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Pwillikers
| | Posted on Sunday, November 22, 2009 - 06:14 pm: | 
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I just returned from a break-in ride on my '09 CR. I'm between 300 and 600 miles and therefore kept the revs to below 7500 rpm. All I can say is HOLY CRAP is this thing fast. 146HP, ~10.5 1/4 mile is intimidating power and speed. It's gonna take some time to re-learn corner exits as compared to my 50HP MZ track bike where I'd just whack it wide open. It'll be time well spent.  Thank god for the horizontal line torque curve. The ZTL brake is quite strong and the suspension very firm and very well sorted. I set it to the manual's recommended settings for my weight. I had thought that with such tight geometry it'd be a twichy ride. It's not. It has a slight resistance to initial turn in. However, once set in the turn, it's stable as a rock. I could eat a sandwich and then take a nap mid turn. I'll probably increase rear ride height and lower the front a smidge. Also, I'll back off on compression damping for more road riding compliance.
I'm thinking there will be many track days for me in 2010. |
Nickg
| | Posted on Sunday, November 22, 2009 - 07:00 pm: |
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you ain't kidding...it is almost scary fast. my front brakes don't seem strong compared to my old ducati's |
Milleniumx1
| | Posted on Sunday, November 22, 2009 - 09:24 pm: |
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I too had that slight resistance to initial turn in when I first rode mine. Loosing it up just a tad from the manual specs made it perfect ... At least for me. Great fun isn't it?!
Mike |
Fmaxwell
| | Posted on Sunday, November 22, 2009 - 11:06 pm: |
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I'll offer a few observations:
1. When the tires are cold or the road is less than completely dry, the engine can quickly overpower the tires and spin them up. Open the throttle too quickly when coming out of a turn and you're down fast.
2. If the bike resists turning, play with the tire pressures first. It's a very flickable bike (at least it seems that way to me).
3. Be very careful with any changes to geometry (raising the forks in the triple trees, increasing shock preload) as the 1125CR is much more sensitive to this than typical bikes with longer wheelbases and less radical steering geometry.
4. The ZTL brake is strong, but I find it to be non-linear. Stopping force increases dramatically with much smaller changes to lever pressure. On my XB12Ss, the Lyndall Gold pads made a world of difference, but I understand that they have fade issues on race tracks. Some report good luck with some of the EBCs.
5. The rear brake is totally without feel. It's provides no real feedback. Racers may disagree, but on the street, it's like pushing my foot down on a two-by-four.
6. I find, on the street, that I have to make myself occasionally push it near redline (lest I wear too low a piston ring ridge into the cylinder bores). If you're in first or second, it climbs to redline scary-fast and if you're in a higher gear, you're at triple-digit speeds before you get near redline.
Enjoy it. Don't wad it up. You can't replace it with a new one in a few years. |
Milt
| | Posted on Sunday, November 22, 2009 - 11:40 pm: |
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"lest I wear too low a piston ring ridge into the cylinder bores"
Could you explain this to me? Do the piston rods stretch measurably at high RPM? |
Skntpig
| | Posted on Sunday, November 22, 2009 - 11:45 pm: |
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no |
Fmaxwell
| | Posted on Monday, November 23, 2009 - 01:28 am: |
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Milt wrote: "Could you explain this to me? Do the piston rods stretch measurably at high RPM?"
Yes, they do. (Skntpig is dead wrong -- perhaps he does not have much engine building experience.) From Wikipedia:
If an engine is only operated at low rpm for its early life (e.g. in a gently driven automobile) then abruptly used in the higher rpm range (e.g. by a new owner), the slight stretching of the connecting rods at high speed can enable the top compression ring to contact the wear ridge, breaking the ring. For this reason it is important that all engines, once initially run-in, are occasionally "exercised" through their full speed range to develop a tapered wear profile rather than a sharp ridge.
Other references to the rod stretch phenomenon:
http://www.cobraclub.com/forum/general-cobra-discu ssion/11522-urgent-torque-setting-forged-tod-caps- ford-302-a.html#post89840
http://yarchive.net/car/cylinder_wear.html
http://www.gixxer.com/forums/showpost.php?p=331200 3&postcount=11
In addition to breaking rings, it can break the piston ring land under the top compression ring. |
Cafefun
| | Posted on Monday, November 23, 2009 - 06:50 am: |
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I know mine won't have a ridge! |
Skntpig
| | Posted on Monday, November 23, 2009 - 07:11 am: |
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Sorry, that was after a few 
I didn't see the word rod and I thought you just said piston. Pistons might stretch a little but the rods stretch more.
