had an 01 for a couple years. went up 1 or two on the rear sprocket. gave some more snap off the bottom. the reed swap did great. but a 3/8 drill bit was single best free mod i did. 1 bore center on each side of the air box, absolutely woke that bike up.. sounded great as well...
Jeeech I spent 5 min on the vid to see if he answered his title question, and he didn't ride it. Let me help Of course the parts of the engine should be working correctly, like replacing those reeds and making sure the engine does not have any air leaks. Proper maintenance stuff. But for an engine to run, you only need 3 things. 1) Compression (and I bet yours is low). 2) spark at the right time 3) A good fuel/air ratio (jetting and oil mix) Jet for 32:1 gas/oil mix. It looks to me, the compression is low, (new piston and rings if the plating is still good, will fix that), and your jetting is rich. When a plug starts to foul out, it can run OK sometimes, and bog more at other times. Lower compression will foul plugs our easier, as the burn is not as hot. If you pull off the cylinder and check the piston for wear and damage, and measure the ring end gap (should be in the owners manual), I think you will find that it needs a top end rebuild. While you are at it with the cylinder off, you will want to check the rod side play (also in the manual should be) to get a good idea if your crank needs to be rebuilt. 3 hard seasons of MX racing on a 2-stroke crank is about the limit. If the rod breaks, they tend to take out the entire engine. Basically, just make sure the engine has no leaks or reed problems, etc., and making sure those 3 things are good above,---and it will run as it should. Doug in Michigan ESP (Earth Surfer performance)
Thanks for the feedback. The reeds did end up fixing the bog, it runs great. I couldn’t ride it at the location I was at so it was tough to tell if it fixed it right then.
Hey man, great video! I have a 2001 as well. Upgrade you power valve stop pin to 5mm on the end of the dowel pin. What this does is advance the power valve giving the bike improved blow down. It helped my bike for sure. Also, get yourself a keihien 38mm air striker carb and toss that TMX. Night and day! Hope this help!
I doubt the blow down time is responsible for your power improvements. The blow down time is only for getting the cylinder pressure to zero (or less as the pipe can actually cause some negative pressure to the exhaust port, sucking up transfer gas into the cylinder.), so the transfers can flow. If you find burnt oil down your transfer walls, that is an indication that you don't have enough blow down time somewhere in the RPM curve, as the higher cylinder pressure is pushing hot exhaust gas down the transfer tunnels and burning the oil on the sides of the tunnels. Where that is happening in the RPM range I have not been able to figure out yet. But with little mods to a 1988 CR250 I once had, that thing ripped, and it had transfer oil burns. The blow down time is more needed as rpm's rise, not the other way around. I suspect the different power valves matched the exhaust port time with the pipe better for the power you got.
@@EarthSurferUSA this is a Mod straight out of Eric Gorrs book and is specific for the 2001 only. “In stock form, the valves don’t allow for enough blowdown timing from 4500-8000rpm, prior to when the valves flip wide open. A simple way to advance the exhaust valves is to make a bushing for the stop pin to limit how far the valves close. A bushing with 5 mm diameter placed over the top of the original stop pin, is ideal for most riders.” Definitely helped for my bike! Thanks for the input!!!
Hey bro i got a 01 cr 125. Something you said. Let me me if it helps. My bike is a dog taking off aways. But sometimes it pulls well in first and second sometimes. So im interested to hear how it works out for you
had an 01 for a couple years. went up 1 or two on the rear sprocket. gave some more snap off the bottom. the reed swap did great. but a 3/8 drill bit was single best free mod i did. 1 bore center on each side of the air box, absolutely woke that bike up.. sounded great as well...
Right on
Jeeech I spent 5 min on the vid to see if he answered his title question, and he didn't ride it. Let me help
Of course the parts of the engine should be working correctly, like replacing those reeds and making sure the engine does not have any air leaks. Proper maintenance stuff.
But for an engine to run, you only need 3 things.
1) Compression (and I bet yours is low).
2) spark at the right time
3) A good fuel/air ratio (jetting and oil mix) Jet for 32:1 gas/oil mix.
It looks to me, the compression is low, (new piston and rings if the plating is still good, will fix that), and your jetting is rich. When a plug starts to foul out, it can run OK sometimes, and bog more at other times. Lower compression will foul plugs our easier, as the burn is not as hot. If you pull off the cylinder and check the piston for wear and damage, and measure the ring end gap (should be in the owners manual), I think you will find that it needs a top end rebuild. While you are at it with the cylinder off, you will want to check the rod side play (also in the manual should be) to get a good idea if your crank needs to be rebuilt. 3 hard seasons of MX racing on a 2-stroke crank is about the limit. If the rod breaks, they tend to take out the entire engine.
Basically, just make sure the engine has no leaks or reed problems, etc., and making sure those 3 things are good above,---and it will run as it should.
Doug in Michigan
ESP (Earth Surfer performance)
Thanks for the feedback. The reeds did end up fixing the bog, it runs great. I couldn’t ride it at the location I was at so it was tough to tell if it fixed it right then.
Hey man, great video! I have a 2001 as well. Upgrade you power valve stop pin to 5mm on the end of the dowel pin. What this does is advance the power valve giving the bike improved blow down. It helped my bike for sure.
Also, get yourself a keihien 38mm air striker carb and toss that TMX. Night and day! Hope this help!
I doubt the blow down time is responsible for your power improvements. The blow down time is only for getting the cylinder pressure to zero (or less as the pipe can actually cause some negative pressure to the exhaust port, sucking up transfer gas into the cylinder.), so the transfers can flow. If you find burnt oil down your transfer walls, that is an indication that you don't have enough blow down time somewhere in the RPM curve, as the higher cylinder pressure is pushing hot exhaust gas down the transfer tunnels and burning the oil on the sides of the tunnels. Where that is happening in the RPM range I have not been able to figure out yet. But with little mods to a 1988 CR250 I once had, that thing ripped, and it had transfer oil burns. The blow down time is more needed as rpm's rise, not the other way around. I suspect the different power valves matched the exhaust port time with the pipe better for the power you got.
Doug in Michigan
ESP (Earth Surfer Performance)
@@EarthSurferUSA this is a Mod straight out of Eric Gorrs book and is specific for the 2001 only. “In stock form, the valves don’t allow for enough blowdown timing from 4500-8000rpm, prior to when the valves flip wide open. A simple way to advance the exhaust valves is to make a bushing for the stop pin to limit how far the valves close. A bushing with 5 mm diameter placed over the top of the original stop pin, is ideal for most riders.”
Definitely helped for my bike! Thanks for the input!!!
less idle time would help the bog too.
Hey bro i got a 01 cr 125. Something you said. Let me me if it helps. My bike is a dog taking off aways. But sometimes it pulls well in first and second sometimes. So im interested to hear how it works out for you
Seems like it fixed it so far buddy