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Okay.... New here and will be blasting you guys with questions that are common sense bs to y'all, but I'm two stroke stupid.

Just to start it off, I road raced with CCS for 7 or 8 years and I have a 2013 R1 that my neighbors HATE. So I'm not completely bike stupid, I've just never had any exposure to two strokes. It'll make for some good learning experiences with my sons and I.

So... I got my son his first bike. It's a 99 YZ250 that runs really well. Doesn't sound 100% stable and a stand alone idle, but it hasn't died. I did find the manual posted on here, which will be a big help when I sit down to sift through the several hundred pages. Until then, I have a few basic getting started questions.

1. Mixing the fuel. My son's not going to be riding it hard for a while. I assume 40:1 is good enough?

1.1. I rejetted my very first bike; a CBR F3 many many many years ago. I only did it because the guy at the bike shop told me it needed it and I can't recall why. What indication is there that the jetting needs tweaked?

2. What kind of oil do you mix with the gas? Same stuff that I put in the weed eater or something special?

3. I've read that 14 psi is a good tire pressure for pavement and fields. This correct? A friend owns a huge wear house and I don't know anyone in Michigan with much land to play on. He has a huge field in the back and acres of open parking lots on the weekend and a mile long road in the middle of nowhere to play and practice on. The nobbies won't offer much traction; but what's best for going from grass to pavement?

4. I've read about top end rebuilds at 30 or so hours. Is this true and what indications are there that it's ready for that?

5. Gear oil. What do you use?

6. The chain seems to be far looser than I'd ever have on the track or street. What's your method of measuring chain tension?

7. With these questions, I'm sure you can understand the grasp (or lack there of) that I hold on two strokes and dirt bikes in general. Anything else I should know or look into?

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First thing to do is buy a good manual for the bike. It will help a ton as far as fixing the bike.

Also read through the posts in the FAQ page at the top of this page. Lots of useful info there also.

40:1 should be fine as long as you jet accordingly. Good method of jetting in the FAQ page.

I run yamalube 2r for premix and Bel-ray gear saver 80w in my trans. A lot of people run ATF type F in their trans. I will be switching myself since it's cheaper (i change my oil a lot)

14psi should be fine. But you can play around with tire pressure for traction. Depending on conditions i run 10-13psi.

Pressure testing and visual inspecting will tell you if you need a rebuild.

Chain adjustment, follow the manual. Off the top of my head my 2002 requires 1-2" of slack directly above the linkage bolt in the swingarm.

Good luck and have fun

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I would get your son all the proper gear, and find him some trails to ride. Fields are okay, but he will get bored with that pretty quick. I would keep him off any pavement. Just about every technical questions you'll have about the bike will be covered in the manual.

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#6- Chain tension. Have someone sit on the bike that can make the bike squat until the swingarm is horizontal to the ground. This will put the wheel & chain in it's farthest rearward location (since it travels in an arc), which puts the chain at it's tightest. You want a slight amount of slack at this point.

 

#4- Top-end rebuilds. You probably won't be needing to do Top-end rebuilds quite as often as recommended, since you won't be stressing the engine like a racer will. Keep an eye on compression, and when it starts to drop, that's a sign that a Top-end is due.

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0. What's an R1 bike? I know nothing about road bikes. Seen too many road bike death videos on youtube to keep me away.

 

1. premix ratio. See http://www.maximausa.com/pdf/Oil%20Migration%20Sheet.pdf

1.1. Jetting needs fixing if the motor doesn't pull smooth and clean under medium load with no hesitation at any throttle position and any crank RPM. More than a small drip of black "spooge" coming out the tail pipe and the jetting is rich at at east one throttle position.

2. Use a good modern 2-stroke bike racing oil. Maxima Super-M is cheap, good and low smoke. Yamalube never let anyone down.

 

2b. Weed eaters don't usually get worked real hard, but 2-stroke air blowers do. Use your good bike oil in the blower. I use Maxima 927 castor oil in my air blower. Smells like fun and it's almost impossible to kill a high revving motor when it's lubed by 927.

 

3a. 14 PSI is up there for tire pressure.  Too much or little air = loss of traction. Stay off pavement.  From grass to hard surfaces I can strongly recommend the Dunlop AT81 front tire. Predictable grip and it's tough too.  On the rear I recommend the Dunlop MX32 (MX3S) for any dirt type. Tough tire. In my experience the MX32 out-lasts the MX52 and of course on medium to soft dirt the MX32 hooks up way better.

