What did you do today? Cobba's rebuild

[cobbadiggabuddyblooo]

https://www.sciencedirect.com/science/a ... 7912000883

Interesting read on plug and earth strap design and impact on flame propagation, initial burn rate and how the earth straps impact on heat transferral.

[Racer-unk]

interesting read indeed. I like the early burn and increase in pressure. So which plug can we use for a TRX?

[cobbadiggabuddyblooo]

My personal choice is a std NGK copper core J plug but I file down the earth strap and side gap them to minimise shrouding and keeps the plug cleaner.
It aids in keeping the plug cooler with a shorter earth strap without robbing heat from the initial burn due to the way the unshrouded spark propagates the flame kernel.
Copper core is a great conductor to wick away heat after combustion.
I also run colder plug ( DPR9EA-9 ) due to the compression I'm running.
I'm not stressed over excess wear of the electrode as the plugs are removed every trackday.



Std TRX motor it's personal taste.
NGK or similar J plugs are cheap and easy to replace each oil change.
Personal choice on iridium plugs is the Denso as the iridium centre core uses a thinner tip compared to the NGK. A little less shrouding and iridium aids in keeping the plug clean too.

[Racer-unk]

Brisk BR10ZS about all i can find.....

[cobbadiggabuddyblooo]

JR8C are your NGK twin earth strap for the TRX.

https://www.ngk.com/product.aspx?zpid=9860


http://www.ngk-racingsparkplugs.com/shop/standard/jr8c/

Side gapping does basicly the same just with 1 earth strap.

[coxylaad]

wow. can I ask do you actually feel any difference with these changes?

I have given up mucking about with stuff like that as I have always found the perceived gains are so marginal as to not be noticeable.

The theory is pretty cool and interesting to know however, but i think it will be stock plugs for me for now.

[Racer-unk]

Read Cobbas link......then decide if its worth a try....☺

[coxylaad]

i skipped to the conclusions, but unless I missed it didn't provide any real world performance statistics?

[cobbadiggabuddyblooo]

No real time noticeable gains in feel but it's about helping to constantly gain the best burn.
I run a richer mix than Stoimetric for power and cooler temps so to keep my power on tap as constant as possible, that's why I do this and have no problem pulling the plugs out every 500km to see how things are cooking inside.
Just like with jetting I change the mains from a 163 in summer to a 167 in winter to keep me in the A/F window I choose to run.

[coxylaad]

That's fair comment. At the end of the day mucking about with bikes is what its all about!

[cobbadiggabuddyblooo]

Fork data base link so handy info

http://litetek.co/Guide_USD_ForkDatabase.html

http://extremecreations.com.au/yamaha-fork-extensions

[cobbadiggabuddyblooo]

Port flow info.....!!!!!!

https://www.cartechbooks.com/techtips/c ... rformance/

[cobbadiggabuddyblooo]

Note to self...

Over racing swing arm weight 5.2kg
All Bearings and bushes in place .
no rear axle or swing arm pivot pin.

Standard TRX swingarm weight 4.9kg
All Bearings and bushes in place
No rear axle or swing arm pivot pin.

[coxylaad]

What's the stock one weigh?

Are you finding the limitations over the stock swingarm now?

[Rod.s]

Note to self...

Over racing swing arm weight 5.2kg
Bearings and bushes in place .
Just no rear axle or swing arm pivot pin.

Ok cough up! what'd you buy and we want pictures!