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CR125 performance tuning...

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OK, been riding the 125 in the tight woods and love it. I took it on the Dirtrider 24hr trip and rode it at Gorman and was wondering what I liked about it as it kind of sucked in the deep sand and open areas but once I got it back to Oregon/Washington and rode it in the tight woods my faith has been restored.

All that said I want to hop it up a little and try some things. First off any of you have the 6DGY04-60 or 59 needle you want to sell me? I called Sudco and they are all out and said they had quite an ordering spike. Hummm, wonder if the CR125 postings had anything to do with this :) So you that do have them, did it make a difference?

Next I want to try a 10mm reed block spacer and see if that helps. I'm going to have the guys here laser me one up and I'll let you know if it helped. Anyone tried this?

I also want to do a power now type mod because I think it would work great on this bike. I notice if I feed the throttle in and not snap it open it pulls better off the bottom and I'm thinking this might help. Again, anyone else try this and want to let us know if it works? I am going to build my own and do the front and back of the slide. This might be the perfect application for this as it is a big carb small piston bike and I have heard they do wonders for the 85cc bikes.

Lets use this tread for the upgrades and what we found and keep it clean and informative OK?

I have a basically stock 04 CR125, am a 200 pound tight trails rider/racer in WA/OR 200-3000 feet / 35-65 degrees (right now), I have the PC muffler on mine and it tested at 92db, am running the 59 needle that came with the bike with a 370 main (runs OK like that, looking for better)

Thanks.

Kelly

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Kelly,

I bought the last of the DGY04-60 and 59 from Sudco. I have the 60 in my 125 now with good results. I would be happy to mail you the 59 to try out. I figure the more testers the better. If you like it, you can get me another one when they come back in stock.

Along with the new needle and undermount dampener mount I ordered a Powernow valve for both the 450 and 125 last week. I expect I will have them this week some time. I will let you know how it goes.

I am also interested in the reed block spacer. But if it is 30mm (I had heard of 10mm from Moose), does that mean the carb sits back 30mm? and will the air boot accommodate?

Consider the needle on the way.....

William

Santa Cruz

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Oh, FYI, I rode a stock KTM125SX this weekend and was surprised that it did not make more power than the Husky. I actually thought the husky was stronger on top but the KTM had better mid and roll on type power which I liked.

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Kelly,

I bought the last of the DGY04-60 and 59 from Sudco. I have the 60 in my 125 now with good results. I would be happy to mail you the 59 to try out. I figure the more testers the better. If you like it, you can get me another one when they come back in stock.

Along with the new needle and undermount dampener mount I ordered a Powernow valve for both the 450 and 125 last week. I expect I will have them this week some time. I will let you know how it goes.

I am also interested in the reed block spacer. But if it is 30mm (I had heard of 10mm from Moose), does that mean the carb sits back 30mm? and will the air boot accommodate?

Consider the needle on the way.....

William

Santa Cruz

Excellent!!! Good talking to you. I'm really interested in if the PN helps a lot or ???

Kelly

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I am trying out the 6DGY4-59 clip 4th from the top and a 370 MJ. Just running up the street out front and it seems to have a stumble at mid throttle. I am going to the Tasky demo day this Sunday and will bring my jetting kit and try out some combinations. After riding my 510 the 125's acceleration isn't exactly a handle bar bender.

800' and 34F

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I am trying out the 6DGY4-59 clip 4th from the top and a 370 MJ. Just running up the street out front and it seems to have a stumble at mid throttle. I am going to the Tasky demo day this Sunday and will bring my jetting kit and try out some combinations. After riding my 510 the 125's acceleration isn't exactly a handle bar bender.

800' and 34F

Question, was the bike fully warmed up and run hard a few times? 595 (above) and I were discussing this and how two strokes need about 5-10 minutes of hard flogging before they really run right.

I have that needle coming (thanks 595) and am going to try top have a spacer plate and powernow type devise on before the HuskyNW demo and try to be there. Thanks.

