2 Strokes Down Under

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. Graph is based on A/C models. The LC’s will be much the same.
HTH,
Arrow.

I think mine must be off the chart! Well lower actually.
Bike is still in many pieces but hope to have it on the road again soon. What would the time frame likely to be to have it set up properly by you arrow? I guess a week either way in travel time from Australia, best thing I supose is to get another pump and send it to you so then I can ride the bike again once it's up and running. Years ago had a rz 350k and it only needed oil filled every 1000k or so from memory. Now the price of quality oil is obcene or any oil for that matter. Local shop wants 30 bucks a Liter, after negotiation $25. Nice oil tho Motul 510

rz250rjapspec wrote:I think mine must be off the chart! Well lower actually.
Bike is still in many pieces but hope to have it on the road again soon. What would the time frame likely to be to have it set up properly by you arrow? I guess a week either way in travel time from Australia, best thing I supose is to get another pump and send it to you so then I can ride the bike again once it's up and running. Years ago had a rz 350k and it only needed oil filled every 1000k or so from memory. Now the price of quality oil is obcene or any oil for that matter. Local shop wants 30 bucks a Liter, after negotiation $25. Nice oil tho Motul 510

Dude, sending spare pumps creates a whole multitude of problems. I have sent back correct pumps before but the bike was not right for the pump as some twonk had fitted a complete side case and worm from another bike, years before and un be known to both parties! Thats the most difficult part about building the pumps, sorting out all the logistical details........... If the pump from the bike was sent to me I would have known right away that it was wrong as I ask the owner to state what bike it's for.

At this time I would need about 1 week before I send the pump back to you. Some times the post takes 5 days, other time two weeks, don't know why that is.

well, well, another mystery gets a bit less murky. Thanks Arrow, interesting read.

Great thread. Post is variable due to a number of factors, time of year, volume of traffic and also where in Aus you are. Post is a movable feast only truly understood only by those who work in it Im afraid :/

Or as Samuel L Jackson might say if he was restoring an LC : "post is a M&$@F#%ker!"
I kind of like the idea of Samuel L Jackson as an Elsie Boy come to think of it.

LOL

Bl@@dy oath !
Ordered a crank seal set and ended up giving up after nearly a month and let others get it in the end.

Eek.
no fun.

Where from? Cranks seals are something you really only want good ones of anyway, go Yamaha or better parts sellers, not (NOT!) Yamabits.

Ahh yes, have seen the yamybits seal failure not real encouraging stuff. I mean these bikes are such a can of worms, you never know what people have changed over the years.

rubber goods should only be purchased from specialist vendors.

Wheres Aaron, he will +1 that comment.... LOL

Aaron sounds like acsensible chap ;-)