Yerf Dog Scout Issues

[corylee03]

This is NOT a go-kart. What a let-down. It is in fact a *utility* UTV.

No it’s technically not a go kart but it is pretty much built the same. Especially since yerf made it. We work with what we got. Should have our go kart tomorrow im hoping.

 

[Denny]

The bar must be very low then!

Thanks. We still have a decent ways to go and then of course there are the things we WANT to done to make it our own.

Oh, the bar here is very low for everything!

 

[corylee03]

Alright so the stuff for the choke cable has been ordered and is somewhere in transit. Bad news is, after riding it a little while, I noticed the belt started to slip and then the chain was skipping teeth as well. None of this is really a surprise. I assumed this area would need attention sooner or later. Just seems to be sooner rather than later.

Also, anyone who has a gy6, does the engine oil run extremely hot? We added oil to it originally to get it going and now that it has been ridden for a couple hours, we decided to change the oil again in case there was anything that it had flushed out. When doing this, I couldn’t touch the drain plug it was so hot. Yes i know that oil get hot in an engine, but this was MUCH hotter than say in my truck right after i have been driving it.

I did change the oil and then cleaned the oil cooler to ensure air was able to move through it. It seemed to be already decently clean. I then also removed the oil line off the oil cooler and ensured the oil pump was pushing oil to the cooler. I also removed the line out of the oil cooler and ensure that it was flowing through the cooler and there was no blockage. All check out. Topped the oil back off and figured we would keep a close eye on it and see what it does with fresh oil and a clean oil cooler.

I think we plan to pull the whole swing arm out from under it so the CVT and chain tensioner are easier to work on. I’ll post more when we get time. Not sure we will have a lot of time with the holiday to work on it.

 

[Denny]

Probably worn sprockets and stretched chain. Variators are probably going to need to be cleaned and repaired and lubed with dry graphite powder or spray. Buy the best quality belt you can find by a name brand. Cheap belts are just that cheap, and won’t last and will melt.

 

[corylee03]

Probably worn sprockets and stretched chain. Variators are probably going to need to be cleaned and repaired and lubed with dry graphite powder or spray. Buy the best quality belt you can find by a name brand. Cheap belts are just that cheap, and won’t last and will melt.

That’s what i have gathered on the belt. Without having looked at it yet, im assuming we will have to get another belt and clean everything up on the CVT. Wuldnt surprise me to need to roller or slide weights either. Not telling how many hours is on this machine since the hour meter is missing. As far as the chain (once again I haven’t inspected anything), i have a very sneaky suspicion that the homemade tensioning system is not working as well as it should. Any particular brand of belt that is known to be a good quality?

 

[Denny]

I have no idea with the gy6 style engines on belt brands, Dayton? Rotary? Mando?

 

[corylee03]

I know in the industrial world we have used both Dayton and gates and had good luck. Now just to match of the size when we tear it apart.

 

[corylee03]

We have pulled the entire swing arm out from under it so we could access the CVT easier. Found out that one of the rear shocks is broken as well so that will need to be replaced. Pulled the cover off the CVT and the belt seems to be in good shape. I haven’t pulled the clutch and variator off yet. It seems that there is a special tool to remove these? We do not have one and didnt have much time or items on hand to make a tool to remove it. Anyone have any good tricks to remove these?

 

[corylee03]

Just some pics to show the fun!

 

[Denny]

Looks like your up to your neck in fun!

 

[corylee03]

Looks like your up to your neck in fun!

Absolutely. We will eventually get it all back together though. Probably going to be a little more delayed than i first hoped but we aren’t in that big of a hurry.

 

[corylee03]

Alright so we managed to use some redneck ingenuity to get the variator and clutch off. As expected the weights have some small flat spots on them and the case, variator, and clutch all had build up inside of it. It seems that the clutch pads still have a little meat on them but they are also glazed over. Think we are just going to go ahead and bite the bullet and order a new clutch and some slide weights. Sure we could clean it all up and get it back functional but at the same time we might as well go ahead and slam the hood on this area for the foreseeable future.

We also got the choke attachment to the carb fixed. Lesson learned there…..watch the shipping costs!

My wife is moving her business into a new space so we have some extra expenses coming down the line so it may be a little bit before i get the rest of this straightened out.