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I'm running PC pipe and stock sil. (I should have my FMF S/A done this week).

Stock needle (60), jetting (390m, 40p) and stock plug and 12-50 gearing and v-force reeds set on low. All in all, I'm pleased with the bike.

The PC pipe is pretty nice. Seems to have a better mid-range and better top then the stock pipe.

I have spoken with a couple of people that run the CR125's. They had very good things to say about the Dynoport pipes (stock low-end pipe and special mid-top pipe).

I got the bike used and this is how it was set-up when I got .It is hard to say what the bike was like with the stock gearing. I Have rode with both the stock and PC pipe and find the PC better suited for what I ride (and how I ride).

I'm a 165 pound average B racer that rides 100% tight single track and the bike really works well for this type of riding.

I plan on playing with the gearing and trying the other needles when Sudco gets some more in.

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I just got the power now valves in this afternoon. Only took a few minutes to pop in the CR125, the 450 will require removing the carb.

But once I get the chance to run it in I'll let everyone know if it is worth the effort and money. The seem like a lot of money for such a simple piece of metal (stainless?). The billet piece for the FCR seems more worth the cost.

William

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Here is an idea I have yet to try but you all might want to try it. As per my post, copy below. You can adjust the reed stop as per the post below. I'm going to try it on my wife's CR125 along with the Moose torque spacer as soon as I get the bike back together. I'm waiting on a special shock spring to be finished being made through Les At LTR. The stock spring was way too stiff for my wife.

The V Force tech was covering his @ss by saying "possibly" or "could" to all suggestions.

"I talked to a Vforce tech guy. He said that yes the Moose reed spacer for the Honda CR125 has the same bolt spacing and pattern as the Husky and it will work. He said yes it could help low end.

He also said that you can adjust the reed stop on the stock Vforce reed system to possibly gain low end and possibly not affecting top end. He said the reed stop has "High" written on one side and "Low" on the other. Take it apart and flip it over to "Low", which will give it less tension and possibly more low end."

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My bike would barely run on the stock (-60 as it came with no extras) needle and the only way to ride it was put it in the full rich position. I changed it out to the -59 needle mentioned above from SUDCO in the middle position (where it should be) and it's a competely different bike now. Corners that used to require 1st gear AND clutch can now be ridden in second gear with very little clutch. I do have the -60 and -58 needles in my toolkit and once I have time I will try them all out.

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Something that might help (for reference purposes) is to identify the fuel type / octane as well as the pre-mix oil brand / type / ratio when posting. Personally, with my tm125, I found that I could get the bike jetted well the 92 octane pump fuel and a varying range of gas/oil ratios, but that 100LL (low lead av gas) mixed at 100:1 Amsoil gas me the widest range of clean jetting (no change from 25F to 85F and EL=0 to EL=4000'). I don't intend to turn this into a fuel / oil brand / ratio thread, but we do need the info for reference. FYI, I am currently running 92 octance Shell fuel with 100:1 Amsoil.

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Something that might help (for reference purposes) is to identify the fuel type / octane as well as the pre-mix oil brand / type / ratio when posting. Personally, with my tm125, I found that I could get the bike jetted well the 92 octane pump fuel and a varying range of gas/oil ratios, but that 100LL (low lead av gas) mixed at 100:1 Amsoil gas me the widest range of clean jetting (no change from 25F to 85F and EL=0 to EL=4000'). I don't intend to turn this into a fuel / oil brand / ratio thread, but we do need the info for reference. FYI, I am currently running 92 octance Shell fuel with 100:1 Amsoil.

that is a good point and I have found different oil makes a difference in jetting and how a bike runs. I am using redline at 40:1 with 92 pump gas.

