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Oil pump and oil question

08 Feb 2020 20:33
Lkeener54
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Oil pump and oil question #1
So i need to test my oil pump. Do i premix so i can un hook pump to see if its pumping? If so what premix. Yamaha 90 HT 1. 1970.

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09 Feb 2020 00:26 09 Feb 2020 23:55 by RT325.
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Oil pump and oil question #2
Yep, just mix about 30mls of oil per liter of fuel. Then undo the oil union at the cylinder & lightly screw a 'short' 6mm screw in the cylinder hole just to stop it sucking heaps of air which will make it idle too fast. Then let the oil union pump into something with mls [cc's] measured on the side. Have the pipe uphill as much as you can so you see a true pumping pulse. Then of course the engine speed & how far around the cable roller is turned all varies the flow. So now i'm lost as never had to do it on mine. Luckily my HT1 pipe actually broke as had got old & brittle but i caught it before damage & saw it pumping out. Someone will be along to advise how much they should pump in a certain time. At minimum stroke the movement should be about 20 thou or a bit less. But full stroke is many times that. Main thing is not to have zero stroke at idle, & have a free moving cable & cable roller so it moves & returns in time with the throttle. Fuel premix chart below to confuse lol [confused me]. I work in Mls per liter.
www.getraceday.com/2-stroke-fuel-oil-mixture-chart/
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09 Feb 2020 06:36
MarkT
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Oil pump and oil question #3
No real reason to run the engine on an early model... you can test output by rotating primer wheel and measuring output per specs... If you run engine, you should still measure output at idle and full throttle or you won't know if pump is putting out right amount.

Rare to have it not installed right or a stripped internal geat but you can verify pump is driven by watching it cycle with engine running...

Easiest method is take pump off and send it to DEET for a rebuild.

1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
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09 Feb 2020 13:36 10 Feb 2020 00:00 by RT325.
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Oil pump and oil question #4
deleted this post as only confusing the issue, but that didn't work as still below. Just refer to what Mark says.
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09 Feb 2020 15:17
MarkT
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Oil pump and oil question #5

RT325 wrote: By full throttle do you mean full oil pump cable roller movement giving full pump stroke but motor at a certain fast idle revs?, not revving the tripe out of it [sorry mark], like--just pull the pump cable at the adjuster. Get a sore finger rotating the plastic serrated wheel for a time,--i think.


Stuff like this has been repeated so many times over and over I don't always re-write all the details. And I'm not going to now. :)

Test 1 is check that the output is in spec with "idle" marks on pump pulley aligned. Certain number of cc per 200 strokes

Test 2 is rotate cam to max... pull cable or rotate throttle grip... doesn't matter, engine isn't running... Just need to make sure pin is at max lift on cam ramp (makes sense when looking at pump) Measure for correct cc's per 200 strokes for max output.

Manuals and specs and bulletins about testing pump are available in the Tech Library.

I use a little dremel rubber sanding drum without sandpaper on a drill... a stud in the drill with a short piece of rubber fuel line pressed on tightly works too... pressed against edge it spins primer wheel very well. Remember the primer wheel only spins one way so pay attention to the arrow on wheel.

Alternative is to run engine on premix and let engine spin the pump. This is a must on bikes after about 1976 when Yamaha started phasing out the primer wheel. Actual output should be tested using either method. And of course if using engine on premix, better to pull pump cable to max than holding WOT with no load.

1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250

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09 Feb 2020 22:41
RT325
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Oil pump and oil question #6
Out in the shed & thought 'bugger', i know what MarkT meant-- i'll go delete my post before he sees it lol--too late. Of course you meant revolve the plastic wheel with pump cable pulled or throttle open [not running]. Not rev the motor. Too hot here & not thinking straight [or getting senile more like].

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20 Feb 2020 16:57 20 Feb 2020 19:39 by Lkeener54.
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Oil pump and oil question #7
Need to ask Deet a question about the oil pump i sent.

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