2 things - Chain and Carb

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otheracco

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Jul 19, 2010
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OK, I'm almost done building this thing.

1.) When the chain is hooked up to the sprocket, I can disengage the clutch and go forward for about 3 feet before the bike stops. However, if I take the chain off of the sprocket, disengage the clutch, and pull the chain with my hand, I can pull forever without it locking up.

I'm pretty sure that the sprocket needs moving in or out, but how do you shim it?




2.) I've worked on motorcycle carbs before, but this is different. It's the Skyhawk GT5 but where's the boot? How can the carb make a vacuum tight seal to the intake without a boot? All I see are 2 whiteish peices of plastic that don't even seem to make full contact with each other. How can this be air tight?
:-||
 
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madscihighpsi

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Sep 5, 2010
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otheracco said:
OK, I'm almost done building this thing.

1.) When the chain is hooked up to the sprocket, I can disengage the clutch and go forward for about 3 feet before the bike stops. However, if I take the chain off of the sprocket, disengage the clutch, and pull the chain with my hand, I can pull forever without it locking up.

I'm pretty sure that the sprocket needs moving in or out, but how do you shim it?




2.) I've worked on motorcycle carbs before, but this is different. It's the Skyhawk GT5 but where's the boot? How can the carb make a vacuum tight seal to the intake without a boot? All I see are 2 whiteish peices of plastic that don't even seem to make full contact with each other. How can this be air tight?
:-||
Click to expand...
Same problems bud.

:-||
 
Wm Holden

Wm Holden

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Jun 1, 2011
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I had to dremel the drive gear to a "rounded" pattern...the grubee instructions show and they concede that their castings are not consistant.(flat top gears are not acceptable)
I could not roll my bike back even 3 feet when I first assembled it..now I can roll back all day.
Also...try to get the chain length so perfect that the "tensioner" is hardly a "tensioner" at all...but more of a "guide to center the chain" on the rear sprocket.
I'm on my 3rd build and these are tips that seem to be relevant across all three bikes.

 
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otheracco

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Jul 19, 2010
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Wm Holden said:
I had to dremel the drive gear to a "rounded" pattern...the grubee instructions show and they concede that their castings are not consistant.(flat top gears are not acceptable)
I could not roll my bike back even 3 feet when I first assembled it..now I can roll back all day.
Click to expand...
I'm not having a problem rolling back, but forward.

I checked the instructions for the drive gear info but didn't find it. Do you mean the gear on the wheel or on the engine.

DuctTapedGoat said:
Try without the white pieces.

On your sprocket, is it convex or concave looking at it from the left side on the bike?
Click to expand...
The sprocket is concave when looking at it from the left side, that's shiny side next to spokes.

What do the white peices do? If I take them out there will be a half inch gap I think. Maybe I'll take a picture of everything tomorrow and post it.
 
DuctTapedGoat

DuctTapedGoat

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Dec 20, 2010
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Cool, that's how the sprocket is supposed to go. Lots of people put it on backwards, so I like to check.

I've heard that's what causes the air leaks, is the white pieces.
 
Wm Holden

Wm Holden

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Jun 1, 2011
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otheracco said:
I'm not having a problem rolling back, but forward.

I checked the instructions for the drive gear info but didn't find it. Do you mean the gear on the wheel or on the engine.


The sprocket is concave when looking at it from the left side, that's shiny side next to spokes.

What do the white peices do? If I take them out there will be a half inch gap I think. Maybe I'll take a picture of everything tomorrow and post it.
Click to expand...
engine...and front or back its alignment..are the engine teeth round or flat on top?
 
DuctTapedGoat

DuctTapedGoat

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Oh, drive sprocket is the sprocket on the engine, driven sprocket is the one on the wheel.

That you're aligned going backwards is good! That means your direct alignment between drive sprocket and driven sprocket is good. The tensioner is used for your forward movement alignment as well as applying tension.
 
O

otheracco

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Jul 19, 2010
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DuctTapedGoat said:
Oh, drive sprocket is the sprocket on the engine, driven sprocket is the one on the wheel.

That you're aligned going backwards is good! That means your direct alignment between drive sprocket and driven sprocket is good. The tensioner is used for your forward movement alignment as well as applying tension.
Click to expand...
OK, good. I just took a few more links off my chain before it started raining. Will test it tomorrow.

Here's a pic of my carb with the white pieces on.



I don't know, but it honestly looks like the white pieces are necessary and if I take them out the inner diameter of the carb at it's smallest will be bigger than the outer diameter of the engine intake piece, so how could it work without the white spacer pieces.

That being said, how can it work WITH the white spacer pieces, because they don't look like they form a tight seal. These instructions that came with it are somewhat helpful but not detailed enough.
 
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otheracco

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Jul 19, 2010
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Greg58 said:
You have the cns2 EPA carb. the spacer is just that, it does not seal anthing. The seal is made with the black washer that the intake slides into. ]
Click to expand...
I was afraid of that. That's a crap design considering the fact that the carb still moves around after you tighten it onto the intake.

I'll rig something else up if I find it's necessary.

I am still having the chain problem. With it just a little taut it's 'almost' coming off of the drive sprocket; that is it's coming halfway off and then reseating without my help. Perfect sprocket alignment I have not.

I'll try adjusting the tensioner tomorrow. I'm sure there are several threads just for this topic; I'll check them out.
 
P

PerryP180

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Jun 24, 2011
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Go ahead and get rid of the stock chain. Get a #41. This chain is much more forgiving on misalignment and loose chains. Most ace hardwares will have them.
 
