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The factory plug for my YZ2050X is a BR8EG.  I've got my jetting much better although a bit rich on the pilot (45 with 2.5 screws out still), but the rest seems to have been better.  As I'm not racing this bike but doing woods riding and rarerly hard in the pipe, I was wondering if using a BR7ES or EG as it will burn hotter and all the fuel pumped into the cylinder.  Anyone running a 250 on a BR7?  Interested in your feedback.

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Use the stock recommended plug. Plug heat range just determines how well it keeps itself clean and at the right temp, it does not change the combustion process.

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I don't think I would change anything unless you are fouling plugs.  In my case though I would probably drop a size in that low speed jet if you are still running rich down low.  You are about out of adjustment for an altitude change as it is.  other than that don't be nervous about buying es series plugs to save some money.   Heat range changes do have their uses though.   I just don't see it for trying to correct jetting. 

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7 minutes ago, ossagp said:

I don't think I would change anything unless you are fouling plugs.  In my case though I would probably drop a size in that low speed jet if you are still running rich down low.  You are about out of adjustment for an altitude change as it is.  other than that don't be nervous about buying es series plugs to save some money.   Heat range changes do have their uses though.   I just don't see it for trying to correct jetting. 

osseagp:  that was the basis from my question, I'm going to drop my pilot.  i've been rich since I bought the bike in March chasing the warm up.  I'm not looking to solve major jetting issues with a plug or oil mixture, however, I do recall from my riding 250s (KX, RM, YZ) back in the 90's and early2k's) that i found that when riding MX tracks and single track woods crawling, I fouled less when running hotter plugs in the woods vs track.  Fouling is what I'm trying to prevent, as I lost my love of trying to change on the trail, or worse forget my fanny pack.

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FIT67

yeah,  we have all done that as a stop gap measure.  it has it's drawbacks is all.   lots of racers at the factory level found that some hotter plugs in the case of supercross racing was almost necessary because they ran some really high float levels so that the bikes didn't run dry when pounding whoop sections and rollers followed by jumps.  Recalling how they used to do so much clutch in reving to keep them cleaned out when they weren't running dry.  you can get some better response as well (byproduct of them running a little cleaner).  

Edited by ossagp

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The factory plug for my YZ2050X is a BR8EG.  I've got my jetting much better although a bit rich on the pilot (45 with 2.5 screws out still), but the rest seems to have been better.  As I'm not racing this bike but doing woods riding and rarerly hard in the pipe, I was wondering if using a BR7ES or EG as it will burn hotter and all the fuel pumped into the cylinder.  Anyone running a 250 on a BR7?  Interested in your feedback.

You're still 3/4 of a turn too far out, are you using high flashpoint mix oil? I'm switching from Yamalube 2R to a lower flashpoint oil because of spooge, bike is running really well though. I would Not change heat range plug, that's just asking for predet on transfer sections.

 

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1 minute ago, HeavyRotation said:


You're still 3/4 of a turn too far out, are you using high flashpoint mix oil? I'm switching from Yamalube 2R to a lower flashpoint oil because of spooge, bike is running really well though.

I'm running Yamalube at 32/1. In my KX and RM I used golden spectro and stopped fouling.  Interested in the flashpoint discussion as I do think that while Yamalube does a good job of lubricating, I don't think I ride hard enough to cleanly burn through everything.  Not sure either that this is a Yamaha issue rather a 2T issue.  

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I run a BR7ES plug in my 250X, there is no problem at all doing this. The ES type plugs make no noticeable difference over the standard G type ( and they are a lot cheaper..).  If you are doing a lot of singletrack or slow speed type riding then going 1 step hotter to a #7 plug is a good idea anyway. It is not a "stop gap" measure.  The KTM 250 and 300 bikes all use a #7 plug and they are a comparable motor in terms of power and usage. Going 1 step hotter can help to keep the plug from fouling If you are not always riding on the pipe, or if your jetting is a bit rich down low.

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I run a BR7ES plug in my 250X, there is no problem at all doing this. The ES type plugs make no noticeable difference over the standard G type ( and they are a lot cheaper..).  If you are doing a lot of singletrack or slow speed type riding then going 1 step hotter to a #7 plug is a good idea anyway. It is not a "stop gap" measure.  The KTM 250 and 300 bikes all use a #7 plug and they are a comparable motor in terms of power and usage. Going 1 step hotter can help to keep the plug from fouling If you are not always riding on the pipe, or if your jetting is a bit rich down low.

