Let's have some fun and dispel some rumors at the same time (updated with verdict)

JM485
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Davis, CA US
3/4/2016 6:52pm Edited Date/Time 3/6/2016 12:51pm
Just hit a certain amount of hours on my 15 yz250 and decided to tear it down for a rebuild. Motor is completely stock, no motor work what-so-ever, and zero dirt has ever made it past the air filter. Bike has been run on a 50/50 mix of 100ll AVgas and pump premium, and one brand of oil only since it was broken in on the stock tank of gas.

Now, here's the challenge. Based on the pictures in this thread, see if you can guess how many hours the bike has on it. If you're really feeling confident, see if you can guess what oil and at what ratio it was run. I'll give you a hint, it the answers to both will be surprising, and will dispel a few rumor that run around here. Good luck, and I'll update with an answer in a day or so.Cool



















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MXR
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City, WA US
3/4/2016 6:57pm
17 hours

Yamalube

32-1
BB67
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721
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W/central, FL US
3/4/2016 7:01pm Edited Date/Time 3/4/2016 7:04pm
84 hrs

amsoil 100-1
Samuel
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Independence, OR US
3/4/2016 7:05pm
Maxima super m, 32:1, 38 hours
Myke
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San Diego, CA US
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2849th
3/4/2016 7:05pm
Golden Spectro 40:1

50 hrs

The Shop

tempura
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JP
3/4/2016 7:06pm
30-35 hours
Yamalube? 40:1
Bultaco
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Planet, VT US
3/4/2016 7:09pm Edited Date/Time 3/4/2016 7:11pm
Chain saw lube. 50:1. 50 hours

The piston looks alot like when i
used to run Castrol R bean oil.
Titan1
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Lehi, UT US
3/4/2016 7:10pm Edited Date/Time 3/4/2016 7:13pm
10 hours...

Bel ray

50:1
RandyS
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Grass Valley, CA US
3/4/2016 7:11pm
157 Hours, Penzoil 10-40 20:1
Cygnus
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Hanover, CO US
3/4/2016 7:12pm
50 hours, golden spectro, 40:1
Lots of blow by what ever it is.
No toil definetly let some dirt through too. Scoring on the cylinder shows that.
JLong
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Haslet, TX US
3/4/2016 7:12pm
32:1, 60 hrs.
gsxrcr28
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Fort Lauderdale, FL US
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3/4/2016 7:14pm
Golden Spectro 40:1, 25 hours
3/4/2016 7:19pm Edited Date/Time 3/4/2016 7:52pm
83.7 hours. Klotz BeNOL. What are you running for filter oil?

Almost forgot. 32:1
JM485
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3/4/2016 7:19pm
Cygnus wrote:
50 hours, golden spectro, 40:1 Lots of blow by what ever it is. No toil definetly let some dirt through too. Scoring on the cylinder shows...
50 hours, golden spectro, 40:1
Lots of blow by what ever it is.
No toil definetly let some dirt through too. Scoring on the cylinder shows that.
The scoring isn't as bad as it looks in the picture, it's just the way the flash hit the little bit of wear that makes it look amplified. I've never found any dirt in the air boot, and when it was taken apart there was zero dirt anywhere.
yzjs7
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Antioch, CA US
3/4/2016 7:24pm
Hmm my guess 50hrs, 40:1, lucas oil
Pool-eh
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3/4/2016 7:35pm
People still run AV gas? Isn't that bad or am I just remembering an old wives tale
bvm111
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Las Vegas, NV US
3/4/2016 7:40pm Edited Date/Time 3/4/2016 7:42pm
42 hours... Motul 800 at 40:1

Prestone anti freeze.... No make that Quaker State!

What did I win? Tongue
lostboy819
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Somewhere, CO US
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3/4/2016 7:48pm Edited Date/Time 3/4/2016 7:52pm
Take a pic from above the piston to see if any wash. From the side view you are running to lean because there is no piston wash. not the best chart but you get the idea. Cant quite tell but it is close if that is wash on the edges on the intake side but none on the exhaust side cant tell without seeing it from above



lostboy819
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3/4/2016 7:54pm Edited Date/Time 3/4/2016 7:56pm
Pool-eh wrote:
People still run AV gas? Isn't that bad or am I just remembering an old wives tale
AVE gas is for airplanes and not ideal for mx as it has some unneeded additives for high altitude and temp variance but I know people who have always run it and never had a problem, still better than pump gas with ethanol.
3/4/2016 8:01pm
Pool-eh wrote:
People still run AV gas? Isn't that bad or am I just remembering an old wives tale
I've been running it for a while. Cheaper than race fuel, better than pump gas unless you got turbo blue at the pump. Some do but most don't. Talked to Eric Gorr about it when he did my cylinder and he had nothing bad to say about it. He thought it's good stuff so that's what I've been running. Just tune your bike to run with it.
3/4/2016 8:01pm
Carbon pattern on cylinder head dome is odd. Do you trail ride a lot?
jeffro503
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St Helens, OR US
3/4/2016 8:06pm
I'll say around 60+hrs at 40:1. Not sure on the oil though.

