Need Help! Pitpro 140XR Rough running

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Gunnerray

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Gday again,

This new Pitpro 140XR is testing me a bit! Have just started giving it a bit more than half throttle after running it in and it wont rev out. Has a massive flat spot at just over half throttle. It just dies if you hold it there! Have pulled the carby apart and checked for dirt it's all clean. The plug looked pretty black. Runs pretty well at low revs, but it feels like not enough fuel? Could be the plug breaking down under load possibly? Has anyone elso come across the same thing? Surely the jetting should be ok for full throttle in the standard setup? The only thing I can see to adjust is the airscrew under the carby, could this help? Apart from that all I can see you can do is the needle clip postion or re jet the thing. I could call Pitpro I suppose but I dont know how they would be able to help unless they tune them down at citymotorbikes? (Im in melb) Any help appreciated thanks.
 
u shouldnt off not went full throttle when running in u are still ment to giv it full throttle on run in just dont hit rev limiter or rev in realy HIGH RANGE REVS but after a while and when the bike gets hot it should get abit better and after a month or so of thrashin it should get abit better but all these 140's have the wrong carby on the grab a 26mm OKO flatside carby and rejet it and it should be sA-WeEt
 
i think most people with the 140 xr re jetted them straight away and gave them a good tune because the standurd setup is pretty poor, or so iv heard
 
Thanks for the quick replies. I would have thought that standard setup would be better than that! Not happy pitpro but I suppose you get what you pay for again. Will be calling pitpro about this I know these bikes need some tlc to get them right but the standard carby/engine setup should run better than that out of the crate. I doubt whether running in the engine for longer will change this problem. It's either got to be a dodgy plug or the carby setup is completely wrong I think. Anymore help on this would be great thanks.
 
yea the standard carb/set up, is pretty average. i haven't had that bad of problems, but i know it can be running better.
 
get the 26mm oko flatside,uni filter,ngk iridium plug,and run 98 octane fuel and u should be going pretty sweet spend that extra 100 buks and youl be glad you did save u alot of headachs trying to fix the standard setup
 
Last edited:
Motoxxx,

Where do you get the 26mm oko flatside carby's from? How much and why are they better do you think?
 
of ebay for about 90 buks delivered they are easier to tune cause u can get to the air/fuel mixture screw unlik on the 30mm mikuni's and they are a better performance carby
 
So Im after the 26mm Keihin replica flatside racing carby from DHZ? Do you really reckon just bolting this on is going to fix the problem? So whats the go with the 30mm mukini is it just too hard to tune or is it too big and the wrong carby for the bike I dont understand? Where do you get jets for these oko's also? Does oko just bolt straight onto the Lifan manifold? Cheers
 
it will come with its own mannifold and all adaptors nessisary on the mikuni the fuel screw is on the bottom and you cant get to it with a screw driver and makes it alot harder to tune with the oko its on the top and you can turn it with your 2 fingers while its running so i can hear and feel the right spot to set it at and there a performance caby aswell so u get more power and better torque/acceleration u can get jets from ebay i think or you locak bike shop should have some
 
the standard carbie can work fairly well but is a absolute pain to tune
on mine I went to a 105 main and middle needle clip position I think, wasn't until I got the air / fuel screw spot on that it was sweet tho (like 1/8 turn off and it will still cough and splutter)
put a 26mm OKO on and took about 2 mins to tune and has been running sweet ever since.

I think what may be causing some of the real bad issues is the fact that (well mine anyways) is that the carbie has a 30mm outlet matching up to a 23mm manifold that then joins to a 28mm intake port. Pick the problem here ? the stupid manifold is way to small and kills the engine higher in the rev range.
 
there you go spooney nows what hes talking about with these bikes
 
yea i've noticed that, when i saw the 23mm manifold, i was like WTF??
my carby runs fine, untill i get to the last 5th of the throttle, then it starts bogging down.
 
I do ?
hahahaha..... I mean yeah I know....

if your bike is the same as mine it will actually be a YX motor not a lifan and the manifold you get in the kit from DHZ will not fit.
You can use the standard manifold but then you are back to square one with a manifold that is to small for the rest of the system.

I was lucky and stumbled across an old manifold that just happened to fit, only just but it did fit.

You will notice that they are running a shorter intake manifold to most other pitbikes that you see around the traps, if you put the bigger/ longer ones on the carbie hits into the frame and tank.
 
Thanks heaps guys think I will get the Oko otherwise It sounds as if it will take way too long to tune! Bit dissapointing from pitpro really, surely they could fix this problem relatively easily. Anyways Im going to get on with it and get this beast crankin out some power! Cheers
 
spoony u know you have knowledge on pit bikes

haha but seriously u DO.

no worries mate was a pleasure helping you out well i hope i did abit lol
 
my 140xr never had these problems, straight out of the box it loved being at full throttle, how many hours do you have on the engine now?
 
Pitproxr,
The engine is still pretty new only about 2 hrs on it max. Still dont see how more running inm would fix the flatspot. Its huge as soon as you open it up it just dies and will stall unless you back off. Going to change the plug first, talk to pitpro see if they can help as I reckon their bikes should perform better than this out of the crate and if all else fails just get the oko carby which by the sounds of it will be worth. Interesting that your bike went well out of the crate, it could be a few things I suppose but maybe my carby is just not even set close to where it needs to be. I reckon they would spend much time a the factory in China testing these bikes!
 
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