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What did you do to your dirty bike today?

I've been trying to improve the bottom end on my RM250 for offroad technical riding. I took it to Moab a couple of weeks ago and it was a handful. It loves to Rev and spin the rear tire or flame out. It is a track bike in stock form not an offroad weapon. I just dropped the needle and installed a smaller power valve jet and retarded the timing in two steps at Hollister today. I finally feel like I'm taming the beast. It has low end torque and ridability it has never had before. Now it is time to work on the suspension.
 
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anytwowilldo said:
I've been trying to improve the bottom end on my RM250 for offroad technical riding. I took it to Moab a couple of weeks ago and it was a handful. It loves to Rev and spin the rear tire or flame out. It is a track bike in stock form not an offroad weapon. I just dropped the needle and installed a smaller power valve jet and retarded the timing in two steps at Hollister today. I finally feel like I'm taming the beast. It has low end torque and ridability it has never had before. Now it is time to work on the suspension.
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Tom, a flywheel weight made a big difference for me in smoothing out the power and making the bike more tractable on tighter trails. It revs slower too and that may or may not be a desired side effect for you.
 
Guoseph said:
Tom, a flywheel weight made a big difference for me in smoothing out the power and making the bike more tractable on tighter trails. It revs slower too and that may or may not be a desired side effect for you.
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It had a flywheel weight installed when I got it along with a Gnarly pipe. I changed the needle to two steps leaner than stock and have now dropped it too. It really needs a ton of fuel pulled out to run well. Again, I finally feel like I'm gaining ground. Every jet and the needle are much leaner than stock.
 
I think your bike just needs jetting and clutch adjustment.

The last thing we need is more power down low. Smooth transition from low to mid, sure. If we wanted power we would be revving it. We don't want power, that's why we are off the throttle lugging it around.
 
Be careful running lean Tom, it really hurts 2ts (lean is mean as the saying goes).
Some motors are built to deliver power in a hit rather than a smooth flow, the RM is one of 'em. I'd get it running the correct AF ratio (a little fat on the bottom with good fuel delivery throughout the band) then try to tame that power band with the typical tricks: thicker base gasket will drop the power lower in the band and reduce overrev: FWW will slow things down a little: you may be able to change how the power valve actuates (spring pre-load at the crank linkage): head squish mods: pipe.

You've got a couple already but remember, there's a reason no-one uses an RM for single track..that motor likes to hit and was built to do it.
 
2strokeYardSale said:
I think your bike just needs jetting and clutch adjustment.

The last thing we need is more power down low. Smooth transition from low to mid, sure. If we wanted power we would be revving it. We don't want power, that's why we are off the throttle lugging it around.
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I believe you are right. I've had a brand new Barnett Dirt Digger clutch in a box for a year, as the old one was like a light switch. When I went to install it I found that even though the clutch basket nut had a lock washer it was loose. You could wiggle it as far as the lock washer would allow with your fingers. I retorqued the nut. The clutch basket and hub are perfect and show virtually no wear. I put the new clutch in and it is awesome. It has a light clutch pull and a much longer engagement. I love it. I rode at Georgetown this weekend and the motor is SOOO much better for offroad. It pulls down low -but still is not perfect on what I believe is the very bottom of the needle. I'm going to keep refining the jetting. It also produces so much less spooge even though I went from 40:1 too 32:1. I'm sure the retarded timing is helping too.
This was the first time I rode with my rebuild forks complete with gold valves. The are so much better than they were before. They don't slap when landing and move through much more of the stroke. I used all but an inch of travel in Georgetown, whereas I left 4 inches unused in Moab. After riding a brand new Husky TE300I and an 8 year old KTM 300XCW I realized that I still have BMW M3 suspension and what I really need is 72 Cadillac Sedan Deville. I'm going to remove fork oil hoping to soften the stroke. I may also rebuild the compression valve stack. I'm getting there and had a blast riding it this past Sunday.
 
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Tom

As you know and I have shared already, I agree with Luke. Lean is usually mean. I've kept my YZ slightly fat off the bottom to keep it tame.

That said, unlike earlier RMs, I think it can be made closer to the YZ. Your motor is supposed to be dimensionally very similar to the YZ. It was the year Suzuki basically copied the YZ, even the same carb. Plus you have a spring adjustable power valve.

Maybe in December we can take a day and really go into and through your motor. Compression, leakdown, squish, and open up the top end. Compare it to the known numbers on my YZ. Could even compare the ports to my second YZ engine on the shelf. Or even swap in my carb.

Luke also brings up a good suggestion I hadnt even considered, a thicker base gasket to change the port timing. Would also reduce the compression slightly (good for a trail bike and pump gas.)

I dont think it would or will take a ton of money to perfect your RMs motor. Pumped that you are enjoying the two stroke life! Bummed I'm not going to make it down to Hollister this weekend.
 
OaklandF4i said:
Tom

As you know and I have shared already, I agree with Luke. Lean is usually mean. I've kept my YZ slightly fat off the bottom to keep it tame.

That said, unlike earlier RMs, I think it can be made closer to the YZ. Your motor is supposed to be dimensionally very similar to the YZ. It was the year Suzuki basically copied the YZ, even the same carb. Plus you have a spring adjustable power valve.

