serious 07 motovert 140 trouble!

[shockerinc]

Hi, I recently bought an 07 motovert 140 and am on mabye the fifth tank of gas... Now the bike wont start, and it blows fuel out the "wrong" end of the carburator, and also leaks out the overflow, i rebuilt the carb and set the float height...nothing, so i SWAPPED carbs and it had the same problem. I then set my intake and exhaust valves to their specified clearances and am still having the exact same problem. And yes I have spark. The only thing I can think of is a bent intake valve but I do not have access to a leak down tester. Any help???? or has anyone had a similiar problem?

 

[motorman]

Sounds like a timing issue to me mate. Looking at your other post, your valve clearances are out also (probably because you were not testing the at TDC??). I would go down that path first. I had the same problem and that's what it turned out to be.

 

[shockerinc]

.003 and .004 is what the dealership told me 2 set the valves at. And i made sure the piston was at tdc compression and not exhaust. I have been a mechainic for about 3 years now wich isnt very long but it still drives me nuts that i cant figure this thing out lol.

 

[Thumpstar Pro]

I would say cdi. Has the bike been ridden in the wet at all? Even pressure washing these bikes can stuff the cdi's in these things. I had the exact symptoms your bike is showing and after 2 top end rebuilds i was having the same issue. So i thought down the electrical road, changed the cdi and i shit you not it started perfectly first kick and sat there and idle. I stood there for maybe two minutes thinking 2 hours of rebuilds and it took me a 10 seconds to plug that in!!!

Oh and bike still running hard!

 

[shockerinc]

hah, no no i tried that, i replaced all the connections and ends of all the wires, checked for spark, then changed the plug and the wire just in case..still nothing, the biggest thing is though...that when i kick it over, it blows gas out of the back of the carb, I think it might have to be that the intake valve is not seating properly, thats why i am thinking bent valve but id like 2 know a little trick or something if anyone has any ideas how i can check that without removing the head?????

 

[Cactus Jack]

Get the "T" mark on the flywheel lined up with the case index mark (TDC at the start of the power stroke with play in both rockers) ... The index mark on the cam sprocket should line up dead on with the index mark on the head ... then fill the inlet port up with fuel ... IF it disappears ... you have either a bent valve or buggered seating surfaces ...

 

[DvDRip]

hey cactus my timing mark doesn't line up dead on, it's about 1 or 2 mm out and if I move the sprocket one notch on the chain it just makes it 1 or 2 mm out the other direction.
should I be worried about this?

 

[Cactus Jack]

Is it advanced (counter clock wise below the mark on the head) or retarded (clockwise to above the mark = stretched cam chain) ? ... 1 mm either way probably won't hurt but you can alter the power curve slightly by advancing or retarding ... You just have to watch piston to valve clearances ...

This link helps explain things ...

Cam Spec Terms - Lunati Power

 

[DvDRip]

well it could be stretched, while I was out my lazy dad who knows nothing of china engines went and removed my cam cover with a hammer then advanced the timing WITHOUT releasing the tensioner.
when I got back I told him to undo whatever he did so he put it so the timing mark on the sprocket is below the mark.
I had never removed the cam cover before this happened so I don't know where the notch was before he bastardized it

he is now banned from touching my bike

 

[shockerinc]

Thanks cactus jack!, thats a smart idea, ima go try that asap.

 

[coolmodee01]

yeah i'm lucky
i recently had this issue of so called stretched timing chain
so i advanced my timeing to where it should be (im lucky i have an adjustable fly wheel on my lifan motor so i tweeked her up and away she went

still mine needs top end done but it's running sweet still so will freshen it up later

 

[Cactus Jack]

When cam chains stretch they usually don't stretch dead evenly along the entire length ... They stretch much quicker with a high lift cam and race springs fitted ... If your timing marks don't line up and you haven't altered the cylinder deck height , base or head gasket thickness ... then chances are your cam chain is stretched ... A stretched chain can cause the cam to pulse and vibrate at high revs ... the signs are ... a varyance in the tooth pitch , arc'd teeth and obvious shiny silver wear on the side of the sprocket ... It's best to fix the problem by fitting a new higher quality cam chain before the damage occurs ... Luckily horizontal engines are designed for quick and easy chain removal and replacement ... With most vertical engines it's a complete engine tear down and case spilt job to replace the cam chain ...

 

[shockerinc]

hmm ok, I have these shiny silver wear marks on my cam sprocket and my bike wont even start still. What i dont get is how having the chain being stretched can alter the timing so bad it wont start???, ooh and i have a lifan 140 motor, how do i loosen the cam chain????

 

[shockerinc]

alright, quick update on the status of my bike. I ripped the head off of her, took out my rockers, and camshaft. NOW when i put fuel in the intake (valves fully closed obviously) and look at the combustion chamber SLOWLY BUT SURELY fuel leaks around all edges of my intake valve. Does this mean the valve is bent (possibly due to not enough valve clearance between valve and head or could it be stretched???? and if so what could cause it to stretch???