Viper Off Road Build

[gjpgonzo]

PROBLEM with Torque Converter

Driver is engaging at idle:
Recap of parts and pieces:
420cc Predator engine
40 Series Torque Converter
Center to center (shaft to jackshaft) 9.75”
Belt is 203788


The driver expands out and grabs the belt at idle, I don’t know if the idle is too high or if I installed something incorrectly. I backed out the idle screw all the way and it did not drop the idle down far enough to help and I don’t see any other way to reduce the idle any further.

Anyone know at what rpm’s the driver is supposed to engage? How do I find what my current idle rpm’s are? It is supposed to be 1800 +-50.

 

[mysteryboy28]

your driven pulley is on backwards. also that small sprocket is sitting out way too far without bearing support. you can get away with support on one side if it is close to a bearing, but yours is like WAY out there. lol. i'm afraid that with 13+ horses the shaft is gonna flex or bend, causing chain slippage and sprocket wear/damage.

if your driven pulley is backwards, the belt will not engage properly, and can get snagged inside the driven pulley.

as for your driver pulley engaging prematurely: they are designed to engage around 1800 rpms. so you need to get your idle down to around 1600 rpms. some kind of digital tach meter should help you figure out what you're currently idling at. odd that the idle screw won't let you go lower... are you sure you're turning the right screw?

the blue Duromax 16hp (overated) motors were plagued with the evil 1800 rpms, which made them very difficult to use with a torque converter, without some kind of modification/intervention of the carb. i had one, and although i was able to get the idle down, it then became a pain in the a$$ to start the motor. so much for having electric start!

 

[gjpgonzo]

your driven pulley is on backwards. also that small sprocket is sitting out way too far without bearing support. you can get away with support on one side if it is close to a bearing, but yours is like WAY out there. lol. i'm afraid that with 13+ horses the shaft is gonna flex or bend, causing chain slippage and sprocket wear/damage.

if your driven pulley is backwards, the belt will not engage properly, and can get snagged inside the driven pulley.

as for your driver pulley engaging prematurely: they are designed to engage around 1800 rpms. so you need to get your idle down to around 1600 rpms. some kind of digital tach meter should help you figure out what you're currently idling at. odd that the idle screw won't let you go lower... are you sure you're turning the right screw?

the blue Duromax 16hp (overated) motors were plagued with the evil 1800 rpms, which made them very difficult to use with a torque converter, without some kind of modification/intervention of the carb. i had one, and although i was able to get the idle down, it then became a pain in the a$$ to start the motor. so much for having electric start!

I knew it was on backwards but…I keep looking at the red spring and it looks like it is supposed to work that way. The coil looks as if when spun it wants to contract (good) like it should, I have the yellow spring and it looks like if I install that one it will want to expand (bad) am I not understanding this correctly? The way it is now when accelerated the driven opens nicely.

Yes I realize that the 10t sprocket is out there and I do plan on moving it closer the pillow bearing.

Yes it is weird that the idle screw does not lower the idle much, I think it is the correct one…it is the black one just behind the choke and above the carb, it seems to work with the gov setting also…..I’m at a real loss with this motor, and how to reduce the rpm’s. Any hints and tricks you can give me would be great.

 

[gjpgonzo]

I knew it was on backwards but…I keep looking at the red spring and it looks like it is supposed to work that way. The coil looks as if when spun it wants to contract (good) like it should, I have the yellow spring and it looks like if I install that one it will want to expand (bad) am I not understanding this correctly? The way it is now when accelerated the driven opens nicely.

Yes I realize that the 10t sprocket is out there and I do plan on moving it closer the pillow bearing.

Yes it is weird that the idle screw does not lower the idle much, I think it is the correct one…it is the black one just behind the choke and above the carb, it seems to work with the gov setting also…..I’m at a real loss with this motor, and how to reduce the rpm’s. Any hints and tricks you can give me would be great.

OMG can someone find me step by step instructions for removing the red spring and installing the yellow spring.....been searching all day but can't find anything......HELP....PLEASE!!!!

 

[landuse]

Look in the FAQ section in the helpful links sticky. I am sure there is something there under comet.

 

[gjpgonzo]

Look in the FAQ section in the helpful links sticky. I am sure there is something there under comet.

