Ignition timing?

[GTCarlos]

Hi All,

I'm getting to know my new Skorpion Traveler. The big problem thus far is that the exhaust pipes get RED hot after 1-2 minutes running. That's essentially why the PO sold the bike.

Thinking I was smart, I pulled the covers to re-set the cam timing, assuming it was off a tooth but as near as I can tell the PO had it assembled correctly. The Decompression system seems to be set up right as well. My next 'guess' is that it might be spark timing.

Is there any way to adjust that or even check the spark timing?
Do you have any others theories?

Thanks.

-Danny
Oakland, CA, USA

[edfmaniac]

It's most likely the pilot jet. It's too small from the factory. The search engine seems to be messed up right now so I can't find the right posts, but there are plenty of discussions here about jetting the stock carbs. Pilot is too lean and the mains are too big.

[MZ in Oz]

Nothing to worry about there, standard jetting is a bit lean at idle, going up one on pilot jet will give better low end response and pipes may not glow so red. I have 2 Skorps and both will get hot pipes when sitting idling, get out and ride it they're not meant to sit .

[GTCarlos]

Thanks "edfmaniac" and "MZ in OZ" for the tips. Sounds like an idle jet is the next item to renovating the old girl.

The bike will mainly be for city riding. I intend to keep the throttle open as often as possible but there will be inevitable long stints on the idle jet so it's definitely a fix I'll try.

So to follow up with a really BASIC question; am I right in assuming the pilot jet is in the slide carb or is there a pilot in both carbs? (Of course there's no reference in either of my 2 books).

Thanks and best regards.

-Danny

[edfmaniac]

Pilot in slide carb only.

[billr]

I had the same issues you describe.
Here's the pilot jet I used...Mikuni #40 pilot jet (part# VM28/486 #40 at your friendly Yamaha dealer)...just don't tell 'em it's for an "MZ"
Much better off idle and less popping on over-run.

I thought this information was on this forum, but I can't find it again? Big thanks to whoever originally posted.
Bill R

[DAVID THOMPSON]

BILLR
what main jets do you have in yours

getting ready to tune up the 97 660 traveller and run it this summer

Want to make sure the carbs have the correct jets for stock pipe

bike has had several owners so i will check it out

Dave

[billr]

BILLR
what main jets do you have in yours
Dave

Dave,
I checked a spare set of carbs I have laying around (broken float post...these were run on the Traveller and performed well)
the primary is a 122
secondary is a 165

I bought a used Holeshot muffler and tried the jetting kit that came with it.
My mileage dropped to 32mpg...from 48-52 on the stock jets.
That main jet is marked 135 and instructions had me raise the needle on groove.
Needless to say, I went back to stock rather quickly.

Hope this helps,
Bill

[MZ in Oz]

Have to agree with you Bill, all this playing around with jets and pipes are a waste of money and time. The small increase in power only kills economy and increases stress on the engine, far better a slight tinkering to get our beasts running clean and smooth and setting the suspension up is far more efficient. What we may lose in outright power/performance is made up by the handling quality and corner speed these bikes a capable of. Friends who have had a ride on my bikes are very surprised how well they do everything, nothing stands out but, just a well balanced unit. It's a pity they came out when the market was all about outright power.

[DAVID THOMPSON]

the picture of mine in the gallery is from the past owner and shows an after market pipe
i am betting the jetting never got set back to stock pipe settings

and when i got it it had only averaged 490 miles a year which means it set a lot

and its set a lot with me as i really prefer the lighter mz saxon tour 500 with rotax motor

the rt 125 has me spoiled as i have always liked small and light bikes

i have always said the rt should have been a 350 cc or 400 at about 25 to 30hp
dave

[GTCarlos]

[quote="MZ in Oz"] What we may lose in outright power/performance is made up by the handling quality and corner speed these bikes a capable of...

I couldn't agree more. If I wanted HP I could buy any number of UJMs with 3X the power. what I'm after is balance, grace and a bit of novelty. Light weight is also a huge plus and I especially love the feel of singles (although this is more over-square than I would chose in a perfect world). My goal with this new-to-me MZ is to get it set-up so it's smooth across the entire rev range. I'll install the Hole Shot pipe that came with the bike because it's a good 10lb. lighter than stock but I'll leave the jetting stock (if possible) to preserve economy.

At my age and level of talent, 40 bhp is plenty for a city bike, extending to maybe 60hp for a full-on Sport machine. Anything over that is silly for the street. Cliche as it is, the "point and squirt" strategy enabled by having 100+ HP only compensates for poor riding skill. And a talented rider still can rarely take advantage of that much power on the street. I'll bet on a better rider on a smaller, lighter bike ANY day of the week.

__
***I__
*******I__
*********** Stepping off my soapbox now.

-Danny

[billr]

What we may lose in outright power/performance is made up by the handling quality and corner speed these bikes a capable of...

Amen,
Box-stock, the darned bike is way better than I am...
I can push myself right to my limit and the Skorp has more.
B

My goal with this new-to-me MZ is to get it set-up so it's smooth across the entire rev range. I'll install the Hole Shot pipe that came with the bike because it's a good 10lb. lighter than stock but I'll leave the jetting stock (if possible) to preserve economy.
-Danny

Danny,
Should be possible. I kept the Holeshot pipe on and went back to the stock main jet and kept the #40 on the pilot. My average mpg went right back to around 50 and there was much less popping on decel with the 40 on the pilot.
Drive-ability was improved also. Both my Skorpions had what I call the "parking garage cough-spit-stumble"...making the turns in the garage, never failed it would cough/spit right as you leaned into that curve to the next deck... .
With the larger pilot jet, that has gone away.
Since then, I went back to the stock system to quiet things back down. One of these days, I'll get a dB killer for the can and see how that does.
Good luck, I'm sure you'll enjoy this bike.
Bill R
Nashville, TN