Manco 606b with Predator 420cc Swap Series 40 Problem

[faultsafe]

Recently took on the mission to build an offroad kart for the track in the back and got ahold of a Manco 606b (Silver Fox) for $150. Engine works great but I need 'more powah baby' so I plan on swapping out the engine for the 420cc predator.

Already have the engine, mounting plate, and am planning on swapping the garbage hex axle for the 1" steel one + split sprockets + hydraulic brakes(recommendations?). (And if all that works, I'll swap the steering to rack and pinion as its garbage)

Having said all that; I have the dumbest problem at the moment. I had a spare 40 series driver from a previous dune buggy and a 30 series back plate so I made the mistake of just ordering the driven pully + other parts from GPS. Well; that was a mistake.

It mounts but the jackshaft isn't nearly long enough and after reaching out to GPS they pretty much told me to buy a cheap 40 series Chinese kit and use its backplate. (Why do they not sell the backplate + jackshaft for the 40 series outside of the $400 kit? Very confused)

So I hit up OMB and they have 40 series plate (and the belts to use) but not the Jackshaft.

I'm new to all this...so appreciate any help you guys can provide.

 

[Denny]

Just go on Amazon and find a kit. Throw away the belt that comes with it and get the equivalent belt in a Genuine Comet. See the chineseum belts are made from pvc or abs or something and don’t grip too well or last too long. In short a waste of money piece of junk.

 

[panchothedog]

I have the O.M.B. 40 series torque converter on one of my karts. Works great.
Very satisfied. The ones you get on Amazon will probably work well also, BUT
I would recommend that you get the whole setup. Driver, driven, jackshaft,
plate and sprocket so everything is matched together. Cheaper that way also.
Ddon't know if you are aware, but ALL 40 series driven clutches will need a reverse wound spring installed in them. They come orientated to be spun
clock wise. So when you spin them counter clock wise ( like on a kart ) they open up, high gear mode, immediately. The O.M.B. Kit includes it but they also
sell the spring separately. Easy to install.

 

[faultsafe]

Understood. Just ordered a whole new kit from Amazon. Not sure if I can return the driven part back to GPS but that's what I get for trying to piece meal it.

Appreciate your help; ordered the yellow spring for the 40 series as well.

Now to weld that engine plate and try to get the new brakes setup and hopefully I'll be off to the races.

 

[panchothedog]

O.M.B. Warehouse also has a group of videos, including one that goes through the installation. They are titled or done by the Grey Goat Garage. Well done, worth watching.

 

[madprofessor]

Not going to install your own jackshaft, using a factory backplate with pre-installed jackshaft? Not my style ................
Here's a copy of a post from earlier today, where I espouse the use of separate jackshaft for 40 series ...................

Excellent reference on item #4, the part about P-85 and P-90 clutches floating 1-2 mm to prevent side-loading. However.............
It only explains to me why I've seen folks here recommending not securing their drivers and/or drivens to their respective shafts. Never knew why people talked about that, good to see where it actually belongs in a mechanical application. Doesn't apply here in the discussion of these lower-hp. motors, likely why it always confused me to read about folks doing that.
The free-floating application sounds good on paper, but doesn't sound even a little bit likely for a 6.5 - 13hp. motor setup, and none of the folks I've read here have complained about oblong wearing out of crankshaft bearings. I don't consider it a reliable method of correcting the constantly shifting alignment of symmetric pulleys mounted with their movable sheaves on the same side.
The infinite possibilities of gear ratio changes provided by having a completely separate jackshaft for the driven pulley with a secondary chain is valuable enough for me to never back away from my insistence on reversing the driven to keep the belt in alignment. 4 sprockets to play with makes for some real changes, both large and small. I last built a 5:1, and a separate jackshaft let it end up 9:1 without changing the axle sprocket further than 60 to 72.

 

[faultsafe]

After about 3 failed attempts I've got this monster off-roading like a banshee out of hell.

