Weekend riding

Yesterday I rode over to Thompsons Track between Kataikati and Tauranga.
I had heard that the Tauranga 4WD Club were buldozing the track to make it more useable. I got there about 1pm to find that the track was completely unaltered.

Today I met Dave (MVX250) at the Whakamarama Caltex at 7:30am.
We rode over to Whangamata where we met up with Colin (TL1000) back from the UK.

Had a meal at the cafe behind the Whangamata surf club in Williamson Park and blabbed some shet.

Back in Tauranga about 12:30pm.
XT did 217km on main tank before hitting reserve using Mobil 98 octane. (Synergy 8000)

Also, my Hiace van clocked up 200,000 km's this weekend.

Kayak Lake Waikaremoana

Well this has nothing to do with the XT400, but was kind of adventurous so I thought I may as well give it a place in the blog.
I was so impressed with the last trip to the lake that I thought I would borrow Dave's kayak and head down in the van to do some paddling.
Headed down on Friday 12th December 2008. Arrived at Mokau Landing about 8:30pm.
Covered 63 kms of gravel in 1 hour 15 mins. About a 50km/h average in 2.8D Hiace in 4WD.

Saturday morning was raining so instead of kayaking I hiked the first part of the great walk from Hopuruahine swing bridge to Whanganui hut and back.
Then headed around to Aniwaniwa and hiked up to lake Waikareiti and back.
Then paddled around a few points near Mokau Landing for about an hour and a half.



Sunday morning was better weather, so I loaded up the kayak and headed out into the lake, through "The Narrows" to the second bay on the left after The Narrows. About a 2 hour paddle.
Set up camp and then paddled down about 3 more bays and back just for a look.
Had a swim, looked around the bush a bit. Ate some food. Went to bed. Very remote spot.

Monday morning, I was woken up at about 5:15am by a full-on morning chorus of native birds.
Packed up camp, loaded up the kayak and paddled back to Mokau Landing. Really motored back into a headwind quite full on. The trip back took 1.5 hours.

Chatted to Craig the camp warden at Mokau Landing. He was a pretty interesting dude to talk to. He spends 9 months of the year as a possum trapper living in a bivvy in the bush near Hopuruawahine. Then for the 3 months of summer he donates his time to DOC as camp warden at Mokau Landing. He has been doing this for about 6 years. Over the winter months he sees about 4 people, so the "massive population" at Mokau Landing is quite a change for him.

Then about midday Monday I drove back to Tauranga. Got a few messages on my mobile phone as I approached Murapara. That kind of made me feel as though my little holiday was over. It is so nice to go somewhere out of mobile phone range for a few days.

Different Octane Fuels

Friday 5th December 2008-12-08

I rode up to Auckland to stay the night at Pick’s place.
Pick and I were crew on Gary’s Mullet boat (Tere Kane) on Saturday, racing to Waiheke as part of the Peter Blake Memorial.
For the record, in the yacht race we were 2nd on line and 1st on handicap. Stayed the night in Oneroa Bay and motored back into Westhaven marina on Saturday morning. Was perfect weather the whole time.
I then rode back to Tauranga dropping in to see Hil (Farmers Market Greenlane) and Jared/Desma/Paul/Peg at Jared and Paul's Mum’s place near Miranda.

Riding from Tauranga to Auckland and back hardly counts as an adventure ride, but it did allow me to try another run on sealed roads using 98 Octane from BP.

Over the past few months I have been experimenting with the different octane fuels to see if there is any real difference.
Well there is a REAL difference.
The tank on the XT400 holds almost exactly 10 litres until it hits reserve and then the reserve holds 3.5 litres.
On 91 octane petrol the bike will do 180-185 km before hitting reserve.
On 95 octane petrol the bike will do 195-200 km before hitting reserve.
On 98 octane petrol the bike will do 215-220 km before hitting reserve.

