Chain and sprocket and my bike's general check up

[benskorpion]

Hey guys,

After having a bit of a check up, it appears that my skorpion requires (amongst other things) a new chain and sproket. Particularly chain, but since the chain looks like it has been badly worn for some time, and this may mean sprocket damage, better to replace it entirely. The current sprocket set up is the standard 15 front and 39 rear. The chain is 520-110 links.

As I am going to replace it, does anybody know where is the best place to get this part in the U.S. West Coast (California) and if I should stick to the standard chain sprocket set up, or go for another set up. What are the advantages of different sprocket ratios? I'm guessing a smaller front sprocket and larger rear one makes for a sportier fast acceleration performance? I'm not interested in crazy speed or acceleration. I plan to use the bike for some distance trips, so maybe the standard set up is best for that? I'm hoping I can fit the new sprockets and chain myself, if its not too big of a job. Anybody with experience doing this job and do they think its realistic for someone new to bikes? Apologies if my questions are dunse in anyway, I'm a complete newbie.

Other things I will need to replace on the bike are:

Engine breather hose
Front brake lever

There was one feature of the bike which the mechanic who did the check up couldn't get his head around. He said that a pipe connected to the carbs was designed to let fuel out of the carbs when they got to full, but that this part (an electrical black box) shut off when the bike shut off, which meant it couldn't do its job when bike was off. He said this just meant I had to make sure that I always turned the switch allowing fuel from the tank into the carbs to off when the bike was turned off. This isn't really a big deal, just something he said, and I was curious about it. I will read up about it myself soon when I take a look at any parts and maintenance documents I have. The mechanic was a nice guy, he understood I was a student on a low budget, and he was just advising me what needed to be done so I could go about doing it on my own. Theres nothing very major wrong with the bike, so overall, I'm pretty happy with how it went.

[billr]

Anybody with experience doing this job and do they think its realistic for someone new to bikes? Apologies if my questions are dunse in anyway, I'm a complete newbie.

The recommended upgrade is a 15/43. Keeps the motor revs up and in the powerband better at top-end.
I changed mine out recently. Stayed with the 15/39 set-up because I do long distance rides and don't really need the snappier performance, nor more top speed, plus it's what I had handy (I've got a "parts-bike" on hand.)
If you're comfortable with a wrench, doing your own work is not too bad. Follow the instructions and remember to tighten everything back up and then check again (don't ask how I know... )
Hardest part about it was removing the chain...have to remove the swing-arm. Which is not a bad thing, since you can service the bearings at the same time.
Good write-up and pictures from one of our members: Linegeist...
Skorpion swingarm strip down
Bill R

Engine breather hose
Front brake lever

Gotta do the breather hose myself, not split yet, but I can see some cracking.
Brake lever...there used to be a guy on UK Ebay that had OEM available. Nothing currently listed.
Digging around in the local shops "extra parts" (junk to most... ) bin, I found one that worked with a bit of judicious grinding. No idea what it came off of, tho'.

Good luck, take your time, you'll get it done.
Bill

[benskorpion]

Thanks for that link and feedback Bill. Very helpful. I will check it out and let you know how I get on with getting the parts and getting them onto the bike

[Bill Jurgenson]

like Bill said, the recommended change is 15/43 for which you need 112 links. This regardless of travel usage. Especially where speed limits keep the bike in the low revv range with the stock ratio.
I run and ran my others over here in Germany at constant ( as much as traffic and limits allow) speeds over 100mph with the 15/43 setup.
Whatever else, do not use a smaller cog than 15t. Root thru the archives for explanations.
Some change in fact to 16/46, of course with longer chain.
You don't need to fart around with a closed chain and removing the swingarm. In 17 years and three Skorpions if my own as well as numerous customer bikes, I have not once removed the swingarm for the chain. In the case of the Yamaha SZR, the counterpart to the MZ, you could not fit a closed chain if your life depended on it; it must be threaded thru the swingarm, something common to quite a number of modern bikes.
I always use a premium racing chain because it runs more easily and does not unnecessarily consume part of the marginal performance, a cheap O-ring chain canuse as much as 3hp just for itself. Good chains are of better stronger steel as well.
So, a good chain is really cheap tuning.

Don't worry about that electric gizmo. The european versions don't even have it. It is completely unnecessary, another outgrowth of Naderism. As long as it works when you are riding, it's OK. You just as well remove it completely, tho, if it seems to be questionable.

[benskorpion]

Thank you Bill J. for the advice and pointers. Very much appreciated.

I'll let you know how I get on

[Skorpion]

[quote="Bill Jurgenson"]like Bill said, the recommended change is 15/43 for which you need 112 links. quote]

Sorry,
I think Bill you meant 110 links, as in the MZ Skorpion manual.

[benskorpion]

Hey guys,

The mechanic got back to me today and said they can't get the tires we agreed on in the right size for the bike. Not available. What tires do you guys recommend on the skorpion? And hopefully he can get them in that size.

