Revving problems ??

[djeuro1981]

When i give the bike acceleration it bogs out it only allows me to gradually rev the bike real slow if i try to just go flat rev it bogs and dies, i have pulled the carby out and cleaned it with carby spray, i did notice that the black plastic gasket on the carby had a crack in it and a chip missing also "maybe thats my problem?? and also noticed that the exhaust to the engine had a bolt snapped and is only held on with 1 bolt??

I weigh 85 kilos and my cousin just got his brand new pitster pro xjr 50ss model today and it flies and it even pops me up on the back wheel in second gear..my bike honestly has no balls what so ever,i tried going up my hill today in second gear and got half way up before the bike died with no power and on the flat it just putts along and thats it..am i better off just chucking this thing to the tip and re buying a brand new bike or does anyone have any suggestions with how i can fix this wreck ??

Thank you all in advance

 

[Cordogs]

Sounds like too much air dude!

I've completely ditch the black plastics on mine and gone with paper gaskets! But yeah too much air dude...


Sort your gaskets, retread or helicoil the head and see how she goes then!



Oh and check your valves

 

[my67xr]

is the plastic insulator cracked ?
is so they are cheap to replace, about $6 from a pit bike shop or ebay - 27mm Carburetor Carby Manifold Gasket 125cc 150cc PIT Quad Dirt Bike ATV Buggy | eBay

how many turns out is your mixture screw too ?

otherwise it sounds like the Pilot jet might be blocked ?
pull the fuel bowl off and it's the one towards the manifold side of the carby.

try taking the air filter off and hold the palm of you hand over the intake to seal it off, then kick it over a couple of times.
it should wet you hand with fuel.
then refit the air filter and try starting the bike, it will take a few kicks.
once it starts see if it is any better.
if it is the pull the pilot jet out and make sure all the holes through it are clean/open.

and remove the mixture screw and spray d\some carby cleaner though the small ports on the air filter side of the carby(with the filter off)
you should see the carby cleaner come out the mixture screw hole and the pilot jet hole.
blow the carby out with compressed air and reassemble it.

 

[djeuro1981]

ok im going to go take some pics then post them here of everything

 

[djeuro1981]

here u go

 

[my67xr]

yeah that would cause a massive air leak.

with the exhaust you should be able to undo the other 10mm headed nut, and drop the exhaust down.
then use a set of decent vise grips, clamp them on tight and undo the stud from the head.
then find a replacement and refit it all again

might pay to replace the exhaust gasket too while you are at it.
PIT Bike Trail Quad PRO ATV Thumpster Exhaust Gasket Diameter 32 MM X 2 | eBay

 

[djeuro1981]

mate thank you so much for your help i have purchased both gaskets you suggested from ebay, means a lot mate that you took the time out to help me

Regards

Shane

 

[djeuro1981]

mate thank you so much for your help i have purchased both gaskets you suggested from ebay, means a lot mate for you to take time out to help me,also any idea where i can get a replacement bolt for the exhaust??

Regards

Shane

 

[my67xr]

they use M6 x 1mm pitch studs that are 45mm long for the exhaust
if you have a bearing shop somewhere close to you they should have them in stock for a couple of $

otherwise i can send you a good used one if you want, just pm me your address and i'll get it in the post tomorrow for you.

 

[djeuro1981]

quick question would a gasket from a 125cc pitbike work for the carby and also the exhaust stud?? for a pitster pro xjr 50ss

 

[djeuro1981]

hi guys replaced the exhaust gasket and bolt and also put a new gasket on the carby and it is still running like a fat kid in a running race

 

[gottagetacheaperhobby]

Pull the bowl of the carby, and remove the jets (the only brass objects in yor carb) and the air screw, and give it a good spray with a can of carby cleaner. You will probably have to clear the holes in the jets with a fine piece of wire and blow it all out with compressed air. What condition is your air filter in?

 

[djeuro1981]

what ill do is ill actually make a video of the bike running, i did winde the mixture screw right to the very end and i can now rev it without ir bogging but it still runs like a slug, is it because its a 50cc or is it still suppose to go good with me being 85kilos on it??

 

[djeuro1981]

also is there a restrictor on these pit bikes or is it how it is??

 

[SwapperMX]

Does sound like a restriction in the pilot circuit still, but yeah, a stock XJR50 is pretty damn slow. What have you got to compare against ??

 

[my67xr]

what ill do is ill actually make a video of the bike running, i did winde the mixture screw right to the very end and i can now rev it without ir bogging but it still runs like a slug, is it because its a 50cc or is it still suppose to go good with me being 85kilos on it??

why would you do that ?

since replacing the manifold carby spacer/insulator,
have you checked it for any air/vacuum leaks yet with some degreaser spray or wd40 spray like Stu mentioned before ?

if you don't get any change in idle after checking then try this,
turn the mixture screw right in , then turn it back out 1.5 full turns

start the bike and warm it up
now turn the central screw in, to raise the idle speed up to about 1800 rpm (normal idle speed is around 1200rpm)
now adjust the mixture screw out .5 of a turn
listen for a idle speed change, and listen to the way the engine runs
you want to adjust it out or in so the idle speed reaches it's highest smoothest point. adjust it .5 a turn at a time at first, let the engine revs settle for 10 seconds or so.
once you get it smooth/high revs, then adjust the mixture screw about 1/8 turn at a time to fine tune it.
once you are happy, then you can turn the central idle speed screw back out so the bike idles at a normal speed

now try the bike out
it may still need some minor adjustment on the mixture screw, but on go a tiny bit at a time and try it out to see if it's any better.

 

[djeuro1981]

Does sound like a restriction in the pilot circuit still, but yeah, a stock XJR50 is pretty damn slow. What have you got to compare against ??

just 2 xjr50's 1 is brand new 2014 model and mine is a 2013 model took it for a good run today and the new bike did beat me by about 4 bike length

 

[djeuro1981]

why would you do that ?

since replacing the manifold carby spacer/insulator,
have you checked it for any air/vacuum leaks yet with some degreaser spray or wd40 spray like Stu mentioned before ?



if you don't get any change in idle after checking then try this,
turn the mixture screw right in , then turn it back out 1.5 full turns

start the bike and warm it up
now turn the central screw in, to raise the idle speed up to about 1800 rpm (normal idle speed is around 1200rpm)
now adjust the mixture screw out .5 of a turn
listen for a idle speed change, and listen to the way the engine runs
you want to adjust it out or in so the idle speed reaches it's highest smoothest point. adjust it .5 a turn at a time at first, let the engine revs settle for 10 seconds or so.
once you get it smooth/high revs, then adjust the mixture screw about 1/8 turn at a time to fine tune it.
once you are happy, then you can turn the central idle speed screw back out so the bike idles at a normal speed

now try the bike out
it may still need some minor adjustment on the mixture screw, but on go a tiny bit at a time and try it out to see if it's any better.

Ok so ill check for air leaks tomorrow with installing the new carby gasket and the new exhaust gasket, and i will play with the mixture and idle screws tomorrow morning, i did go for a ride today and it seemed to go ok but i did notice when i came to a complete stop on the bike it either was revving high or it would just die on me with low to no idle what so ever, and i also did notice that when i hit 4th gear it just bogged and didnt really build up and more speed...