CRF-150, kx85, or yz85?

[Solomon Ralston]

Hey everybody, recently my son has been wanting to get a bigger bike. He has been looking a lot at two strokes because he wants something different. He has had four strokes for a while and loves fixing them. He says part of the reason he would like a two stroke is he wants to learn about them through maintenance.  So, we have been looking for used bikes, mainly kx and yz 85cc two strokes, but today, we stumbled upon a CRF-150 at a good price. I think he would rather get a two stroke, but is open to the 150 as well. FYI- he has a 125 four stroke right now and rides it on trails as well as throughout our little neighborhood. Let me know what you guys think- any tips or info would be appreciated!

[EmpireofDerp]

If he's big enough for a 150 he's big enough for a KX100.

[Solomon Ralston]

I figured it might work, but am having a hard time finding any 100s. I could be wrong, but I figured an 85 would be a good enough upgrade from a 125. What I am really wondering though is should he focus on finding an 85 or a 100? Or a CRF-150?

[shrubitup]

Purchased KX85 in January for my Son. First bike. became small by April. He's 14 and 5'4". Have a KX100 now and he loves it. They are few and far between because they're an in-between bike that people tend to hang on to. I already have nearly a grand more into it than KBB value so I'd rather just keep it and urge the smaller daughters to try riding it.

If shopping two stroke minis, get one with a power valve!! The YZ85 didn't have one until 2019. KX85 and KX100 both have power valves. So does the RM85L.

[Solomon Ralston]

Would you mind elaborating on why the power valve is important? I have also looked at cr85s- do those have power valves?

[shrubitup]

4 minutes ago, Solomon Ralston said:

Would you mind elaborating on why the power valve is important? I have also looked at cr85s- do those have power valves?

Makes the power curve more linear and useful. Sudden blasts of power are reduced. CR85 does not have a power valve.

[Solomon Ralston]

Okay thanks- also do you think there is any way at all a 125 two stroke would fit him? He is about 5 foot 3 and small for his age but I expect him to grow a good bit.

[EmpireofDerp]

Okay thanks- also do you think there is any way at all a 125 two stroke would fit him? He is about 5 foot 3 and small for his age but I expect him to grow a good bit.

That's a full sized mx bike, I'd go smaller for now. I was 5' 8 and 125 when i went to a kx125 and it was a handful.

[Solomon Ralston]

That’s what I figured- just gets on my nerves a bit that when I search for used bikes half of them that come up are 125s, so I thought why not ask.

[shrubitup]

1 minute ago, Solomon Ralston said:

Okay thanks- also do you think there is any way at all a 125 two stroke would fit him? He is about 5 foot 3 and small for his age but I expect him to grow a good bit.

When he's 5'5" yes. They weight about 40 pounds more than a KX100 but you said he was riding DRZ125 which weighs 25 pounds more than the KX100. Many of the 125s are 38+ inch tall seats. I have a shorter year KTM at 36 inches and my son can tippy toe that now in MX boots at 5'4".

[Solomon Ralston]

Alright- but would an 85 or 100 two stroke be a better investment than a Crf 150? He would mainly use it for trail riding and cruising around our small neighbourhood.

[shrubitup]

Just now, Solomon Ralston said:

Alright- but would an 85 or 100 two stroke be a better investment than a Crf 150? He would mainly use it for trail riding and cruising around our small neighbourhood.

The 100 can be made into a good intermediate level trail bike. I personally would not buy a used CRF150R because the motors aren't as durable and require expensive rebuilds. The CRF150R is difficult to re-start when hot too.

 

[Solomon Ralston]

Okay- so I guess I need to start looking for a kx100. Thanks for all the help!

[Solomon Ralston]

Actually- I spoke too soon, I have another question-If I am having lots of trouble finding a 100, would an 85 still be an upgrade in power compared to a 125?

[KcDavis]

Yes

[EmpireofDerp]

Yes, a 2t 85 makes way more power than a 4t 125.

[Solomon Ralston]

That was my guess, but thank you for confirming it! 