Maybe in December we can take a day and really go into and through your motor. Compression, leakdown, squish, and open up the top end. Compare it to the known numbers on my YZ. Could even compare the ports to my second YZ engine on the shelf. Or even swap in my carb.

Luke also brings up a good suggestion I hadnt even considered, a thicker base gasket to change the port timing. Would also reduce the compression slightly (good for a trail bike and pump gas.)

I dont think it would or will take a ton of money to perfect your RMs motor. Pumped that you are enjoying the two stroke life! Bummed I'm not going to make it down to Hollister this weekend.
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I'd love to hangout and go through the motor.

I'm bummed you won't be making it to Hollister for there Hareball. Both my Nephews will be on course this year. I can't wait for the smack talk to start. :rofl
 
ThumperX said:
Picked up a very worn, tampered with, TTR125 that's been bored out to 150. It runs really rich, thinking about picking up a different carburetor.
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Hey ThumperX,

Do you think a TTR125 would be about the right size for a 11/12yr old girl? My daughter has been riding a CRF70 for several years and I think it's time for an upgrade but I'm not sure if the TTR would be too tall for her.
 
I don't think it's too tall. It's a pretty compact bike. The one I have has the big wheels but it's still a tiny thing.
 
Hard to gauge how big a 12 yo girl is, best way is to go to s dealer and have her sit on some bikes.
Ttr125 came in small or big wheel, kick or electric start. Pick the combo you want.
I have a big wheel electric start for my wife and I ride it with my kids.
 
This past weekend at Hollister I blew a fork seal on my 2015 YZ250F. I'm about to order a rebuild kit and the few special tools I need to replace the seals myself.

Question: for the KYB forks that I have, do I need a fork oil level tool? I've watched a few how-to videos, and it looks like with the dual-chamber style forks there is no use for a fork oil level tool. Is that right?

I'm only planning on getting the Yamaha OEM fork seal kit, 48mm seal driver, Motion Pro seal bullet (I know I don't really need this), and a Tusk dual-chamber fork cap wrench, and of course fork oil.

Anything I'm missing (that should be ordered with these parts)? I'll get 600 grit or misc other stuff locally if I need it.
 
No oil level tool needed but you will need something to measure out ~320cc like a Ratio Rite cup. Dual chamber forks go by volume not by level.

Special tools needed: cap wrench, cartridge holder, cartridge wrench

The Tusk cap wrench might have a holder on its other side, I forget. Actually I don't think you need the cartridge wrench just to do the seals. But as long as you have the forks apart you can clean the cartridge and change the oil.

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Thanks that’s very helpful. Yeah I was thinking of buying a Ratio Rite Cup also. I’ll check on the Tusk tool and will get a holder if it doesn’t have that as part of it. :thumbup
 
I'm pretty sure the Tusk cap tool has a holder. Let me go in the garage and check...

Yes it does. Google suggests it's sold with the cartridge tool.

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Remember to break the caps loose before removing the forks from the bike. The tool may not fit with your bar clamp hardware and you may have to take the caps off with the forks in a padded vice.
 
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I pulled the 40 pilot jet out of my RM and installed a 38 and rode it this past weekend at Carnegie. It is running really really well but not perfect down low yet. I'm so close. I'm going to install a leaner needle and try again. The more fuel I pull out the crisper it runs. I'm nowhere near too lean as it still smokes and produces spuge. After installing the gold valves the fork was SOOO much better but I wanted it even softer so I pulled about 15MM of oil out of both legs. What an improvement it made! It is softer yet and I'm using all the travel finally! I'm getting there!
 
Eric in Davis said:
This past weekend at Hollister I blew a fork seal on my 2015 YZ250F. I'm about to order a rebuild kit and the few special tools I need to replace the seals myself.

Question: for the KYB forks that I have, do I need a fork oil level tool? I've watched a few how-to videos, and it looks like with the dual-chamber style forks there is no use for a fork oil level tool. Is that right?

I'm only planning on getting the Yamaha OEM fork seal kit, 48mm seal driver, Motion Pro seal bullet (I know I don't really need this), and a Tusk dual-chamber fork cap wrench, and of course fork oil.

Anything I'm missing (that should be ordered with these parts)? I'll get 600 grit or misc other stuff locally if I need it.
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Seal grease?
 
I picked up a 2008 Ktm 200 xcw last week and rode it at Carnagie this past weekend on Sunday! Conditions were epic, it was crowded, and it was a blast to ride that bike!

I've spent the week tweaking it and ordering goodies. Yesterday I wired up a headlight and heated grips (think snow trip). Today the rekluse is arriving and hopefully I'll get it installed and like it.

This bike is a serious cheater compared to the cr250 and I'm really hoping it gets me out riding more and more.
 
Eric in Davis said:
This past weekend at Hollister I blew a fork seal on my 2015 YZ250F. I'm about to order a rebuild kit and the few special tools I need to replace the seals myself.

Question: for the KYB forks that I have, do I need a fork oil level tool? I've watched a few how-to videos, and it looks like with the dual-chamber style forks there is no use for a fork oil level tool. Is that right?

I'm only planning on getting the Yamaha OEM fork seal kit, 48mm seal driver, Motion Pro seal bullet (I know I don't really need this), and a Tusk dual-chamber fork cap wrench, and of course fork oil.

Anything I'm missing (that should be ordered with these parts)? I'll get 600 grit or misc other stuff locally if I need it.
Click to expand...

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