Oil Pump or Premix = Good Cop || Bad Cop

[Milan]

Some previous threads on the above subject intermixed with other subjects.

So want to get the consensus from what everyone is doing, & why.

Pros & Cons of each.

I have my idea, which I will state a little later, after some comments.

Oil Pump:
adjustments
how do you know the ratio

Premix:
what ratio
out riding & need gas.

M

[m in sc]

one rd i have no place for it, water pump is there.

another: weight savings and simplicity.

otherwise, i always run them.  both r5s are on them as is the t500, etc.

[Arrow]

The maximum output for the oil pump is 5.1~5.7cc for 200 strokes. This is for both lines together, and at maximum stroke.

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[soonerbillz]

On one of the FB groups.. this question always starts long drawn out cat fights
But it is a good question.  :cheesy:
Ill say I run the pump in my enduros, always reliable. My old Suzuki 185 had one and it never failed either.

What I want to know is how hard it really is to rebuild a pump.. having never done so.

[Arrow]

Rebuilding a pump is quite easy, but;

It must be disassembled and assembled correctly with the correct parts.

The check valves need to be checked for correct operation while the casting is still bare.

You must know if what you are putting back together is fit for purpose.

Will need a reshim after building, ie not just the shims that were on it before.

Examples are; One guy rebuilt his motor and the pump, then rebuilt the motor again and I rebuilt the pump.

A motor blew up on the dyno, Due to incorrect seals.

Wrong pump on the bike is common. The photo below is left over gears JUST from the wrong pump on the bike.



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[Milan]

So we are now getting into the some of the Cons for the oil pump.

If its working it has to be adjusted and checked after certain periods
After adjustment, how do you know if you are getting the proper CC's of oil, unless its checked
Rebuilding must be done meticulously otherwise you get what Arrow posted.

Not everyone, including me, know how to do that

[Arrow]

The output check that I posted about is something that you won't need to do very often at all.

The checking of the minimum stroke is something you should be doing every 2000 miles, adjustment of that is not always necessary, its basically just a check of the gap. This is virtually all the maintenance required for the pump.
The main 10mm bore (the heart of a good pump) is capable of moon miles.

The cams can wear out if spec. and there can be wear on mostly the external areas, but the flow check will show if this is the case, that's what it's for checking every combination of wear.

I've seen pumps as early as 1967 still well in spec. I've thrown away pumps from 1995 where every part is scrap.

The correct minimum stroke which is a very easy check, controls the amount of oil that comes out of the pump all the way through the rev range.

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[m in sc]

the only con to a pump, IMHO, is caused by how it was (mis) treated and (not) maintained. Just like anything mechanical. 

[Milan]

So how about some Premix folks to discuss.

Mix ratio is always exact to the spec you mixed it at.
No wear & tear as in the pump.

how about getting more fluid in the case, an ounce + more due to the gear volume that is not there anymore.


How do you adjust the ratio with the pump = the shims.
What if you want to run heavy or lighter on the oil, as the oil these days is better then back then.

[m in sc]

I have 4 bikes on premix.. I run 3oz to a galllon. no need to change ratio if the bikes tuned for it. 

[Arrow]

So how about some Premix folks to discuss.

Mix ratio is always exact to the spec you mixed it at.
No wear & tear as in the pump.

how about getting more fluid in the case, an ounce + more due to the gear volume that is not there anymore.


How do you adjust the ratio with the pump = the shims.
What if you want to run heavy or lighter on the oil, as the oil these days is better then back then.

I would never adjust a pump less than standard. 2 strokes don't last as long as 4 strokes so less oil is not good.

I had a guy call me recently, 5 years or so after I built a pump for him. He said its been faultless, "but it smokes just a tad less than it did 5 years ago".
What milage has it done since the job, I asked? 15000 (miles)
I said when did you last check the minimum stroke, he said never!

It should have been checked 7 times in that milage.

I mention this in my advice doc.
There is only so much you can do to help people and keep these bikes running well.

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[Milan]

m in sc
3 oz per gallon
So 42.7 to 1 ratio.

I was hesitant to 36 to 1

So my pump is out right now. from PO
In discussions with Arrow about sending mine to him, and also finding a replacement one.

I was drinking beers this past weekend, and was thinking about just staying with the premix.

[m in sc]

modern oil its fine. back in the old days i was a firm believer in 4 oz to a gallon but not nec, and i -thrash on- my motors. 3 oz gallon is fine. 3.5 if i thrown in some castor for smell. 

[85RZwade]

My RZ has over 37K miles on the original pump; the LC I'm building will most likely be premix, as I don't anticipate it being a long-range tourer. I keep my fuel life simple by buying good quality two-stroke oil and mixing 40:1, and filling everything from that same can. Chain saws, line trimmers, blowers, my KTM and even the lawnmower when I feel like smelling some oil in the air.

[Milan]

" Long Range Tourer "

Whats your definition of that, & why not.


Yes I like the idea of 1 mix for all equipment.