DIY Go Kart Forum

DIY Go Kart Forum (http://www.diygokarts.com/vb/index.php)
-   Engines & Clutches (http://www.diygokarts.com/vb/forumdisplay.php?f=18)
-   -   Comet 40 setup (http://www.diygokarts.com/vb/showthread.php?t=42065)

turnleftandgasit 09-17-2019 05:27 PM

Comet 40 setup
 
2 Attachment(s)
I bought this kart and it runs great except it only goes 17 mph. It tops out in less than 50 ft and just stays there. Like it is stuck in 1 gear. I thought the TQ was set up wrong in the 1st picture so I switched it around and now I have nothing. So it was correct in the first picture? Why only 17 mph? 10/58 on the chain. 3600 rpm should be 33 mph.

gman3850 09-18-2019 12:36 AM

The driven is using the wrong doing so it will never shift you need the yellow spring.

turnleftandgasit 09-18-2019 07:00 AM

In the first picture you can see the driven is inboard and it is in about an inch in on the shaft. It had no lock collar on it. It could slide in and out on the shaft as it pleased. Is this why it didn't shift? It used that energy to slide on the shaft instead of opening the pulley?

Tpdingo 09-18-2019 08:29 AM

Quote:

Originally Posted by turnleftandgasit (Post 533028)
In the first picture you can see the driven is inboard and it is in about an inch in on the shaft. It had no lock collar on it. It could slide in and out on the shaft as it pleased. Is this why it didn't shift? It used that energy to slide on the shaft instead of opening the pulley?

Still needs to be reverse wound. The belt will kinda pull into the groove. See how it is wound now? It can't "back down" because it would need to be wound the other way for it to work.

turnleftandgasit 09-18-2019 01:23 PM

So it needs turned back around and a reverse wound spring?

Tpdingo 09-18-2019 07:32 PM

Quote:

Originally Posted by turnleftandgasit (Post 533068)
So it needs turned back around and a reverse wound spring?

It needs to be rewound but otherwise it is in the correct orientation.

turnleftandgasit 09-18-2019 08:20 PM

thanks

turnleftandgasit 09-18-2019 10:32 PM

Yellow spring ordered, along with 3 circuit bored out carb, header, valve springs, throttle cable and air cleaner.

Tpdingo 09-19-2019 11:59 AM

Quote:

Originally Posted by turnleftandgasit (Post 533136)
Yellow spring ordered, along with 3 circuit bored out carb, header, valve springs, throttle cable and air cleaner.

Did you check before you install the yellow spring that the sheaves are moving freely on both the driver and driven?

turnleftandgasit 09-19-2019 07:58 PM

Parts aren't in yet, but I am doing a full cleanup of it.

mediumsizedhog 10-03-2019 01:34 PM

Quote:

Originally Posted by turnleftandgasit (Post 533188)
Parts aren't in yet, but I am doing a full cleanup of it.

I don't think you need parts for the driven pully, just need to flip it around and hold it still with lock collars. I also don't think either direction will affect your speed, just belt alignment/wear, but thats why its floating right now. You can use it the way it is if it floats and itll just slide to align the belt.

What motor?
Governed or ungovered?
Jackshaft sprocket teeth count?
Axle sprocket tooth count?
Tire diameter?

Need to know all of this, 17 MPH could be right. Just as an example, say its a Predator 212 governed to 3600 RPM. Lets take 8 inch diameter tires, 10 tooth jackshaft sprocket, 60 tooth axle sprocket, your top speed will be like 15 mph according to kartcalc.net

turnleftandgasit 10-03-2019 03:10 PM

predator 420
this one is governed
10
58
18

33 mph

---------- Post added at 03:10 PM ---------- Previous post was at 02:50 PM ----------

You can follow along in the photo section. It is Polaris XB1.
Predator 420 with HD springs, header, 24mm carb off a gx620. Governor is still at stock speed.
Predator 420 with billet rod and flywheel, small cam and 620 carb is waiting to go on it once the front end and rear axle are done. 28hp/40tq. Dyno tuned

mediumsizedhog 10-03-2019 03:25 PM

Quote:

