What did you do today? Cobba's rebuild

[cobbadiggabuddyblooo]

Most of Lakeside corners are off camber on exits and motorcycles use " the bus stop " which is the single lane goat track to slow things down where there is no overtaking.
I was averaging 1.min 08-.09 and 1.06's when is get no traffic and free run.
Troy Bayliss runs 56 sec...
Mick Doohan says if you can master Lakeside you can master any track.

The race glass on front moves around a lot I find and is not as rigid as the abs std fairing.
The end of each session I need to straighten the radiator/fairing bracket, and I didn't take the modded bracket I usually use.
I can feel the swing arm flex now so might look at bracing the std arm to see how it feels.

[dicky]

Dirty looking track in places

Weird "not harmonic" imbalances going on with yer camera monnt versus chassis vibration

Most of the weird looking movement is probably from FB's image stabilization routines that try to keep what they think is the the main image steady.
You see it a lot on bike vids.

[dandywarhol]

Dirty looking track in places

Weird "not harmonic" imbalances going on with yer camera monnt versus chassis vibration

Most of the weird looking movement is probably from FB's image stabilization routines that try to keep what they think is the the main image steady.
You see it a lot on bike vids.

Not convinced dicky - I mounted my cheapo SJ Cam onto the fairing on my SZR660 and the harmonics gave a very similar distortion. I mounted it onto the preload screw on the fork leg by one of these with a soft rubber insert and it was a whole lot better.

[coxylaad]

you mustnt run much preload I couldnt mount fcuk all to mine

[dandywarhol]

you mustnt run much preload I couldnt mount fcuk all to mine

I run no preload on stock way up forks, cos I haven't got the Racetech spacers cut to the correct length

[cobbadiggabuddyblooo]

Note to self... On A/F ratios as a guide


6:1....rich burn limit
9:1....black smoke low power
11.5:1. Best Rich Torque at WOT
12.2:1. Safe Best Power at WOT
13.3:1. Lean Best Torque
14.6:1. Stoichiometric

Target 11.5 - 13.3 : 1 for best power
Idle. 12.5 - cold
12.8 - warm

https://www.youtube.com/watch?v=-nD340K ... e=youtu.be

Footage taken on 10th Febuary 2017 ( Summer 36*c )
Various throttle positions around track... WOT on main straight...
std tank height and my gauze air filter under sealed tank.
163.5 main jet WOT results
11.9...55000rpm .... 13.5... 7500rpm (190kph)


FYI But not relevant ..................................
15.5..... Lean cruise
16.5..... Usual best economy
18.0..... Lean burn limit ( carbies )
22. ". ". ". ( EFI. )

[Mincehead]

[cobbadiggabuddyblooo]

Camshaft weights....

STD TRX850
inlet camshaft ..... 824.5 grams
exhaust camshaft.. 770.0 grams

PENNER Asymmetric
inlet camshaft....... 797.8 grams
Exhaust camshaft... 749.1 grams

[Mincehead]

You use Penner`s? I`ve not heard of these.

[cobbadiggabuddyblooo]

Yes, Google Ulf Penner, it's his own profile/duration combination who works in close with Killers mate Huby and his race bikes and he's engineered a few hybrid TDM900/R6 6 speeds for the TRX too .

[cobbadiggabuddyblooo]

Searching around, I found plenty of conflicting views on forums but some of the manufacturers of plugs, coils and leads where just as conflicting.
One company, Tempest Aviation gave an excellent explaination to the reason why resistors are placed in spark plugs.
The biggest job is to provide a flatter clean spark with no spikes through the spark duration.
That's the trade off with resistance, a little less voltage and slightly longer consistant spark burn duration.
A bit like squeezing the end of a hose and having 1 litre of water flowing through it... It will be a little more consistant squirt but over a longer period than just a 1 litre dump through an open hose that will trickle , dump and trickle a lot faster with a predominant spike in the middle.

