No Name Frame and Throwin Chains

[MamaTried]

Hello. My son and I are building first kart and are a bit stumped on a few things. From the photos we were hoping a few could shed some light…

This build comes from a $50 frame my son found – we have no idea its make, possibly just a backyard project frame as I can’t find markings anywhere. No roll cage, no seat belt, no side guards. Front pedals have this rubber tubing arching over column and connecting them – seems a bit weird but maybe allows for surer contact with pedals in turns, etc.? Has welded tabs for other fittings it seems. Seems odd not even a seat support though. Anyhow its grown on us as a frame!

We did a stage two on a new pred 212. Everything but the gov removal and 18lb springs. Figured we’d go this far, and see how it goes. Added a TC 30 with 12/60 sprockets and 35 chain. 14” rear turf with 12” front tires. (Had 12’s all around originally, but needed more clearance.) 1” live axle. Added a forklift seat I found on northern tool.

It runs great and seems pretty powerful but having darndest time keeping it from throwing the 35 chain. Did all the alignment tricks, straight edge, etc. Originally, I added thick rubber bushings on the mount and engine plates to help cut down on vibration. I’m beginning to think bushings are allowing engine to rack a bit under load and in turns.

Planning on going to 41 chain but sprocket will need to be pretty big to maintain 6:1. What do you think? Would 5:1 be ok for this set-up – mostly off-road/yards? 35 chain was a cheapo with aluminum split sprocket. Like aviation all these things together might add up to our problem.

Thank you for any insights!

 

[jmaack]

I'd get rid of bushings definitely.

 

[itsid]

the rubber engine mounts are very likely the culprit indeed.

also: why the secondary engine plate?
get rid of that too and just mount the bare engine to the bare frame

chain alignment then is been done adjusting the axle sprocket, not the engine.
just undo it's fixture and get it roughly in the correct position,
then with the rear jacked up, spin the wheels a bit and the sprockethub should align itself,
if it's stuck a light tap will take care (everything looks nice and clean.. I don't see any issues really)
once it is aligned that way just tighten the hub back up and you're done.

'sid

 

[JTSpeedDemon]

Yes!

Just get rid of that second engine plate & the bushings, and bolt that sucker right down to the engine plate! All that means the engine can twist a little, so it's no wonder you're throwing chains!

And

 

[mckutzy]

A couple of things...
Its going to vibrate .. Thats the name of the game.... Some people dont like this.. but thats how it is with these industrial engines...Its not a car, its a gokart. No bushings needed.

Another thing, why the extra motor plate?? does it not fit the existing one?

Lastly... I dont see you having a kill switch handy.
Id suggest unplugging the low oil switch and hooking up a wire with a momentary switch inline to ground.... Mount this near the wheel strut and itll be at a handy spot in case of emergency...

 

[MamaTried]

Thanks all! I have a tendency to overthink stuff! Bushings sounded like a good idea but will get to work on this.

The frame plate spacing doesn't leave much room for the TC rear housing. I had an OMB plate from a prior motovox build and thought the added height would also help as TC sits pretty low. As long as it clears the sprocket no issues with such a short chain? Great advice on moving the axle sprocket to line up with the engine.

I'm guessing the 35 chain and sprocket set-up should be OK? I'll get a better chain and maybe sprocket guards would also help things. Thanks for the advice on the kill switch. I have one from a CRF50 that I think will work.

Any thoughts on the frame make or age? Welds seem pretty strong with consistent beads so looks possibly manufactured.

Thanks again!

 

[JTSpeedDemon]

Short chains are oftentimes good in fact!

 

[itsid]

while a chain can certainly be too short, or rather two sprockets can be too close together

what you have looks to be a fairly common layout for a yard kart like yours;
and while I cannot name make or model, your engine plate doesn't seem to be lower than
the average yard kart engine plate (say on a carter, kartco, ken bar, manco, yerfdog etc...)
very few have raised engine plates,
many don't even have their axle that far below the frame rails.

So my best guess would be, you will be fine.

if you're worried however, just keep the secondary engine plate in place for now,
just remove those rubber grommets and see if that already solves the problem.
saves you from reloacting the sprocket hub.
It on it's own shouldn't cause any troubles at least.

if it's still throwing chain however the next step would be to indeed remove it
and then work from there..

it's still not impossible that the axle isn't perfectly parallel with the TC's jackshaft;
the fewer adjustable parts there are, the easier it'll be to identify the part that's causing the issue

'sid

 

[MamaTried]

Thanks for the additional insights! I'll post some revised photos on outcome!

 

[MamaTried]

Fix is in!

While getting to work with the great suggestions I also wanted to fix something bugging me. The live axle sure had a lot of slop in it and as this was one area I didn't break-down for rehab I figured lets start there.

Tightening the axle clamps didn't do anything and sure seemed to be a large gap in the bearing hanger. What the heck - maybe wrong width bearings?

Nope. Whoever had it before didn't hang the clamps right! Probably didn't help the chain throwing problem. Anyhow photos show corrected hanger clamps!