 

3b. If your buddy doesn't mind then put down some witch hats in the that open field and get your son to cut out some laps on a marked out track (hats on the inside of each corner). Suggest your boy to work on cutting in some lines. Get some ruts happening, then braking and accel bumps.  If he's got any Jonathan Lingston Seagull in him them there's years of fun he could have in some plain old field. ;)  He could make knee deep berm corners just by riding clean lines.

 

4. Top end life is a function of run time and load and RPMs.

 

5. Use ATF type-F for winter or heavy duty diesel oil for summer or 2-stroke trans oil and change it often.

 

6. Loose is good. Watch the pros on TV.  If it gets looser then it's dead. Usually the front sprocket is toast when the chain is dead, and a steel tooth rear should last 2 or 3 chains. Quality O or X-ring sealed chains usually wont stretch much at all, but the rollers wear out. If your boy will ride often in damp gritty conditions a lot then 15 hrs from a std chain or 40 from a sealed chain might be all you get. It get's expensive.

 

7a. Get him some good protective gear. Fly helmets are good value these days (safety per $). Cheap heavy boots might seem protective, but they might also cause him to crash or seriously blow out a knee. EKS brand google are great value. Especially their Beer Googles.

7b. Don't neglect the air filter. You need at least two, so you can rotate them quick and easily. When they look black on the outside or have sat for more than 6 weeks, then swap it out.  I like the ease of use of the alcohol based (red) NoToil filter oil+cleaner products and never seem to have a problem with early motor wear.

7c. Don't neglect the brakes. A full bleed and new pads is wise. As is removing the calipers, cleaning the pistons and greasing the pins.

 

7d. Don't neglect the adjustment of the controls. Lever positions, clutch grab point, handlebar position.  Make sure he learns how effect the front brake is.

 

7e. Arm pump can be a problem. Very common. It's not all mental despite common claims. Or due to a lack of fitness.  Often just the opposite.  Suspension setup matters a lot. Also the bar bend choice can make a big difference (eg. swept or flat). Lastly if he get's arm pump then one trick is to wait until the pump goes down, then ride again. Don't wait for any less or more time. Get it ride, and it's gone for the day. Hydration matters. Consider a camelbak if he really gets into it and cuts laps for long sessions.

 

7f. Don't neglect bike setup. He'll then learn 5x as fast since he wont have to fight the bike wanting to do weird shit.  Springs on both end MUST match his weight. The rear suspension sag (spring preload) then must be set for his weight. Then adjust the fork height for balanced cornering. Suspension oil typically wears out faster than the motor top end.  Adjust the clickers. Find some setup guides online. There are many.

 

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Everything Numro said.

I'll just add to bleed the air out of the forks every so often also. Add bleeders for easy release if you can.

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Holy shit!!! You guys have a wealth of information. Thanks a million!!!

I have plenty of helmets and a dirt bike helmet that fits him. Not ideal, but I have a set of full racing leathers that will fit him. Not great, but it'll be enough to protect him in a fall on his first few rides. I have a couple sets of road racing boots too, but I can't imagine those would be worth a shit in the dirt.

I do have two air filters for it, didn't know they needed changed so much though.

I can set up the suspension on a road bike. I'll have to look at how to do it on a dirt bike though. Shouldn't be too hard.

And this is an R1

ImageUploadedByThumper Talk1458657484.000601.jpg

Thanks again for all the info. There's a lot of shit here that I wouldn't have thought of.

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Road racing leathers will be uncomfortable (totally different position) and HOT.  I would just spend a couple hundo and get him some cheap pads and a jersey/pant combo.  It takes a LOT of gear to match the cost of ONE trip to the ER, don't ask me how I know...

 

Sag should be 25% front 33% rear.  You can play with sag and fork height in the triples to effect weight balance and turning feel.

 

I like my rebound fast and compression firm, but clicker settings wil be heavily rider dependent.  

 

HAVE FUN!!!

Edited by bikedude987

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Welcome Jester.  Lots of info here, and the search tool will be your best friend.  These guys have given great advice, I just wanted to say....looks like you got some heat in them there tires!  Q3's?

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Welcome Jester. Lots of info here, and the search tool will be your best friend. These guys have given great advice, I just wanted to say....looks like you got some heat in them there tires! Q3's?

Thank ya sir. And yeah. A shit ton of great info here. I've been leaning on the search too some to find more and just read up. Here and Google. Tons of info all around.