[Bill Jurgenson]

Bridgestone BT45
Use 140/70 for the rear. The 4" rim is too narrow for 150 tires. Again, this has been thrashed before. Makers reference rim sizes for 150/60:
Pirelli/Metzeler: 4,25"
Bridgestone: 4,5"
The BT 45 is your best choice for all-round riding and stands up relatively long. It is also quite good in the wet. Don't be cecieved by it supposedly being old-fashioned. We racing these tire in classic classes where 18" and larger rims are prescribed; on things like this 100hp 1200cc, 190kg Laverda

or on 1000 Guzzis.

I used these myself on my Skorpions, once I had fit the rims (Brembo 3" front and 3,5" rear) the bike was originally supposed to have. At the moment I have Heidenau K66 on my green SP in a extra soft racing version. These are veritable rain tire and really great - but short lived.
Otherwise for hard sporty riding I recommend BT090
I use and have used these since they became available on both the Skorpions with 4" rim and on the SZR. They have great grip cold out of the garage and great in the rain. They are not good for race track, tho, becasue they heat up under those conditions too fast. It is just that that make them so popular with the supermoto group; they are very easy to drift, something I learned rather more unwillingly on the track. Didn't go down; they are extremely foreseeable, but it ain't fast. It is fun. The BT090 is not for those whose only criterium is mileage.
In the meantime, the [url=http://www.bridgestone.com/products/motorcycle_tires/products/battlax/bt003rs_h.html]BT003r[\url] is avaiable and I have heard only good things about it from those Skorpion rider who have tried it. I have not yeat, but intend to mount them on the Yamaha when the present 090 are finished.

No sporting radial tire good in the rain is good for mileage. For me it is safety first. In my own experience with lots and lots of tires from Pirelli, Metzeler, Michelin, Bridgestone, even Dunlop and Avon (igad!), cold grip and wet grip are the first criteria, followed by handling. How man miles a tire lasts is unimportant - or rather only an aspect in comparison of otherwise very similar tires. On the road I prefer Bridgestone above all others by a wide margin. I won't even touch Dunlop or Avon, and am wary of Michelin from personal experience. Always in reference to the Skorpion or SZR, not to much heavier, vastly more powerful bikes where Pilot Powers etc are very good.
For what it is worth, I raced with Pirelli SuperCorsa, Pirelli Dragon Rain, and Bridgestone slicks.

We use SuperCorsa with the Bimota:

and as said, BT45 on the Laverda:

quite easy to see the dual-compound tread here and also that tire is ridden to the very edge. like the Pirelli on the Bimota.
So, you can see that the "old-fashioned" BT45 is up to the job.

OT, you also see the factory 3-1 megaphone; too bad I don't have a sound clip of this 180º 3 cylinder scream that brings the fans running to see if they guessed right...
and while ob the topic or growls and roars, the Bimota is so brutal, that people run for cover: over 130DB, out of range of most instruments.

[billr]

Bridgestone BT45
Use 140/70 for the rear.
The BT 45 is your best choice for all-round riding and stands up relatively long. It is also quite good in the wet.

Another vote for the BT-45s and the 140/70 rear. I ran a set for a bit over 6K miles.
Currently on Avon Road Riders, same size. They're decent, but I don't get the same feel like I did with the Bridgestones, wet or dry.
Now, if they make it well over 6k, I may stick with them. Just won't be able to hit the swervies too hard...
Bill R

[Bill Jurgenson]

it's not the Bimota but an NCR motor and gives you a bit of an idea:
http://youtu.be/YIFfGNC0lhY

and I found this of a Laverda with that works 3-1:
http://youtu.be/jMidiX2Dok0

BTW, both bikes have never been anything but racers. The Laverda from 1978 with Campagnolo mag wheels, the Bimota ran in the BOT.

[Old Dog]

[quote="Bill Jurgenson"]like Bill said, the recommended change is 15/43 for which you need 112 links.
I always use a premium racing chain because it runs more easily and does not unnecessarily consume part of the marginal performance, a cheap O-ring chain canuse as much as 3hp just for itself. Good chains are of better stronger steel as well.
So, a good chain is really cheap tuning.
[/quote]

With a split link from memory, eh Bill?

[Bill Jurgenson]

I use a rivet link but you need the proper tool for that.

http://www.hein-gericke.co.uk/technical/tools/speciality-tool/hg-kettentrenn-und-vernietwerkzeug.html

RK also offers a "Break-off" link AFAIK. Otherwise it is best to invest in the proper tool.
Perhaps this:
http://www.motionpro.com/motorcycle/partno/08-0467/

[sulby]

Hi all.
Front and rear sprocket kit with chain.
Can anyone point me in the right direction for buying a 25/43 112 link chain and sprocket kit.
It seems this isthe way to go but cant seem to find a kit to buy.

cheers.
Gaz.

[chisleu]

Hi all.
Front and rear sprocket kit with chain.
Can anyone point me in the right direction for buying a 25/43 112 link chain and sprocket kit.
It seems this isthe way to go but cant seem to find a kit to buy.

cheers.
Gaz.

I have not found a kit either. If you can't find them elseware, off-the-road.de has them individually. I'm guessing you mean 15/43.