Go Back   DIY Go Kart Forum > Building Plans And Advice > Engines & Clutches

Notices

Reply
 
Thread Tools Display Modes
  #1  
Old 04-21-2019, 10:21 PM
Kade Kade is offline
Junior Member
 
Join Date: Apr 2019
Location: Norwood Louisiana
Posts: 6
Thanks: 1
Thanked 0 Times in 0 Posts
Default Loss of speed

I'm almost positive my clutch is toast on my go kart, especially since it has a tendency to smoke a little and is constantly throwing metal all over the place. I've noticed that I've lost about 6 MPH off of my top speed and was wondering if it could be from the clutch slipping at high RPMs. I hate to be that new guy that keeps beating the hypothetical horse when it comes to clutches, but I could use all the help I can get
Reply With Quote
  #2  
Old 04-21-2019, 11:01 PM
mckutzy mckutzy is online now
Senior Member
 
Join Date: May 2008
Location: bc, canada
Posts: 7,344
Thanks: 812
Thanked 1,753 Times in 1,447 Posts
Default

As said in another thread...Do you oil it every 2hr of use???
Whats the gear ratio?
Whats the motor?
OD of tire size?

Smoke and metal shards are a good examples of a time to stop and think there might be a problem....
__________________
10yr+ club..... My current ride- http://www.diygokarts.com/vb/showthread.php?t=5461
Reply With Quote
The Following User Says Thank You to mckutzy For This Useful Post:
Kade (04-21-2019)
  #3  
Old 04-21-2019, 11:08 PM
Kade Kade is offline
Junior Member
 
Join Date: Apr 2019
Location: Norwood Louisiana
Posts: 6
Thanks: 1
Thanked 0 Times in 0 Posts
Default

Thanks for the reply. I'm not sure about the gear ratio,I keep forgetting to count the teeth on the sprocket. I'm running a 13 in tall tire, and the motor is a predator 212 that I gutted the air box, cut the muffler off, and put a .038 main jet in the carb. I don't oil it as much as I should. It was pretty beat up looking when I bought the kart a few months ago
Reply With Quote
  #4  
Old 04-22-2019, 06:57 AM
J.S.@SMS J.S.@SMS is offline
Here 8am-? Mon-Fri
 
Join Date: Sep 2018
Location: Weeki Wachee Fl.
Posts: 472
Thanks: 51
Thanked 86 Times in 76 Posts
Default

What, exactly, do you mean when you say that you cut the muffler off? You should make sure that it's at least half a foot long, if not longer, or that it has a muffler. If you're exhaust is too short, you might warp a valve, which will need to be replaced.

The gearing is the only problem that I can think of (besides the exhaust). The engine build is questionable, no offense, but it shouldn't be the reason the clutch is toast, literally.
__________________
If a picture is worth a thousand words, what is a video worth?
Reply With Quote
  #5  
Old 04-22-2019, 07:49 AM
Kade Kade is offline
Junior Member
 
Join Date: Apr 2019
Location: Norwood Louisiana
Posts: 6
Thanks: 1
Thanked 0 Times in 0 Posts
Default

None taken. This is my first attempt at hot rodding one of these small engines and I'll be the first to admit that it's a questionable build. It's got a 2 foot long header pipe that I made on it, so it's not just an open exhaust port. And like I said. I picked the motor and clutch up second hand and they looked like they had been put through their paces long before I got my hands on it. I figured the clutch would go bad sooner or later
Reply With Quote
  #6  
Old 04-23-2019, 01:05 AM
landuse's Avatar
landuse landuse is offline
Moderator
 
Join Date: Nov 2010
Location: Pietermaritzburg, South Africa
Posts: 17,229
Thanks: 2,058
Thanked 3,408 Times in 2,777 Posts
Default

There is nothing we can really help you with until we know what your gear ratio is. We can only speculate. So get outside and count the sprocket teeth
Reply With Quote
  #7  
Old 04-23-2019, 11:48 AM
Kade Kade is offline
Junior Member
 
