CRF 250 using oil

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#1
Does any one elses CRF250 use oil. I fill it to the top mark on the dip stick and it goes down. After 1 moto it was halfway down so I left it to see if it just doesnt like to be filled to the top mark. but after the 2nd moto it's down to the bottom mark. It smokes when its cold but I dont notice it after it's warmed up.
 

High Lord Gomer

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#2
It has a dipstick?

The CRF450s I've messed with "appear" to have a high oil level (on the engine side) for a while after you shut them off. It has to do with the oil being pushed out of the crank well by pressure through a one-way valve. It takles a while for the level in the crank well and the flywheel area to equalize.

Both my 03 and my son's 04 used oil when new and even smoke a little when first started cold.
 
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#3
Hi Gomer, yes the 250 has a dip stick , unlike the 450. I feel better now that I heard yours used a little oil and smoked when cold. I also have a new yz250 and it does'nt smoke , even cold and has'nt used any oil. I'm thinkin about running it on the low side of the stick to see if it's just using oil cause it thinks it's over full. If an engine was over full that would cause it to smoke would'nt it? The problem is that it only holds 3/4 of a quart so there's not much flexibility there
 
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#4
The tech at the dealer where i bought mine instructed me to watch the oil level closely the first few hours. Said something like "honda told us to tell customers to watch it because it will consume a lot during break in"

btw, What oil are you guys running?? synthetic??
 

Rich Rohrich

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#5
Most four-stroke engines are designed with a piston that carries two compression rings and an oil ring package (two thin rings seperated by a spacer) . The second compression ring on these pistons really serves more as an oil scraper than a compression ring. This second rind scrapes oil off the cylinder wall which helps prevent it from slipping by the top compression ring and burning in the combustion chamber. It's a common trend for ultra high speed engines to use only a single compression ring and the oil ring package in an effort to reduce friction losses and to allow the piston to be as short and light as possible to permit the high speeds these engines can safely run at. The CRF engine is designed with this current engineering thinking and only uses a single compression ring. When the engine is cold it is difficult for the single compression ring to stop all the oil. This situation is at it's worst when the engine is new, but it will always do it to some degree even when the engine is broken in. Single compression ring four-strokes always tend to use more oil then their dual ring competitors. Using a little bit of oil in exchange for performance is a good trade off in the long run for most of us.
 
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#6
Rich, that makes sense and it helps me to not worry about it but my son and I also have a new YZ250f and it never smokes, hot or cold. Ive been using honda 10w40 and yamaha 20w40 mineral but will switch to synthetic or semi soon. The Honda has about 7 hrs. and the Yamaha maybe 5 hrs on it. The dealer told me it was better to break it in with mineral oil
 

Rich Rohrich

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#7
The Yamaha uses the conventional two compression ring design. All my YZF engines smoke a lot less than my CRF450. No getting around it. :)

There is some logic to breaking the engine in with mineral based oils. I always recommend that with a new engine for the first hour or so, in most cases beyond those first few hours it's OK to switch to synthetic if you want.
 
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#8
Thanx Rich , you sound like you are pretty familiar with these engines. I'm going synthetic on the next oil change. I change the oil every race week . What is your opinion on using Valvoline or Castrol 10w40 or 20w 50 synthetic from the auto parts store. It's alot cheaper, the oil is in there such a short time and the book just says not to use the "energy conserving" oil 5w30or10w30. Also what do you think about the 15w40 oils commonly used in diesels?
 
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#9
I hav been running on 10-40 oil on both my crf450 and they have worked just fine. my old 02 crf used a bit of oil but nothing alarming.
 

Rich Rohrich

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#10
Originally posted by CRSpeedy
Thanx Rich , you sound like you are pretty familiar with these engines. I'm going synthetic on the next oil change. I change the oil every race week . What is your opinion on using Valvoline or Castrol 10w40 or 20w 50 synthetic from the auto parts store.
I've never used Castrol or Valvoline synthetic so I can't be of any real help.


Originally posted by CRSpeedy

Also what do you think about the 15w40 oils commonly used in diesels?
I've used Mobil Delvac 1 synthetic diesel oil with great results in a number engines.

Here's a link with some additional info on the subject. http://www.ericgorr.com/techarticles/mototech_june_1999.htm
 
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#11
Thats cool, I was a bit concerned about the smoke at start-up...but mine isn't even fully broke in yet. Dang snow lol
 
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#12
I have about 15 hours (havent rode in 15 years....slow) on my 04 CRF 450. It smokes on start up but thats about it. It gets less and less every time. I think I will probably stick with convetional oil due to the fact I change it just about every ride.
 

Rich Rohrich

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#15
MX955 said:
I have a 2004 CRF250 with 14.6 hours on it,(there is a hour meter on it)and mine seems to be going through about 1/4 of a quart every 3 hours.Does this seem excessive.
Nope, that's about right. Depending on the oil and the number of hours on the engine it will tend to be in the neighborhood of about 1ounce per hour on the CRF450s. So far the feedback I have gotten is the 250s use a simialr amount once they are broken in.
 
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