Still couldn't find anything, so I just went ahead and did it, don't know what I was afraid of it was easy....
But I have one question...when rear wheels up off the ground...should they gently spin at idle with some resistance to stop if I try to hold them?

 

[exenos]

Nothing wrong with that.

Sent from my XT1032 using Tapatalk

 

[landuse]

Still couldn't find anything, so I just went ahead and did it, don't know what I was afraid of it was easy....
But I have one question...when rear wheels up off the ground...should they gently spin at idle with some resistance to stop if I try to hold them?

That sound fine. If it is rolling when not off the ground, that is a problem

EDIT: THIS is the link I was referring to. I don't know if it would help

 

[gjpgonzo]

That sound fine. If it is rolling when not off the ground, that is a problem

EDIT: THIS is the link I was referring to. I don't know if it would help

Here are some pics of how I compressed the Driven, and some of the Driven installed….let me know what you think.

 

[landuse]

Looking good

 

[gjpgonzo]

Progress...She's ALIVE

We took it out for its maiden voyage, OMG that was so much fun, that 420cc Predator engine is awesome, very quick and lots of speed. Everything went well, and nothing broke…yet

Here are some more pics….if all goes well after beating it up for a bit, we are going to tear it all down, have everything sandblasted, then prime and paint.

 

[landuse]

I would not use your harness until you have put a rollcage on. The rule of thumb is that you only have a harness if you have a rollcage, otherwise not. You want to be thrown clear of a caqgeless kart, not pinned under it

Edit: Awesome kart!!

 

[gjpgonzo]

I would not use your harness until you have put a rollcage on. The rule of thumb is that you only have a harness if you have a rollcage, otherwise not. You want to be thrown clear of a caqgeless kart, not pinned under it

Edit: Awesome kart!!

I don’t completely agree with that, if I hit a big bump, or a sharp turn I don’t want to be thrown, the wide nerf bars, the tall front, and the high piece above the seat should be enough if you roll.

 

[fowler]

because getting thrown out and breaking your arm is better than the kart rolling on your head

the roll bar behind the seat is just for looks in this kart
itll just fold

if u are getting thrown out in corners than u probably wanna modify the seat to have sides

 

[landuse]

I don’t completely agree with that, if I hit a big bump, or a sharp turn I don’t want to be thrown, the wide nerf bars, the tall front, and the high piece above the seat should be enough if you roll.

It is not just me making things up. It is accepted practice in yard karts and buggies

 

[OzFab]

I would not use your harness until you have put a rollcage on. The rule of thumb is that you only have a harness if you have a rollcage, otherwise not. You want to be thrown clear of a caqgeless kart, not pinned under it

Edit: Awesome kart!!

I don’t completely agree with that, if I hit a big bump, or a sharp turn I don’t want to be thrown, the wide nerf bars, the tall front, and the high piece above the seat should be enough if you roll.

because getting thrown out and breaking your arm is better than the kart rolling on your head

the roll bar behind the seat is just for looks in this kart
itll just fold

if u are getting thrown out in corners than u probably wanna modify the seat to have sides

It is not just me making things up. It is accepted practice in yard karts and buggies

I can see both sides of this argument &, I have to say, I agree with fowler here; the loop above the seat is mostly cosmetic & will likely break or, at least, bend in the event of a rollover...

 

[gjpgonzo]

Need axle help

We found an awesome trail the other day, but unfortunately the bumps were a bit too much for the axle. It bent and I don’t know why, before I go and buy a new one, can someone help me understand why it bent and maybe how I can prevent it from happening again?

 

[landuse]

We found an awesome trail the other day, but unfortunately the bumps were a bit too much for the axle. It bent and I don’t know why, before I go and buy a new one, can someone help me understand why it bent and maybe how I can prevent it from happening again?

Where did it bend? Have you got a pic or two? Was it a 1" axle"

 

[mckutzy]

I'm going to guess.
The drive or off drive side? Not in the middle.
It got bent as the tires are hanging a little off of being supported properly when you gaver.
If in the middle, might be the same.

Need pics of the damage.

 

[gjpgonzo]

1" solid steel axle, no pics but its an over all bend, wondering if I need a third bearing in the middle of the axle to relieve the strain, or shorten the length of the axle so the wheels are closer to the frame.