Skorpion Sport Cup MPG?

[koler]

Hey guys,

Let me just start off by saying this forum is awesome, you guys have been very helpful.

I took my Skorp on a small trip (about 750 miles) and noticed that my mpg was pretty abysmal. I was getting low 30s going 85mph on a flat, straight highway. When I commute during the week I still can only get mid 30s, maybe high 30s if I am really taking it easy. I have a feeling this may be atypical for the bike. I recently did an oil change, clean the chain every 500 miles, and even ran some carb cleaner through my tank.

What do you guys usually get out of your bike?

[edfmaniac]

That's pretty poor mileage indeed. You should be getting close to 50mpg. What main jets are you running?

[edfmaniac]

Here's a quote from an old post of mine. "If you are concerned with mileage and only mileage, adjust the screw that delays the secondary carb to it's maximum delay and never open the throttle enough to send vacuum to the second carb. You'll get around 60mpg. Either that or intentionally mount the diaphragm where it has a huge leak and doesn't work. When I bought my Skorpion from the previous owner, the secondary wasn't opening and I routinely got close to that 60 mark. Once I started doing the normal mods and maintenance, I quickly discovered the bad diaphragm seal, found tons of missing power and the mileage dropped to between 40 and 50 depending on my mood." You may want to check that setting controlling when the CV(secondary) carb opens.

[DAVID THOMPSON]

usa gallons
i fill my 660 up and i go on reserve at about 100 miles on a full tank
i know its bad but have not had time to sort it out

but part of its the bad gas over here
the rt125 gets less than 50mpg on the regular stuff and is a hard starter
but almost 65mpg on the 90 octane no ethanol
and starts easy

look here for a station http://pure-gas.org/
Dave

[koler]

Dave,

I am getting about 100 miles before I have to go reserve when I fill up my tank which is just over 3 US gallons (hence the low 30s mpg).

As far as the bad gas over here (due to the ethanol content), the closest non-ethanol station is 4+ hours away, so it really is not feasible for me to use anything but the normal gas (also I usually fill up with 91, is that needed or am I just wasting money and should throw in 89 or 87?).

Edfmaniac,

Thank you for the suggestion, but I am not mechanically proficient enough to fully understand how to implement your suggestion or even answer your question about my main jets. To give you an idea of where I am at, I did my first motorcycle oil change a few weeks ago and at the same time redid my brake pads and brake fluid. I feel as though I have an acceptable underlying knowledge of mechanical systems, so if you could point me to a few youtube videos on how to adjust carb delays with specifics on the location of my bike, I could probably knock it out.

[edfmaniac]

I don't think there are any videos for the adjustment in question, but it's easy to figure out. You'll need to pull the tank to get to it which involves a few bolts on the tank and pulling the fuel line. Once the tank is free, pull it off so you can see what's going on. Find the large slotted screw on the top side of the carbs, in the middle. If it's screwed in until it stops, both carbs open at the same time. As you back it out the carb on the right, the one with the large diaphragm on top, opens later and later, kinda like the second set of barrels on a 4 barrel carb. There's a proper factory setting, or at least one that's generally accepted by the MZ community, but I always played with mine as I tried out different jets and needle settings. Once you've familiarized yourself with where it is and how it works, any adjustments in the future can probably be done just by picking the tank up enough to get the screwdriver in there.

Actually, here's a quick video that shows the screw. It's the one in the center that moves with the throttle. This view would be from the front of the bike looking towards the rear. Look for the slight delay between the two carbs. http://www.youtube.com/watch?v=M7xz3ufTc-E

[DAVID THOMPSON]

a word on removing the tank on a mz 660 there is a bracket on the rear of the mz tank
DO NOT TRY TO REMOVE THE BRACKET FROM THE TANK
take the bracket loose from the bike
the taps in the tank will turn loose and then you have a real mess
and new tanks are ????
dave

[Srinath]

a word on removing the tank on a mz 660 there is a bracket on the rear of the mz tank
DO NOT TRY TO REMOVE THE BRACKET FROM THE TANK
take the bracket loose from the bike
the taps in the tank will turn loose and then you have a real mess
and new tanks are ????
dave

My 2001 I removed the bracket off the frame. The thing will not even come off the tank. I tried and failed to get it out. The bolts spin and never come loose. Making me think, the nut in the plastic tank is spinning ... so I took the bracket off the frame and wiggle that out and then get the tank out.

The 96 I just got, had a missing bolt in the tank that was holding the bracket on. The other bolt was loose, I removed that and the tank actually came off very very easy.
I have no idea which is better, but neither of the tanks leak. Thank god.
Cool.
Srinath.

[DAVID THOMPSON]

this is a problem that owners need to know about
so they do not ruin a tank
dave

[Srinath]

I'll leave the tank bolts in place frm now, but the bracket is hard to get out upward, it come out easy straight back, but the front of the tank needs to be picked up vertically.
I probably could fab a bracket that goes over the frame ears. So it will lift up easy.
Cool.
Srinath.

[edfmaniac]

You may have to work it but it comes out. Same goes for putting it back in. You may have to squeeze the mount together and cuss at it to get it to fit in between the ears on the frame, but it will go back in.

[Srinath]

You may have to work it but it comes out. Same goes for putting it back in. You may have to squeeze the mount together and cuss at it to get it to fit in between the ears on the frame, but it will go back in.

By forcing the thing that only wants to come out naturally rearward - by forcing it to go upward - how much stress are you placing on the 2 bolts that are threaded into steel sleeves embeded in plastic. Sadly I think the 01 is almost too far gone to properly fix it. I am hoping to get the thing refabbed on the 96 with a bracket that properly comes up and out and let me see if I cant swap it in the 01.
I can machine and weld (or have people that can, I dont have anyone that can fix plastic ... if it even can be fixed.
Cool.
Srinath.

[edfmaniac]

You don't pull straight up. The bracket will flex rearward enough, while still bolted to the tank, for it to pop out about half way up the bracket. Sure, you are going to put a little stress on the tank, but mine came out dozens of times without cracking or breaking, Maybe I got lucky. It goes back in the same way. Stab the front of the tank in where it belongs and then gently bend the bracket ends towards the center of the bike while flexing the whole bracket towards the rear and it will pop in about half way up. Or you could make a new bracket.

[edfmaniac]

Oh, and plastic can be fixed. A friend of mine does auto body work and said there are plastic welding kits for doing just that, welding plastic. It takes practice, and you have to test for what type of plastic to use, but evidently it works well enough to repair plastic car parts.

[koler]

Thanks for the suggestions about removing my gas tank, I have some time off next week and I will probably use it to tinker with my bike a bit. I was considering cleaning my carbs (I have a feeling it has been quite some time since the bike has had them cleaned), but if I am not completely comfortable taking the tank off I may want to bring it to a mechanic.