lifan 110 bog at high revs, any help would be most greatfull

[Danlar_94]

hi there chaps i am new to this forum and wondered if anybody could give me a little help... i recently bought a second hand 110 lifan engine for my pitbike, at high revs the bike just runs so flat and litterally has no top end pull... i have changed litterally most things i can think of... i have change numerous different carbs and settings, i have rewired the bike completely i.e. cdi, coil, lead, plug and new loom... the only other things i can think off is exhaust...? timing..? or could it be the head itself..?
it really is testing my patience to another level lol ;P... all i seem to be doing is buying new parts and not getting nowhere...
i think maybe the timing could be retarded by a tooth...? the valves do not hit the piston though.. is it possible to be 1 tooth out and the valves not hit piston..?
Any help would be hugely appreciated
cheers

 

[my67xr]

hi, welcome to Miniriders,

have you tried re-jetting any of the carbys, it sounds like they are too rich?
what carby do you have on it now, and what pilot and main jet are in it?

 

[Danlar_94]

couldnt tell you off the top of my head bud... i know that i have had 3 different carbs on it now all different sized jets... the problem is consistent as it is generally always the same... i thought it may be elecrtical as it doesnt splutter or miss atall, when flat out it just sits at a low rpm it seems, i have had it next to my mates bike also with lifan 110 and his absolutely eats mine... only difference between the two is his has an outer rotar kit i do believe... i do have a resnable knowlage of engines and do generally come to a conclusion but this has bent me over and trated me like a ***** lol...

 

[motodevo]

It will run 1 tooth out and act exactly as you have described(dont ask me how i know!), easy enough to check

 

[rotn50]

If you are running the inner rotor kit(lightened flywheel) then these can be a problem and if it does the same with any Carby then it just may well be electrical, have you had the magneto cover off to check that the coils the flywheel turns inside of are not loose? If it is the red coils and red CDI these units can last years or not long at all but mostly not long at all, they can also playup all thru the rev range, sometimes also sounding like the rev limiter is kicking in at lower revs.

 

[Danlar_94]

i have chopped and changed between my new electrics and old electrics i.e. tryied other cdi with new loom, it did have one of those blue race cdi's on them but i have come to the conclusion they aint worth a wank, so ive gone back to the standard black one which i have read are supposidly more reliable which is what i would be happy with... thanks for your input rotn50...
motodevo, i did replace the barrel and head on the engine when i bought it as i bought it with piston and rings needed, i set the bottom end to tdc by eye as i couldnt find no marks what so ever and the head to 9 oclock as marks show... the head and barrell i am using now are off my old lifan engine, which ran prety much the same, i.e. diddnt splutter but just struggled reaching higher revs... would you say it is running slighlty retarded..? therefore advance it up 1 tooth and turn it over to see if valves hit..? and give it a whirl if they dont..? thanks

 

[zwebx]

maybe advance the ignition timing.. have you checked the spark plug gap?

 

[my67xr]

the flywheel should have a marking of TDC that lines up with the marking on the case at 12 o'clock

 

[motodevo]

If you have no marks on the flywheel/rotor(T mark on rotor lined up with notch on crank case at 12 0clock or if its electric start there is a screw out inspection cap on the top of stator cover) then take the rotor off and set it using the keyway on the crank at the 9 oclock position, use a ruler going from the head mark, through the centre of the cam sprocket mark to the centre of the keyway in the crank. Thats how i do it if i'm putting together an engine from bits and pieces(I'm cheap) as it saves you from putting the rotor on to align it

 

[Danlar_94]

i have changed the and checked spark plug pal and is fine... how do advance ignition timing.. thanks

 

[Danlar_94]

cheers motodevo i'll have a check in a little while and report back later to let you know, thank you all you may have solved my never ending headache

 

[motodevo]

beauty of internet forums, if you got a problem someone else has likely been in the same situation and know what your going through. I gotta go to bed, my alarm goes off in 4 1/2 hours for work, god i hate getting up for work mondays, let us know how you get on

 

[rotn50]

Okay, if you had a race CDI(blue) and now using the stock one I take it you have an outerrotor kit and your mate must Have the inner rotor kit.

 

[Danlar_94]

my mag bolts on and the open side faces inwards onto my stator plate, on his the coils are inside on the outer case and his mag faces outwards... so my cover which goes over the mag is purely a cover where his actually holds the coils and the mag spins facing outwards...? confused mate tbh

 

[my67xr]

so your engine is/was an electric start then.
i'm pretty sure if your starter is under the motor you can take the parts off for electric start and use standard bits back on it.
that way your motor will look the same as your mates, and use the same parts, eg stator etc

 

[motodevo]

You can remove the leccy start type stator setup and replace with a conventional style setup, I have done it to one of my motors, but you will have a gap wheere the chain for the starter chain ran through either at the top or bottom of the statorcover lip depending on whether its top or bottom starter motor, its only about 6mm wide and 30mm long, I just filled with silicon to keep water out of the stator. But the way I read it your mates is the electric start type and your is the conventional type

 

[Danlar_94]

No it deffinately ain't an electric start pal... Sorted the cam timing out and she runs an awful lot better now, only problem is took it out in some awe fully fun wet conditions, spun the back wheel up a wee tad to much and broke the pickup point off the stator plate... Easy fix though... Cheers for you help lads

 

[motodevo]

Cool, glad you sorted it, I knew it sounded exactly like it was one tooth out from when I did it myself

 

[my67xr]

the broken stator plates are common ,
the chain stretches, jumps off the sprocket, then snaps pickup mount off the plate.

you could fit an outer rotor kit to it to make it go a bit better, they cost around $80 for the complete kit.

 

[motodevo]

There a good kit xr's listed, adjustable timing and the added benefit of the pick up being in a less vulnerable position