As far as the chain tensioner…it is def a robust set up but lacks adjustability. I have looked at other (and cheaper) ways of doing it but i think it’s probably going to be best to go ahead and get the factory set up back on it.

Good news is….the wife is already asking if we can put a new roof on it. Reeling her in slowly on the idea of fixing it up!

So has anyone ever messed with the CVTs on the GY6’s? We were thinking of doing slide weights but going a different on the weights. Haven’t decided which weights to use or if we want to change to a different contra spring. Still researching. Any input from someone that has some experience with this would be greatly appreciated. We live in a very hilly area but we also dont plan to be hauling much weight with this thing. It is more or less going to be a “pavement princess”. My son says that he would rather do a little heavier weight to gain a little more top end, but I am not in much of a hurry for much anymore so Im leaning a little more towards a lighter weight that will provide a little better pulling power up hills. In the grand scheme of things, probably neither will be wrong. I do see the added benefit from a little more road speed to get to our farms that we have leased, but i also dont want to struggle up any type of incline.

As far as the contra spring, i still have to find some more information on tuning this whole set up together. We have decided to replace the entire clutch and the price difference between the 2 are almost nothing.

 

[Denny]

I think going lighter will serve you better in the long run with hills.

 

[panchothedog]

Lighter weights will let the engine rev higher before clutch engagement, which will give the kart stronger acceleration. I have never worked with a GY6 torque converter, but I have worked a LOT with the standard 30 and 40 series torque converters. I'm sure the principle is the same. It's been my experience that a higher engagement rpm will let the engine get into the upper rpm range and increase top speed. This has been with modified ungoverned predator engines. Stronger springs in the driver have the same affect. If you have a variety of spring tensions available, it is easy to build it just the way you want it.

 

[panchothedog]

Having the wife on board is better than having $300 extra to spend on parts.

 

[corylee03]

Lighter weights will let the engine rev higher before clutch engagement, which will give the kart stronger acceleration. I have never worked with a GY6 torque converter, but I have worked a LOT with the standard 30 and 40 series torque converters. I'm sure the principle is the same. It's been my experience that a higher engagement rpm will let the engine get into the upper rpm range and increase top speed. This has been with modified ungoverned predator engines. Stronger springs in the driver have the same affect. If you have a variety of spring tensions available, it is easy to build it just the way you want it.

Im sure the principles are the exact same. Just different naming for whatever reason.

I do not have a variety on hand so i will have to be ordering some. Just want to make sure i understand correctly. If not, please correct me!

The lighter weights will take more RPMs to engage the variator (or engine side pulley) since there will not be as much mass “slinging” to the outside to cause it to engage. This will allow the engine to be at a higher RPM and take off with more power causing more acceleration.

The next part is what I am a little confused on. The higher engagement RPM will allow the engine to get into the upper RPM range and increase top speed? So a lighter weight will cause both more acceleration and a higher top speed? I was under the impression that it would decrease top end speed. More or less it was a trade off between top end speed and bottom end pull.

 

[Denny]

It usually increases top speed because the engine is making more torque and horsepower at a higher RPM.

 

[corylee03]

It usually increases top speed because the engine is making more torque and horsepower at a higher RPM.

Alright then. Well it had 13g roller weights in it then. We will probably go back with 11g slider weights. I would imagine we will notice at least a little difference with that change.

 

[Denny]

Only experimentation will tell.

 

[panchothedog]

Most torque converters, once into the higher gear range tend to limit peak rpm due to the load placed on the engine. My experiences are with modified ungoverned engines running aftermarket cams. But unless your engine is at its all out max rpm with the stock converter setup, the same will hold true. Any engine will make more power at a higher rpm, up until you reach the limits of it's valve train and cam. If you weren't already there, there is more to be had by letting it rev higher before it starts to work. Do you know how to drive a stick shift car? Dump the clutch at 1500 rpm. Now dump the clutch at 3500 rpm. You're giving the engine the opportunity to live in a higher ( more powerful ) rpm range. I wasn't assuming you had multiple sets of springs laying around. But if there is a selection of stiffer ones for sale, you can customize your setup to your own liking. The spring sets for the common 30 series are dirt cheap. Like $10 a set.
I probably have 10 sets in my spare parts box.