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

Notices

Closed Thread
 
Thread Tools Display Modes
  #1  
Old 05-25-2017, 05:43 AM
Abtheman28 Abtheman28 is offline
Junior Member
 
Join Date: Mar 2014
Location: New Zealand
Posts: 28
Thanks: 5
Thanked 0 Times in 0 Posts
Default Modified Gx200

Hey guys,

I have a highly modified gx200.....everything engine related is replaced minus the crank and ignition coil. For ages now it's been running like a dream! No issues at all. The other day my son was riding the go kart around our section at home whizzing around having a great time, then all of a sudden it coughed and splattered just above idle and stalled the motor. I got it running again straight away with no issues and as soon as I bring the motor above idle it's coughs and runs like a bag of crap then stalls each and every time. A list below shows what I have done to try and fix the issue....

Stripped and cleaned carb, blow out ports with air gun. (no issues found, and replaced gaskets)
Changed spark plug with a new one
Changed fuel and cleared fuel lines with new fuel also install new fuel filter.
Removed head and inspected valves (no issues), install new head gasket.
Reset valve clearances

After all the above work it still has the same problem....

Is it posssible the ignition coil could be causing the issue of cutting the motor out above idle, and make it run like a bag a crap also? It's the only thing that it could be as far as I can see based on what I've done. Any help would be much appreciated! Also the other issue I have is I noticed the plug was very carboned up.... (very black) what can I do to help this issue and run the motor more stochmetric? I am running a modified stock carb (bored) etc.
  #2  
Old 05-25-2017, 07:58 AM
mckutzy mckutzy is offline
Senior Member
 
Join Date: May 2008
Location: bc, canada
Posts: 7,462
Thanks: 834
Thanked 1,788 Times in 1,478 Posts
Default

Could check the air gap, incase the coil slipped...
__________________
10yr+ club..... My current ride- http://www.diygokarts.com/vb/showthread.php?t=5461
  #3  
Old 05-25-2017, 08:36 AM
Whitetrashrocker's Avatar
Whitetrashrocker Whitetrashrocker is offline
Inmate #952016
 
Join Date: Sep 2016
Location: Southern New Mexico
Posts: 2,090
Thanks: 303
Thanked 807 Times in 626 Posts
Default

Possible ignition wire shorting out?

Sooty black plug is either oil burn or really rich.
__________________
Think for yourself, Question authority.
  #4  
Old 05-25-2017, 08:45 AM
KartFab's Avatar
KartFab KartFab is offline
Senior Member
 
Join Date: Jan 2013
Location: Dallas, TX
Posts: 3,299
Thanks: 497
Thanked 1,455 Times in 1,028 Posts
Default

Flywheel key sheared?
__________________
Free Go Kart Plans https://kartfab.com Go Kart Videos https://www.youtube.com/c/KartFab
  #5  
Old 05-25-2017, 02:27 PM
Abtheman28 Abtheman28 is offline
Junior Member
 
Join Date: Mar 2014
Location: New Zealand
Posts: 28
Thanks: 5
Thanked 0 Times in 0 Posts
Default

Quote:
Originally Posted by mckutzy View Post
Could check the air gap, incase the coil slipped...

Cheers mate. Yeah I forgot to mention I also removed the ignition coil and sanded the coil contacts plus magnets on flywheel as they were rusted slightly. Reset gap between coil and flywheel... (same issue running) I will pull flywheel today and see if they key is sheared or not.

---------- Post added at 07:27 AM ---------- Previous post was at 07:21 AM ----------

Quote:
Originally Posted by Whitetrashrocker View Post
Possible ignition wire shorting out?

Sooty black plug is either oil burn or really rich.
Cheers, I also have another ignition coil on order. Hoping either the coil or the flywheel key are the issue, if not I'm lost!
  #6  
Old 05-25-2017, 02:45 PM
Whitetrashrocker's Avatar
Whitetrashrocker Whitetrashrocker is offline
Inmate #952016
 
Join Date: Sep 2016
Location: Southern New Mexico
Posts: 2,090
Thanks: 303
Thanked 807 Times in 626 Posts
Default

I meant to say the kill switch wire shorting too.
Un plug the ground on the coil and see if problem persists.
__________________
Think for yourself, Question authority.

Last edited by Whitetrashrocker; 05-25-2017 at 03:53 PM. Reason: Spell check was drunk again.
  #7  
Old 05-25-2017, 02:52 PM
Abtheman28 Abtheman28 is offline
Junior Member
 
Join Date: Mar 2014
Location: New Zealand
Posts: 28
Thanks: 5
Thanked 0 Times in 0 Posts
Default

Quote:
Originally Posted by Whitetrashrocker View Post
I meant to say the kill switch wire shorting too.
In plug the ground on the coil and see if problem persists.

