james, as coops, i am also from australia,we do currently use mg tyres,we use what we call the mg red tyre (medium/good grip tyre) in our 100s yamaha class & jnr max rotax.they are a very good tyre here,as they preform very consistantly over a race journey.from new they may drop 3 tenths on their 2nd meeting.but we get 3 meets of club level racing from them.as over here rotax have pressured our governing body (aka) to be world aligned,so we will be using the mojo dd2 tyre from february 2008.so that is why some of our astute competitors are sussing out your forum for some early set up & tyre pressure tips.your climate is a little similar to us in australia.in tag 125cc over here we use the mg yellow tyre(high grip) it is a very grippy tyre well suited to the leopards ,fireball & biland that make up the tag 125cc class , as well as some rotax max runners ( who have to use the controlled tyre from rotax to run in this class) good to read your comments, wayne

GGR .

Geoff,

I do not know who gave you the idea that YJL are the same as the D2. The person who told you this and sold the tyres to you must either desperate to sell the tyres or trying to pull a fast one on you.

The YJL are medium hard compound tyres which is a replacement for the old YEQ. It is more of a rental kart tyre except it has better grip than the actual rental tyres YDS. The medium compound tyres from Bridgestone is either the YJB or the YGK. The latter is a little bit harder than YJB but then YGK were made for the Rotax engines in the first place. I would have thought that if you wanted to test the least you would get would be the YGK tyres.

The Mojo D2 is better than the YGK and on par with the YJB. If you have done the testing on YJL, then you have to redo your testing and setup with the actual D2 tyres which will arrive on 7/2 and by the time it is cleared out of customs will be around the 10-12 February. They will be available for sale from Kartmore Racing Services ONLY. Please contact me if you need the tyres.

Here's the Bridgestone web site which state the compound positioning. As stated in the web site, YJL is classified as "Hobby Racing" tyres while YGK is for Rotax

Compound Positioning
http://www.bridgestone-karttires.com/technology.php

Bridgestone Kart Tyres Product & Classification

http://www.bridgestone-karttires.com/product.php

The old brochure (2007)

http://www.kartingasia.com/karting_pictures/v/misc/Bridgestone.jpg.html?g2_imageViewsIndex=1

When Ellis123 said that when you put 20 psi in the mojos he became 8 tenths faster, like he said this only works sometimes for a few reasons. The first and main reason is because when the tires are at such high psi, they make a curve in the tire making the contact patch to the ground much smaller. This would make them usually more slippery but since the mojos have low grip, the extra heat compensates for this, and makes for faster acceleration due to less friction due to less contact patch. The reason why this doesnt always work is because it has to be hot enough out to make the tires heat up to the point where they get a curve in them. If it is too hot out, then they will still get too much grip even though they have the curve due to extreme overheating. It might only work on some karts also, do you drive a CRG Ellis?8)