Aprilia RS 125 won't start - unusual problem.

[Daugaard]

Hello BCF

Last year my motorcycle went dead on the road. I have not taken care of it since.

What happened was, the bike lost a lot of power! When I shifted to the 5th gear, the bike didn't have any torque to put out power - it dropped in RPM and I had to downshift into 4th gear. When i got to the nearest unconditional right of way, the bike went out, and I have not been able to power it up since. When I try to start it, the motorcycle sounds very different than it used too.

What I know:
-The piston is going up and down just fine (also when the electrical starter is engaged).
-The sparkplug delivers a good connection and spark.
-It gets gas and air just fine.
-I tried to put it in the 1st. gear, and the motorcycle is running forward when hitting the electrical starter.

What could this problem be?

-Daugaard

[Ariel Badger]

Believe me after 10 years of BCF a 125 not starting is not an unusual problem. Do you have compression, put your thumb over the plughole and turn over the motor and it should blow past your thumb.
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[Kickstart]

Hi

Compression check. Firstly as above, but better to buy a compression tester and try it properly (take plug out, screw in tester, crank over with the throttle wide open until the reading stops going up - take care the hold the spark plug against an earth while cranking to give the ignition system an easier time).

Should be well over 100psi in good condition, a bit under 100psi and it will still run but be marginal. Suspect yours is a long way under 100psi

All the best

Katy
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[Taught2BCauti...]

^^This^^

You need 4 basic things to make the engine run:

1. Correct fuel/air mixture.
2. Good compression.
3. A spark to ignite the compressed fuel/air mixture.
4. The spark needs to happen at the right time.

You say 1 and 3 are fine, that just leaves 2 and 4 to be checked.
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[stevo as b4]

I reckon it's been run or thrashed too long past the maintenance interval like most of these bikes are.

First thing I would do is make sure you have the right tools to remove the engine and a workshop manual, and around £500 for a worst case scenario re-build budget. I expect your going to need to spend at least half that on parts depending on how fucked it is and what's reusable?