Oil Pump Graph.

[arrow]

Hi Guy’s, as part of the oil pump service I offer, I ask all my customers if they want a standard setup on the shims or a set up for a little more oil. As I have done all the research, this might be a bit confusing to some people who just run their bikes and don’t worry too much about the finer details. I have produced a graph to help explain what all this means. The vertical axis is the ratio of fuel to oil. The horizontal axis is the throttle position.

The red line is the standard 10 thou setup and you can see the ratio of fuel /oil starts off at around 90:1. This reaches 20:1 at around the ¾ throttle position after going through various values according to throttle position. It stays at approx 20:1 right up to full bore.

The green line is the setup with the minimum stroke set to 12 thou. Here you can see the ratio starts off at 75:1 and also has various values along to the ¾ throttle position. Oiling is increased between tick over and the ¾ position.

The blue line is where I run my bike, with the stroke set to 14 thou. You will see from the graph that the ratio starts off at 64:1 and follows the same curve as the other two values, although oiling between tick over and the 3/4 throttle position is increased still further.

As many people run pre-mix at 30:1 or so, I see no reason why the bikes should run 90:1 at any time. The pumps were set up back in the day to keep up with ever stricter legislation and poor quality oils compared with what we have today, (smoke issue). Indeed the early A/B air cooled models oiled much more than the later E/F models. There is not an issue after 3/4 throttle as 20:1 is plenty of oil even for a tuned engine. The LC’s will be much the same.
HTH,
Arrow.

[Delbert]

Very interestng , thanks for sharing

[jon]

I read for a while that you obviously know RD oil pumps.

I have a question regarding RD250LC and RD350LC oil pumps.

Obviously they are different, but can they be setup to perform the same?

I was just about to get a 350 pump as I have upgraded my 250 with 350 head/barrels, and it seems a shame to throw away the 250 pump.

[butchers]

Apr 21, 2013 19:09:04 GMT 1 jon said:

I read for a while that you obviously know RD oil pumps.

I have a question regarding RD250LC and RD350LC oil pumps.

Obviously they are different, but can they be setup to perform the same?

I was just about to get a 350 pump as I have upgraded my 250 with 350 head/barrels, and it seems a shame to throw away the 250 pump.

350 has a different drive wheel but i'm sure Gaz will tel you exactly the difference

[arrow]

Apr 21, 2013 19:09:04 GMT 1 jon said:

I read for a while that you obviously know RD oil pumps.

I have a question regarding RD250LC and RD350LC oil pumps.

Obviously they are different, but can they be setup to perform the same?

I was just about to get a 350 pump as I have upgraded my 250 with 350 head/barrels, and it seems a shame to throw away the 250 pump.

The only thing that is different is the internal gear and then the paint mark. I have a spare internal gear here for a 350 which I can swap over for you. And you will also need a 350 worm which I have. PM me for details.

[gringo]

Guys, you probably know this but if you don't, Arrow is the man to talk to if you need advice or your pump refurbed or repaired, very knowledgable guy who offers a first class service.

[Taylormade]

Blimey arrow! so if I've got this right, in standard set up its actually very lean for the first quarter throttle??

These figures always mess with my head?!?, I just work off the principle of my petrol strimmers at home, put it this way I ran them at 50:1 (manufactures recommendation).... It seized!!!! Brought another only to be told "ignore the recommendations" run at 25:1 !! Double the amount, so
That's 40ml of oil for every Litre of fuel, bit oily but runs well....!
I've digressed from LCs but I think I've got it right??
So what happens when you fit expansion chambers, if you increase the fuel by rejetting surely you increase the out put from your pump to compensate? But by how much??

[arrow]

Hi, Taylormade, Yes you got it right, very lean for the first quarter throttle. Yamaha were proud to announce that the auto lube system used a third less oil than a pre-mix system, (don’t know why that’s good news) The issue of re-jetting and increasing oil has been brought up on a few forums. I am now of the opinion that a standard set up is ok given that most pumps I see are running a zero stroke (which is zero oil up to 1/4 throttle) due to not being looked at in 30+ years. Only the occasional one is as it should be. It should be noted that once the pump is bedded in and re-shimmed it will not need to be touched for around three years, and even then it may still be in spec.
As stated I run my pump with a 14 thou gap and two years after a full re-build the engine is still really sweet.

[Taylormade]

Thanks Arrow, that's quite worrying really
I purchased my 350LC last November and am enjoying this first season, bike is using oil well and runs sweet! However I think this winter will see me remove the pump and send to you for an overhaul! I will PM you nearer the time! as I want to enjoy whatever weather we get over the next couple of months I'm of the opinion "if it ain't broke don't try n fix it" so don't want to take it off the road right now. I did remove the cover with the engine running to se if anything was happening and could see the pulley sort of moving in and out as it was running so assumed a small amount of movement was good in the fact I could see it working! Cable and pulley was also set correct with throttle response so Hope mine lasts till winter

[arrow]

Sounds like its working ok, happy days.

[Taylormade]

Thanks for the chat arrow, will be in touch later in the year.......

[arrow]

[m1ke]

Can we sticky this?

[m1ke]

Wheres the sticky.....

[m1ke]

Also just a confirmation here arrow, your talking about 10 thou being standard, whereas the haynes manual and the yamaha spec book I have say 0.10mm is the standard setup.....

Which is right?

