R1Z is running

[James P]

Richard,

My TZR has a basically standard 2AW engine (standard air intake system with Jackal exhausts), standard gearing, standard tyre sizes etc. and usually manages to travel 20-25km per litre of fuel mixture (autolube system removed). That range is achieved with varied terrain and riding style over distances of about 150-250km...although I probably spend most of the time with the throttle in the quarter to half range.

If you are getting barely 12km for each litre (not including oil...!) then something still seems wrong. The colour of the spark plugs will likely only give you an idea of the running conditions at the engine speed and throttle opening which existed when you stopped the engine. It would be interesting to know whether you have any oily deposits at the silencer outlets...
You may like to try some 'plug chops' at different throttle positions (e.g. quarter, half, three-quarter and full) when the engine is pulling well, with medium load. The results may not be conclusive though - using an oxygen sensor in the stream of the exhaust gases may give a clearer result (again, check at the aforementioned throttle openings).

Regards,
James

[oldiggy]

Hi James 20km =12.4 miles for 1 litre = 56mpg. 25km = 15.5 miles for 1 litre 70 mpg are you running on one cylinder ? 😳

[James P]

Hi James 20km =12.4 miles for 1 litre = 56mpg. 25km = 15.5 miles for 1 litre 70 mpg are you running on one cylinder ? 😳

I won't argue with your conversions, but the figures I mentioned are (approximately) those that I have obtained. I don't religiously record distances travelled or quantities of fuel used, but have recorded them on some occasions. I did mention that most of my riding time is spent between quarter and half throttle - I doubt that I would achieve the same fuel economy if I rode everywhere at full throttle!

In my opinion, Richard should be getting more than 12km from a litre of fuel. I owned an RG500 for about seven years - it was completely standard and would get only 10km from a litre of fuel for varied riding . An R1-Z should fare significantly better...

Regards,
James

PS - I also once owned a Mazda RX2 with an extended bridgeport 13B engine. That only managed 5km for each litre of fuel, but its hardly a fair comparison in this situation!

[FZRichard]

James, yes I do have significant oily deposits on the silencer tips. I am using the autolube system still also.

I have thought about putting on some O2 sensors but read somewhere the oil in the exhaust stream causes them to fail.

[FZRichard]

If I were to run a couple of tanks of fuel without the autolube system, how do I do it. Which lines do I need to remove from the autolube pump?

How much oil per litre of fuel needs to be added to the fuel tank, also can I use the same size main and pilot jets?

I am running Castrol TTS.

[James P]

Hi James 20km =12.4 miles for 1 litre = 56mpg. 25km = 15.5 miles for 1 litre 70 mpg are you running on one cylinder ? 😳

I won't argue with your conversions, but the figures I mentioned are (approximately) those that I have obtained. I don't religiously record distances travelled or quantities of fuel used, but have recorded them on some occasions. I did mention that most of my riding time is spent between quarter and half throttle - I doubt that I would achieve the same fuel economy if I rode everywhere at full throttle!

In my opinion, Richard should be getting more than 12km from a litre of fuel. I owned an RG500 for about seven years - it was completely standard and would get only 10km from a litre of fuel for varied riding . An R1-Z should fare significantly better...

Regards,
James

PS - I also once owned a Mazda RX2 with an extended bridgeport 13B engine. That only managed 5km for each litre of fuel, but its hardly a fair comparison in this situation!

Well, in an attempt to put my money where my mouth is, I have failed ...and succeeded !

I went for a ride on the TZR yesterday and headed straight for the petrol pump. On arrival, the trip meter said 210km (nearly all from my last outing). I put in exactly 12.0 litres of fuel and added 360ml of oil to fill the tank. Based on those figures, I had achieved 17km per litre of fuel mixture (or 17.5km per litre if considering fuel only) on my last ride - not very encouraging for my previous assertion of 20-25km per litre . I reset the trip meter to zero and carried on.
After riding for a bit, I found myself at a convenient petrol source, so decided to fill up again and check the figures. The trip meter now said 175.5km and I added 8.1 litres of fuel, along with a little over 240ml of oil, to again fill the tank. Those figures equate to 21km per litre of fuel mixture (or nearly 22km per litre if considering fuel only).
Most of my outings are similar in terms of varying terrain and varying speeds - there is no aspect of my previous outing I can think of which may explain the higher fuel consumption. Again, I spend most of the time in the range of quarter to half throttle. Yesterday, I made a mental note that I had on quite a few occasions momentarily opened the throttle up to about three-quarters when accelerating in the lower gears (the TZR is quite fast enough for me up to this throttle opening!)...which is probably not much different from what I have usually done on other outings.
I should mention that my TZR is a little lighter than standard, having Jackal exhausts, no battery and no separate oil tank. The location of the bathroom scales eluded me yesterday, so I can't be very specific about the weight saving. I am however sure that weight reduction will have at least some positive effect on fuel economy.

