hi rebulit engine a 6 weeks ago and is fully warn in now, bike power seems to be fine but my bike has trobble starting some times need 7 kicks also wont start without choke on, but the worst thing is idles at 1400 rev fine ride down road stop at lights ect it ill idle fine the drop to where nearly dies then pic up fine to 1400 rpm again, had 2 carbs on it and both seem to do same thing, anh help would be appreciated
air screw mate. or your right hand side crank seal is letting oil in to the bottom end ,change your spark plug to and air filter put a vid or pics up .
wont be seals as all new around 900 km a go and were geiuine part. try plug and air filter and tryed leaning and richining mixture just woundering if there could be an ait leak maybe in inlet manifold only thing that isnt new on bike
if you run the bike does it start raising and lowering its rpms? ,do know for definete sapray some wd40 around the inlet while its running you soon know let mek know if the rpms go up or down
read this m8 it got me sorted my carb had a hole in it :
Compression is the first test of all tests...
Spark is the 2nd test
Fuel is the 3rd test, and each of the above has a routine in order to follow, so you are not guessing.
Vac Leaks:
A vac leak is unmetered air allowed in error to get by the intake. This effects carbs and injection equally bad....
You do not want a vac leak on any engine ever, but they are very common.
Sometimes you might not know it if the leak is small, and other times a engine won't start at all. So symptoms run a broad range of what a vac leak can do.
Some symptoms are a sudden lean condition, which can result in loss of power instantly and a matching increase in fuel consumtion.
This might be found to be true if heat cracked a vac line to the pet****s while you were riding, or the line just lifted off
Other types of symtoms cause what is known as "Hunting" Which is idle RMP that will not stay correct. The idle goes up to a given range maybe even to 2,200 rpm and then will drop to 600 RPM and go right back up as if a demon has the grips.. Or the bike might go to 2,200 RPM and stall forcing youi to restart.
Lesser leaks might effect idle, and what was correct yesterday suddenly is high today.
Turning down the over all Throttle linkage screw (THE ONE MAIN ONE MADE FOR FINGERS) will work to lower idle sometimes but is a mis-adjusting when you should not do that..
If the leak becomes worse the idle will do what ever the leak demands..
The leak leans out the correct mix of 14% to 17% fuel to air and makes the mix undeterminable, ALWAYS lean...
On bikes each carb can have leaks, and manifold mount for any carb can have vac leaks.
Any throttle plate shaft can leak on either end. Any vac lines can leak on either end.
And any test port can have a bad cap, and so also leak.
The way a internal combustion engine works creates vacuum. I have never seen any bike with a vac pump.
In my experience vac lines in general do not deal with heat and weather well. They crack, split, and become brittle, and should be replaced once a year, as well as gravity feed fuel lines.
To locate a vac leak you need a can of WD-40 which is probably the best thing you can use WD-40 for.
Also you can use WD-40 to test whether or not idle mix is right. This chemical beats ether hands down for use as a engine starter as well, and will not cause engine damage in moderate amounts.
WD-40 makes what you can't see, and probably what you can't hear findable.
You need to listen to know....
SO to tell if idle mix is right, Spritz a shot right at the intake with a running engine, and listen...
Does the idle go up? Or does the idle go down?
If things are correct the engine has all the fuel it wants and the idle will drop, as the engine wants no more...
If the idle goes up you are lean.......
If you have 4 carbs and all go down but one, then that one is lean.... Why it is lean remains a question.
Maybe the setting is wrong, and the pilot is in to far (mix screw on a car).
[ Often a book setting will say 2, or 2 1/2 turns out. That is a place where a fresh built engine should run to start, and IS NOT always the best mix for any given clyinder]
Or maybe you have a vac leak...and so adding fuel in the form of WD-40 causes the idle to jump to who knows what, and that depends on the unmetered air.
It is possible for a bike to run on 2 clys out of 4, and have the two dead clys fire up above idle speeds as the engine approaches mid range RPM.
So finding leaks becomes a bit of hit and miss, as you spritz about the carbs after a initial shot into the carbs.
Each time you spritz you must listen, so with a air cooled bike you might want a fan on the engine.
Places to spritz are the manifolds looking for loose clamps, throttle shaft ends, and any vac line ends and components vacuum operated. On injected bikes any Throttle body lines, and injector bases, also any vac operated components as you find them.
Often times vac leaks are mis diagnoised as clogged carbs, and bad plugs, wires, pick ups coils and more...
no only ideals funny after its been run if left just to ideal its fine no air leaks sprayed wd on and around carb and no change gunna check the jettings and stuff
