Predator and chains...

[TedP]

Are Predator 6.5 engines too strong for #35 chain? I'm having a terrible time with regard to chain ever since replacing the 5hp Tecumseh with the Predator.

 

[madprofessor]

Personally haven't had any problems with common #35 chain ordered from ebay in 10' lengths for $15 with free shipping. Been using it on Predator 6.5hp. motors that have been hotrodded up to 12+hp. and 15+hp. with only stretching seen so far.
GPS sells some expensive "RLV gold on gold Xtreme Performance" #35 chain in 5' length for $35 that comes pre-stretched and very light weight, but unless your build is really difficult to make tension adjustments on, I'd stay with the cheaper common stuff.
NOTE: I do use high dollar chain and cable lube on my stuff, important for any chain. Motocross taught me long ago not to gunk up a chain with thick lube because dirt magnets to it and eats the chain. Lube that penetrates deep and slings off excess, leaving a film behind, is the right stuff for any application of mine.

 

[TedP]

Personally haven't had any problems with common #35 chain ordered from ebay in 10' lengths for $15 with free shipping. Been using it on Predator 6.5hp. motors that have been hotrodded up to 12+hp. and 15+hp. with only stretching seen so far.
GPS sells some expensive "RLV gold on gold Xtreme Performance" #35 chain in 5' length for $35 that comes pre-stretched and very light weight, but unless your build is really difficult to make tension adjustments on, I'd stay with the cheaper common stuff.
NOTE: I do use high dollar chain and cable lube on my stuff, important for any chain. Motocross taught me long ago not to gunk up a chain with thick lube because dirt magnets to it and eats the chain. Lube that penetrates deep and slings off excess, leaving a film behind, is the right stuff for any application of mine.

Thanks for the reply. These poor kids have had this engine since Christmas 2019 and can't get more than a half-hour of fun out of this thing at any one time. It throws the chain off, which was a little lateral movement in the axle, but now that i've got that fixed, it wants to lose master links. Last thing I did was adjust tension, had one of the boys ride for maybe 100-200 yards, and chain is loose again. Engine's not moving. Only thing that comes to mind is the possibility that the axle has a slight bend to it, making the sprocket move. Frustrating. And embarrassing. I'm one of those "nothing I can't fix" kind of guys. SMH

 

[Denny]

I like 40 for anything above 4 hp. Seems to take the abuse better. Just my opinion.

 

[madprofessor]

Wondering about the master links you're losing. Several things can cause that, but easily fixed.
Very common that people put the master on backwards. Correct way has the solid end of the link reaching the next sprocket first, ahead of and trailing the open end of the link.
Another is simply not getting the circlip pushed all the way on with the tip of a screwdriver, until it's bottomed out.
I think what's most likely in your case would be due to the chain loosening. A loose chain will jump and skip teeth under load, snatching the heck out of it. That can break a solid link, so certainly can snatch a master link some funny way.
Note: Personal experience with HALF LINKS with that microscopic shear pin holding it in place.............When my chain was still flexing my motor plate down, causing a loose chain situation for a second under load, the snatching it did popped the half link, but 2 master links were unaffected.
Half links are a really great thing where they're needed, but I'll avoid using them whenever I can from now on.

 

[madprofessor]

Note what I just said about the motor mounting plate flexing down under load. It's 17" x 6"? or so, and only welded at the 2 ends.
The chain seems to get tight when adjusting, but under load would skip. So look for what may be happening when the kart's moving, as opposed to what you can see when it's still.
Note: Only cure for mine was more more more welded steel.

 

[Mammoth]

Regina chain is much stronger, and its riveted so no master link to brake. Holds up to my 420cc when no other chain would.

 

[madprofessor]

Regina chain riveted? Tell me more. Do you use some kind of specialty tool to rivet chain ends together instead of using a master link?

 

[TedP]

Note what I just said about the motor mounting plate flexing down under load. It's 17" x 6"? or so, and only welded at the 2 ends.
The chain seems to get tight when adjusting, but under load would skip. So look for what may be happening when the kart's moving, as opposed to what you can see when it's still.
Note: Only cure for mine was more more more welded steel.

I don't think the mount plate is flexing, but I'll check it. I could sure use a bigger one to allow me some more adjustment. I've put a zillion master links on, but since my eyes aren't as good as they used to be, I'll double-check that as well.

Something in the back of my mind, something about the crankshaft being so closely aligned with the axle, is a negative for some reason. Could be my imagination, dunno. Anyone ever heard anything like that?

Thanks all, for the input. I'll do some more checking and report back.

 

[TedP]

Regina chain riveted? Tell me more. Do you use some kind of specialty tool to rivet chain ends together instead of using a master link?