G

gubba

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Dec 29, 2008
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the sprocket on the motor is also called the 'power' sprocket.
position the tentioner where the top and bottom chains are exactly vertical to each other. this is a good starting point.
remove the excessive slack (1 inch up and down is very good)
note if the chain is rolling off the rear sprocket toward the spokes or toward the frame.
move the tentioner bracket in or out SLIGHTLY to guide the bottom chain onto the center of the rear sprocket.

i have built over 30 of these for customers and i do the following to all of them........
cut off a 2" piece of medium garden hose and split it longways. put this between the frame and the bracket.
replace the provided tention bolts with ACE hardware's hardest matching size bolts (not the roller shaft bolt....lol) and tighten the crap out of them. this will help keep the bracket from 'drawing' the roller into the spokes..... disaster

there will surely be other methods offerd but i have found this works best in all of my applications.

good luck

stay dry
gubba
 
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otheracco

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Jul 19, 2010
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DuctTapedGoat said:
Don't they sell an intake that matches the CNS carb specifically so you can dodge the spacer thing?
Click to expand...
I don't know, I'm not going to look unless the plastic spacer breaks.

gubba said:
the sprocket on the motor is also called the 'power' sprocket.
position the tentioner where the top and bottom chains are exactly vertical to each other. this is a good starting point.
remove the excessive slack (1 inch up and down is very good)
note if the chain is rolling off the rear sprocket toward the spokes or toward the frame.
move the tentioner bracket in or out SLIGHTLY to guide the bottom chain onto the center of the rear sprocket.

i have built over 30 of these for customers and i do the following to all of them........
cut off a 2" piece of medium garden hose and split it longways. put this between the frame and the bracket.
replace the provided tention bolts with ACE hardware's hardest matching size bolts (not the roller shaft bolt....lol) and tighten the crap out of them. this will help keep the bracket from 'drawing' the roller into the spokes..... disaster

there will surely be other methods offerd but i have found this works best in all of my applications.

good luck

stay dry
gubba
Click to expand...
I'll try these suggestions if I need to except that I'll probably use a blown innertube instead of piece of hose.

I have good news, the chain is on and not coming off, but it seems pretty darn tight.

Here's what it says in my instructions about the chain

Proper
chain length is when top chain has ¼ inch to ½” deflection with the bottom side of the chain loop tight.

I'm foggy on what they mean by 'deflection'. My chain is pretty tight, but if I push down on it, it will move, but it has no noticeable deflection from gravity alone.

Here are 2 pics. The first one I'm not pushing down, the second I am pushing down with a fair amount of force (but without 'hulking' it).




I didn't measure the deflection, but you can see the red mark I photoshopped on there to show the deflection.

The bottom of the chain moved up when I pushed down on the top and there's a white mark clearly visible below the bottom side of the chain to see the deflection there as well.

I guess my question is 'when people say deflection, do they mean deflection with you having to push down?'.

Anyway, how's it look?
 
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gubba

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Dec 29, 2008
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CCO'''''
glad its better.....
the chain appears a little tight......
a spinoff from the chineese manual......
they instruct you for about the tention you show. this is to help break-in the rear sprocket teeth.
use a small hand grinder and 'dress' the teeth of the rear sprocket.... these sprockets are chrome plated. take a couple of trips up and down both sides of each tooth and round off the flat tip of the tooth. use a medium grinding tool and go all the way down to the bottom of the V and up the other side. rounding off the tip will help guide the tooth into the link.
loosen the roller a little and tap ther roller down until there is a bit of slack. using you finger under the top chain and lift the chain lightly. you should have about i inch of slack from bottem to top...... this IS NOT exccesive (this 'travel' is called the deflection amount)
it will also allow the chain to adjust to the center of the link. lube the chain. you will instantly notice more horsepower and performance.

NOTE !
grubee kits are now putting BICYCLE chains in the kit BAD BAD
replace now with a 415 chain. some can use a #41. i only use a #415. this is the chain most of the non-grubee kits include the 415 . you can get a 415 from thatsdax.com for about $15.00
i WILL NOT use the bike chain in some kits on any build

stay dry....
gubba
 
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DuctTapedGoat

DuctTapedGoat

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Dec 20, 2010
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It's all bicycle chain due to the pitch - but what they put in the kits is 410, bicycle chain is 210.

Not that I'm sticking up for em, it's got no room for alignment play which makes it junk, but just so we're all on the same page.
 
O

otheracco

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Jul 19, 2010
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OK, I got it running! The chain is coming off at least once a mile, but if it stretches it might fix itself. I'll have to get some kind of grinder wheel to use with my drill to fix the sprocket teeth.

Anyway, now I could use help tuning it.

It's perfectly fine when going at idle, but when I hit the gas it did bog down until I adjusted the fuel/air mix screw and turned it all the way in. It only went in 1.25 turns and won't go no more. Now it's much better, but still leaves a lot to be desired. It's still sluggish when I hit the gas.
Here's a picture, correct me if I'm wrong, but I believe the screw on the right is idle mix and the left is regular mix.



Anyway, this screw (left one) is maxed now but it's still sluggish. What's next besides getting a different carb?

Other than that, this throttle cable is way too long, so is the kill switch cable.
The clutch in particular becomes harder to disengage depending on where you move the throttle cable. What's the best way to secure this thing?

Finally, my wheel sprocket became misaligned.
I readjusted it and here's the picture. I got it here with a rubber mallet, how's it look?

 
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otheracco

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