Pirelli Scorpion MT90/AT

[RibRoy]

Hi,
I have Pirelli Scorpion MT90/AT front and rear on my 950 SE. I normally go 60-70 % tarmac ( No highway, only twisty backroad tarmac) and the rest is gravel/very easy enduro. I also enjoy a track day now and then. The last time I went to a track I was a little to fast/low on a 90 degree turn that ends in a hill ( Slaktern/Rudskogen for Norske lesere :)) The rear just spun out with absolutely no warning, and I got a good ride on my arse with the bike in front of me. ( I'm not a very skilled driver) So to the point: If I change from 140/80-18 to 150/70-18, will this give me a better grip at trackdays without compromising handling on gravel/ligth enduro?

Sorry for crappy English and what might be a stupid question.

[O.C.F.RIDER]

Originally Posted by RibRoy

Hi,
I have Pirelli Scorpion MT90/AT front and rear on my 950 SE. I normally go 60-70 % tarmac ( No highway, only twisty backroad tarmac) and the rest is gravel/very easy enduro. I also enjoy a track day now and then. The last time I went to a track I was a little to fast/low on a 90 degree turn that ends in a hill ( Slaktern/Rudskogen for Norske lesere :)) The rear just spun out with absolutely no warning, and I got a good ride on my arse with the bike in front of me. ( I'm not a very skilled driver) So to the point: If I change from 140/80-18 to 150/70-18, will this give me a better grip at trackdays without compromising handling on gravel/ligth enduro?

Sorry for crappy English and what might be a stupid question.

No, because the 150 will be wrapped to tight on that skinny rim. You'll need a wider (Adv) rim to get a bigger footprint.

[midfat]

Look at the thread I started on the Conti Trail Attack 2 tires. I also had the Scorpions and I know EXACTLY what you are talking about on the tires sliding around. On several occasions, coming out of a corner with just a little throttle application, the rear would become very light and start to step out. It's fun when you just stay on the gas and carve a nice stripe, but it's also a little un-nerving. Going to a 150 will just make matters worse because it will pinch the beads on the narrow rim and change the radius of the tire. For these reasons, I'm just picked up a set of Conti TA2s.

It just goes to show you that, as good as the 950SE is on pavement, it really, REALLY, like dirt. If it matters, the Dunlop 908 Rally Raid was fantastic on the pavement (compared to the Scorpion).

[Misery Goat]

You should be able to scrape pegs on a 140 or 150 Scorpion on the SE. Make sure you have good body position when you're in the curve, ie scooch slightly to the outside of the seat with your hips turned in the direction of the turn. The bike should fall in nice and easy and stay planted if you're properly counter balanced.

[midfat]

Is suspect that as the rear Scorp wears, it develops a rather pronounce flat center profile. When you lean over, the tire effectively gets "up on edge." On the extreme edge profile, when you get into the throttle, it easily breaks. I could be completely wrong, but that's my theory.

[Night Falcon]

cant speak for the SE but on the adventure the 150 was a great tire for road. Never stepped out on me once. I did loose the front once with an MT90 on in a tight hair-pin corner, but it was a bit bald

[andresg]

hi,
I used to hace the same problem in my 690 enduro R, which is very nervous on the throttle.
I've used two rear Continental TKC 80 Twinduro 140-80 R18 at different tire pressure without mayor improvements on the grip nor cornering.

I just have installed a Heidenau K60 scout, 140-80 R18 and noticed a great positive difference on the grip.

I recommend you to look for the Heidenau 150-70 R18 scout and give it a chance.

[RibRoy]

Hi,
I'm also lucky enough to have one extra SE950 :) Altough I bought it for parts, its fully functional and i have TKC80 front and Heidenau k60 back. I have never used this bike on trackdays so I cant compare. However it feel like it has a lot poorer grip/stability on tarmac than my SE with P Scorpion.

O.C.F Rider: Do you know the widt of SE and ADV rim? After all its only 5mm on each side that differs on the 140 vs 150. The hight is 80% of 140 ( 112mm) vs 70% of 150 (105mm) wich make the 150/70 a little bit lower. Have you tried 140 vs 150 on the same rim or is it your theory?

midfat: The Conti TA2 looks like its no good on gravel, but exellent on tarmac. What confuses me is that you say 908 is a better tire than Scorpion on the pavement. Shure does not looks like a performer other than off road.

BTW the Scorp was almost new when it slipped. I checked the pattern several during the trackday, and I was far down on the sides of the tire, Wearing off those little "Hairs" (the things from the making of the tire) all the way to the end of the pattern/side. I might have got so low that I actually run out of pattern, and over the edge/side. This was on the last lap of the day, and I was trying to find the "limit". Sure found it, but was expecting som kind of warning. Not this sudden and complete loss of grip.

Judging by looks only, I think maybe http://www.metzeler.com/site/com/pro.../Tourance.html in front and the new http://www.metzeler.com/site/uk/prod...e/Karoo-3.html back (will be delivered in both 150/70 and 140/80- 18') could be interresting to test.

[Misery Goat]

You can run 140s and 150s on the SE rim. I have logged thousands of miles on both. If the tire was brand new it's possible you didn't scrub it in properly before you laid it down. Most likely it's you.

[RibRoy]

Originally Posted by Misery Goat

You can run 140s and 150s on the SE rim. I have logged thousands of miles on both. If the tire was brand new it's possible you didn't scrub it in properly before you laid it down. Most likely it's you.

Hi, did you try with the same tire but in different dim?

I had some 300 km on the tire ( also in sand/gravel), so I think the slippery thing from the mould would be off by then. But of course, this was the first time I was so low on the sides

[KEELAYMONSTER]

Something else that hasnt been mentioned is tire pressure. Depending on how many laps you completed prior to low siding is goin to tell, roughly, how much heat would be in the tire. If pressure is too low the tire can easily overheat and become greasy and cause what you are explaining. Too high of tire pressure will not allow the tire to reach optimum temperature for grip, again causing close to the same problem. On the track tire pressure is very crucial. Usually when using a DOT (in America) or road legal tire they are not designed to reach track operating temperatures. Even with the propper tire pressure they have a tendency to get greasy when they are heated up. Would you happen to have a picture of the tire after the accident? Prefferably before you rode on it again. It might shine some light on your lean angle and what exactly was going on.

[O.C.F.RIDER]

Originally Posted by RibRoy

Hi,

O.C.F Rider: Do you know the widt of SE and ADV rim? After all its only 5mm on each side that differs on the 140 vs 150. The hight is 80% of 140 ( 112mm) vs 70% of 150 (105mm) wich make the 150/70 a little bit lower. Have you tried 140 vs 150 on the same rim or is it your theory?

I'm not sure of the rim width on the SE, 3" or less I think, and on my '04 Adv."S" the rear is 4", the newer ones went to 4 1/2". According to some who shall remain nameless, you can run a 150 on the skinny SE rim, and they're right, you can. That doesn't mean the thing fits right though. It's WAY to big for that rim. And as for scraping the pegs on your SE, I'd like to meet you if you can.

Chris

[Misery Goat]

Originally Posted by RibRoy

Hi, did you try with the same tire but in different dim?

I had some 300 km on the tire ( also in sand/gravel), so I think the slippery thing from the mould would be off by then. But of course, this was the first time I was so low on the sides

You're over-thinking this, 140 or 150, it doesn't matter. You don't need to be a pro-rider to lay the bike down in the twisties. Just keep riding and work on your skills.