Join Date: Apr 2019
Location: Norwood Louisiana
Posts: 6
Thanks: 1
Thanked 0 Times in 0 Posts
Default

56 on the wheel and 10 on the clutch
Reply With Quote
  #8  
Old 04-23-2019, 01:21 PM
JTSpeedDemon's Avatar
JTSpeedDemon JTSpeedDemon is offline
Currently flathead-crazed
 
Join Date: Jan 2019
Location: Texas
Posts: 1,874
Thanks: 442
Thanked 219 Times in 201 Posts
Default

So, are we talking a 400 lbs. total two seater off road kart? A 200 lbs. total one seater on road kart? The weight is really the deciding factor. If you have something like the latter, then you can probably get away with a 5.6/1 gear ratio(I have 5.5/1 on my one seater yard kart).
__________________
Local Bird Engineering Nut
Reply With Quote
  #9  
Old 04-23-2019, 02:57 PM
Kade Kade is offline
Junior Member
 
Join Date: Apr 2019
Location: Norwood Louisiana
Posts: 6
Thanks: 1
Thanked 0 Times in 0 Posts
Default

It's just a small light weight thunder kart
Reply With Quote
  #10  
Old 04-23-2019, 04:54 PM
JTSpeedDemon's Avatar
JTSpeedDemon JTSpeedDemon is offline
Currently flathead-crazed
 
Join Date: Jan 2019
Location: Texas
Posts: 1,874
Thanks: 442
Thanked 219 Times in 201 Posts
Default

Your clutch is probably just worn out, just replace it with a high quality one and you should(note:should) be good to go.
__________________
Local Bird Engineering Nut
Reply With Quote
  #11  
Old 04-23-2019, 06:20 PM
Kade Kade is offline
Junior Member
 
Join Date: Apr 2019
Location: Norwood Louisiana
Posts: 6
Thanks: 1
Thanked 0 Times in 0 Posts
Default

Thanks for all the help. I'll take any information I can get my hands on
Reply With Quote
  #12  
Old 04-23-2019, 08:08 PM
itsid's Avatar
itsid itsid is online now
Moderator
 
Join Date: Jul 2013
Location: Ruhrpott [Germany]
Posts: 9,995
Thanks: 1,366
Thanked 4,226 Times in 3,166 Posts
Default

13" wheels and 5.6:1 are quite a bit of a stretch
especially since thunderkarts are not exactly lightweight really..
(120 lbs plus or thereabouts)
adding another 200 lbs for an adult rider
and you already need to gear closer to 7:1 in order to not burn the clutch

5.6:1 is tough even if you are below 180lbs of total weight (which I doubt is at all possible)

I don't know what elevations we're looking at here;
if you need to climb the occasional hill or not, if your roads are all perfectly flat and smooth

but I HIGHLY suggest you to get a 65T axle sprocket instead.
(frankly I'd say you might even need more depending on the exact weight)

Fun fact:
in some fuzzy edge cases,
it's even likely that gearing LOWER makes the kart go FASTER,
namely when the engine's power is not enough to fully rev up under load (with the bad gear ratio)
once the gear ratio allows the engine to rev up higher it could 'over compensate' for the lower gear ratio with added rpms under load
I think yours might be a candidate for such borderline cases ...
__________________
Jokes about german sausage are the wurst.
Reply With Quote
The Following User Says Thank You to itsid For This Useful Post:
pearl111 (04-24-2019)
  #13  
Old 04-24-2019, 12:07 AM
landuse's Avatar
landuse landuse is offline
Moderator
 
Join Date: Nov 2010
Location: Pietermaritzburg, South Africa
Posts: 17,229
Thanks: 2,058
Thanked 3,408 Times in 2,777 Posts
Default

I would gear lower like Itsid says. Get a 72T sprocket if ground clearance allows. You won't regret it
Reply With Quote
The Following User Says Thank You to landuse For This Useful Post:
pearl111 (04-24-2019)
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 08:34 PM.