Here is what I hope to have accomplished for testing this weekend. The 6DGY04-59 needle (thanks 595), I'm building a power now type carb divider plate for the front and rear of the slide and I am making a 10mm reed block spacer plate. Might flip the stops on the reed block as Flame suggested. I did this on my 02 WR250 but did not notice much of a difference. Once I smash the stock pipe I will try a doma or PC pipe.

Kelly

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Since I have two of these bikes I can use one as a control. So far I am happier the stock jetting and needle. I removed the 6DGY4-59 that I had yesterday and put the stock -59 in with it raised all the way. Kept the 370 main jet. This is the recommended set up per Bill's Cycle with the exception that Bill wants 40-1 premix.

Using Shell 92 with ELF synthetic at 32-1. 800' 45F

The stock set up rolls on from idle with no stumble all the way through the power band.

The modified set up starts well but about mid throttle stumbles and after that lights off like an F15 on afterburner. I think it has better acceleration than stock, you just have to deal with the stumble.

Ideas anyone?

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Since I have two of these bikes I can use one as a control. So far I am happier the stock jetting and needle. I removed the 6DGY4-59 that I had yesterday and put the stock -59 in with it raised all the way. Kept the 370 main jet. This is the recommended set up per Bill's Cycle with the exception that Bill wants 40-1 premix.

Using Shell 92 with ELF synthetic at 32-1. 800' 45F

The stock set up rolls on from idle with no stumble all the way through the power band.

The modified set up starts well but about mid throttle stumbles and after that lights off like an F15 on afterburner. I think it has better acceleration than stock, you just have to deal with the stumble.

Ideas anyone?

Mid range is usally a needle problem. Maybe you have it too rich by being all the way up, lower it one and see if it helps. It might need to be lowered two.

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I raised the stock needle (60) one position and noticed a mid range stumble also. I put it back to stock and liked it better. Last weekend I tried the included -59 needle in the middle position and noticed more mid and roll on but it seemed like it did not want to get to the top end as fast.

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OK, got some stuff done.

First off I had the guys laser up some carb dividers. I CAD them up slightly large (.002) so all I had to do to install them was take a hack saw blade and score a slight groove and them tap them in. This worked great and they are in there tight. I did it to the front and back of the slide.

Here are the parts...

hus-carb-div-2.jpg

Here they are installed...

hus-carb-div-1.jpg

You might have noticed the hole. This is how the version two powernow is built and I drilled the one on my 03 YZF and did notice a difference so I included it in the original design.

Then I had the guys laser up a reed block spacer. We used 3/8ths aluminum which ends up shy of 10mm at 9.70mm. This works out to 33.7cc of volume. As my dealer did not have a gasket in stock I'm going to get some gasket material and fastion my own and then button this up.

reed-sp-1.jpg

I think I am going to flip the stops over on the reeds also. Additionally I will be installing the 6DGY04-59 needle if it gets here by tomorrow which it should. If all goes well I will be testing Friday and will post results Friday night.

I spoke with Jerry at Langston Racing and he said he only has one Doma CR125 left and he thinks it is going today. He will not be getting more unless we can come up with about 15 or so people that want them. I hear it works well. I could have snapped it up but did not. He also mentioned that the east coast scramble guys are running a head that has inserts for different compresion ratios and is the ticket for more bottom. I would imagine you would need to run race fuel so it did not ping inself to death but I want to make it run as good as possible on pump gas.

yes, I'm a mad scientist, always have been. Did any of you see what I did to the forks on my YZF250?

RC-front.jpg

Worked great! Like the Enzo and others the idea is it gives the air in the forks a place to bleed to on small impacts and will not flow enough on big ones. You end up with the best of both worlds, soft on the smaller stuff and progressively stiffer the harder you hit it.

If I had some spare caps for the husky I would give that approach another spin as I really liked it.

