Suzuki Quadracer HQ
LT250R Quadracer => LT250R - Engine => Topic started by: Chrisr on June 22, 2013, 01:16:06 pm
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I finally got the chance to pull this motor today. Gonna build a stand for it then do a leak down test. Also need to replace the bent shifter shaft. I ran it this morning, same thing smoking like hell and idled high. Bump the throttle and it smokes worse. The exhaust didn't smell like Maxima like it normally does so I'm still thinking crank seal. When I pulled the pipe fuel and oil poured out. Oh........I shipped my other motor up to Carl today also.
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Soooooo....if burning oil is considered part of the fuel's combustible mix, what is the stoichiometric ratio of 927?
I think I remember seeing the heating value of pure castor oil is somewhere around 18,000 BTUs per pound.
Gasoline's heating value is around 17,000 to 20,000 BTUs per pound. Methanol is around 9,000 BTUs per pound and ethanol is somewhere around 12,000 BTUs per pound. I think that most petroleum based oils and greases are in the 15,000 to 23,000 BTUs per pound.
The ratios of the heating values of a substance is usually directly related to the stoichiometric combustion ratio.
The theme of the above post was to point out that: You would not need to change more than a couple of jet sizes to produce the same A/F ratio going from straight gasoline to 20:1 premix.
The above theory seems to agree with my years of experience tuning engines on the dyno. I have observed very little difference in jetting for max power as I change from one premix ratio to another.
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Soooooo....if burning oil is considered part of the fuel's combustible mix, what is the stoichiometric ratio of 927?
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You just want a little bit of lubrication on the seal lip so it doesn't fold and pop the spring out when you slide the crank into it. I usually use what ever oil is to be run in it on the bearings for assembly lube.
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I'm interested on the locktite & grease thing
I read the manual after I installed the crank seals last time and realized they do recommend using thread locker on outside lip that seats in to the cases.
But on the grease, do you put grease on the inside lip that rides on the crank or do you pack the actual entire internal surface that faces the crack bearings?
Thanks
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if it only smokes alot on start up thats fine, how does it smoke after you been riding. did you rock quad before you started it to mix up fuel, it could have just been a lean start up if gas was not mixed well.
If you are using the right oil and fuel it does not need shaking before you ride. If you need to shake it before you ride it will be impossible to keep you bike jetted as the day goes on. If you need to shake it before you ride your lubrication will also be inconsistent as you ride.
Most two strokes smoke less after they are warmed up because more of the oil burns when the engine is hot. Remember oil is also a fuel but it takes more heat to ignite it.
Too many guys over compensate when trying to jet their carbs for different fuel/oil ratios. A 20:1 fuel/oil ratio is 5 % oil. This means that if the oil in the premix DID NOT BURN you would need to richen your main jet 5% going from straight gasoline to a 20:1 premix ratio. 1 main jet size is about 3%.
To summarize: Changing from a 40:1 ratio to a 20:1 ratio is 2.5% or about 1 main jet if none of the oil burned. The majority of the oil DOES burn when the engine is up to temp and you are riding it hard so there is little change that needs to be made to the main jet when you are changing oil ratios.
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if it only smokes alot on start up thats fine, how does it smoke after you been riding. did you rock quad before you started it to mix up fuel, it could have just been a lean start up if gas was not mixed well.
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I usually use Ultra Grey on the outside of all seals and a little grease on the inside.
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haha.......That damn picture kills me every time I see it. Anyways, I'm wandering if water in the gas may be my problem. The gas is about a month in a half old and I've had rain measured in feet around here the past month not to mention I live on a pond in the woods so moisture is abound.
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The longer you look at it, the funnier it gets.
So true!!!
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The longer you look at it, the funnier it gets.
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Cliff!!!! Why do you have Mitches baby picture?
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you know what i ment dick face
(http://i231.photobucket.com/albums/ee8/west_texas_king/1261379314134.png)
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2 strokes are self lubricating
No they're not, you have to put oil into the fuel.
Omit that step and see how long it self-lubricates :p
Self lubricating with the proper fuel :P
i miss that quote pyramid we worked so hard on...
Quote pyramid initiated!
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i locktite the outside of the seals. just gives a little extra something to keep them in
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Whats this about blue locate on outside of seal ? I'm about to put my bottom end back together sooo. :o
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you know what i ment dick face
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2 strokes are self lubricating
No they're not, you have to put oil into the fuel.
Omit that step and see how long it self-lubricates :p
Self lubricating with the proper fuel :P
i miss that quote pyramid we worked so hard on...
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2 strokes are self lubricating
No they're not, you have to put oil into the fuel.
Omit that step and see how long it self-lubricates :p
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i grease my seals on the crank. You do NOT want oil to transfer between the seals. 2 strokes are self lubricating. If oil passes through the seal. Than air can. Do a leak down test.
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Hmm, maybe an air leak in the carb boot?
Always try the easiest thing first...
That is a high possibility, I looked it over real good and when flexed you can see some slight cracking where the boot flattens out towards the bolts. Can't tell how bad it is without pulling it off but I ordered a new boot and gasket online from East Coast Honda today to replace it.
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Hmm, maybe an air leak in the carb boot?
Always try the easiest thing first...
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I haven't changed anything with the carb jetting since I rode it last. It idled and ran good and sure didn't bellow smoke like it does now. The only difference between when it was last rode and now is I replaced a stripped exhaust stud and reoiled the air filter.
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Are you sure the revving is because of an air leak, or do you think it might be improper carb jetting?
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I wouldnt, you need oil to go threw the bearings
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Fired up the 250 for the first time in a little over a week today. When it busted off it revved up on it's own...........then the smoke started. Guess I'm replacing crank seals tomorrow. I know about using blue Loctite on the outside of the seal but does anyone pack the inside of the seal with grease? Been doing it on pumps and gearboxes for years but wasn't sure about a 2 stroke motor.