Originally Posted by turnleftandgasit (Post 534073)
predator 420
this one is governed
10
58
18

33 mph

---------- Post added at 03:10 PM ---------- Previous post was at 02:50 PM ----------

You can follow along in the photo section. It is Polaris XB1.
Predator 420 with HD springs, header, 24mm carb off a gx620. Governor is still at stock speed.
Predator 420 with billet rod and flywheel, small cam and 620 carb is waiting to go on it once the front end and rear axle are done. 28hp/40tq. Dyno tuned

Well in that case 17 mph means something is wrong. Try flipping the driven unit.

turnleftandgasit 10-03-2019 04:03 PM

I did flip it and it wouldn't move an inch. I didn't try locking it down in the original orientation, but wish I had. It now has the yellow spring in it and am waiting on a coil.

itsid 10-03-2019 10:45 PM

yes first picture is correct.
it needs to be fixed in place though (locking collar, shorter or just moved over shaft!)

installing a reverse wound spring is frankly the wrong way of fixing that IMHO
(in which case it needs to be a floating installation [i.e. the driven pully must move 7/8" inboard.. and that's going to hit against the frame then!!])

So no.. yellow spring is not the way to go!

'sid

turnleftandgasit 10-05-2019 05:01 PM

New red spring ordered, buttons, med weights, red driver springs, bronze bushing, 54/10 sprockets with hub assembly and a 40 chain.

This will be 4 less teeth on the axle. With the added power, and higher engagement, I don't think it will be noticeable.

turnleftandgasit 10-14-2019 07:57 PM

1 Attachment(s)
Red spring installed, put back in original orientation and again I have only one speed. Now it does run pretty good. It will spin doughnuts on dry pavement no problem but the driven does not open at all. Again looking for input as I am ready to just buy a new comet driven and be done with it.

turnleftandgasit 10-15-2019 03:47 PM

swapped yellow spring into it and still nothing. Kart runs 21 mph in single stage. That is 4 mph increase from when I got it. Ordering a new comet 40 driver and driven. Tired of messing with it.

itsid 10-15-2019 11:30 PM

I took another closer look at the second pic you posted in the first post up there..

quite obviously the TC cannot shift up properly and is stuck maybe 30% the way up the driver sheaves.
Main cause is lack of power..
maybe my assumptions have been incorrect..
I was assuming a 9hp engine and 15" wheels ..
but now I checked with the calc and that'd only be 27.7 mph
and to get to 33 that'd rquire 18" wheels..
and if my assumption on hp were off too (like say just a 6horse powerplant)
we could be onto something (since that'd certainly wouldn't gain full speed at all..
and rusted sheaves surely are no improvement, worn sticky weights aren't and so on and so forth..

Wait.. you checked the rollers in the driver already?
if they're no longer perfectly round, slipped off track or such, you certainly won't be able to shift up.

'sid

turnleftandgasit 10-16-2019 06:42 AM

Lack of power is not a cause. It will spin doughnuts on dry pavement no issue.
18 inch tires, 5.40 gear ratio, predator 420 with header pipe and gx 620 carb.
The driven clutch will not open up at all. The driver opens up ok, not the smoothest but reaches full extension. The driver is just a 7.5 inch pulley that won't open in either orientation with either the yellow or red spring in it. The driven has been taken apart and I used wire brushes to clean and polish the moving parts, so it slides in and out like you did with your first college GF.

---------- Post added at 06:39 AM ---------- Previous post was at 06:21 AM ----------

New TQ will be here tomorrow (gotta love next day air). I will try to figure out the issue, so they can sit on the shelf as spares. I would have ordered the 44 driven but I don't have room for it due to the crossbar in front of the motor. The new motor mount will have to address that as I will be running a larger Comet or CVTech TQ

---------- Post added at 06:42 AM ---------- Previous post was at 06:39 AM ----------

This is the video I followed to clean up the driven. As I said above, I hadn't gotten to the driver yet as it was opening and closing.

https://www.youtube.com/watch?v=a3FC...ature=youtu.be


All times are GMT -6. The time now is 01:31 PM.

Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.