I bought a 06 yz 250 that had been used by a quick mx rider. Slapped some lights on it and did a 2 day enduro the following weekend. Not having time to go through the bike and it was a stop gap whilst my woods bike was unexpectedly in bits. I just rocked up and rode it. Fouled plugs three times on the first day. Blagged a #7 plug off of a ktm300 rider who stopped to help. The bike didn't foul all day on the second day.

Pulled the carb after to see what was going on, and found it on a 182 main jet and the clip one position richer. Corrected the jetting and have been fine with a #8 plug since.

I would not have issue switching to a plug a grade either side depending on the riding I was doing.

Remember a lot of vehicles have thermostats in the cooling systems to regulate cylinder temps a bit better. The yz as a balls out racer doesn't, so we may have to make minor adjustments to factory specs to tailor the bike to work better for us along with the conditions and riding styles we are using the bike for.
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A 7 isn't going to hurt anything and may actually help you given how you say you ride. If you need heat, a hotter plug can help you drive the heat in a little deeper which can be a good thing but as mentioned above don't substitute it for jetting and remember rich jetting makes an engine run cooler.

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6 hours ago, FITZI6_7 said:

I'm running Yamalube at 32/1. In my KX and RM I used golden spectro and stopped fouling.  Interested in the flashpoint discussion as I do think that while Yamalube does a good job of lubricating, I don't think I ride hard enough to cleanly burn through everything.  Not sure either that this is a Yamaha issue rather a 2T issue.  

Although the list below doesn't have Yamalube in it, it is some interesting information. I've seen this list posted on a few forums.

I also read that one person thought that Yamalube might have a flashpoint of 205F (based on information that he heard on who actually manufactures the oil and looked up the manufacturers specs) so that number can only be looked at as speculation.

 

Castrol Power RS- 163 F
Maxima Bio 2T - 180 F
Lucas Semi Synthetic - 182 F
Amsoil Interceptor - 183 F
Motul 710 - 190 F
Amsoil Dominator- 194 F
Bel Ray Si7 - 194 F
Castrol 2T - 194 F
Bel Ray MC1 - 208 F
Maxima Super M Injector - 220 F
Red Line Two-Stroke Racing Oil - 221 °F
Motorex Cross Power 2T - 230 F
Amsoil Saber Pro - 237 F
Maxima Formula K2 - 240 F
Motul Bio 2T - 255 F
Maxima Super M - 280 F
Maxima Castor 927 - 420 F
Bel Ray H1R - 435 F
Motul 800 - 485 F

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15 hours ago, dmrogers said:

Although the list below doesn't have Yamalube in it, it is some interesting information. I've seen this list posted on a few forums.

I also read that one person thought that Yamalube might have a flashpoint of 205F (based on information that he heard on who actually manufactures the oil and looked up the manufacturers specs) so that number can only be looked at as speculation.

 

Castrol Power RS- 163 F
Maxima Bio 2T - 180 F
Lucas Semi Synthetic - 182 F
Amsoil Interceptor - 183 F
Motul 710 - 190 F
Amsoil Dominator- 194 F
Bel Ray Si7 - 194 F
Castrol 2T - 194 F
Bel Ray MC1 - 208 F
Maxima Super M Injector - 220 F
Red Line Two-Stroke Racing Oil - 221 °F
Motorex Cross Power 2T - 230 F
Amsoil Saber Pro - 237 F
Maxima Formula K2 - 240 F
Motul Bio 2T - 255 F
Maxima Super M - 280 F
Maxima Castor 927 - 420 F
Bel Ray H1R - 435 F
Motul 800 - 485 F

Yamalube 2R has a flashpoint of 255°F

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Interesting topic and thanks for the input.  I think I'm going to try a spin around this weekend if I can get my hands on a "7" and go from there after I put one step leaner on the pilot.  Golden Spectro which I used before has a 170 flashpoint.  which now I realize why it always worked but didn't before.   If I change oil, I'll probably go back to an "8" and see how it does but I recall going one step hotter and using golden spectro.  will still keep the 32:1 ratio though and get a 

 

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Interesting topic and thanks for the input.  I think I'm going to try a spin around this weekend if I can get my hands on a "7" and go from there after I put one step leaner on the pilot.  Golden Spectro which I used before has a 170 flashpoint.  which now I realize why it always worked but didn't before.   If I change oil, I'll probably go back to an "8" and see how it does but I recall going one step hotter and using golden spectro.  will still keep the 32:1 ratio though and get a 
 

Not sure what I was gonna finish with there.
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Yeah, do it.  In your situation I would use the BR7.

