crf250... before it kills me

mxtech1 wrote:

In all honesty, you need to just ride it and get used to the powerband. Leave the internals of the engine alone. You're best bet would...

In all honesty, you need to just ride it and get used to the powerband. Leave the internals of the engine alone. You're best bet would be to run a smaller rear sprocket to take some of the punch and extreme acceleration out of the engine. Once you get used to it, you're probably going to be asking for more!

This is how you guys do it in the race car world too, right? Changing gears to tune the RPM range and to alter how that power is delivered.

scooter5002 wrote:

40hp? Not likely. Unless you are riding a works bike. Having said that, there's more to the equation than just power alone. Was the bike set...

40hp? Not likely. Unless you are riding a works bike. Having said that, there's more to the equation than just power alone. Was the bike set up for you? As in rider weight and suspension settings matching? If you are 50 lbs heavier than what the bike is set up to carry, what you think is a power problem is far more than that. It's an overall chassis thing. You've been gone a long time, a lot to get re-acquainted with. Don't expect to get decent performance without adjusting the machine first. Don't tell me, let me guess. You're from Florida and you rode sand. Half the problem right there. Suggestion for a bike. Kawi 250F. Haven't owned one, but ridden one. At 265 lbs in gear, I was impressed. Awesome spread of power, enough to drag me around a tight sandy track without struggling. Be careful in what you buy. Lots of junk out there (with a "Just installed it" fresh top-end. Lol.) Welcome back, have fun, and enjoy. Doc Sweden had a beautiful 09 Kaw for sale but I think he might be back in the homeland now. That being Sweden.

stevesxm wrote:

hi, new here and appreciate some help, please. i did some mx 20 years ago and now want to do some more to get back in...

hi, new here and appreciate some help, please. i did some mx 20 years ago and now want to do some more to get back in shape. have, esentially minimal skills now but will catch on quick... except... the equipment now is so goddamned fast i can't control it to remember how. i rode a 4 stroke 250 yesterday and it was just uncontrollable and i could never get it stable enough to work on technique... so... i see this thing has about 40 hp and a 14 to 1 compression ratio. could i run a couple or three headgaskets or cylinder base gaskets to knock the compression ratio down and take 10 hp off this thing so i can remember how to ride it before i get killed ? i've never had one of these motors apart but have had every other kind of motor apart so doing the work is no issue... what i need to know is if there is anything trick or wierd about these that would preclude doing that...

please ... no wise ass comments about being a pussy... i have had a long and very sucessful career in race cars and know that you don't actually have to experience the crash just to prove that it's going to happen...

thanks.

steve

JOHN CHOATE wrote:

Geez, where the heck are you riding in So Fla? Thundercross or did the Krome Ave track open back up? A heavy flywheel weight may help...

Geez, where the heck are you riding in So Fla? Thundercross or did the Krome Ave track open back up?

A heavy flywheel weight may help take some of the punch away too.

gazzar70 wrote:

Why is it that when someone asks a question that they get shot down with answers like: just get use to the power' ;dont be a...

Why is it that when someone asks a question that they get shot down with answers like: just get use to the power' ;dont be a pussy etc. I bought my crf second hand from a guy who raced and had it professionaly tuned. It had a CP 13.5 to 1 piston in it but it also had 2 base gaskets in it. Not sure why but running head gaskets. not sure why but it would take some of the compression out of it and there was no issues with it. You could even use a piston from a previous year to lower compression. It would also help with reliability. I would ask a race shop for more info though.

mxtech1 wrote:

sir stevesxm, i still stand by my original post. make a gearing change and see how that works. A heavier flywheel weight would also be a...

sir stevesxm, i still stand by my original post. make a gearing change and see how that works. A heavier flywheel weight would also be a good recomendation as someone else pointed out as it will slow down the engine RPM and make it more manegable.

Barrett57 wrote:

This sounds really stupid, but are you sure its a 250f? I knew someone who brought a 450 and thought it was a 250f, and someone...

This sounds really stupid, but are you sure its a 250f?

