Change the oil input from manifold to gas line

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Change the oil input from manifold to gas line

N G /

Sep 12, 2008 11:18AM

Question:

Has anyone tried putting the oil from the oil injection pump into a "t" in the gas line before the carb, instead of using the nipple on the intake port? Would probably need to jet up one size but it would give you a better oil distribution.

I've seen this on other 2-stoke motors. I'm getting ready to change the intake manifold on my bike to a larger one that doesn't provide an input for the oil. I can put in a new oil port on the manifold, but t-ing into the fuel line would be easier.

Thanks!

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Re: Change the oil input from manifold to gas line

Responsible Jon /

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philip

Sep 12, 2008 12:37PM

That won't work well. The oil mix is metered for distribution with the fuel after it is in vapor form, not for sitting the fuel line. It will be just as easy to tap a hole into your intake and fit it with a little nipple available at any hardware store! Good luck!

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Re: Change the oil input from manifold to gas line

Silverfox Sullivan /

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silverfox

Sep 12, 2008 01:51PM

Not to argue with splatman, but I see no problem with doing what you want to do. As the oil mixes with the fuel in the line, and then in the float bowl, and then in the main jet it will be sufficiently disbursed.

No different really than pre-mixing.

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Re: Change the oil input from manifold to gas line

Responsible Jon /

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philip

Sep 12, 2008 02:07PM

Silverfox, I'm not entirely sure my idea is right, but let me see if I can work it out some more.

The oil injector puts the oil into the intake manifold after the atomization of the fuel, which is then blasted and sucked along by the incoming charge, and becomes distributed into the mixture. It seems like if it were just going to drip into the fuel line, that it would not be violent enough to mix it very well, even though things vibrate like crazy on a moped. I don't imagine the mix would be correct if it was pushing oil into the fuel line.

Someone school me, please!

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Re: Change the oil input from manifold to gas line

N G /

noiseguy

Sep 12, 2008 05:13PM

To add fuel to the discussion, we've seen 2-stroke outboard motors with this arrangement. I'm just not sure why it wasn't done on this bike.

I don't think it's a matter of dispersion; the air crossing the intake will disperse the oil, as will the gradual mix with the fuel at the line level. I'm more concerned with gas backflowing up the oil line, but I don't think it will be a big issue.

I do think you'll need to upjet, as the oil+fuel mix will be leaner, with less octane per volume of fuel.

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Re: Change the oil input from manifold to gas line

bk /

bkurbexpress

Sep 12, 2008 05:22PM

I was planning to do this to one of my hondas that has an oil pump with a oil inlet into the carb after changing the carb out for a better one that has no inlet. I think it would work fine.

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Re: Change the oil input from manifold to gas line

bzenk /

bzenk

Sep 12, 2008 05:33PM

I have taken apart three Honda Express bikes and the

early Express bikes had an oil inlet at the base of the manifold. I also noticed the mufflers on the early bikes were full of oil and that they ran colder plugs than the BP4HS.

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