40 series question

[Jean Luc Picard]

Hi all, I just picked up a yerf dog 3202 and slapped in a new predator 420 with the only mods to it being governor removal. I also picked up a go power sports 40 series torque converter kit. My question is about aligning the front and rear pulleys, do I align the the back plates? or just center the belt. Also do I run the driver facing out away from the engine? I do believe you do from the video I seen. Thanks in advance for all of the help.

 

[itsid]

series 40 run INBOARD (cam pointing towards the engine)
exceptions require reverse wound spring in the driven [yellow]

and no, you align the center belt it must run perfectly straight and perpendicular to the shafts.

since this is a symmetrical unit the belt will remain straight when the inwards pointing cam opens the moveable sheave
(it'll open the same amount the belt will be push towards the engine by the moveable sheave of the driver)

If you install a reverse wound spring and run the TC outboard (like you would a series 30 TC)
you need to allow the driver to float on the jackshaft (7/8" IIRC)

if you have the GPS kit (with a massive steel backplate) then yes, it should come with a reverse wound spring and the cam needs to point outboard..
they ignore the floating driven for some reason though which I do not actually like very much...
but ah well.. so be it

'sid

PS here's a manual for you

 

[Jean Luc Picard]

The kit I have is the go power sports kit, it has that big thick steel backing plate. The driven has a yellow spring and the side with the spring came and installed facing outwards away from the engine. Now I installed the driver with the big nut facing away from the engine. I have the belt perfectly straight right now but from the go power sports video on YouTube they say to align the back portion which faces the engine but when I did that it seemed to me just wrong because it made the belt look slightly slanted so I put it back straight. Now another issue I'm having is that the chain keeps coming off every time I drift it at wot? I made sure to level the engine mount and make everything square, I even used a straight edge to align the sprockets. I did notice today that I am getting excessive chain stretch even know it's a new #40 chain. I'm thinking that the #40 chain is not beefie enough that or maybe it just needs to be broken in idk lol but that's my guess, I'm just used to atv mx chains and do not have much faith in those kart chains because I've always had issues with them. Thanks for all of the help bud, I really appreciate it.

 

[itsid]

yeah, that's why the driven should allow to float (it'll self align then.. still less than ideal but okay)

Aanyways GPS ignores that (since that'd mean they would have to bend the backplate into an S shape) thus the belt has to be crooked at one point (either low or high ratio) and in this case it's better to have it crooked at lower engine speeds

#40 is beefy enough for sure, #41 is NOT
but if you have the feeling it's still too weak, get 420 chain it's almost exactly the smae dimension as narrow #41 and should fit your sprockets nicely, but is the beefiest of the three.

Jumping chain when drifting can be caused by lateral play in the rear axle..
side load pushes the axle to one side and the sprockets are no longer aligned.

'sid

PS PLEASE keep in mind this is an internet forum, not a whatsapp message,
use paragraphs! it's a pain to read your posts with that blob of text!

 

[Jean Luc Picard]

My apologies for the long script. I'm used to another forum which everyone keeps the text together.


So I should keep the belt centered in both the driver and driven? Excuse my lack of knowledge on the kart setups, I am used to scooter cvt's although they seem similar.


I understand that the 420 chain is narrower then the #40 chain, would this be an issue on my #40 sprockets? I'm assuming (NO) seeing that #40 and 420 are so close and the only difference being roller width #40 5/16" and 420 1/4" if I go with a 420 chain that would make it easier seeing I have plenty of pro taper gold.

I do not think that lateral G's under acceleration is shifting the axle from one side to the other, seeing that the axle has dimples for the bearings which have serrated set screws. I'm thinking that the chain is stretching and loosening allowing the chain to skip the sprocket when turning abruptly, but I'm not 100% sure.

One other thing I noticed was my engine mounts appears to have a bit of flex to it. I don't know how this is seeing it's an 1/8" steel big block engine plate from go power sports that I welded to the frame. I may just reinforce it and add a third bearing support right under the engine plate for axle flex just to be safe.

Thanks for all of the help bud.

 

[kenworth85]

The GPS 420 mount has to be beefed up my 420 flexed enough to loosen the chain.

 

[Jean Luc Picard]

@kenworth85 yeah I agree 100% I should had known that 1/8" thick mild steel plate is no where near strong enough for the weight of a 420. I will take some 1" square stock and run it down both sides then run a piece through the center and that should do it. Thanks for all of the advice fellas, I really appreciate it.

 

[Joe-405]

I had that kit.......... The belt is supposed to be parallel with the plate at full speed. So it will sit crooked when at idle. I have a YouTube video of mine checking the alignment. Or you can go look at my mini me drag bike build thread and see the pics.

 

[anickode]

Putting 420 chain on sprockets that are only designed for 40 chain will cause binding issues. The pitch will line up, but the sprocket will be too thick for the chain to fully seat in the teeth.

 

[Jean Luc Picard]

@joe-405 So just align the two pulleys back plates that are towards the engine side right like in the gps youtube vid? I really wish these things came with instructions crying out loud. Maybe I'm making this harder then it needs to be huh.