Won't start - backfiring

[nudedaytona]

I've got a problem with the bike - its an Aprilia RS250

It won't start. I kick the shit out of it using the kickstart, what sometimes happens is there is a loud backfire type noise from the exhaust and then stalls. Othertimes it idles poorly for a few seconds before dying.

I wonder if its the exhaust gaskets? Does anyone have any ideas?

[Drew]

It aint the exhaust gaskets.

There are a multitude of things that could be wrong, but I'll ignore the terminal options for now.

RGV's do something similar when the battery is dead flat, or the charging system isn't working, causing week spark. (and since the RS is just an RGV rip off, I'm sure it could be common.)

Easy test is to hook it up with jumper leads to a charged battery, and try starting it.

Hope this helps.

[nudedaytona]

The battery was dead, but I just replaced it with a new one. Still have the problem.

[TimeOut]

Was the new one fully charged? if they've been sitting for a while they can lose it

[nudedaytona]

Yes. Just got it from the shop today and stuck it in.

[Rob Taylor]

Yea but you will still have to charge the new battery.Pull the plug out and check it.If crapy replace it.Try that... Maybe coil fault too.

[racefactory]

top end blown? that's backfire inducing isn't it?

[Squiggles]

havent done something silly like gotten ya ht leads mixed up? (Front on the rear and rear on the front...)

[Drew]

top end blown? that's backfire inducing isn't it?

I said we weren't lookin at the terminal options yet!!! LOL

I would bet teh bike would still run on one cylinder if it had melted down, unlikely to have shit itself on both at the same time.

[MotoGirl]

Maybe you could ask someone on the Aprilia forum (http://www.apriliaforum.com/forums/f...splay.php?f=19).

This is a huge resource for everything Aprilia and has helped me with my RSVR numerous times...

[nudedaytona]

My thinking now is that it could be the exhaust valves (power valves). Does anyone have any experience or comments about these?

Its NOT the battery they charged it up at the shop so it was ready for me to pick up.

[nudedaytona]

havent done something silly like gotten ya ht leads mixed up? (Front on the rear and rear on the front...)

Don't know what you're talking about - ht leads?

[nudedaytona]

top end blown? that's backfire inducing isn't it?

I will take one cylinder off and have a look.

[CookMySock]

Don't know what you're talking about - ht leads?

Spark plug leads.

DB

[Drew]

My thinking now is that it could be the exhaust valves (power valves). Does anyone have any experience or comments about these?

Its NOT the battery they charged it up at the shop so it was ready for me to pick up.

Yep, dropped power valves are common, but most of the time the bike will still run, on one cylinder at low RPM and the other cylinder starts firing at higher RPM.