Running premix gas

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oncewaslost1982
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Running premix gas

Post by oncewaslost1982 »

I have an 80 express II that I run premix in and have bypassed the oil tank. Can anyone tell me if this is safe to do with my spree? What mix should I run? 40:1? What do i need to do to bypass the oil injection system? Thanks for any help.
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Post by nate_lohs »

i would also like to know. ive got a spree with a leaky oil pump and id like to just run premix. would it be best to premix to the stock jet or jet to a premix ratio?
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oncewaslost1982
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Post by oncewaslost1982 »

I am thinking that the piston and cylinder would be just fine with running a premix fuel in the tank. It is still going to get the proper lubrication right? I would just feel better running premix because then I would know that the engine was getting the oil it needs and not have to worry about how well the oil pump mixer or whatever mixes the oil and fuel is working. Correct me if I am wrong.....
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Post by nate_lohs »

yea thats right. im running premix in my elite. what you have to do is either plug the hole for the pump. or ive also heard you can take the pump out and grind down the shaft so it doesnt spin. you have to make sure you jet according to your premix ratio. im running 50:1 in my elite. im just wondering if anyone knows what ratio would go with the stock spree jet.
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oncewaslost1982
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Post by oncewaslost1982 »

pardon my ignorance, but i have a couple more questions on this issue. Why could you not just run a 40 or 50 to one ratio with the carburetor all stock? what size jets come in the stock spree carburetor? also, why do you need to stop the oil pump form spinning? couldnt you just leave it alone and just run your premix formula through the gas tank as normal?
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noiseguy
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Post by noiseguy »

50:1 should be fine.

Adding oil means you're running slightly leaner (more oil = less gas.) Maybe a slight bump up from 65 -> 68, for example. Not really a big deal. Any other opinions on this? Plug chop is the ultimate test, really.

You have to plug the oiler hole. You also want to plug as much of the hole as possible; the removed volume from the crankcase (missing oiler shaft) actually lowers compression and performance. That's why guys grind off the teeth and put them back in.

I'm betting if you let it spin dry, it eventually seizes and messes up the crank... why take the chance?
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Premix Idea

Post by DingoPepper »

Here's a thought. Has anyone ever tried running premix and adding the premix to the oil tank as well? Just a thought. I don't trust the injector totally myself, but haven't done anything about it as of yet.

Seems like doing this would negate the need to disable the pump, but I don't know how well it would actually run with this setup.
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Re: Running premix gas

Post by Joemeyster3k »

Dingo pepper I like the way u think!!! Anyone have ideas on running premix in both tanks. Would the oil and fuel ratio viscosity be too thin to run properly and the Honda Spree oil pump reservoir? Heck of an idea tho!!!! Prob old post can't find an answer anywhere else!!!
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eclark5483
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Re: Premix Idea

Post by eclark5483 »

DingoPepper wrote:Here's a thought. Has anyone ever tried running premix and adding the premix to the oil tank as well? Just a thought. I don't trust the injector totally myself, but haven't done anything about it as of yet.

Seems like doing this would negate the need to disable the pump, but I don't know how well it would actually run with this setup.
This would be useful if using a BBK. If you run premix and the pump, you would want to run 96:1 in the tank.

The oil pump runs on a linear plane. It increases output the higher the engine revs. To figure out what ratio you are at, you have to know the high and low ratios that the pump is running at.

So for instance, let's say your pump is running at 70:1 at idle... if you put 96:1 in the tank, you add 70+96=166

You then take that number, and divide it by 2, twice.. so 166/2=83, then 83/2= 41.5:1 ratio on the low side... now...

Since the pump increases output linear, lets say at full throttle, the pump is producing 50:1. So you again do math 50+96=146

146/2=73, then 73/2=36.5:1

So what you get when you premix and run the pump, is 41.5:1 at idle, and 36.5:1 full throttle. While this is just fine for many engines and just fine for a BBK, the Spree likes a bit leaner mix to run proper.

Since you can't/don't want to run at 70:1, which is the pumps low end, and want to get close to 50:1, which would be it's highest ratio, you really don't want to run much richer on the oil in a premix then 50:1 if you take out the pump. Unless of course, you install a BBK. In which case, 40:1 is acceptable. Running more then 50:1 on a stock piston will make you run lean on the fuel.

Like noiseguy was saying, a bump from a #65 jet, to a #68 would probably be in order to compensate for the loss of fuel.

Remember, when you try making the carb do something it wasn't intended to do, like provide oil, then you are decreasing the amount of fuel it is able to pass through the venturi.

I know removing the pump sounds like it might be a better thing to do, but really... ever hear of a pump going bad?

If anything, just order a new O-ring for the pump since it's probably over 30 years old and you should be good.

The ring is Part Number: 91301-147-023 and can be found at most any Honda dealer and online store pretty cheap. I'd advise going to the local dealer to save yourself ridiculous shipping charges.
Here is one link to where you can find it:

http://honda.mymcparts.com/p/Honda_1986 ... 7-023.html

But anyway, alot of people attempt to change the dynamics of the Spree in the hopes of increasing performance. What they usually end up learning the hard way, or pass on to someone else to fix... is that the Spree runs best when you restore it back to it's stock setup with the correct plug, correct filter, correct oil pump, correct airbox, etc.

A good tune up using correct parts, should see you over 30 miles an hour even on a low geared Spree. Anything else, you're just asking to burn out that piston.
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Wheelman-111
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Re: Running premix gas

Post by Wheelman-111 »

Greetings:

I'm thinking DP is talking about putting FUEL with oil mixed into it in the oil tank, to prevent the pump from running dry and seizing. While it's a safe bet that running the pump completely dry will eventually cause it to seize, it's not proven that fuel, along with a bit of oil, will prevent that. I would think that if you're going to the trouble of pre-mixing, you might as well eliminate the tiny extra bit of drag produced at the pump shaft and save as much as possible of the three mighty horsepower for additional forward thrust.
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