I found this quite remarkable. The above data is true for long distance runs and commuting on sealed roads. (NOT adventure riding)

The small distance variation of about 5 km that you see is probably due to a few varying factors:
1. Just how full I fill the tank.
2. The commuting / around-town component versus the open road component on any given tank full.
3. How aggressively I ride (or what mood I am in) on any given tank full.
4. Probably some other factors that I can’t dream up right now. (Head winds, hills, tyre pressures, tongue position, rider/luggage weight, air density and temperature, chain lubriciousness etc, etc)

I do notice that the bike does not run as well on 91 octane fuel. It seems ever so slightly less powerful and will “pink” at low revs with lots of throttle.

So the question is; which fuel is the most cost effective?
Well as of today, the price of petrol is:
- 91 $1.40 per litre
- 95 $1.46 per litre
- 98 $1.54 per litre

So this gives:
- 91 185 km / (10 litres x $1.40 per litre) = 13.21 km per dollar
- 95 200 km / (10 litres x $1.46 per litre) = 13.70 km per dollar
- 98 220 km / (10 litres x $1.54 per litre) = 14.29 km per dollar

Clearly it is best for my wallet and probably my engine to run 98 octane whenever I can.
I am very surprised to see that there is a 91 to 98 difference of 14.29 – 13.21 = 1.08 km per dollar.
Or put another way, a 91 to 98 difference of 3.5 km/litre. This means that on 98 octane, my bike sees about a 20% increase in fuel efficiency (km/l) compared to 91 octane! (22km/litre / 18.5 km/litre => 18.9% more )

To me this seems a little hard to believe. However, I have done at least 2 tanks on each type of fuel. I am very confident in terms of the repeatability and consistency of the data.

Also, here are the maximum distances possible on a complete (13.5 litre) tank full of petrol:
- 91 13.5 litres x 18.5 km/litre = 250 km
- 95 13.5 litres x 20.0 km/litre = 270 km
- 98 13.5 litres x 22.0 km/litre = 297 km

The extra 47 km in fuel range seen between 91 and 98 octane fuel will definitely come in handy from time to time.
It would be interesting to find out the TRUE octane ratings of the fuels and see what the relationship between true octane rating and mileage is for my engine.

I guess I should also try "Force 10" from Gull. It is rated at 98 Octane (Marketing Octane not True Octane) It contains "up to" 10% ethanol. So I guess it is possible that it has no ethanol at all. (Jeez, I am developing an intense disliking of marketing speak).

Had to replace a Ventura pack rack lock-nut that I lost ($7 at Bayride Yamaha).
The silicone rubber repair job on the CV diaphragm seems to be holding in there.
Got a quote back from Bayride Yamaha:
- New gear lever ex-Australia $43
- New CV diaphragm complete with throttle slide ex Japan $137
I ordered the gear lever but NOT the new CV diaphragm complete with throttle slide.

Gear Lever, Air Filter, and Carbies.

Yesterday I got the gear lever welded up at Smiths Motorcycles in Tauranga ($8)
I pulled the cardboard air filter out, washed it out in water with laundry powder, and put it in the hot water cupboard to dry out. It was pretty filthy.
The air box had about 50 mls of thick brown liquid in the bottom, no doubt from the river crossing on the Takahue Saddle track.
I pulled off the carbies and found that the diaphragm on the CV carb had 2 small holes in it. I had a go at repairing it with silicone RTV poo. Left it overnight to set. You can see the light shining through the 2 small holes in the picture below.
Today I enquired as to the price and availability of a new gear lever and carby diaphragm at Bayride Yamaha in Tauranga.
Still waiting for my man "Hakan" to get back to me about possible spares that he may have for the XT. Especially washable air filter and gear lever.



It is now tomorrow. Thursday 4th December 2008
I put the welded up gear lever on, carbies back in, and air filter back in.
Seems to be running good and the throttle shuts down properly to idle now regardless of how slow or fast you snap the throttle shut.
Not sure how long the silicone repair job on the CV diaphragm will last, but even if it fails, one carby will still be operational, so it won't be a total show-stopper.