And those are pilot power cups. Race tires so not so good for street use but I can still get better prices on the race tires from my racing days than the street tires, so that's what I go with. I spent a weekend at my dad's house in southern ohio and upped the tire pressure a bit and had some fun in the hills of ohio and Kentucky for a weekend. I love crotch rockets. Never been a real fan of dirt bikes. I had a Honda 400 years and years ago. Learned how to do stand up wheelies on it, sold it for $600 more than I paid for it, and started doing track days. Did a lot if sliding on it, but I don't think I ever got more than two feet off the ground. Wasn't comfortable enough myself. But I love street bikes. With my kid so stoked over the 250, I may have to get another dirt bike to ride with him though.

We went to the store tonight and came home to find that he pulled the truck out and pulled the yz from the back garage to wash it. Asked him why "well that's the best way to get to know all the parts and pieces."

I think I'll keep the kid.

ImageUploadedByThumper Talk1458693907.294090.jpg

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Road racing leathers will be uncomfortable (totally different position) and HOT. I would just spend a couple hundo and get him some cheap pads and a jersey/pant combo. It takes a LOT of gear to match the cost of ONE trip to the ER, don't ask me how I know...

Sag should be 25% front 33% rear. You can play with sag and fork height in the triples to effect weight balance and turning feel.

I like my rebound fast and compression firm, but clicker settings wil be heavily rider dependent.

HAVE FUN!!!

Racing leathers would suck on a dirt bike. But he's just learning and I'm in southern Michigan (unfortunately). The 15 day forecast has a top temperature of 56 degrees. I don't think he'll get too hot on his first few days of riding. Even if he does, he'll be okay. We will head out and find some good gear for him in the next few weeks. I have some puma racing boots that will work early on, but the actual dirt bike ones will be a lot more protective. The leathers would do better than anything else early on. He's gonna fall and I even have a back protector.

I'll post videos.

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Tusk from Rocky Mountain atv/mc has cheap but decent gear. I myself am a total novice on my yz250 but I got it from a guy who's been riding and racing mx and harescrambles for 40+ years so I got a wealth of knowledge from him. To reiterate what was said, 40:1 is a good ratio for the premix. I personally use klotz r50 and castrol synthetic 10w40 for the crankcase oil.

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Okay.... New here and will be blasting you guys with questions that are common sense bs to y'all, but I'm two stroke stupid.

Just to start it off, I road raced with CCS for 7 or 8 years and I have a 2013 R1 that my neighbors HATE. So I'm not completely bike stupid, I've just never had any exposure to two strokes. It'll make for some good learning experiences with my sons and I.

So... I got my son his first bike. It's a 99 YZ250 that runs really well. Doesn't sound 100% stable and a stand alone idle, but it hasn't died. I did find the manual posted on here, which will be a big help when I sit down to sift through the several hundred pages. Until then, I have a few basic getting started questions.

1. Mixing the fuel. My son's not going to be riding it hard for a while. I assume 40:1 is good enough?

1.1. I rejetted my very first bike; a CBR F3 many many many years ago. I only did it because the guy at the bike shop told me it needed it and I can't recall why. What indication is there that the jetting needs tweaked?

2. What kind of oil do you mix with the gas? Same stuff that I put in the weed eater or something special?

3. I've read that 14 psi is a good tire pressure for pavement and fields. This correct? A friend owns a huge wear house and I don't know anyone in Michigan with much land to play on. He has a huge field in the back and acres of open parking lots on the weekend and a mile long road in the middle of nowhere to play and practice on. The nobbies won't offer much traction; but what's best for going from grass to pavement?

4. I've read about top end rebuilds at 30 or so hours. Is this true and what indications are there that it's ready for that?

5. Gear oil. What do you use?

6. The chain seems to be far looser than I'd ever have on the track or street. What's your method of measuring chain tension?

7. With these questions, I'm sure you can understand the grasp (or lack there of) that I hold on two strokes and dirt bikes in general. Anything else I should know or look into?

1. Start from here (excerpt from Motocross Action)

 

Main jet: 172

Pilot jet: 50

Power jet: 80

Needle: N3VF, with clip position at 2nd from top

Air screw: 1-3/4 turns out (or counter-clockwise)

Note: The 1999 Yamaha YZ250 used a PWM38 Keihin carb with a power jet (previous YZ250s did not have power jets).

2. Preferably semi- to fully-synthetic 2-stroke oil - there are heaps of high quality offroad-specific blend of 2-stroke to choose from Yamalube (petroleum base oils to semi-synthetics), Maxima, Amsoil, Motul, Motorex, Silkolene, IPone, Putoline, Redline etc. Having said that, i just have confidence more with Motul 800 2T offroad-line. Be aware though that the ester-base Motul 800 is the 2T oil with the highest flash point amongst all the 2T oils in the market. It might not be the right oil for your son, unless he really rides hard and you want an oil that doesn't thin out too quickly across varying range of temperatures. I mix mine anywhere 40 : 1 to 32 : 1 and rejet for that mix.