Using a hotter plug (single step) is a great thing for 85cc MX bikes ridden slowly by beginner kids.

Low loads, low RPMs, low compression, rich jetting (for the conditions), retarded spark timing, will all cause cooler spark plug temps and can all be compensated for by a hotter plug, to keep the plug clean.

The proper fix for your 250X is probably the jetting and the squish clearance (velocity).  Tighter squish wont need rich jetting. In my experience the Yam needle is a compromise between 1/4 to 1/2 throttle. With corrected squish and jetting you could probably use a BR9 plug all day without fouling it.

I don't understand how a premix oil flashpoint of 170 or 470F would matter when the combustion flame is about 4000F.  BUT that's assuming a full clean burn happens.  I use Motual 800 or Maxima 927 and I've never fouled a plug. I don't rev the motor hard, or use rich jetting. I've also been using a BR9ES plug for the past 5 months. But I also have the zook needle and 1.4mm squish clearance.

In the Tech Info doc on the NGK website it says "Before changing fouled spark plugs, be sure to eliminate root cause of fouling"

Edited by numroe
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Thanks. I have not done any squish work and probably won't till fall/winter rebuild time.

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On 6/8/2017 at 2:35 PM, William1 said:

Use the stock recommended plug. Plug heat range just determines how well it keeps itself clean and at the right temp, it does not change the combustion process.

If your not fouling plugs who cares! Mine runs Abit rich but has plenty of power, I'm not racing for money so don't care.

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If you look at the yamaha operation manual they recommend to go for a 7 plug if you ride at higher altitude: this mean plug number have a real action on fuel combustion %.

I think it is same principle if you ride single track at low/med rpm.

You do not want to lean too much your jetting to protect your engine so you can decrease plug number to burn more fuel.

I am living at 11000 feet and ride 250yzx on mountain single track: 70% of the time in low/med rpm.

I will try the 7 soon as yamaha operation manuel recommend.

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On 6/8/2017 at 11:31 AM, FITZI6_7 said:

The factory plug for my YZ2050X is a BR8EG.  I've got my jetting much better although a bit rich on the pilot (45 with 2.5 screws out still), but the rest seems to have been better.  As I'm not racing this bike but doing woods riding and rarerly hard in the pipe, I was wondering if using a BR7ES or EG as it will burn hotter and all the fuel pumped into the cylinder.  Anyone running a 250 on a BR7?  Interested in your feedback.

What elevation are you at.?    Have you adjusted your needle yet?  If not, I suggest you do that before you go any lower on the pilot jet.... I'm at 4K' and up and am running a 45 pilot between 3/4 and 1.5 turns out running suzuki needles this and 45-48 last year with the stock needles.  I don't have a drop of spoodge unless it gets really hot or high altitude and I don't compensate,,..you can certainly mask a rich needle with a lean pilot but only so far.... It's a whole system and needs to be tuned as such..  What main do you run.?  If you have adjusted these then disregard.. Im certainly not against using an hotter plug (do this on my daughters kx85). But the X just flat out doesn't need it.    I don't think my air screw even goes 2.5 turns out..

Edited by Nevada Al

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What elevation are you at.?    Have you adjusted your needle yet?  If not, I suggest you do that before you go any lower on the pilot jet.... I'm at 4K' and up and am running a 45 pilot between 3/4 and 1.5 turns out running suzuki needles this and 45-48 last year with the stock needles.  I don't have a drop of spoodge unless it gets really hot or high altitude and I don't compensate,,..you can certainly mask a rich needle with a lean pilot but only so far.... It's a whole system and needs to be tuned as such..  What main do you run.?  If you have adjusted these then disregard.. Im certainly not against using an hotter plug (do this on my daughters kx85). But the X just flat out doesn't need it.    I don't think my air screw even goes 2.5 turns out..

45 pilot, stock needle on 1st clip 168 main. Ride between 0-5k ft

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