Thanks! I'll give that a go shortly and see how I get on.
  #8  
Old 05-25-2017, 04:36 PM
Poboy kartman Poboy kartman is offline
Banned
 
Join Date: Jul 2013
Location: White Settlement Texas
Posts: 12,463
Thanks: 3,769
Thanked 2,954 Times in 2,300 Posts
Default

OK...let's back this up and make it a little simpler. People want to act like they know something, and are really, there own worst enemies.

If you shoot carb cleaner in the carb, does it run for a few seconds? If so, you need either a carb clean or new carb.

If not, you have an electrical issue, which we can talk about....
The Following User Says Thank You to Poboy kartman For This Useful Post:
Flyinhillbilly (05-26-2017)
  #9  
Old 05-25-2017, 09:49 PM
Abtheman28 Abtheman28 is offline
Junior Member
 
Join Date: Mar 2014
Location: New Zealand
Posts: 28
Thanks: 5
Thanked 0 Times in 0 Posts
Default

Quote:
Originally Posted by Poboy kartman View Post
OK...let's back this up and make it a little simpler. People want to act like they know something, and are really, there own worst enemies.

If you shoot carb cleaner in the carb, does it run for a few seconds? If so, you need either a carb clean or new carb.

If not, you have an electrical issue, which we can talk about....
Hey mate,

Thanks for your advice. Well I carried on today with trying to fix the issue. I had pre ordered a brand new ignition coil for the motor which I installed in the hope it may be that... but it was not the problem! The motor still coughs and farts then stalls. I completely changed the carb from the modified one back to the stock carb and same issue. I also unplugged the small lead which comes off the coil....one connection to kill switch On steering wheel and the other connection to the start stop switch on the back of the flywheel cover and this also made no change. I am now at a stage where I really don't know what else it could be as I've checked almost everything apart from cylinder compression. Is there a chance the rings on the piston could be the issue? The motor was fully rebuilt about 2yrs ago and has probably only had 5hrs of use since then. Up until the other day is was running perfect!
  #10  
Old 05-25-2017, 10:05 PM
Whitetrashrocker's Avatar
Whitetrashrocker Whitetrashrocker is offline
Inmate #952016
 
Join Date: Sep 2016
Location: Southern New Mexico
Posts: 2,090
Thanks: 303
Thanked 807 Times in 626 Posts
Default

Ok it sound like you have a grasp on engines, kinda.

Pull spark plug and reinstall wire, hold plug to engine and pull cord. Check for spark. Yes, no? Sounds like it has spark.
Is gas getting into cylinder? Clean plug and reinstall. Choke and gas on pull over a few. Pull plug, wet?
Compression? Put finger on spark plug hole hold tight, pull rope. Blow finger off?

If all passes and I'm sure it will. You either haven't cleaned the carb or you might have a sheared flywheel key.

It's really hard to tell from my chair....
__________________
Think for yourself, Question authority.
  #11  
Old 05-26-2017, 12:28 AM
Bbqjoe Bbqjoe is offline
Banned
 
Join Date: May 2016
Location: Location, Location
Posts: 3,463
Thanks: 64
Thanked 1,003 Times in 716 Posts
Default

Fuel cap.

Take off fuel cap. Start engine, watch it run,...Do happy dance!
  #12  
Old 05-26-2017, 12:37 AM
Abtheman28 Abtheman28 is offline
Junior Member
 
Join Date: Mar 2014
Location: New Zealand
Posts: 28
Thanks: 5
Thanked 0 Times in 0 Posts
Default

Quote:
Originally Posted by Whitetrashrocker View Post
Ok it sound like you have a grasp on engines, kinda.

Pull spark plug and reinstall wire, hold plug to engine and pull cord. Check for spark. Yes, no? Sounds like it has spark.
Is gas getting into cylinder? Clean plug and reinstall. Choke and gas on pull over a few. Pull plug, wet?
Compression? Put finger on spark plug hole hold tight, pull rope. Blow finger off?

If all passes and I'm sure it will. You either haven't cleaned the carb or you might have a sheared flywheel key.

It's really hard to tell from my chair....

Ok, I have checked the spark and it's a real good one!
Have checked the flywheel key and it's in good condition, no issues.
Have checked for raw fuel on plug and after cranking the motor over and over and over the plug is still dry.

As I mentioned earlier I had the same issues with running the motor on both the modified carb and the stock one. I cleaned the modified carb about 3 times, totally stripped it down and blew out all the ports and saw carb cleaning coming through each one also. Next test is compression once I get a tester for it

---------- Post added at 05:37 PM ---------- Previous post was at 05:35 PM ----------

Quote:
Originally Posted by Bbqjoe View Post
Fuel cap.

Take off fuel cap. Start engine, watch it run,...Do happy dance!