3. 8 psi to <10 psi in slippery trails (give or take), while 10 psi to 12 psi in groomed tracks. In soft sands or desert sands, usually you don't want your tires to be stiff; it's base on feelers....

4. 30 to 40 hours depending on your usage, sometimes even less - you can also change rings in between hours, again depending on how you use the bike. It's relative to experience somehow....

 

5. Choice can be anywhere from petroleum-base to semi-synthetic ones. I prefer petroleum base oil anywhere from SAE40 up for all wet-sump type.

 

6. I use the wheelbase as my guide in adjusting and tensioning my chain other than the fact of other factors (sag etc) - the stock wheelbase of the Yamaha YZ250 is 58.3 inches. Mine is set less than that because it helps me in tight turns and dealing with switchbacks in single-track tight goat trails' ascents and descents

7. You're fine, don't worry too much about it. Moreover, there are heaps of wonderful people here at TT who are more in the know and more than happy to advise you sir. This social dirt bike site is a wealth of info for anyone.

Cheers and good luck!

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We went to the store tonight and came home to find that he pulled the truck out and pulled the yz from the back garage to wash it. Asked him why "well that's the best way to get to know all the parts and pieces."

I think I'll keep the kid.

That's awesome.  Hopefully he will catch the dirt bike bug and explain to you what you've been missing.

 

My boy is 10 and rides a KX65 (almost time for an 85), and just last weekend his told me how awesome he thinks dirt is. He's riding WOT a lot now, and learning to whip it off jumps quite well mainly by watching the pros on TV and experimenting little by little. I setup his suspension so it does what he needs on jumps and around corners.

 

Dirt is awesome in so many ways. Ignoring jumping which of course is a lot of fun. eg.  Learning to look well forward and trust the machine to deal with the terrain is a real buzz.  You can back into hard pack corners like a road bike, and float over soft but rough sand tracks like no road bike will ever feel. You can get seriously tired and fit, while having fun, and dirt biking on rough tracks at your best speed uses every single muscle in your body. So after a while you can hit the dirt and literally bounce back up from minor crashes.   You can hit corner ruts hard enough to bottom out the suspension, and generate cornering Gs on dirt that make you seriously feel the weight of your face, head and arms pulling you down.   I think railing various ruts in soft dirt while the rear tire eats is so simple but the best feeling. That's what I was thinking when I suggested your boy rides around a snakey track marked by witch's hats.

About safety gear...

The road suit should be fine for starters. I think you need protection in this order:  Helmet, boots, gloves, shins/knees, chest, hips, elbows.  When he gets better he'll rarely scrape/hit his elbows but when learning they can cop it. Especially if the bike is setup poorly.

Don't rely on helmet standards to think all helmets are equal. You don't get what you pay for either. Some helmets seem to be made for taking dirt naps.  You must at least get a helmet with dual density foam and a soft outer shell. That's best for avoiding common dirt riding concussions.

I love my MotoX Vest. It's bull rider's vest technology but designed for moto.  With that vest on I can hit the dirt so hard or take a bar or branch in the torso and it's no problem. When crashing I've improved at letting the vest take the big impacts. I've looped out with a stuck throttle in 4th going down a slight hill and slammed on my back then summersaulted forward and just got up. MotoXvest rules.  Before the vest I broke too many ribs and was very lucky to not to more serious damage to my kidneys and spine.  My boy wears a $50 French made horse riding vest and he wont ride without it, since it gives him so much more confidence and it's worked well for him. I'm getting him a motoXvest this year for his birthday.   The vests get real hot in summer (it can get plenty hot and humid here) but I don't care since the overheating is a good heart work out, and you get used to it, and once you know you're about to fade out you pull off and strip you vest and top to bare skin.

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0. What's an R1 bike? I know nothing about road bikes. Seen too many road bike death videos on youtube to keep me away.

 

1. premix ratio. See http://www.maximausa.com/pdf/Oil%20Migration%20Sheet.pdf

1.1. Jetting needs fixing if the motor doesn't pull smooth and clean under medium load with no hesitation at any throttle position and any crank RPM. More than a small drip of black "spooge" coming out the tail pipe and the jetting is rich at at east one throttle position.

2. Use a good modern 2-stroke bike racing oil. Maxima Super-M is cheap, good and low smoke. Yamalube never let anyone down.

