RS250 running troubles

[Ollie.T]

Hey all,
I bought a RS250 a couple of weeks ago, and while most of the time it runs mint, occasionally (twice now) it just bogs down and refuses to play nicely.

The first time it happened was after a blast over the paekakariki hill rd, it ran brilliantly until about 1km from home when it lost power (didnt die but extremely reluctant to accelerate at all). When I got home, I noticed that the top pipe was cold.
I changed the plugs out, the top one was pretty oiled up and the bike ran fine again.

Last night it did it again, I was riding down the motorway when I felt it losing power, when I pulled off to the side, it died. I called the missus and she came out with tools and spare plugs, however 20 minutes later, before she got there, I got it started again. It ran for about 1km before dying again. I managed to do this all the way home. It seemed to be running fine this morning, took it for a quick spin and when I pulled the plugs to check them, they seemed ok.

One of my mates has a RGV250 (which has the same engine) and he says im probably just not riding it hard enough and flooding the top cylinder and the best way to fix this is ride it like its stolen!

Has anyone else encountered this problem? Should I follow my mates advice and wring it out or do you guys think there is something else going on?

[frogfeaturesFZR]

Google aprilia AF1 forums. Those guys know EVERYTHING about RS 250's

[Slavvy]

Maybe you're losing spark on one cylinder intermittently? That would explain the bogging down and the plug getting fouled.

[marty]

when I bought my first RS it had the wrong plugs fitted - you need to find out if you need resistored ones or not, and which ones are fitted. Mine would run fine for ages, then suddenly decide they didn't want to spark any more.

[White trash]

Sounds like you're running the wrong plugs for the type of riding you're doing Ollie. Perhaps too rich on the oil pump too.

At the risk of soundling like I'm telling you how to suck eggs, you need to ride it far differently to your old GN.

[jim.cox]

maybe water in the fuel ?

try draining the tank completely...

[imdying]

You need somewhere to start.

• How long have you had the bike?
• When did you last replace the rings?
• When did you last remove the expansion chambers for a quick inspection of the barrels/pistons?
• When did you last remove the barrels for a full inspection of the barrels/pistons?
• What brand/model of plugs are in it?
• Do the plugs come out oily?
• What fuel are you using?
• What expansion chambers are you using?
• What size jets are you using?
• What sort of air filter are you using?
• When did you last clean the air filter?

The AF1 forums are ok, but you'll get better replies on things other than "How shiny should my swingarm be?" or "How pretty is my new paint job!" from the rgv250.co.uk forums.

It's not something simple like a set of Arrows on standard jets being too rich is it?

[aprilia_RS250]

Never had issues with mine. You have to look after these bikes like a needy girlfriend.

To ask the obvious, what kind of 2 stroke oil are you using? These bike don't like changing oil type and brands. Use Castrol TTS or the Motul fs stuff, and stick with it.

I think 99% of my riding I keep the revs over 5.5k rpm. You have to, 2 strokes like to rev, otherwise they'll bog up.

Give it a full fang every so often. You'll also see guys at race events warming them up by blipping. Just twist the throttle x5 all the way every few seconds, after the first min of warming up, when it stops dashing "cold". Make sure you take a full whiff of that 2 stroke smoke, it gives you special rossi like abilities

[F5 Dave]

. . .
Last night it did it again, I was riding down the motorway when I felt it losing power, when I pulled off to the side, it died. ?. . .

This is the only part that makes me uneasy. You should not foul a plug on the motorway. Heck if jetted properly you should never foul a plug & you don't need to rev them like crazy all the time unless they are jetted too rich somewhere in the range. My last dirtbike would only let me know the plugs was passed its best by after about a year or so & never fouled up until then & even then not terminally. Not to say your's is jetting properly esp if non std.

anyway, back to the above. that quoted alone makes me think fuel starvation.


Id' check fuel tank breather & any filters in the system. Makes sense the top one starves first. I'd also clean out the carbs.

I could be wrong, but worth checking. I have a hatred of fuel filters installed where it kinks the fuel line. Can be hard to see that it is occurring with the tank in place.

[imdying]

You should not foul a plug on the motorway. Heck if jetted properly you should never foul a plug & you don't need to rev them like crazy all the time unless they are jetted too rich somewhere in the range.

I agree. Sure give them a regular caning to burn out partly combusted deposits excess oil etc, but those won't foul the plugs.

[Ollie.T]

Well I decided (or jetstar decided for me by canceling my flight) to give the bike a trial by fire and rode it from wgtn to chch, following my mates advice. It ran brilliantly. (I did have another mate in chch on standby with a trailer...)

I'm still gonna pull it apart and give the carbs a bit of a huck-out but it seems like I was just riding it like a nana!

[Chancebmx25]

your mate with the rgv250 is all shit. dont open it up when its bogging. itll only flood the cylinders, have u checked that the sparkplugs are the correct type? download urself a user manual for starters, secondly check your jets, check ur carbs in general, then your oil pump, you could be running to lean or way to rich. but if one cylinder isnt getting any power then its prob your plugs, check leads, ignition coils. there a simple motor when tuned properly run nuts. just get yourself a manual for starters itll explain everything. or come over to myn or visit imdying for the best of help. dont take it to get a service itll be something simple seeing its such a simple motor. Now scram to rgv.co.uk and get urself a manual and be prepared to read.... u should know by now.. owning a two stroke is not like ur inline 4 250's cbr's and ninjas and what not. Get that thing running nuts and ull love it.