I knew someone who brought a 450 and thought it was a 250f, and someone who brought a cr500 thinking it was a cr250.

stevesxm wrote:

well... it said 250 all over it and the guy said it was a 250... but having said that, if it wasn't written on it and...

well... it said 250 all over it and the guy said it was a 250... but having said that, if it wasn't written on it and he hadn't said it, i would not know what i was looking at... so i can only say thats the way it was represented.

the mcnish quote is funny. i actually know know him and raced in imsa when he did. my favorite quote was from arnold palmer who said " it's very interesting... it seems that the harder i work , the luckier i always seem to be "

back to the bike... one of the problems i had was the size and weight. all my experience was on an early 90's rm125. much lower seat height, much lighter bike. at 5'9 , 160 i found this 250 big and unwieldy which didn't help anything either. i rode a honda crf230 the other day and liked it a lot. i figure to buy that and ride myself back into shape and then move up. the other thing i notice about these new generation bikes is that even the civilian version mx bikes are almost full race bikes. big compression ratio, big power, great suspension but also requiring race bike maintainance schedule. ride an hour , work for three . throw the top ends away every 20 hours sort of thing... doesn't sound like you can be anything but deadly serious about it anymore...

Barrett57 wrote:

It probably is a 250 but the markings should be on the cylinder. [IMG]http://i369.photobucket.com/albums/oo139/willbarrett/crf250_top_end_repair-1.jpg[/IMG] I used to go to Le mans 24 hours every year,(along with...

It probably is a 250 but the markings should be on the cylinder.



I used to go to Le mans 24 hours every year,(along with travelling around watching F3 and the British GT) we used to stay up all night cheering on mcnish and the rest of the audis, hope to go back in 2012 and see him finish after his horrific crash this year, i was watching on the internet (managed to watch 18 hours of it!) and it was such a relief to see him get out and find out no one was hurt.

And yeah, modern bikes do require a lot of time spent on them, Although I brought a brand new 2011 KTM 150 from new last year and rode every weekend for a season at a decent speed (local B class) and did about 40-50 hours on one piston, it was pushing it but it survived!

Perhaps you could try some of the things others have mentioned, get the bike set up, and maybe add a fly wheel weight? also, what year is it? have fun anyway! you can only get better.

stevesxm wrote:

if had to buy a 250 right now, i would drop the cr and maybe have a look at the flywheel which really was a clever...

if had to buy a 250 right now, i would drop the cr and maybe have a look at the flywheel which really was a clever idea . but the fact is that i didn't like the chassis fit at all. so i figure to do this 230 for a while . whats the worst than can happen ? i actually remember what to do and get better than the bike after a while... so then i get another bike. if i try to do that with the 250 the re-learning process will take a lot longer because ill fight both ends of the spectrum... chassis and motor... and in the end, i can punch up the 230 a bit cheap and then move on from there. i didn't notice your location, the UK. your boy lewis has really lost his brain... and the humiliating thing of letting button beat him... no wonder he's crazy.

Barrett57 wrote:

If you feel like youll get confidence back on the crf230, go for it! The first time i rode a motocross bike i rode my cr80...

If you feel like youll get confidence back on the crf230, go for it! The first time i rode a motocross bike i rode my cr80 straight into a fence! i then learnt to ride on a little mini bike until i got my confidence back. after all, we`re in this for fun.

And im not sure hamilton ever had a brain to loose, i know a few people that raced him while he was in karts, apparantly he was exactly the same when he raced them.

sec114 wrote:

time on the bike will be your friend. roll on power easily and use mainly 2nd(corners) and 3rd gear(short straights). hondas in general have headshake in...

time on the bike will be your friend. roll on power easily and use mainly 2nd(corners) and 3rd gear(short straights). hondas in general have headshake in certain circumstances and take some time to set suspension up and get a balance to minimize headshake. ride within limits, have fun cornering (what honda's do best), and things will click for you. good luck, and stay safe

sec114 wrote:

time on the bike will be your friend. roll on power easily and use mainly 2nd(corners) and 3rd gear(short straights). hondas in general have headshake in...

time on the bike will be your friend. roll on power easily and use mainly 2nd(corners) and 3rd gear(short straights). hondas in general have headshake in certain circumstances and take some time to set suspension up and get a balance to minimize headshake. ride within limits, have fun cornering (what honda's do best), and things will click for you. good luck, and stay safe

stevesxm wrote:

understood and thats the plan. i used to tell my students when i was driver coaching... " you don't actually have to HAVE the crash to...

understood and thats the plan. i used to tell my students when i was driver coaching... " you don't actually have to HAVE the crash to know its going to happen..."

sec114 wrote:

set rear sag at about 105mm (roughly 4&1/8") to take some of the bias off the front wheel to calm down the headshake. drop forks flush...

