Intermittent 4 stroking

GoldenMotor.com

Henshooter

New Member
Feb 10, 2014
275
0
0
Melbourne au
Hi guys I'll start with the running specs of my motor and then get to the problem .

Standard 66cc chinagirl kit with angle fire head and speed carby (the one with the red air filter) ,replaced standard CDI cable with good automotive one , kit has run for approx 2 months . Full flushed fuel system and it's as clean as a whistle so no issue with fuel , changed from 16:1 kit recommended to 32:1 fuel mix , no contamination issues .
about 2weeks ago I had issues where she would stall out constantly ,turns out it was an issue with crap in the tank preventing proper fuel flow ,I've since rectified this by giving the whole system a full flush ,later it had a spontaneous issue with fuel leaking from the bowl ,reseated the bowl seal and slightly bent the brass tang arms to lower the level of fuel in the bowl and changed the float out ,checked the jet and she's as clean as .

Now I did a chop test and it indicated she was running slightly lean , so I moved the needle down a notch and it seemed to improve the running of the motor for a few days ,but now she is constantly 4 stroking intermittently at either middle or top end ,I can actually feel her lose power at top end and 4 stroke ,I'll release the throttle and she will fire up as normal but it's like she runs well for a few seconds and then 4 strokes ,then runs normal ,I've made every adjustment to fine tune the carby but one way she runs lean the other she 4 strokes .

I'm at a loss as to what steps to take to get her running like normal again
Is it normal for the motor to 4 stroke occasionally or is there something I can do to resolve this issue ie is it ok to run her ever so slightly lean ,it's not like she is running overly lean just a very slight white haze on the plug


Help I'm lost
Regards Henshooter
 

maniac57

Old, Fat, and still faster than you
Oct 8, 2011
4,484
22
0
memphis Tn
Drop a jet size and raise the needle back up. When it pulls up to top then four strokes, the jet is too big. The needle is fully out at this point so your jet is the controlling factor.
Remember to raise the needle back up when you swap to a smaller main and approach peak power carefully.
I like my engines tuned to pull hard up to the redline and four stroke just a bit at partial throttle cruising speeds.
And some four stroking is simply the nature of the bbeast with these motors, so don't worry about it too much. You will know when it's too far, jetting it just under max power is a good idea for engine life.
 

Henshooter

New Member
Feb 10, 2014
275
0
0
Melbourne au
I'm running a .65 at the moment maniac ,what is the recommended size I should go for ,I've got the c clip sitting in the middle notch at the moment ,should I raise it one notch ie would it possibly be sitting one notch to low
 

Venice Motor Bikes

Custom Builder / Dealer/Los Angeles
Mar 20, 2008
7,266
1,797
113
Los Angeles, CA.
I would bend the tongs back (to raise the fuel level back up), keep the needle around the center & then test... after testing?, I might re-jet one size smaller than stock (if needed).

Just remember.... The correct way to adjust the fuel mixture is with a bigger (or smaller) jet, not by float or needle. ;)
 

Henshooter

New Member
Feb 10, 2014
275
0
0
Melbourne au
I would probably put the needle back to were it was and try a different heat range on your plug.
Theon ,Theon ,Theon you are a champion my friend , I decided to swap up the plug to one that was a better heat range (well according to the sales guy , I wouldn't have a clue) gapped it to .25 with my sp gapper and damned if she doesn't miss a single beat now , belle now runs like the first day I cranked her up again ( I swear I've said that 20 times now).

It has shown me the lesson of how different each and every chinagirl motor is , my last build was called horse and acted as such , he just needed regular feeding ,the occasional brush down and general health care , every morning he started up and worked , damn hard at that too .

Belle my latest build is sweet and subtle and most of all delicate , the smallest of issues and she gets upset and won't cooperate , she has asked for a regular clean and polish , and if I don't give her daily attention she gets disgruntled and behaves badly .
SHE is definately a she and as such requires a finesse of attention that horse didn't give two hoots about , admittedly I miss horse like heck and on foresight wish I hadn't sold him but there comes a time when we must part with our builds and horse is now happily running a young bloke to and from work every day.

Sorry for the rant but I have just realised this revelation
Regards Henshooten dance1
 

Henshooter

New Member
Feb 10, 2014
275
0
0
Melbourne au
The brand is Surefire cost me $12 ,not sure of the number though ATM , I'll have to dig the box out and check on that ( I'm clueless to the numbers) , I have got an Ngk one and the one you gave me but even gapped correctly I could never get them to run correctly .

The guy I got it from seemed to be knowledgable with them as I brought in the original one with the kit and said it was for a chinagirl ,immediately he got this one and said plenty of guys had purchased them for those kits ,took him for his word and he was correct

I'll get back to you with the numbers ,I'm at the outlaws ATM

Regards Henshooter
 

mapbike

Well-Known Member
Mar 14, 2010
5,502
109
63
Central Area of Texas
Glad to hear you got-er going good there Henshooter, im curious about that plug and number also, never had a spark plug make that much differwnce on any of my engines unless it was fouled or just a bad plug.

Ride safe and enjoy....

Map
.wee.
 

jeffromoocow

New Member
Oct 8, 2013
7
0
0
Crawfordville, FL
Me too!!! Mine is doing something very similar and I switched from an NGK B5HS to a stock china girl plug and she runs better, but still four stroking at the top end intermittently.
 

Henshooter

New Member
Feb 10, 2014
275
0
0
Melbourne au
Ok I found the box ,I looked at the plug itself and it only has Surefire in small letters , the box has these letters and numbers on it RJ2YXLE and states on the box ,high performance plug for 2stroke engines performance garenteed , it has small writing about platinum but can't really read it as I had to go swimming in the trash to get it out + rain and it's kind of soggy and destroyed .
Not sure if it's the correct one I should use but I've done a chop test and it is a beautiful colour and the motor runs relatively cool ,not a single missed fire at all and starting ,she fires up immediately with full accessible throttle ,whereas the other plugs I've tried it takes 2 to 3 minutes for the engine to warm up and it still won't reach full throttle range for at least 5 minutes just putts along until it reaches full speed

The only weird thing I did notice is it's shape and patterns are identical to the stock kit version except the original is called a fire king ,I'm going to try the original kit version to see what it performs like .

Seems weird that a quality Plug won't run the motor well but I suppose nothing is impossible with these motors

Regards Henshooter