More YerfDog Comet fun - Center Distances

[jamyers]

Yow, this thing is getting to be a pain...got the crankshaft spacer worked out, got the driver and driven lined up juuuust right, and now the center-to-center distance makes no sense.

It's got a 6" driven unit, and a brand new 203591A belt.

Everyplace on the Internet says that with a 6" driven, I want between 7 9/16" and 7 5/8" center to center. OK, but the cardboard sleeve the belt came in clearly says 7 1/2".

Using the original engine/jackshaft/frame bolt holes, I measure 7 inches, plus/minus 1/8".

This makes no sense, the kart is nowhere near where it should be?

Anyways, I fired up the torch and cut slots in the jackshaft and frame mounting plates so I can move the engine or jackshaft to whatever distance I want, I'm planning on the 7 9/16" and 7 5/8", unless somebody thinks the 7 1/2" number would be better.

Any rule of thumb measurement on how slack the belt should be when installed?

 

[Blazkowiez]

If you kept the orig distance between the clutches and simply installed a 6" driven clutch it would've been the cheapest belt Comet offers, a 203589. Any local lawnmower shop that sells Rotary parts can sell you an 8487 replacement belt for 30+ dollars.

 

[jamyers]

If you kept the orig distance between the clutches and simply installed a 6" driven clutch it would've been the cheapest belt Comet offers, a 203589. Any local lawnmower shop that sells Rotary parts can sell you an 8487 replacement belt for 30+ dollars.

I was hoping you'd chime in on this, Blaz!

That's good info, as you'll read below I'll be able to do just that in the future.

Actually, it does have a 6" driven unit, and as far as I could tell I did have the original distance - or at least the engine, jackshaft, and frame were all together using what looked like the original mounting holes. The previous owners had drilled a whole slew of extra holes in both the jackshaft and the engine mounting plates, so it was a best-guessing-game.
Plus, it was a bona-fide basket case when I got it, both driver and driven units were in pieces in a box (with some extra parts that don't go to anything that I can tell).

At any rate, I played "connect-the-dot" with my acetylene torch and turned the holes into nice long adjustment slots, so now I can put the engine and jackshaft pretty much wherever I want them. I also reinforced the frame plate with a bit of heavy angle-iron underneath it just in case.

I went with splitting the 7 9/16 and 7 5/8 center-center distances and lined up the backsides of the driver/driven units with a straight-edge.

Ran it last night, and it seems to work great - I've got to look at the throttle assy, it doesn't ALWAYS return to idle. Might need an extra spring, or maybe the gov isn't set right (new Predator engine).

 

[Doc Sprocket]

Regarding the throttle- make sure the throttle arm pivot has been loosened off, and a return spring acts directly upon it. Make sure there is a return spring that acts on the pedal (or rod if applicable). Lastly, if the cable is not in pristine condition, replace it. Cable drag is a bad thing.

 

[jamyers]

Regarding the throttle- make sure the throttle arm pivot has been loosened off, and a return spring acts directly upon it. Make sure there is a return spring that acts on the pedal (or rod if applicable). Lastly, if the cable is not in pristine condition, replace it. Cable drag is a bad thing.

Yup, loosened the nut on the arm pivot, the cable is good with it's own return spring. With the engine off it'll go back to "idle", but with it running it's not 100% - I'll likely add another spring directly on the throttle arm end.

 

[Doc Sprocket]

Gotta have 2 springs...