Josh....you've obviously been riding the snot out of her. Do you plan on sticking with the YZ250? I still have my 06' RM250 , but am planning on picking up a new 16' YZ 250 sometime this summer. Was going to sell the RM , but I'll wait until after I get the YZ , fall in love with it , then part ways with my RM if I feel good about doing so.
motokiwi
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2t4L, AL US
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3/4/2016 8:09pm Edited Date/Time 3/4/2016 8:16pm
31 hrs Lucas oil at 44:1
BobPA
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PA US
3/4/2016 8:16pm
50 hours

Something with a bit of castor? Maybe 927

40:1

Looks like a lot of trail riding...and possibly a bit on the lean side...but it is really tough to go off piston wash in that pic.
JM485
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3/4/2016 8:26pm
Carbon pattern on cylinder head dome is odd. Do you trail ride a lot?
Yes sir, bike gets used for pretty much everything under the sun. Moto, hillclimbs, trails, and even an endurocross. I figured the burn pattern was good, since the carbon was on the exhaust side. As far as I understand, fresh mixture should be directed toward the intake side of the cylinder in order to keep it from shooting directly out the exhaust port, and since the intake side is clean I figured that was a good indicator of that happening. Last ride before tear down was a mix of trails and hillclimbs.

I have to say I'm very impressed with some of the answers so far, I'm learning a lot and you guys definately know your stuff.
Big Lenny
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Compton, CA US
3/4/2016 8:27pm
Pool-eh wrote:
People still run AV gas? Isn't that bad or am I just remembering an old wives tale
lostboy819 wrote:
AVE gas is for airplanes and not ideal for mx as it has some unneeded additives for high altitude and temp variance but I know people...
AVE gas is for airplanes and not ideal for mx as it has some unneeded additives for high altitude and temp variance but I know people who have always run it and never had a problem, still better than pump gas with ethanol.
This is true, I think you can get by using it but only for short I have known people that screwed up their bikes using it....
JM485
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3/4/2016 8:32pm
jeffro503 wrote:
I'll say around 60+hrs at 40:1. Not sure on the oil though. Josh....you've obviously been riding the snot out of her. Do you plan on sticking...
I'll say around 60+hrs at 40:1. Not sure on the oil though.

Josh....you've obviously been riding the snot out of her. Do you plan on sticking with the YZ250? I still have my 06' RM250 , but am planning on picking up a new 16' YZ 250 sometime this summer. Was going to sell the RM , but I'll wait until after I get the YZ , fall in love with it , then part ways with my RM if I feel good about doing so.
Jeff, I'm definately planning to stick with the yz for a long time! I feel like it rides very similarly to the rm, and I like that I don't have to worry about rust with the aluminum frame. I don't think you'll find a better replacement for the rm, I never thought I would consider selling mine but now I'm thinking about it. If it weren't for the sentimental value it would be gone, the yz does everything the rm did for me and then some. If you can keep both bikes I wouldn't rule that option out though, I still love those rm's, especially our rc editions since I was a huge rc fan as a kid (still am), but when you pull the trigger on the yz I'm sure you will love it, they're great bikes!

When you pick that thing up, grab "that Oregon guy and his new Canadian wife" and make the trip down, we'll put it through its paces!Wink
BobPA
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3/4/2016 8:38pm
Pool-eh wrote:
People still run AV gas? Isn't that bad or am I just remembering an old wives tale
lostboy819 wrote:
AVE gas is for airplanes and not ideal for mx as it has some unneeded additives for high altitude and temp variance but I know people...
AVE gas is for airplanes and not ideal for mx as it has some unneeded additives for high altitude and temp variance but I know people who have always run it and never had a problem, still better than pump gas with ethanol.
Big Lenny wrote:
This is true, I think you can get by using it but only for short I have known people that screwed up their bikes using it....
Screwed up how? AV gas is fine for two strokes, you just need to spend some time and jet it accordingly....just like any other fuel. Not only is it relatively cheap, but it is also incredibly consistent. I, along with a few of my friends, have hundreds of hours on our stand up jet ski burning AV gas, with zero issues. Jet ski engines do not live an easy life mind you.

I ran 100LL in 125's for years with great results, my current rig runs fine on 93...so there is no reason to waste the $.

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