Yes the rods stretch a measurable amount and an engine builder should account for the rod material and high RPM final length.
Are the '25 internals cast or forged? I really have no idea. My bad |
Vagelis46
| | Posted on Monday, November 23, 2009 - 07:34 am: |
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What is this MZ track bike ?? |
Pwillikers
| | Posted on Monday, November 23, 2009 - 09:01 am: |
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1996 MZ Skorpion Sport. Quality German make, now regrettably out of business. 660cc single cylinder, five valve (three intake, two exhaust), SOHC engine (engine manufactured by Yamaha), Michelin Pilot Race tires, upgraded front suspension with springs and Racetech Gold Valves, EBC GFA race pads, a Dale Walker Hole Shot exhaust and jetting.
Sporty bike, flat torque curve, light, agile and very fun to ride but kinda slow. It's top speed on TX World Speedway's long back straight is 110MPH with throttle cable stretched tight, my nose on the gas cap and a slight tail wind. Everyone passes me. But, it is greatly satisfying to dog them and re-pass them through the infield; alas only to be passed again and eventually dropped for dead.
(Message edited by pwillikers on November 23, 2009) |
Milt
| | Posted on Monday, November 23, 2009 - 09:11 am: |
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Is MZ the new Blast? |
Ridenusa4l
| | Posted on Monday, November 23, 2009 - 09:31 am: |
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it uses the SAME engine as a 1st gen yamaha raptor 660...very interesting
Jake |
Fmaxwell
| | Posted on Monday, November 23, 2009 - 09:38 am: |
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@Skntpig
Hey, you're a good guy. Thanks for the follow-up.
I'm just guessing the the 1125 is going to be using forged given the RPMs reached and horsepower produced. No solid evidence -- just a guess.
@Vagelis46 & Milt
The MZ Skorpion Sport 660 was based on a Yamaha single (which is why it had five valves). It's greatly respected for its superb handling. It's no Blast. |
Metalrabbit
| | Posted on Monday, November 23, 2009 - 09:53 am: |
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boy I can't wait to "stretch" my engine parts again. I think "thermal expansion" is the more accurate term here. Thats why you warm the engine up before you rock an roll. |
Homer007
| | Posted on Monday, November 23, 2009 - 10:02 am: |
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cylinder wear ridges occurred in older engines. with today's metallurgy technology, the issue is minimized if it even exists at all. |
Fmaxwell
| | Posted on Monday, November 23, 2009 - 10:27 am: |
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@Metalrabbit
It really is not thermal because it's related to engine RPM rather than speed. It's something that Erik Buell and Rotax could probably calculate from computer modeling.
@Homer007:
I agree that it's an almost non-existent issue today, with Nikasil cylinder deposition technology being common. The Buell's new and service limits on bore size are only .001" different. Still I'd rather bounce up to redline occasionally, just to make sure that any ridge that exists is at the very top of the stroke at the highest redline. |
Vagelis46
| | Posted on Monday, November 23, 2009 - 01:01 pm: |
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Pwillikers,
I also like Michelin Pilot Race, EBC GFA on my superlight and underpowered Aprilia RS 250 2stroke V-2. I also find my Buell rock steady midcorner. Buell's handling is phenomenal even compared with my RS250.
About the 1125's slight resistance to turning in, it is a typical Buell characteristic, until you set it up correctly. Try gradualy increasing the rear preload, before droping the front end. I have read many Buell riders that when they set the rear preload to max, they got better feedback from the rear and better turning in. Dropping the front, will make Buell's agressive geometry, too agressive, and you might get into problems. Do not reduce the front preload, because you will crash as Trevor Franklin of MCN did, when he tried this to fix 1125's slow turn in.
What is your weight ? If you are +90kg try setting the rear preload to maximum, but do it gradualy. |
Pwillikers
| | Posted on Saturday, November 28, 2009 - 09:24 am: |
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HA! One of my most memorable track days was at the Motorsport Ranch in Cresson, TX. The entire day I was passing or being passed by an older Italian rider on an Aprilia RS250. He was a really pleasant and interesting guy as well. It was huge fun. The only downside was, when I wasnt' leading, I was breathing two stroke exhaust. Race gas exhaust is bad enough but two strokes... |
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