Need Help! Pitpro 140XR Rough running

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u could always get a manifold that is 26mm and hack it and get it welded
thats what my mate did runs great with the oko
 
ok now im a bit confused? master spoon you reckon that if my engine is a yx then the kit from dhz (26mm oko carby) wont fit and I have to use the standard pitpro 23mm manifold? Got me confused now as I thought all pitpro 140XR's Have Lifan engines. How do you tell the difference between a lifan and a jialing/yx. This is getting confusing as Im still very new to china bikes. Just want to fix this problem with the flatspot. Also I see oko make a 28mm carby too is this better again for the 140's? I still dont understand how these oko's are so much betterb than the mukuni's is it purely because the air screw is easy to get to? Or is it becasue it's a flatslide carby and these are better and the manifold is wider too? Sorry guys just dont want to waste money on something that might not work.
 
u cant (its nearly imposible ) to tune the 30mm mikuni cause u cant get to the screw when the bike is running so u cant tune it cause u need yourbike running to tune it propery, i took i bolt of my manifold everytime i had to adjust it to try and get it better but after the 4th or 5th time and not getting hardly anywhere i just left it how it is l0l
 
ok Gunnerray, two easy ways to pick if you have a lifan of YX motor. Firstly does it have lifan moulded on the side cases? first hint its not a lifan.
Next is go looking for your engine number, will normally have a sticker on the RHS of the casing and is engraved on the LHS under the sprocket there somewhere.
If it says its a 1P55FMJ its a lifan 140cc
If it says its a 1P56FMJ its a YX 140cc

the 26mm OKO is the preferred choice for the 140cc unless its a heavily worked motor as apparently you will get a flat spot with a 28mm because there is not enough vacume for the larger venturi.

To if it fits or not I will try clarify this a bit, the carbie will fit, BUT the manifold is to big and makes the carbie hit the frame or tank (depends on which way you lean it). This means you can either use the standard 23mm pitpro manifold (as it is smaller and keeps the carbie lower) or possibly space the tank up enough until you have enough clearance.

I was lucky enough to stumble across a 26mm manifold that just fitted with my 26mm OKO, doesn't fit with my 30mm Mikuni tho.
 
Just thought i would shed some light on the pit pros!! I have have very few probs with mine apart from a sticky throttle/choke from using too much notoil on the filter. Running in should be done gradually and its good to open the throttle occassionally during running in so long as you dont let the engine get too hot.
Get rid of the factory oil and go for a semi sinthetic oil like silkoline. Dont worry the clutch wont slip as its only semi synthetic. Change your plug and so long as the fuel is of good grade you should be right. Try using the higher octane. Go hard and then check all your nuts and bolts....
 
For those who are unsure there is a special bent screw driver for tuning the 30 mm carbies... Talk to the guys at the pit bike shops in bayswater.
 
Thanks MasterSpoon I will have to double check but im pretty sure it's a yx. It definitely doesn't say lifan on the side. had no idea that these's engines were almost identical and was also under the impression that all pitpro140xr's had lifan engines as per their website! thanks for the info about the 28mm oko wont get that one. Ok so worst case if i get the 26mm oko do you reckon if i use the 23mm standard manifold that it will work ok? I know what you said about being back at square one! not ideal. Suppose its a case of trial and error or I suppose like you said I could try to rig the longer one clear of the tank. Could give it a go. Are the yx's just as good as the lifan engines in your experience?

Motoxxx,
Understand your point about tuning with the airscrew underneath! Im just still a little peeved that the standard setup id obviously no good! Thanks again for this info, saving me a lot of headaches!!
 
You can buy a right angle screwdriver from some hardware stores and this makes the Mikuni alot easier to tune. I have even made my own.
 
on bikeboy's comment he said to ditch the oil for semi synthetic
very bad idea
semi synthetic is too good for the motor straight away and it wont let anything bed properly
i prefer to use mineral for the first 2 changes and then use semi synthetic
 
Sorry to flog a dead horse with this problem but I am wondering if any other pitpro 140xr riders have the same problem as I have with the top end flat spot. Would be interesting to know. Also do you think that this is ok just to accept that the bike has this problem (and pay to fix it myself as suggested in this thread) or do you think it's reasonable for me to try to get pitpro to fix it as the bike is brand new and still under warranty? Also as suggested with getting a right angled screwdriver to play with the airsrew underneath the carby does this really have a big effect on a problem such as mine? Im just really wondering what the go is as obviously other pitpro 140XR's must go just fine with the standard 30mm mukuni setup these carby's must be jetted identically?
 
pitpro cant fix it mate they probly could but it will still be the same carby its better to spend the extra 100 buks and you no its right plus u have alot better carby aswell as i said just get

-26mm oko carby
-uni filter
-new iridium plug
-run 98 octane fuel

and you should be sweet pitpro wont put a new carby on for you they will just say it needs a tune or sothing
 
Yeah I think you might be right there motoxxx it will be the same carby. Wonder why though that they all dont have this problem some go good some dont. Will have to bite the bullett I think where do you get the iridium plug's from? do the bike shops's sell them in the small sizes? So you have a DHZ 140 do you? Is that the same donk as mine? Do they come with that oko carby standard?
 
no no chinas of ebay cume with oko i dont think maybe the c4 moto but now sure just spend 100 mate my dhz has this problem and its been the since the start and i cant get rid of it but i sold the bike so its not my worry now but just get the oko and u can get a iridium from bike shop or car shop

the donk in yours is a 1p56fmj and mine is a 1p55fmj its the older modle then your yx motor
 
Yeah right, its all becoming a little clearer slowly. When you put the oko on your bike did you have to rejet it or just play with the airscrew to get it sounding right? Does your bike rev out fine now with no flatspot's? I suppose the bigger manifold helps as MasterSpoon says.
 
price options for those that care and don't mind tinkering
Fix and tune the Mikuni $5-$10
replace with OKO 26mm $80-$100

From my experience I found the OKO to give better performance and let the motor rev out more but the bigger manifold would be helping this also.

On my mikuni I ran a 105main and 27.5 pilot from memory
needle clip on the middle position, bite the bullet and just remove the bolt/ nut that holds the carbie onto the manifold and adjust your carbie that way. The right angle screw drivers are a great idea however the carbie sits very low on the 140XR (as you would have noticed by the fins cut down from factory to allow the carbie to clear) and you may still have problems with getting at the screw.

If you have somewhere reasonably open to play around in you could probably get the Mikuni dialed in in under an hour and then its pretty much set.
 
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