A spark that ramps up in intensity at the start may cause an incomplete ignition of fuel plus a ramp down of intensity at the end can cause damage to the electrode.
They gave boundaries too on the resistors ohms that allow this between 600 ohm and up to 5k to also deal with unwanted RF and compression of band width.
Obviously why different plug manufacturers have their own ideas of resistors fitted in their plugs.
Some are specific just to smooth out the spike with lower values and some are hi value ohm ,multi functional to deal with suppression of RF and or fuel burn issues like combustion chamber shape...

But as Rod has made me aware, AVIATION FUEL is governed by strict guidelines so you get the same grade of aviation fuel where ever you go in the world.

So that statement in itself clarified what I had learnt from other material read in papers and thesis's by professional engineers that answered my question.
Thanks Rod...

Why Yamaha run resistor caps on top of their resistor plugs.
FUEL...!!!!

Every day fuel sold at the Servo has different guidelines all around the world so the nice clean hi octane fuel you buy locally here in Australia will differ from fuel purchased in the centre of some obscure or 3 rd world country.
Most late model motorcycles that run resistor plugs and caps are sold all around the world so they need to accomidate for this.
So the resistor in the plug cap adds further to the spark burn duration of the plug at the expense of not being quite as high voltage and intensity to allow for irregularities in fuel from country to country to initiate a complete burn...

Do I need that resistor in my bike????
I know I only run fresh 98 Ron BP in my bike so I have no fear in removing the resistor from the plug cap.
The resistor in the spark plugs I use are a 5k resistor and I believe this is ample to stop unwanted RF corrupting the ignition .
The 5 k resistor in most of your every day spark plugs serves this duel purpose of a constant clean spark plus compress any unwanted RF within a tolerable band width so should not impede the electronics on my TRX.

Thanks again Rod for just fine tuning my learnings on this subject ...
What triggered this search for answers...
I remember IGNITECH made me aware you need to run either resistor plugs OR. Resistor caps to suppress unwanted RF...
Early model ignitechs where a common mod on Ducati's years ago and they encountered this problem of corrupting the IGNITECH . The problem was sorted by fitting either option, resistor caps or resistor plugs...

Added info...
The optimum spark burn time can vary from 0.8Ms to 2.2Ms on your average motor vehicle dependent on the resistance.
Get outside these boundaries and it's time to start looking at where you have a resistance issue at the detriment of performance or misfire...
This info was sourced from another paper written on the subject..

Extra extra info....

Why didn't I find this link earlier....

Here is the simplest explanation in a link, again from an aviation stand point but relevant...

http://www.ultralightnews.ca/articles/r ... dplugs.htm

Now the IGNITECH when set on AUTO for the dwell and why... Here is your answer...
It also answers the question indirectly on why it is advantageous to run the coils via a relay...

http://dtec.net.au/Ignition%20Coil%20Dw ... ration.htm

http://www.springer.com/cda/content/doc ... p180213825

Or read the inductive ignition section in here as it explains how how the voltage / coil / load is dealt with via the ECU to deal with dwell...
Heat should not be an issue with my coil set up and the relay with provide a more consistant spark intensity.

[cobbadiggabuddyblooo]

Time to modify the plug caps and remove the resistor and then look at a little more gap.

[trixynut]

Interesting stuff as always.
I can see the point about fuel. Pretty much all bike and car engines are detuned for our 'first world' market so they will also work without modification in the 'third world' markets they are also sold into, and its all down to the different grades of fuel available in both.

[Rod.s]

Brian this is what you need some Elf102Ron..

[dandywarhol]

Interesting stuff.

I use 50/50 mix of AVGAS and Super Unleaded in my 250 Yamaha race bike. The mix burns faster than neat AVGAS but there is a small quantity of ethanol in S/Unleaded. Aviation petrol is consistent worldwide without any water content - you wouldn't want these VW engined single seaters to freeze at 20,000 ft