RM65 is this normal?

[OldTimer]

My 8yr old just graduated from a CRF50 to an RM65. I was pretty nervous about him making the transition. But, not to fear, after working through the initial first gear stalls at take off he was zipping around in no time. Once he discovered the powerband I think he heard angels sing and quickly joined the ranks of the adrynaline junkies :cool: . After just 3 or 4 rides he's jumping hills that he was afraid to even ride up on his 50.
Okay, now my question is... is it normal for the powerband to kick in way up the rpm range? It doesn't 'hit' until you think it's already used up the rpm range and is on the verge if winding out by the time it does hit (needs to be up-shifted immediately). In fact, lately he's been short shifting and staying just below Valhala because it has a barely perceptable little sputter just before it 'hits', making it seem like it's maxxed out rpm wise.
Can I coax the 'hit' to come a little sooner? The aforementioned little sputter sounds sounds like it may be over rich. I plan to drop the needle down a notch to see what happens there. Is that a good starting point?

 

[Martin Cole]

HI, this is quite normal. Both the KX and RM 65s thrive on revs and turn into little rocketships when they get in the powerband. Kids soon learn the value of keeping the engine in the right area to maintain the speed but its a big step getting used to keeping it there (that's the point where Dads get more scared than their prodigies and after all that time wishing they'd get more air under the wheels and blast their way out of corners you suddenly start wishing they would slow it down a bit!)
If the jetting is too rich then lean it off so it comes right, but this won't affect the power band - only perhaps make it sharper. The only easy ways to make it more flexible are to install a different set of reed petals and/or try out different exhaust pipes. Some will smooth out the kick and bring the power in a little sooner. Other than that you need to get some porting work done but sacrificing top-end power for flexibility is about the only route.
Plenty of practice and the experience that comes from saddle time is about the best way to tackle it. You just have to block your ears to the sound and let them rev the nuts off the engine. Fortunately they are very robust and will stand a great deal of abuse. Change the oil quite regularly and they should remain highly reliable. Gearbox and clutch generally stand up well to all that is thrown at them with a standard engine but highly tuned motors can put a lot of strain on gearbox parts.
MC.

 

[Gazza2005au]

RM65 is this normal?

yep thats normal if the kid can handle the power band than let him go for it thats the only way he'll learn no use him learning to ride a racing two stroke without flogging it :) the RM is a different ball game to the CRF the CRF is a four stroke (slug) great for beginers as they can rev the tits off it and the power wont really kick in and has a wide throttle as for the RM u might need to teach him how to ride on one wheel lol... ;)

 

[OldTimer]

Thanks guys.
Dropping the needle a notch got the little sputter out of it and the power comes in much better.
The thing I noticed today is that he seems to have decided that he's more comfortable riding just below the powerband, he starts to feather the throttle just before it hits so that it won't run away with him. That's fine with me. When he's ready, he can always reach down and get some more. I mean, he's riding great and airing it out plenty. In fact, today he was clearing a flat top and landing on the "sweet spot" about twenty feet away!
What worries me is whether or not lugging the bike out of turns is harder on the engine than keeping it topped out. He likes to keep the bike in third gear and feather the clutch a little as he comes out of the turns. I keep after him about short shifting and riding a gear or two higher than necessary, but if it's not hurting the bike, then I'd just as soon let him ride it his way and work himself into a comfortable rythm (without developing too many bad habits).

 

[Gazza2005au]

if his riding on a normal size MX track his doing fine let him ride the way he wants untill he gets use to it i had a RM80 a few years back now 3rd gear into turns on a propper size MX track was a perfect gear but i was hitting it fast

 

[Martin Cole]

You will probably find if your lad is riding on his own he will only ride the RM how he feels most comfortable. The best way to keep him progressing is to get him to ride in company. If he's trying to keep up with faster kids he will very soon start using the extra power to keep with them. Chasing the others, particularly if he's in close company, will bring him on much faster. You can spend hours practising on your own but its not so good if there's nothing to aim at. Try to make his sessions positive by timing his laps and encouraging him to clip a second or two off everytime you go.
It sounds by the way he is jumping he's not far off the point where he will be reasonably competitive. Get him entered into some meetings. Competition brings them on faster than anything else.
Good luck.
MC

 

[OldTimer]

That's great advice. Sometimes the most obvious answers are the hardest to see. I guess it is kinda silly to try to get a kid (or anyone else for that matter) ready to compete by practicing alone. We're going to a hare scramble in the middle of May. That'll give him a chance to size up the competition.
The more important question in the mean time is whether or not lugging the bike is worse for it than running it wide open. I'm thinkin' if putting around on it is going to save me some rebuild time then, by all means, putt. Conversly, if wringing it out helps keep the tools off it then, run it boy!
You know, dad has a little self-intrest in this thing too.

 

[Gazza2005au]

the life of the motor is all in the running in process if u run it in perfect than the motor can be rode how ever u like and it will last a long time as the instructions say u have to putt around on it untill its ran in thats atlease a few tanks so it wont do any damage your son ridding like u have mention above atlease he takes the bike right up the rev range untill it starts to peak