Having said that; I have a few small problems I'm hoping you guys will have insight into:

I did the 'cheap' series 40 off of amazon and replaced the belt with a go powersports one (and yellow spring) as suggested.
However, at a stop the belt squeaks INSANELY loud.

Also, the series 40 seems to not always disengage when returning to idle. Ran over my foot a couple times with that one.

I also have insane understeer at the moment but am looking into adding camber and a rack and pinion steering system because you have to manhandle the steering.

One last thing; my top speed appears to be right at 35 before the governor shuts me down. This seems awfully low. I'm hoping I didn't forget to preload the spring when swapping it out, or maybe I'm just geared way too high? Will just increasing the teeth on the jackshaft sprocket resolve this?

I plan on destroying the rear axle/tires (as its hex and rusted on there) before replacing the whole axle with split sprockets that I can easily adjust.

 

[Denny]

You didn’t follow my instructions did you. Throw away that GPS belt and clean the pulley shieves with BRAKE clean. Then install a GENUINE COMET BELT. Then take it out and rip around. It will make a difference.

 

[faultsafe]

Right, you are my guy.

My sincerest apologies for thinking GPS were selling the legit one.

I'll start digging for the genuine one. If you happen to have a link from which you source them, I'd appreciate the assist.

 

[Denny]

I dig through the BS ones on Amazon and look for the ones that say GENUINE COMET on the belt sleeve.

 

[panchothedog]

You can change springs and weights in the drive clutch and it won't creep at
idle, better for your feet. Only problem is as the engagement rpm increases so
does the high gear lock up point. On mine it fixed the creap but then the engine
was topped out on the governor long before the clutch was in high gear. I had
always planed on modifying the engine and removing the governor and once that was done it has plenty of rpm so high gear and 45+ mph come easy.

 

[faultsafe]

Never give up, never surrender!

Ok so I figured out what was wrong. First and foremost I went to the belt that came with the series 40 kit from amazon and that got rid of my idle creep/squeaking. That's what I get for just copying some random belt number from some one who did the same thing. Bah.

When that didn't resolve my slipping (and loud as hell banging) when 'GETTING ON IT' on pavement; I went back to research. Long story short; I had listened to too many people it seems. I had reversed my driver pulley as per the series 40 torque converter instructions. I had also installed a yellow reverse spring as per people on this forum. Here is the thing; you do ONE OR THE OTHER (or reverse the driven). Not both.

I spent about 20 minutes trying to line it up naturally (both being 'outboard' (?)) with the yellow spring before remembering I could just flip back to the red one because I had reversed the drive pulley already. Threw it all together and feels much better now. I can still make the belt slip if I punch it on asphalt but I'm pretty sure that's because of the rather large back tires on it combined with the governor shutting it down when it starts spinning.

Rack and pinion steering kit has been ordered. My arms are killing me after driving(read:man handling) that monster around the back track for the last half hour. It's easier to steer by just kicking out the back than to actually steer. Fun times.

 

[faultsafe]

Only problem is as the engagement rpm increases so
does the high gear lock up point. On mine it fixed the creap but then the engine
was topped out on the governor long before the clutch was in high gear.

I have the heavy weight kit coming as per red beard's garage suggestion on youtube.

Also I have to admit I should have put what engine I'm actually using. I said predator 420cc thinking I'd get more support like an idiot. I'm actually running a DuroMax XP18HP 440cc from Amazon.

Good to know about the loss in top speed with the weights. I plan on removing the governor after the stage 1 kit so I doubt I'll run into those limits. (I was on the fence about removing it but my research seems to suggest that the 'valve float' situation will some what protect the engine from self destructing (why once you replace the springs to fix that you need to replace the internals cause you're going to go to a higher RPM)).

Obviously I don't want to be at that RPM that often but for doing donuts or kicking loose the back end on turns; I think it will be fine.

Only one way to find out. Onwards and upwards.