[arrow]

Oh dear, I've been waiting for someone to ask that one! That question has a very long answer. But briefly;
10 thou is the top of the standard setting for virtually all of the bikes that use this type of pump. There are 2 types of 1m1 pulley and 2 types of 4L1 pulley. The 4L1 pulley in the Haynes manual (Lc manual) will oil less than the other "3" mark 4L1 pulley which does not explain the 0.1mm spec. The later 1m1 pulley top mark is equivalent to the final mark on a 4L1 3 mark pulley. The 0.1mm (4 thou) gap would give a starting fuel oil ratio of, wait for it..........235:1 (is there anyone at all out there happy to run there bike on that at any time at all?) The reasons for the 0.1 mm gap are not in the best interest of the engine. Also this gap can very easily reduce to zero in quite a short time giving no oil at all until the throttle is opened. If anyone wants the 0.1mm gap I will send the pump back unshimmed so the owner can shim the pump. Indeed I would not shim a pump to 0.1mm even with Yamaha's chief engineer stood over me.
That's the quick answer!

Edit; MOST people that have the pump service have the gap set to 12 thou. I can't tell you how many there are but its a LOT. I am yet to receive one complaint, if I do, I will sort it, I've basically re written the text books.
Arrow.

[m1ke]

Thanks for clarifying that, just like to clarify when I see a big difference.

I set my pump to 12 thou anyway and dont have any complaints.

[Roofmonster]

My pump is set to 12 thou (by Arrow of course) and it doesn't smoke excessively on tickover or foul the plugs. I suppose the only thing it may be doing is using a tiny fraction more oil (not that I have noticed any difference though) but, with the mileage I do , I figure 2 stroke oil is much cheaper than a rebuild any day.

[nikfubar]

I set mine to 0.3mm (12 thou) after my melt down & also set the pump to the 3rd mark on the wheel as the engine has a fast road tune & the bike was spitting black shit out the back of the pipes. So I backed off the wheel to the middle notch as the manual says & now it's all good

[arrow]

Some people have been asking about the uprated pump and how this would affect the graph. With a standard bike running the uprated pump (not that its for the standard bike) the final 20:1 value would become 17.6:1
On the big bore long stroke motor burning more fuel the value would be about the same as standard, ie 20:1
The uprated pump can also be shimmed to alter the 0~3/4 throttle setting, same as the standard pump can be shimmed.
HTH.

[lb]

What the recommended shim size for 250 pumps?

[arrow]

Sept 2, 2013 12:39:45 GMT 1 lb said:

What the recommended shim size for 250 pumps?

The shim size will vary from pump to pump but the recommended minimum stroke for the 250lc is 0.2~0.25mm or 8~10 thou.
The shim stack can be anything from say 25~40 thou to achieve this, or a single purpose made shim of the required thickness.

[arrow]

Please note, for anyone that's interested. Due to further developments, my up-rated pump is now rated to +18% as opposed to +12% as was the prototype.

On The graph this would make the 20:1 flat line go to 16.4:1 if used on a standard bike.

[marsbar350]

dont know how you do all this stuff gary
a lot of premix guys on the big bore motors should looking closely at this mod

[arrow]

It was good just to be able to develop the new pump. Its there for people if they need it.

[arrow]

Up-date. I made a discovery a while back which I will share with you now. The shims actually control the oiling right up to full bore. Let me explain.
The pulley on the 250/350 lc and ypvs (and other models) only has a 2.05mm difference in height from the idle to full bore position. The cams have an average depth of 2.2mm. If the shim gap is zero (some are less than zero ie negative) then the maximum stroke will only be 2.05mm. If the shims are set correctly to give a gap of 0.25mm (standard) then the maximum stroke will be 2.2mm (the shim gap allows the full depth of the cams to be used) with a clearance of 0.1mm between the large washer and the checking heel on the pulley at the full bore position.
HTH, Arrow.

[arrow]

Bump to help forum member.

[kostas]

Mar 3, 2014 1:30:13 GMT 1 arrow said:

Up-date. I made a discovery a while back which I will share with you now. The shims actually control the oiling right up to full bore. Let me explain.
The pulley on the 250/350 lc and ypvs (and other models) only has a 2.05mm difference in height from the idle to full bore position. The cams have an average depth of 2.2mm. If the shim gap is zero (some are less than zero ie negative) then the maximum stroke will only be 2.05mm. If the shims are set correctly to give a gap of 0.25mm (standard) then the maximum stroke will be 2.2mm (the shim gap allows the full depth of the cams to be used) with a clearance of 0.1mm between the large washer and the checking heel on the pulley at the full bore position.
HTH, Arrow.

So according to the above the lines on the graph should run parallel to each other??
Did I get this right?

Kostas

[arrow]

Jan 7, 2015 18:58:26 GMT 1 kostas said:

Mar 3, 2014 1:30:13 GMT 1 arrow said:

Up-date. I made a discovery a while back which I will share with you now. The shims actually control the oiling right up to full bore. Let me explain.
The pulley on the 250/350 lc and ypvs (and other models) only has a 2.05mm difference in height from the idle to full bore position. The cams have an average depth of 2.2mm. If the shim gap is zero (some are less than zero ie negative) then the maximum stroke will only be 2.05mm. If the shims are set correctly to give a gap of 0.25mm (standard) then the maximum stroke will be 2.2mm (the shim gap allows the full depth of the cams to be used) with a clearance of 0.1mm between the large washer and the checking heel on the pulley at the full bore position.
HTH, Arrow.

So according to the above the lines on the graph should run parallel to each other??
Did I get this right?

Kostas

Hi Kostas, no matey. It simply means that if the shim gap is less than standard then the final 20:1 value will not be reached. The lines will never run parallel as this represents the fact that the shims have proportionately less effect on the stroke as the throttle becomes fully open.

[earthman]

May 19, 2013 9:35:25 GMT 1 m1ke said:

Can we sticky this?

And get bloody PB to bring the actual graph back.