[SilvFx]

FYI....you probably need to be a bit more precise in your model designations when you talk about CRF150 since Honda makes 3 models:

• CRF150R water cooled 4 stroke 17"/14" MX bike
• CRF150RB  watercooled 4 stroke 19"/16" MX bike
• CRF150F aircooled 4 stroke 19"/16" trail bike

If he is mainly doing trail riding and is 5' 3" and you expect him to grow, I would keep looking for KX100 as a move up bike.  The 100 2t will have a slight bit more low end torque than the 85 2t, but the better part is the wheels will be 19"/16" vs. 17"/14" on the typical 85 2t.  The bigger the wheel the better it goes over obstacles when trail riding.  The lb/hp ratio of the 85/100 's is almost identical to the 125 2t's.  And, just so you know it, they absolutely rip compared to his aircooled 125 4 stroke trail bike he is riding right now.  Frankly, make sure he is currently 'outriding' the motor, brakes and suspension of his aircooled trail bike before moving him up to the 85/100 2t.  And, make sure he is an aggressive rider/personality.  Google some videos of the KX100.  You will be both impressed and stunned about how quick these things are (27-29 HP in stock form and nearly all of it at the top end).

Some additional info.  Here is a list of large wheel (19"/16") MX bikes:

• KTM 85 SX...large wheel (they sell a version with 19/16)
• KTM 105 SX/XC
• RM85L
• RM100 (older model offered by Suzuki that was basically the KX100 in different color) pretty much replace by RM85L
• YZ85 (with large wheel kit - fairly rare as the kit itself with larger wheels and longer swingarm was over $1000)
• CR85RB (I think Honda stopped offering in 2007 and replaced with CRF150RB 4t)
• KX100

One last note, on the KX100 it comes stock with a recommended a NGK 10.5 spark plug that runs fairly cold and it's pretty easy to foul that spark plug while trail riding.  We used an NGK 8 or 9 plug when trail riding and didn't have anymore fouling issues.

[Solomon Ralston]

Thanks for all the info! Wouldn’t have known most of that without a while of research.

[EmpireofDerp]

FYI....you probably need to be a bit more precise in your model designations when you talk about CRF150 since Honda makes 3 models:

• CRF150R water cooled 4 stroke 17"/14" MX bike
• CRF150RB  watercooled 4 stroke 19"/16" MX bike
• CRF150F aircooled 4 stroke 19"/16" trail bike

If he is mainly doing trail riding and is 5' 3" and you expect him to grow, I would keep looking for KX100 as a move up bike.  The 100 2t will have a slight bit more low end torque than the 85 2t, but the better part is the wheels will be 19"/16" vs. 17"/14" on the typical 85 2t.  The bigger the wheel the better it goes over obstacles when trail riding.  The lb/hp ratio of the 85/100 's is almost identical to the 125 2t's.  And, just so you know it, they absolutely rip compared to his aircooled 125 4 stroke trail bike he is riding right now.  Frankly, make sure he is currently 'outriding' the motor, brakes and suspension of his aircooled trail bike before moving him up to the 85/100 2t.  And, make sure he is an aggressive rider/personality.  Google some videos of the KX100.  You will be both impressed and stunned about how quick these things are (27-29 HP in stock form and nearly all of it at the top end).
Some additional info.  Here is a list of large wheel (19"/16") MX bikes:

• KTM 85 SX...large wheel (they sell a version with 19/16)
• KTM 105 SX/XC
• RM85L
• RM100 (older model offered by Suzuki that was basically the KX100 in different color) pretty much replace by RM85L
• YZ85 (with large wheel kit - fairly rare as the kit itself with larger wheels and longer swingarm was over $1000)
• CR85RB (I think Honda stopped offering in 2007 and replaced with CRF150RB 4t)
• KX100

One last note, on the KX100 it comes stock with a recommended a NGK 10.5 spark plug that runs fairly cold and it's pretty easy to foul that spark plug while trail riding.  We used an NGK 8 or 9 plug when trail riding and didn't have anymore fouling issues.

Agreed, i have hurt myself on an old kx80, people underestimate how fast an 80cc 2t bike is.