set rear sag at about 105mm (roughly 4&1/8") to take some of the bias off the front wheel to calm down the headshake. drop forks flush with top of triple clamps and with bike on stand, take a flathead screwdriver, and on top of each fork leg let out any built up air (you will hear if there is any as you loosen) then re-tighten this air bleed screw. local guys you meet at tracks will probably be kind and helpful also.

sec114 wrote:

set rear sag at about 105mm (roughly 4&1/8") to take some of the bias off the front wheel to calm down the headshake. drop forks flush...

set rear sag at about 105mm (roughly 4&1/8") to take some of the bias off the front wheel to calm down the headshake. drop forks flush with top of triple clamps and with bike on stand, take a flathead screwdriver, and on top of each fork leg let out any built up air (you will hear if there is any as you loosen) then re-tighten this air bleed screw. local guys you meet at tracks will probably be kind and helpful also.

stevesxm wrote:

nobody technically savy here at all so please... run that all by me again.... where is the sag measured and how is it adjusted ? the...

nobody technically savy here at all so please... run that all by me again.... where is the sag measured and how is it adjusted ? the air bleed is a compression preload ?

sec114 wrote:

basically sag is how far bike sinks when you sit on it. this is measured by the following.... bike on stand and measure from rear axle...

basically sag is how far bike sinks when you sit on it. this is measured by the following....
bike on stand and measure from rear axle to a point on your rear fender; write this # down.
now with help of friend/wife etc place bike on ground and sit on it and have measurement taken from same spot on rear fender. the measurement you want is roughly 4" less. this is adjusted by at top of your spring is a double nut system; you loosen the top nut with a screwdriver and hammer (counter clockwise) then the nut below it you will be free to either tighten or loosen up to adjust the amount of sag you have. in general you should just go 2 full turns and sit on bike to re check sag number again (write the measurement # down).
i know it sounds intimidating reading it on here but also go to TRANSWORLDMOTOCROSS site and in top right tab is a "HOW TO" section. click the how to and go to page 2, and at bottom is a video section with steve matthes on "how to set race sag".

the air bleed in all forks is common. it is NOT THE screw in the dead center (that is compression) but the screw that is just above it. it is also a short screw and will be out in around only 2 turns.
i hope i have helped and not confused you to bad?

stevesxm wrote:

no, not at all. i designed and manufactured race cars for a living and raced all maner of formula cars for a long time. i am...

no, not at all. i designed and manufactured race cars for a living and raced all maner of formula cars for a long time. i am well familar with chassis set up techniques. i just don't where anything is or what anything does or where the hell any of it should be on one of these bikes yet... i'm happy to get all the advice i can and try everything to work up a database.

sec114 wrote:

and also on transworld motocross site. page 2 in the HOW TO section (about half way down page) has a video of "setting compression and rebound...

and also on transworld motocross site. page 2 in the HOW TO section (about half way down page) has a video of "setting compression and rebound dampping" you will like to watch. just remember to go just 2 clicks either way and test that setting. good luck.

mxtech1 wrote:

If you had any idea what you were talking about maybe your post would have been more helpful, but instead you chimed in with a negative...

If you had any idea what you were talking about maybe your post would have been more helpful, but instead you chimed in with a negative remark, taking only one small phrase of what i said in an otherwise helpful reply regarding a gearing change.

FYI, a high compression piston is the equivalent to adding a pipe and silencer. Raising the compression increases power across the powerband and actually takes some of the lack of low end out of a stock engine. Running two base gakets with a high compression piston takes about 1/2 a point of compression, so you're high compression piston isnt so high with 2 base gaskets. There are no reliability issues with high compression pistons if you maintenence your bike correctly.

gazzar70 wrote:

Hi MXECH 1, That was not a personal attack. Its just that I keep hearing the same comment on getting use to the bike when someone...

Hi MXECH 1, That was not a personal attack. Its just that I keep hearing the same comment on getting use to the bike when someone has a specific question about bike set up etc. I do think that todays bikes with there higher compression and short strokes make the bikes harder to ride at low rpms and need to be riden at higher rpm's which is a bit daunting for new riders. He is probably better off on the 230 but the suspension would suck on rough tracks and jumps. Bye the way, can you tell me if a 2007 piston will be ok to run in my 2008 crf 250 as I have a new one from a previous bike. Cheers mate.