​

 

[madprofessor]

You could have avoided all of those mismatch, reverse, inverse, float, misalign, etc. by just throwing away the backplate and installing your own jackshaft on the kart with an adjustable slider. The 40 series just doesn't set up well on a backplate with its stubby little too-short built-in jackshaft. All that flipping either driver or driven over, using a reverse spring, etc. ad nauseum will never come into the picture with a separate jackshaft. See construction pics below of 30 series on a backplate, feeding separate fixed jackshaft but with a tensioner on secondary chain.

 

[panchothedog]

MAD
I ain't gonna let you get away with bad mouthing the 40 series torque converter using the plate system like that. Installing the reverse wound spring was maybe a 25 minute job ( it was a lot easier than changing springs on a 30 series
driven unit ) and flipping the driver 180 took as long as it takes to turn your wrist sideways, maybe 1/2 of a second. The whole system works perfectly.
in communicating Eric Adams, the Grey Goat Garage, he told me that they have used the same system they sell ( the one I bought ) on modified 420cc
engines of 25 HP. with no issues. I don't have any problems with a jack shaft system, they certainly work. BUT if your kart doesn't already have one, like mine and possibly many others and you want to install a big block engine
( anything with a 1" output shaft ) the ease and convenience of installing a plate
system VS fabricating and welding up a jack shaft system it was a no brainer.
I feel the comments you made in the previous post were not warranted. I might be wrong but I am reasonably certain you do not own a kart with a 40 series,
jack shaft or not and were only expressing your opinion. I wanted to give mine because it differs drastically from yours, but is based on user experience.

 

[madprofessor]

Pancho, you've stated correctly about a few things............
Yes, I never installed a 40 series, that's why I've researched them so much, to learn all about them without actually doing the work.
Yes, I was only expressing my opinion.
Yes, for just ease and convenience, a backplate is no-brainer-simpler than fabbing your own jackshaft. Note the pics of my kart that has a 30 series on a backplate and a separate jackshaft as well. I certainly know how much simpler a backplate is.
Yes, a jackshaft system will certainly work.

Now please note, I have never said a word about how much power a 40 series can take, as I don't know, and as I've read about people using them on nice V-twin motors without any problems, much less on a simple 420cc.
Please note that I said.................

You could have avoided all of those mismatch, reverse, inverse, float, misalign, etc.

That's not mindless hyperbole, it's a fact. Since faultsafe expressed how he's repeatedly been dealing with all the various problems he'd had over at least 3 different tries and multiple parts, it seemed to me appropriate to express my own version of simple fab. The fact that it was already too late for him to do a separate jackshaft from the start means that my statement was just my opinion about the start of a build, to avoid all of those missteps he dealt with along the way, not what he should be doing now. "......could have avoided......." is the past tense form of speech on the subject. "......could avoid......" would be the present form, if I wanted to say it's what he should do now after the fact, and would be multiplicably dumb.
Thanks for your politely stated input Pancho. I hope you can see that I wasn't bad-mouthing the job of making a 40 series backplate work as correctly as everyone else's 40 series backplate, and that I know creating locomotion out of nothing is fantastic no matter how you do it.

 

[Denny]

You guys do realize he has fixed the problem already, right. Your getting worked up over nothing.

 

[panchothedog]

Not worked up. Not at all, really. I just didn't want folks who might be considering a 40 series plate system to close the door on the idea.
and MAD'S rebuttal of my comments were really quite eloquent.

 

[Denny]

He is quite the writer and his heart is in the right place. He just does not have all the right facts sometimes. But he does mean well.

 

[madprofessor]

He just does not have all the right facts sometimes.

You're surely correct about that, Denny. Hence the reason I sponge up info from all of you on everything that I can, in an attempt to straighten the endless number of neural pathways that I knotted up back in the early 1970's. Or regrow some of the ones I simply incinerated. Timothy Leary, Tom Wolfe, Ken Kesey, and the Merry Pranksters all had nothing on me, and Lucy in the Sky with Diamonds was my girlfriend.