2-stroke Surley Instgator Mule

KCvale · Sep 17, 2014

This customer build arrived as a bare Surley frame and bunch of parts he choose.

He wants a single speed Mule for trail riding with a top speed of about 15MPH but able to climb a cliff.

With the disc brake it had to be jackshafted but the 7-speed was replaced with a single sprocket.

It's a small frame to fit an engine in, due to the nearly straight seat post and tight fit we had to weld up a new intake from a couple we had around.

We have to test it some more but I think it came out nice.

Rudz · Sep 18, 2014

I hate that the frame comes in such a small size. Looks beautiful tho. I'd want a high compression head, but, doesn't look like there's room

KCvale · Oct 6, 2014

Rudz said:
I hate that the frame comes in such a small size. Looks beautiful tho. I'd want a high compression head, but, doesn't look like there's room

Most likely no room for an HC head, a straight head anyway, but this build was designed do be a torque monster.

After some test rides I changed the drive a bit.

This mule has so much torque it took out HD Z410 chain twice.
The engine side has 415 but I can't use it on the right side, it's too wide where the chains cross.

I did some checking and found some KMC HL710 1/2 link chain.

I have tried it in the past and hated it but these new ones have a pretty easy to use cotter pin master link which is just a peg as every link is self contained.
This stuff is double tough and easier to work with these days.

Look mom! No Tensioners!

The customer didn't want speed or gears, just a solid reliable mule that would climb a cliff.
This would make short work of the Grand Canyon mule trail ;-}

And even without a kick-stand there is always a handy natural parking spot ;-}

This is no fun to ride to the store (~13MPH max) but handy as a drop vehicle on an outdoor adventure which is what the customer designed it for.

spanners · Oct 6, 2014

Very cool looking bike ,you did a fine job on it, I'd bet the owner is pleased with it.

KCvale · Oct 6, 2014

Thanks.
If your monitor will support it each of those pics are 2800 pixels wide for super detail if you click the pic.

Rudz · Oct 7, 2014

I'm still drooling over steel framed fat tire jack shafted beauty.

Goat Herder · Oct 7, 2014

Problem with that type of gearing at 15 max mph the motor will overheat. Especially on a July day! Ask me how I know? I wounder if more torque coulda been had as a direct stock chain drive. Would help the extra chain drag and a real heavy duty chain could have been used. A Win Win at a more budgeted build too and poteintally more solid..

KCvale · Oct 7, 2014

Goat Herder said:
Problem with that type of gearing at 15 max mph the motor will overheat. Especially on a July day!
Ask me how I know?
I wounder if more torque coulda been had as a direct stock chain drive.
Would help the extra chain drag and a real heavy duty chain could have been used.
A Win Win at a more budgeted build too and poteintally more solid..

No overheating issues test riding it hard in 100+F temps, I put an Iridium spark plug with the right temp number for use in everything.

Direct drive wasn't an option with that nice rear disc brake and fat tires and it would have had to have been a pretty big custom sprocket to get it geared this low.

This is what the customer wanted and that's all that matters.

Goat Herder · Oct 7, 2014

At some point you talk them into some of this stuff lol no?

KCvale · Oct 7, 2014

Goat Herder said:
At some point you talk them into some of this stuff lol no?

Sure, in fact I usually converse with all of my customers about their needs, budget and intended use and make suggestions.

This customer already knew what he wanted so it was just little things like informing him he couldn't do all hydraulic brakes as there is no dual pull for them so he went with semi-hydraulic brakes, the tensioner issue and single sprocket in the 7-speed hub, etc.

The normal stuff, just high dollar parts he bought and sent to me to use.
I love building things like this ;-}

Jonda500 · Nov 9, 2014

if you welded up the single speed sprockets' freewheel you'd be able to use engine braking when going back down the cliff! (-and roll starts become possible -and the engine can't stall when you throttle down)

KCvale · Nov 9, 2014

No Jonda, that won't work and it don't matter, this is geared so low one kick starts it and those 2 big discs are awesome.

Jonda500 · Nov 9, 2014

Sorry KCvale, dont get me wrong- I think it's awsome like it is and I'm not trying to make you change it!
So theoretically only, if the freewheel doesn't freewheel the rear wheel and engine & jackshaft will always turn together if the wheel or motor is turned, but the pedals wont as they have their own freewheel.
I wonder if you'd be kind enough to explain to a newbie exactly why "that wont work"?
John

KCvale · Nov 10, 2014

Jonda500 said:
Sorry KCvale, dont get me wrong- I think it's awsome like it is and I'm not trying to make you change it!
So theoretically only, if the freewheel doesn't freewheel the rear wheel and engine & jackshaft will always turn together if the wheel or motor is turned, but the pedals wont as they have their own freewheel.
I wonder if you'd be kind enough to explain to a newbie exactly why "that wont work"?
John

That hub has an internal freeweel, you'd have to bust it open to get to it.

Goat Herder · Nov 10, 2014

KCvale said:
No Jonda, that won't work and it don't matter, this is geared so low one kick starts it and those 2 big discs are awesome.

What those two small disks look microscopic to me laff

KCvale · Nov 13, 2014

Goat Herder said:
What those two small disks look microscopic to me

hehhe, ya, not 12" so death traps even with pads so big it takes dual cylinders to move them ;-}

I love these cable/hydraulic combo disc brakes, both on a dual pull and it only takes 2 fingers to come to an orderly prompt stop.

Goat Herder · Nov 13, 2014

Wait till you go to plain ol anything in a 203 rotor? Then check back. I do realize those are prolly the best brakes you've seen yet. Once you go disk anything there is no going back. IMHO

Still a nice little machine.

I just worry about the scoffers giving disk brakes a bad name for experaince with these small rotor brakes from todays department stores. Get a 203 on front leave the rear stock that would prolly be perfect for me.

All you gotta do is get a bigger rotor make a mount adaptor or just buy one. Here is the funny part put your calaper on that new rotor. You will have a brake that will never fade on a trail or street. I know from the small one I played with a Shimono Hydraulic. The pads wore out immediately. The leverage from a motor bike had overcome it's limitations.

The money I save buying a few pads in bulk on a 203 lasts me forever aside from the 50 mph geared Morini right now. For how I ride my brakes don't ever fade..

KCvale · Nov 14, 2014

Those are 160mm rotors and they came with the stand-offs.

That's the biggest the HY/RD hybrid hydraulic/cable caliper would take.
http://trpbrakes.com/category.php?productid=1198&catid=206

The thing has a top speed of 15MPH, more than enough Berry berry good brakes ;-}

Jonda500 · Nov 14, 2014

I think the back one wouldn't want to be overly powerful because the engine would stall every time you accidently allowed the rear wheel to skid!

Goat Herder · Nov 14, 2014

Jonda500 said:
I think the back one wouldn't want to be overly powerful because the engine would stall every time you accidently allowed the rear wheel to skid!

When you ride a bike that has a clutch that is what it is for...do you stall your cars too? When on the road one needs to know how to use their machine. Could get somebody killed!

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