 

2b. Weed eaters don't usually get worked real hard, but 2-stroke air blowers do. Use your good bike oil in the blower. I use Maxima 927 castor oil in my air blower. Smells like fun and it's almost impossible to kill a high revving motor when it's lubed by 927.

 

3a. 14 PSI is up there for tire pressure.  Too much or little air = loss of traction. Stay off pavement.  From grass to hard surfaces I can strongly recommend the Dunlop AT81 front tire. Predictable grip and it's tough too.  On the rear I recommend the Dunlop MX32 (MX3S) for any dirt type. Tough tire. In my experience the MX32 out-lasts the MX52 and of course on medium to soft dirt the MX32 hooks up way better.

 

3b. If your buddy doesn't mind then put down some witch hats in the that open field and get your son to cut out some laps on a marked out track (hats on the inside of each corner). Suggest your boy to work on cutting in some lines. Get some ruts happening, then braking and accel bumps.  If he's got any Jonathan Lingston Seagull in him them there's years of fun he could have in some plain old field. ;)  He could make knee deep berm corners just by riding clean lines.

 

4. Top end life is a function of run time and load and RPMs.

 

5. Use ATF type-F for winter or heavy duty diesel oil for summer or 2-stroke trans oil and change it often.

 

6. Loose is good. Watch the pros on TV.  If it gets looser then it's dead. Usually the front sprocket is toast when the chain is dead, and a steel tooth rear should last 2 or 3 chains. Quality O or X-ring sealed chains usually wont stretch much at all, but the rollers wear out. If your boy will ride often in damp gritty conditions a lot then 15 hrs from a std chain or 40 from a sealed chain might be all you get. It get's expensive.

 

7a. Get him some good protective gear. Fly helmets are good value these days (safety per $). Cheap heavy boots might seem protective, but they might also cause him to crash or seriously blow out a knee. EKS brand google are great value. Especially their Beer Googles.

7b. Don't neglect the air filter. You need at least two, so you can rotate them quick and easily. When they look black on the outside or have sat for more than 6 weeks, then swap it out.  I like the ease of use of the alcohol based (red) NoToil filter oil+cleaner products and never seem to have a problem with early motor wear.

7c. Don't neglect the brakes. A full bleed and new pads is wise. As is removing the calipers, cleaning the pistons and greasing the pins.

 

7d. Don't neglect the adjustment of the controls. Lever positions, clutch grab point, handlebar position.  Make sure he learns how effect the front brake is.

 

7e. Arm pump can be a problem. Very common. It's not all mental despite common claims. Or due to a lack of fitness.  Often just the opposite.  Suspension setup matters a lot. Also the bar bend choice can make a big difference (eg. swept or flat). Lastly if he get's arm pump then one trick is to wait until the pump goes down, then ride again. Don't wait for any less or more time. Get it ride, and it's gone for the day. Hydration matters. Consider a camelbak if he really gets into it and cuts laps for long sessions.

 

7f. Don't neglect bike setup. He'll then learn 5x as fast since he wont have to fight the bike wanting to do weird shit.  Springs on both end MUST match his weight. The rear suspension sag (spring preload) then must be set for his weight. Then adjust the fork height for balanced cornering. Suspension oil typically wears out faster than the motor top end.  Adjust the clickers. Find some setup guides online. There are many.

Hi Numroe, would you happen to be an American leaving in Australia?

Just out of curiosity, been observing on how you spell words and how you construct sentences.... The "tire" pretty much gave it away you "might" be an American, mate :D

Thanks also for sharing this list.

Have a good day....

Edited by YZ109

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Hi Numroe, would you happen to be an American leaving in Australia?

Just out of curiosity, been observing on how you spell words and how you construct sentences.... The "tire" pretty much gave it away you "might" be an American, mate :D

Thanks also for sharing this list.

Have a good day....

No mate. Lived here all my life. VERY proud Aussie.  Sometimes I write for those who I think will be reading it. We are small minority here on TT.

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No mate. Lived here all my life. VERY proud Aussie.  Sometimes I write for those who I think will be reading it. We are small minority here on TT.

Or so i thought too.... Coz i do the same thing. I write in American English when i'm here, and when i'm writing to my Canadian and English superiors, i write in British Commonwealth English.

I wanted to see how you write meters or metre etc but wasn't able to see them mate, until i saw the tire instead of "tyre", hence why i had 2nd thoughts hahahaha!!!! :D

I'm not from Australia as you know from my profile but i have worked a lot of times with you guys, so with American nationals as well in my nature of job ---- mining.

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