James, yes I do have significant oily deposits on the silencer tips. I am using the autolube system still also.
I have thought about putting on some O2 sensors but read somewhere the oil in the exhaust stream causes them to fail.

If I were to run a couple of tanks of fuel without the autolube system, how do I do it. Which lines do I need to remove from the autolube pump?
How much oil per litre of fuel needs to be added to the fuel tank, also can I use the same size main and pilot jets? I am running Castrol TTS.

Richard,

While it would be difficult to quantify (or otherwise compare via the internet) the extent of the oily deposits in your silencer outlets, they would seem to suggest that your mixture is generally rich. It is true that oxygen sensors (at least the ones I know about) will eventually be ruined by persistent exposure to oil-laden exhaust gases, but it is still possible to get some useful information from them. I should stress that I haven't used an oxygen sensor myself (I prefer EGT & CHT indicators to gain an impression of running conditions), but I know that some people use them to set their jetting and then remove them afterwards to prolong their life (a friend of mine does this and tells me it is very useful). This method does of course have a disadvantage in that combustion conditions may later change due to poor/different fuel, developing air leaks and other troubles which will upset the engine's running and possibly lead to disaster.

It seems to me that your seemingly poor fuel consumption is all related to the petrol, not necessarily the oil. If your oil pump operation has been set correctly and everything is working, there would not appear to be any advantage to try running with pre-mixed fuel and oil (unless you have other reasons for wanting to convert - I did!). If you want to gain an idea of your oil consumption just for interest, I daresay the most accurate method (for the home mechanic) may be to temporarily replace the oil tank with a graduated container so you can quantify a change in oil level to determine consumption. However, it may be difficult to gain any meaningful comparison with known data. The only official information vaguely related to oil consumption I have been able to find is in the figures for oil pump output; 0.75-1.00ml per 200 strokes at minimum output (closed throttle??) and 10.3-11.4ml per 200 strokes at maximum output (full throttle??). Using these figures to check your own pump would require running at a constant engine speed and constant throttle opening for a length of time sufficient to produce an accurately measurable quantity of oil...all with the oil pipes feeding into a suitable container and the bike running with oil from another source.

For your info; If you do want to convert to pre-mixed fuel and oil (and make the conversion easily reversible), remove the pump assembly from the clutch cover and blank off the aperture with Yamaha part 161-15426-00 (or make your own blanking plate - anyone with hand tool skills can do it) and a gasket. Remove the oil hoses from the fittings on the inlet rubbers and turn the right-hand fitting about 180 degrees to face the left-hand fitting (be careful not to break the 'barb' off), then connect the two together with a short length of hose. The oil tank can be removed from the frame, or left in place if you plan to convert back to standard.
Some people have reported the need for different pilot jets when using pre-mixed fuel and oil, but that didn't work for me - I went back to standard size pilot jets. It is possible to obtain finer adjustment by changing the pilot air jet (I did some theoretical calculations, mentioned here - http://pure2strokespirit.net/forums/index.php?topic=8107.0), but you may find it makes little difference in practice. As a general recommendation, if you find 22.5 pilot jets (with standard pilot air jets) too rich, just use the standard 20 pilot jets. As far as the other jetting parameters (main, atomiser and needle) are concerned, there is no substitute for a systematic check. However, you may well find the standard settings suitable (i.e. a little on the rich side).

To get back to your fuel consumption problem; If you mostly ride in the range of quarter to three-quarter throttle, the atomisers and needles will be the aspects to concentrate on (have you so far eliminated the chance of worn or incorrect atomisers?). There is also the chance of floats sticking open and choke/starter plungers not sealing properly - both of these faults may be due to carb body damage, as well as wear or incorrect adjustment of the moving parts. If all of your investigations have been inconclusive so far, I still recommend a dyno session with an experienced two-stroke specialist. In particular, check the air-fuel ratio at several different throttle openings (at least quarter, half, three-quarter and full) and look for any obvious dips in the power and torque curves across the normal range of engine speed (e.g. 3,000-10,000rpm).

If you find anything obvious in your investigations (whatever you try next), please let us know!

Regards,
James

[biggz]

I don't like to contradict James (sorry), but stock pilot jets for the R1-Z are 12.5, so the next richer setting would be 15.

Laurie

[James P]

I don't like to contradict James (sorry), but stock pilot jets for the R1-Z are 12.5, so the next richer setting would be 15.
Laurie

I was about to correct my mistake, but Laurie beat me to it!

What I wrote applies to the TZR but yes, the R1-Z uses 12.5 pilot jets. I don't know why they are so small compared to all versions of the TM28SS. I have some experience with TM24 and TMX35 carbs, which also strangely use pilot jets much smaller than comparable other Mikuni carbs. I can only wonder whether the pilot air passages are smaller in these carbs...and perhaps too in the R1-Z's TM26SS.

Regards,
James