New to this, but what symptoms of the motor running properly would a fuel cap cause? I am not running a fuel pump it's only gravity fed from the tank to the carb
  #13  
Old 05-26-2017, 12:42 AM
Bbqjoe Bbqjoe is offline
Banned
 
Join Date: May 2016
Location: Location, Location
Posts: 3,463
Thanks: 64
Thanked 1,003 Times in 716 Posts
Default

Quote:
Originally Posted by Abtheman28 View Post
Ok, I have checked the spark and it's a real good one!
Have checked the flywheel key and it's in good condition, no issues.
Have checked for raw fuel on plug and after cranking the motor over and over and over the plug is still dry.

As I mentioned earlier I had the same issues with running the motor on both the modified carb and the stock one. I cleaned the modified carb about 3 times, totally stripped it down and blew out all the ports and saw carb cleaning coming through each one also. Next test is compression once I get a tester for it

---------- Post added at 05:37 PM ---------- Previous post was at 05:35 PM ----------




New to this, but what symptoms of the motor running properly would a fuel cap cause? I am not running a fuel pump it's only gravity fed from the tank to the carb
Fuel caps fail to breathe sometimes. This creates a vacuum in the tank, gas barely or not at all getting to engine. Go try it real quick. I'll wait.....
  #14  
Old 05-26-2017, 01:05 AM
Abtheman28 Abtheman28 is offline
Junior Member
 
Join Date: Mar 2014
Location: New Zealand
Posts: 28
Thanks: 5
Thanked 0 Times in 0 Posts
Default

Quote:
Originally Posted by Bbqjoe View Post
Fuel caps fail to breathe sometimes. This creates a vacuum in the tank, gas barely or not at all getting to engine. Go try it real quick. I'll wait.....
Got the engine running but will trial it Tomorrow with no fuel cap. It's always once it's under load it ****s itself. Fingers crossed!
  #15  
Old 05-26-2017, 01:08 AM
Bbqjoe Bbqjoe is offline
Banned
 
Join Date: May 2016
Location: Location, Location
Posts: 3,463
Thanks: 64
Thanked 1,003 Times in 716 Posts
Default

It's simple really.


I'll have my people get a hold of your people, and your people can just give the check to my people.
  #16  
Old 05-26-2017, 02:43 AM
Abtheman28 Abtheman28 is offline
Junior Member
 
Join Date: Mar 2014
Location: New Zealand
Posts: 28
Thanks: 5
Thanked 0 Times in 0 Posts
Default

When I do the compression test what sort of reading should I expect to see from a flat top piston, and also what pressure would be classed as a failed test?
  #17  
Old 05-26-2017, 07:49 AM
Whitetrashrocker's Avatar
Whitetrashrocker Whitetrashrocker is offline
Inmate #952016
 
Join Date: Sep 2016
Location: Southern New Mexico
Posts: 2,090
Thanks: 303
Thanked 807 Times in 626 Posts
Default

A simple compression​ test is to hold your finger on the sparkplug hole. Pull rope. It should pop your finger off. If you get a real compression gauge I'm gonna guess anything over say 70 or 80 psi would be good.

But yet you say it runs? Sorta

Sounds like a fuel delivery problem.
__________________
Think for yourself, Question authority.
  #18  
Old 05-26-2017, 08:37 AM
KartFab's Avatar
KartFab KartFab is offline
Senior Member
 
Join Date: Jan 2013
Location: Dallas, TX
Posts: 3,299
Thanks: 497
Thanked 1,455 Times in 1,028 Posts
Default

Quote:
Originally Posted by Abtheman28 View Post
When I do the compression test what sort of reading should I expect to see from a flat top piston, and also what pressure would be classed as a failed test?
Since the cam has a compression release, it's kind of a crap shoot.
Gx620 has 120 psi cranking w/electric start

But I've also seen 65 psi in the pull start ones w/zero issues.

If it's bad cylinder walls or bad rings or improper valve seal etc....you get the compression test first, then pour a tiny bit of oil in the spark plug hole, then turn it over a few times to spread it around, then recheck pressure. If pressure goes up, then you have a sealing problem
__________________
Free Go Kart Plans https://kartfab.com Go Kart Videos https://www.youtube.com/c/KartFab
  #19  
Old 05-26-2017, 08:43 AM
Bbqjoe Bbqjoe is offline
Banned
 
Join Date: May 2016
Location: Location, Location
Posts: 3,463
Thanks: 64
Thanked 1,003 Times in 716 Posts
Default

Quote:
Originally Posted by KartFab View Post
you have a sealing problem
This would be a ceiling problem.

Oh wait, sealing.
Attached Images
 
  #20  
Old 05-26-2017, 04:14 PM
Kleyny Kleyny is offline
Senior Member
 
Join Date: Jan 2017
Location: Brisbane Australia
Posts: 140
Thanks: 11
Thanked 21 Times in 18 Posts
Default

Shouldn't the compression test be done with the motor wound backwards to remove the decomp mechanism out of the equation?
I don't know I haven't tested the theory but this is what has been said a few times.

Whats everyones thoughts on it?
Closed Thread

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 02:35 PM.