Also was running a 20" front wheel and autoclutch on that bike. :)

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I spoke with Jerry at Langston Racing and he said he only has one Doma CR125 left and he thinks it is going today. He will not be getting more unless we can come up with about 15 or so people that want them. I hear it works well. I could have snapped it up but did not. :)

I ran a Doma pipe and shorty silencer on my WR125 for a while, until I twanged it. You don't get the 'fuller' bottom end of the stock pipe but it really wakes up the mid to top. That bike would kick hard. Dip the clutch to get it spinning and it would take off. Better suited to more open terrain and mx style special tests I reckon. There wasn't a lot of bottom end loss but it didn't feel quite as smooth off the bottom as stock.

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Kelly,

The carb dividers looks really good.

Are they welded in?

Will the plate and weld effect the small intake hole on the left of the intake (is that a choke hole? note I think I see that is not weld but casting flashing).

I will be curious to see if it also helps in the trailing side of the carb (like the Powernow Plus I just fit to my FCR carb). If so you will have to make a few more plates up for our consumption.

I also noticed that when I installed the intake side of the Power now valve on the 41mm FCR TE450 carb, the divider plate was a good 4-5mm short of touching the slide and that the edge that was closest to the slide was narrower then the carb throat by a few milimeters on each side. I would think that it should be as close to the side as possible and tight to the bore all the way through to be effective (other wise why the "new" hole in the divider Powernow is using to equalize the pressure a bit).

I'm assuming that the the intake bell can fit all the FCR carbs and that the trailing edge would be tighter on a 35 or 37mm carb.

A product of trying to fit one part to more applications?

Where the Powernow Plus was tight to the bore and to the slide, which seems correct.

Kelly will you be making any extra spacers? and what about cutting them so that they have a divider or cross divider in it to straighten out the incoming gas charge? Or does the reed cage intrude into the spacer (I haven't taken one apart yet)?

Any thoughts?

William

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Kelly,

The carb dividers looks really good.

Are they welded in?

Will the plate and weld effect the small intake hole on the left of the intake (is that a choke hole? note I think I see that is not weld but casting flashing).

I will be curious to see if it also helps in the trailing side of the carb (like the Powernow Plus I just fit to my FCR carb). If so you will have to make a few more plates up for our consumption.

I also noticed that when I installed the intake side of the Power now valve on the 41mm FCR TE450 carb, the divider plate was a good 4-5mm short of touching the slide and that the edge that was closest to the slide was narrower then the carb throat by a few milimeters on each side. I would think that it should be as close to the side as possible and tight to the bore all the way through to be effective (other wise why the "new" hole in the divider Powernow is using to equalize the pressure a bit).

I'm assuming that the the intake bell can fit all the FCR carbs and that the trailing edge would be tighter on a 35 or 37mm carb.

A product of trying to fit one part to more applications?

Where the Powernow Plus was tight to the bore and to the slide, which seems correct.

Kelly will you be making any extra spacers? and what about cutting them so that they have a divider or cross divider in it to straighten out the incoming gas charge? Or does the reed cage intrude into the spacer (I haven't taken one apart yet)?

Any thoughts?

William

William,

The dividers are a press fit, no welding. The air box side one is trapped from moving by the bell shape and air box boot and the front side one is trapped by the press fit and intake boot. Neather of them are going anywhere. I would assume the better the seal to the slide the better it will work. this one seals up very tight. I also think the PN2 hole creates flow right over the needle area and helps draw fuel. It was a noticeable difference on my 03YZF250 when I drilled it so I included it.

As for the reed block spacer it goes between the reeds and the case so the reed block sticks through it and you cannot have a divider in it. Basically all it does is allow more crank case volume.

My plan is to test this stuff and sort it out and offer a power up kit. Not sure if I can sell the divider plates as it is a patented part / idea but we will see. I am building several sized reed block spacers and will try several as well as a few slides with different numbers. My 02 WR250 came with to slides (3 and a 4) which makes a big difference in power types so I am going to experiment with that also. Once I find the optimum combo I will package the powerup kit and sell it all together with the needle and everything. Thats the plan.

Thanks.

Kelly

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