AxeHealey HalfDork
3/26/20 7:17 a.m.

More like Quaranresfresh but that doesn't sound as good. My trusty pit bike...

Has an issue.

It won't shut off. Sometime last fall after one of my rides to work, the kill switch stopped working and the only way to shut it off was to pull the wire from the spark plug. Fun! The flywheel will not come off so I've decided to replace the engine. It was a bit tired anyway.

Everything came off last night and I started to mock things up. 

In it's configuration from the factory, the gas tank is really in the way.


Things left to do:

  1. New 5/8" clutch - to be delivered next Tuesday
  2. Longer fuel line
  3. Fuel tank mount
  4. Engine mount
  5. Decide whether to wire in the handlebar kill switch or not (there's one on the front of the engine already)
  6. Figure out the throttle cable - it comes out of the side of this engine which is not ideal
  7. Oil
  8. Fuel
  9. Ride
Datsun310Guy UltimaDork
3/26/20 7:44 a.m.

I worked for a builder and I cut the lawns at the model homes. 

We had POS mowers and had to pull off the wire that was a steel clip type and many times I shot the spark up my arm.  

That and stepping on nails are really bad memories from that job.  And the mystery poop boxes I'd have to throw out.  

wheelsmithy UltraDork
3/26/20 7:48 a.m.

This, I like!

captainawesome HalfDork
3/26/20 8:24 a.m.

I love the Invader style mag wheels on it!

AxeHealey HalfDork
3/26/20 8:47 a.m.

In reply to captainawesome :

They were one of the things that sold me on it.

2' of 1/8" ID fuel line on order, should be here next week.

On a break from work today, I'm planning to take a bunch of measurements to figure out the engine mount. I've got (what I think) is a creative way to mount the tank. We'll see if it works.

captainawesome HalfDork
3/26/20 11:21 a.m.

Will the tank brackets allow you to rotate it 180 so the cap is up front? I assume you already tried that, but just curious.

AxeHealey HalfDork
3/26/20 11:59 a.m.

In reply to captainawesome :

They will but then the pickup is in the front and with all the massive Gs caused by acceleration, I don't want to be starved for fuel!

In all seriousness, if my simple mounting idea doesn't pan out, that's probably the way I'll go. 

AxeHealey HalfDork
3/26/20 1:12 p.m.

Well I went to the basement armed with a couple minutes, a tape measure, pen and a piece of paper and ended up not needing much more than 30 seconds. The current engine mounts are blocks of aluminum with threaded holes. One set of holes mounts the aluminum to the frame, the other is for the engine. Although the mounting plate for the new engine is smaller than the old, I realized all I have to do is chop the blocks into smaller pieces to give me more movement. I'll end up with 4 separate mounts, each with two threaded holes.

AxeHealey HalfDork
3/27/20 8:19 a.m.

Cut up the engine mounts with an angle grinder. I need a band saw. 

Engine mounted. Annoyingly, the rabbit/turtle lever seems to not allow bolts to drop in the rear so it looks like I'll have to remove that assembly to install the engine. I'll give it a closer look.

Now that the engine is essentially in its final resting place, I think I'll turn my attention to the throttle cable. 

Oh - and I think the fuel tank mount can be even simpler than I originally thought. 

AxeHealey HalfDork
3/27/20 8:39 p.m.

Pretty sure I've got the accelerator cable setup figured.

I'll shorten the cable by a lot and it'll run down the top tube and then along the left side of the valve cover. The little bracket pictured bolts to the valve cover and then the cable will come out of the housing there, through the cotter pin I've put through the throttle linkage and then a simple screw cable stay.

AxeHealey HalfDork
3/29/20 3:45 p.m.

Fuel line run. I'll try to get it up on to the gas tank outlet a bit further but it is SNUG.

The tank is currently held on by zip ties and it's very solid. Nonetheless I'll probably replace the zip ties with some really long hose clamps.

AxeHealey HalfDork
4/2/20 9:46 a.m.

The clutch showed up yesterday so that's the last of the parts needed. A question for anyone watching... There's about 1/8" of available movement of the clutch on the output shaft. Do I need to make a spacer or can I just toss a bolt with a washer on the end? I'm pretty sure centrifugal clutches like some movement but I have no idea if that's too much.

AxeHealey HalfDork
4/4/20 7:17 a.m.

Well it runs. I somehow did the throttle backwards - that was a fun WOT start... Strange thing is that it'll rev up just fine but completely shuts off under load.

AxeHealey HalfDork
4/6/20 12:41 p.m.

Well, the throttle is now working correctly but it's still shutting off under load. My two thoughts are:

  1. The fuel line I have isn't big enough and it's running out of fuel
  2. Me removing the Rabbit/Turtle lever (pictured below) has something to do with it


Any thoughts, anyone? Where the long arm is attached is a pin that goes into the engine and it rotates maybe 270 degrees. I have a hard time believing that has anything to do with it.


...literally as I'm typing this it occurs to me that maybe it is has low oil level shut of and once I start moving it triggers...

EvanB (Forum Supporter)
EvanB (Forum Supporter) MegaDork
4/6/20 12:43 p.m.

I have the 6.5hp predator on a go kart. If I slide too much the engine shuts off from the low oil shutoff. I haven't got around to disabling it or fixing the other issues with the kart. 

AxeHealey HalfDork
4/6/20 12:49 p.m.

YEP!!!! That was it! I suppose all that's left now is getting the correct bolt and washer for the output shaft and figuring out how to mount the chain guards.

Oh, and zip ties aren't up to the task of holding the fuel tank in place.

Our Preferred Partners