No top end power

[toyota4x4]

Hey guys i'm having a little bit of a problem with my 125.

Because of a cracked sump, I went and bought a second hand engine with the intention of swapping it in.

I bought the engine based as 'not running' although it does run, just as the guy said (and I have since found out) it dies when you open the throttle.

I thought at first that it may have been his carby, but I swapped on my own and its still displaying the same symptons. I have had a go at adjusting the values so I don't think thats the problem either. Also, the timing all lines up.

The engine had the stator/magneto under the flywheel replaced just before I bought it and since then had developed the problem.

Is it possible that the pickup on the new stator is in a slightly different position than the old one and this has thrown out the timing? Or is there something else that could be causing the problem?

It revs up okay (nothing special) when its in neutral but when trying to ride in say first gear, once I open the throttle (anything past 3/4 or thereabouts) it chokes and almost stalls.

Any ideas on what to do would be appreciated. Cheers

 

[Poulsen8r]

Looks like your spot on their mate. Is it possible for you to swap your old flywheel and stator onto this new motor? If not just have a look at the ignition timing and see if you can adjust it. I have never done it so maybe someone else here can help you out more.

 

[toyota4x4]

unfortunately the stator pickup on the flywheel was destroyed at the same time as the sump due to the chain breaking... so no luck there.

basically what i was hoping to do is move the timing chain forward/back a tooth if the pickup is the cause of the problem.

 

[Poulsen8r]

The timing chain adjusts valve timing though, so if it is set properly i would not adjust it unless you really know what your doing... When a motor is not under load it does not require any spark advance and that is propably why it revs up fine in neutral but when its under load it needs the spark advance to make power. Is there anyway for you to adjust the ignition timing at the flywheel?

 

[toyota4x4]

I'm not too sure to be honest. I don't think theres a way to move the pickup at all?

 

[01nutracing]

Also what exact things have you changed over? eg. cdi and stuff or just the actual motor and carb?

 

[toyota4x4]

The only thing i've replaced in the bike is the engine. Everything else remains the same.

The engine that I put in however only had the problem since the stator was replaced according to the guy I bought it off... (who paid something ridiculous like $220 to a bike shop to replace it)

I have replaced one myself on my old pitbike for $30 inc postage off ebay, however the one that was put in to this engine is different... so with any luck it will be adjustable.

Which way should i be moving the pickup to retard or advance the timing?

 

[STICK]

Get some viagra

 

[headsmess]

looking from the left hand side, engine spins anti clockwise, so to ADVANCE, the pickup has to go clockwise, to RETARD, it goes anti clockwise...filing slots in the mounting brackets will allow for adjustments... if you have a timing light available, you can check all this... the line marked"F" before the line marked "T" is for "fire" at idle. then the first line BEFORE THAT line is for mid range???? and the line before that is top end... both are unmarked... take a look, they are usually there... two close together, unmarked, then one marked f, then one marked t... with a timing light, the "f" will be visible with the engine running at idle.

but my suggestion? if it is an electrical/timing prob...

get a piece of paper... line the magnet on the rotor up with the pickup coil. slip paper in between the two. loosen the pickups mounting bracket, and use the paper to achieve the correct gap. retighten the screws. test it out

the rotor may also not suit the coils inside the rotor now...so at top end, the field is too weak to keep the plug sparking... i dont know... but then, they were replaced together, yes?

theres a man somewhere here that can answer everything by the name of cactus.... if he reads this.... you might just be throwing all us fools off by suggesting the timing....


um... you still got the old engine? i need a clutch cover the old lifan 125... $20 bucks pickup if youre in sydney... for the cover...more for the whole engine... i wouldnt bother with postage, i got other sources...just asking

 

[toyota4x4]

okay thanks for that. you've given me a few leads on what the problem might be so ill have to go retrieve the bike from my mates place and see how it goes.

im based in brisbane, and the old engine isnt a lifan. pretty sure it doesnt have a brand on it? il have to check.

 

[toyota4x4]

problem solved

turns out there was a metal bracket/spacer under the pickup which was pushing it too far out from the engine which meant it was lining up very well with the one on the flywheel.

pulled it off and it seems to have fixed the problem

thanks for the help guys