aprilia af1 125 wont start rotax 123 engine

[rockers]

hi all, i got it started for the 1st time since ive had it was told it had a rebuild before i got it so needs runing in,
when i got it started it sounded sweet then after 2 mins it stopped ...
took plug out and it was wet with petrol and black oil.
gave it a clean and tried to start but no luck, also tried a new plug but no joy.
took carb and reed valve out and looking into the engine it looks pretty wet and little oily, would this suggest that its flooded ? it doesnt start at all not even a splutter. so would this be my problem ? and if so what the best way to de-flood the engine so to speak.

Cheers

Rocky

[stirlinggaz]

hi,
when you had it running, did you leave it to idle for a bit?
this can foul plugs.
(best just not to idle it, but set off & keep it nice & slow till warmed up)
if its flooded & the bikes indoors, take the plug out, hit the starter a few times with the throttle wide open, & then leave it overnight.
any petrol left, should evaporate.
what plug are you using?
try a br9.
also, dont forget, that the battery, especially if its an old one, will flatten very quickly after a few attempts with the electric starter.
try bumping it into 2nd.
or charge the battery up overnight.
& then test for a spark.
if your getting a decent spark, move onto the carb.
is there fuel getting to the carb?
(open the drain screw for a second or 2, to see if fuel pisses out the bottom)
then onto cylinder.
have you tested the compression?
i'd be checking this properly, especially if its just been re-built.
who rebuilt it? which gasket was used?
cheers,
GAZ

[Kickstart]

Hi

Draining the petrol from the engine is easy on the 123 engine. Under the engine, just in front of the starter motor there is a bolt (goes up pretty much vertically). This is there for locking the engine at top dead centre when setting the ignition timing but also makes a very convenient drain for the cases.

If you do try cranking the engine over with the plug out then make sure the kill switch is off (the AF1 will crank over with the kill switch off). Otherwise if the engine is full of petrol it will spray it out of the plug hole and the spark plug will likely ignite it.

I take it you are getting a spark? If the ignition timing is out then the engine may run but may well have problems. Unforunatly checking / setting the ignition timing requires a dial gauge and some faffing around.

If it is flooding that easily then it is probably well worth checking the carb settings carefully. Mainly the float height and the idle screw position. Could also be the needle valve, but that would have resulted in it flooding without the engine running so probably not that.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[rockers]

Hi cheers for the reply

i have got a decent spark
i didnt let it idle as such just rev'ed a little no much tho
am jumping off another battery so have loads of power.
fuel must be coming from the carb as before i got the bits to get it going i had taken the carb and reed valve off to clean and check them and looking into the engine it wasnt wet, but now am trying to start it there is fuel there its pretty wet.
compression- havnt got anything to test it but thumb over spark plug and theres alot of force back so should be good.
dont know who rebuilt the engine, i cant see round the edges the gasket looks to be green if that helps
its in the garage now spark plug out air filter off and no fuel line joined up.

my only thought is it is letting the fuel through willy nilly and flooding the engine being when i first tried to start the engine is had no fuel it and it started and died now theres fuel there in the engine (flooded maybe) it isnt starting

[rockers]

posted before me

i set the timing vial topdead and backwards 1.8mm i think it is or19 degree

[Kickstart]

Hi

1.8mm before TDC is correct.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[rockers]

ok so timing is correct, i have got a decent spark and fuel going to the engine even if its to much.
what would you guy recommend the best way to try and start without flooding the engine ?

Cheers

rocky

[rockers]

hi all, been out again trying to start with no luck
the most i get is big pop smoke out of carb and exhaust what this about ?
have re checked the timing and its + - .08 which shouldn't stop it from starting ?

I am starting to get pretty F**ked of with the bike tbh

any help would be good

[Kickstart]

Hi

If the timing is within 0.08mm of where it should be then I would expect it should start fine.

Check the jetting as above. Also check that the reed valves are sealing as you shouldn't get a pop out of the carb.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[rockers]

Check the openings close properly ? like sit flat on reed valve ?

I dont get why it wont start and why it stopped it started pretty fine friday then stopped which i dont know why it did ?

thing i have notice is there is a cable coming from the power valve ? going to no where was told screws into a bit on the brake ? wtf

Would this stop it running if the power valve is in the wrong postion ?

Cheers

Rocky

[Kickstart]

Hi

The reed valves should seal against the reed block. If it doesn't then it can be a pain (had this with my YSR and it made it a pig to start).

The cable from the power valve is there so that when you press the back brake the power valve is opened. Idea is that around town it gets frequently opened to stop it sticking. Again shouldn't have much effect in stopping it starting, and it still has the spring to close it (or should).

Have you checked the jetting?

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[rockers]

what do you mean by checking the jetting ? the jet size or that its all clear ?

Cheers

Rocky

[Kickstart]

Hi

That the idle jet adjuster is the correct number of turns out. Think it should be one turn out (ie, screw it in unless it just starts to go tight and then undo one full turn).

Float height should be 23.5mm~24.5mm.

At idle the other jets should be pretty irrelevant.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[rockers]

ok will check that aswell, any idea what causes the pop now and a again ? when trying to start

[Kickstart]

Hi

Depends where the pops are from. From the carb suggests the reed valves aren't sealing. From the exhaust suggests it has dumped loads of petrol into the exhaust and is trying to ignite it.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[rockers]

ohright, puff of smooke came out of the carb and exhasut

[rockers]

ok been out checked all on the carb idle needle was spot on
check the reed valve and if i hold it up to the light in some places you can just about see some light couple thou most

got the same just poped, puff of smoke etc
when i take the plug out its wet and has a black oil on it aswell.
would flushing the engine through with petrol help at all removing any crappy oil ?

Cheers

Rocky

[rockers]

any ideas ?

[Kickstart]

Hi

Have you let it dry out thoroughly? Take the plug out and the "drain" out (one for setting the timing) and leave it standing for a good few hours. Make sure the petrol is turned off.

Then put in a new plug and try it then.

Probably worth sourcing some new reed valves if you can see a gap.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[rockers]

Yeh i can see slight light on the reed valve will that stop it from starting ?

the drain plug as such, would i run some petrol through the spark plug hole and out the bottem to clean any crap out of the engine etc ?

Cheers

Rocky

[Kickstart]

Hi

Reed valves not sealing can cause hard starting. However I would still expect it to eventually.

I wouldn't run petrol through it. For a start it is the petrol you want to get rid of, an petrol will remove the oil from the bearings, etc.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[rockers]

oh ok, cheers

Rocky

[rockers]

ok, still no luck

carb apart and cleaned again

theres nothing not a hint of starting, if i spray a tiny bit of easy start i just get a pop and a puff of smoke.

anyone any ideas ?

[Kickstart]

Hi

Not sure. I would expect it to start like that, even for just a short while. Probably worth having a thorough check. Check the compression. Check the ignition timing is correct (can go out if the woodruff key locating the flywheel shears off). Etc.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[rockers]

Hi
is there any 'proper' way to test if any fuel is entering the engine ?
as with auto start is the only way i can get it to pop.