Went to move the sprocket inward to meet the plate but seemed like the key was spot-welded restricting RH movement. In any event it wouldn't budge. Pushed it over as far as I could, then had to use the riser plate to ensure the TC cleared frame.

After that removed those rubber bushings. Tightened it all up and it rips perfectly! Down the road I think I will still move to a 41 chain set-and go with new bearings hung on three-bolt hangers. Seems to hold fine but man that's a small chain. Maybe its just in comparison to my Triumph or Kawasaki KDX chains!

Frame ID update: After some real deep dives in the interwebs it seems this frame is a late 80's or 90's Invader Fun Kart Jr. (3 1/2" shorter steering column). NorCal Invaders were nice sprint karts from a family company (out of business now) and I guess this was their "yard" line sold for a while to help pay the bills.

Don't know how good they were, but as mentioned the frame is solid with nice welds. Roll cage and nerf bars were optional but ours didn't come with any. (They seemed a little janky from photos anyways...)

Thanks again to all for the great help! My twin boys just love drifting on wet grass in that little kart!. They get their licenses next year so thankful for this time I have with them now. And they sure know now what it might be like getting their own project cars - How to research, source and install right! (With help from DIY!)

 

[landuse]

It's awesome that you got everything fixed!! Its nice to see kids enjoying themselves

 

[itsid]

great you got it fixed

And wow, someone really hammered that sprocket hub on,
that chisel mark does not seem to be unintentional
(a locking collar would've been the better fixture back then)

Anyays, as long as the kart's now fully functional that's some other days problem to solve
(looks to me like an angle grinder will be the easiest way to resolve that)

Invader karts went OOB in 2006
but are back in business since 2013
https://www.invaderkart.com/invader-history/
(Gary's grandson Cole now)

but I'm not positive you have an invader fun kart tbh..
the front bumper is a perfect match, true
but that front bar you have just above it I have not seen on any invader fun karts nor ads.
and the rest of the chassis geometry doesn't seem to be a perfect match either..
I might be wrong though
best source for compiled ads and pics:
http://www.vdm46.com/invader-kart.html
(I admit some images are quite small and there aren't too many confirmed Invader fun karts around these days)

Anyways, doesn't matter too much IMHO, a nice solid fun kart is a great thing to have,
and it isn't really important if it's some known pedigree company or not.
if it handles well and takes the abuse of a pubertarian boy re-enacting the best scenes from Bullit (as if they know Bullit *giggle*) it might not end up as a collectors item,
but surely deserves to be maintained and loved

'sid

PS If you really want to know if it is an invader, just drop Invader Karts an email,
I almost bet Cole knows all Invader karts in person and could easily tell if one is or isn't

 

[Stew]

Nice kart! I will need a new seat for the kart I'm breathing new life into and I may just have to steal your forklift seat idea.

Stewart

 

[MamaTried]

Thanks for all the great links, 'sid! Sure seems like there were a lot of variants for those Fun Karts. Real interesting story on the Invader company history.

That bar above the front bumper is some type of rubber tubing someone added. Maybe to keep the pedal bar-ends from catching in a youths pant leg or something?

But like you say, the important thing is that it's a solid kart frame and holds up really well!

 

[MamaTried]

Seat

Finding a seat to fit wasn't easy, Stewart. Our kart rails are really narrow. Plus the mount straps were offset in height. Front one was on top of the rail and the back one was welded under! All the seats on kart parts sites were either way too wide, or pricey racing seats.

Found this one and it's also adjustable.(And padded!) Metal seat pan was a plus, too as it didn't need any back struts for support - this frame didn't have any.

Had to make a plate for it (wood) and used rubber bushings in the back to make the mount even. You can see a bit of it to the left of the engine photo. LMK if you want a link for the seat - it was about $80 if I remember correctly...

 

[itsid]

..
That bar above the front bumper is some type of rubber tubing someone added. Maybe to keep the pedal bar-ends from catching in a youths pant leg or something?

Oh jeez..
thank you!

that thing really tripped me off so badly,
I couldn't tell it's not the same colour / material as the chassis
on my computer screen (it's a bit aged by now.. and so am I )

Yes if I substract that bit, the Invaders are indeed the closest kart I can find.
The "lowrider" from the nineties is the first with a non straight side rail IIRC.
followed by the ones that came with the brush guard
(it's no roll bar it's just to keep branches off someone's face )

But I'd rule out those "fun kart" series, since those all had Nerf bars AFAIK
and those were attached to a small tube sticking out of the side of the kart chassis.
You don't have no such nerf bar mounts on your kart.
And since the "fun karts" are an iteration (as far as I can tell) of said Lowrider chassis
(the lowrider was available later on with nerf bars as well)
here's one "deLuxe" I think with nerf bars


I would say it'd be one of those earlier Lowriders.
It'd be 66" long according to the original ad,
since you still have front and rear bumper that should be an easy verification

'sid