The guy at Stealthy does not know anything about availability for this aplication. He said that Chuck (the owner I guess) will be back from the "6 days" thowards the end of the month and he would be the one to know.
I guess unless this is some kind of a "stealth" program within the company, they dont have any plans to offer these anytime soon.
I have not had the oportunity to see behind the case cover yet but there does not seem to be a lot of real estate inside there. I wonder how difficult this is going to be.
Well, there is always the local machine shop. I guess I can cook me one.
Also, has anybody installed that pro circuit pipe. It is suposed to have an arrestor and to lower the noise output too. Any comments?

All good ideas but do NOT run lower octane fuel, that is asking for detonation.

anyword on the fly wheel weights yet? need one for my GF's 150RB, REALLY BADDDD

Kurt you are 100% right about running low octane. I guess that I am triyng to find the least "invasive" method to reducing that punch. Just trying to "think in reverse".
As far as the FWW, it looks that I will be going to the machine shop sometime soon.

Hey mook see you are in Fl. I am in Miami, where are you.

redrider305 said:

If you can't wait for Steahly to come out with a fly wheel weight, which I'm sure he will, having met the guy, you could try a Google search on "Moose Racing" out of Colorado. A number of years ago I had them add welded on FWW's to an ATK 406 and Honda TRX250R four wheeler, both two smokes. The FWW is rebalanced after welding which is critical if you don't want the engine  to shake apart. Not all machine shops have the capacity to balance FW"s so be careful and ask questions if you use a local shop. Lastly you could also consider having an exhaust header pipe torque stuffer ring made by a machine shop. This ring with a sleeve welded to it, which was commercially made for Yamaha 350 Warriors, fits into the opening of the  header pipe, reducing volume and increasing back pressure. The result is more bottom end in the engine. You would have to play with the diameter of the ring/sleeve in order to get the power characteristic you want.

yz440e said:

Avoid using multiple head gaskets-this may cause head gasket failure-instead use multiple base gaskets if you decide to go this route to lower compression-they are under less internal pressure than the head gasket.

I'm about 8hrs North of you, about 1 more hr North of Tampa. I live in the Pasco/Spring hill part of Florida

redrider305 said:

crower cams makes a cam that lowers the power by 2000 rpm.