Stihl used to sell a chain tool. Bench mounted. We made chain saw chains from rolls of chain. You'd spin the crank, which would peen the end of the pin as you tighten from the other end of the pin. Likely something like that.

 

[Mammoth]

I don't have the rivet tool so I carefully peened it with a hammer. Just have to give the chain pins a slight mushroom shape so the link won't fall off.

 

[madprofessor]

Searched Regina chain, really high end stuff. Saw the line of tools for aligning pins, setting rivets, and breaking tools. Specialty of really heavy chain, but some 1/2" also. Just numbers new to me, like 415 chain. Didn't list where you can buy their tools though.
Ted, the plate flexing on me was just my example of anything that can happen under load but look normal again when you stop.
On that shaft proximity, I posted once about big/little sprockets being close together, causing less teeth on the smaller sprocket to fully engage all at once. Most people seemed to think it wasn't of any real importance.

 

[Karttekk]

#35 chain will work with that engine. Tractor Supply offers #35 chain along with other sizes. Replace the chain, put the back of the kart on stands then run it. Use a straight edge to ensure the clutch and drive sprockets are aligned, make sure the drive sprocket teeth aren't worn or pointy, make sure the engine is secured properly, look for a wobbly axle and like was mentioned previously, make sure the closed end of the master link retaining clip is facing the direction of chain travel.

 

[madprofessor]

Karttekk just reminded me, another chain tension problem I've had a lot is the "engine is secured properly".
Because Dad, I've always been insistent on having motors mounted on vibration isolators. 4-packs of Asuza type "motor mounting grommets" are dirt cheap, and very firm rubber.
Step 1: Started using them exclusively when the ones I cut from Home Depot rubber stoppers were too squishy.
Step 2: Quit putting grommets on top of engine foot, making bolt isolation top and bottom. Too squishy.
Step 3: Want to quit putting rubber under the motor too. Too squishy. A little help? Ideas? Anybody?
Problem is you have to loosen the bolts to slide the motor for tensioning, letting the rubber expand. You run your adjuster bolt tight, liking the tension you get, then tighten down the motor.
Rubber compresses, even a little is too much, and now the chain's looser than you adjusted for.
Little sprocket with only 4 teeth fully engaged to boot, chain goes skippity doodah.

 

[madprofessor]

Thanks all, but I just figured out the answer.............
Build a solid chain tensioner on my primary (skippy) chain going down like the solid one I built on my secondary chain going back. Will add pics of it. Used a 22-tooth idler sprocket with 1/2" bore, mounted on slack side of chain. Had to have something there, axle and jackshaft don't slide.
Slide/adjust motor until chain is good and snug, tighten it down solidly to fully compress the rubber. Then tighten new tensioner to how I like it.
Ted, note how many teeth the chain grabs when sprockets are spread far apart.

 

[TedP]

Searched Regina chain, really high end stuff. Saw the line of tools for aligning pins, setting rivets, and breaking tools. Specialty of really heavy chain, but some 1/2" also. Just numbers new to me, like 415 chain. Didn't list where you can buy their tools though.
Ted, the plate flexing on me was just my example of anything that can happen under load but look normal again when you stop.
On that shaft proximity, I posted once about big/little sprockets being close together, causing less teeth on the smaller sprocket to fully engage all at once. Most people seemed to think it wasn't of any real importance.

Thanks for checking in. I have since discovered that the mounting plate is fairly off-level. And, I think I'd do better if I had more travel on the plate, better adjustability, so I'm going to extend the back of the frame out a few inches and move the engine back. It's a big one for that short back end, with gas tank intact. I'll update as things progress.

 

[madprofessor]

Get a quality straight-edge of some kind. Kept an aluminum yardstick in my service truck for decades, flexed to get in tight spots, then turned 90 degrees gave a perfect straight-edge. Aligned thousands of industrial pulleys and sprockets with it.
Maybe a good 1-foot ruler (metal, or brass-edged) would work for you. Just press it up against as much of the larger sprocket as possible, so it extends off both sides, not just half of it.
Let that be your edge for aligning to the smaller sprocket. It will tell you if they're mounted inline, and if either one is tilted.
Remember that flex under load can tilt the sprockets while running, be straight again when stopped.

 

[madprofessor]

Look at Seaweed's thread "Chain Jumping", carefully read long post by "Anderkart", just read it myself. It's the best chain tutorial I've ever seen.

 

[Denny]

Do not rubber mount the engine.

 

[madprofessor]

Denny, you have experience with that? What's it like insofar as vibration throughout the frame when the motor foot and the frame become one unit with no isolation? What I can recall about the little karts from my kid years doesn't count.