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oscarthegrouch

Joined:

Oct 05

Posts: 2997

aprillia rs 250 broke kcmc :)

kc my mate has a rs that the powervalves fcucked and went into the piston .......he has replaced the valves with these and now it makes no power unless on full throttle ...he replaced the nipped piston and has jumped through hoops but it is still shite the bike is with mick abbey at the minute mick and he hasn't solved it yet

iinformation for you

! i have not looked at this bike yet I'm thinking cdi/ecu fault

2 powervalves are opening and closing

3 he has nipped a transfer port in the barrel ?

4it hasent been assembled properly

5 it flies on full throttle but emtys the tank aftr 65 miles

please help as he is gonna sell it and i havent had a go yet:biggrin:

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  • Posted 245 days ago (15 August 2013 23:58)

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eatcs01

Joined:

Aug 02

Posts: 3222

eatcs01 says:

RS250

It sounds like the power valves aren't working properly. Sounds like they are stuck OPEN...

I know the RGVs had the problem of the power valves dropping into the cylinders, but I thought Aprilia had solved it on their bikes.

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oscarthegrouch

Joined:

Oct 05

Posts: 2997

what happens

is the central dowel wears loose which allows the valve to hit the piston ...........and no the only thing aprilia did was some porting different carbs ? and ecu work .

ps the valves seem to be operating and no i ain't seen the bike yet

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kcmc

Joined:

Jan 08

Posts: 6559

kcmc says:

Hi Oscar

Having problems with my puter at the moment,see if i can post this then:wacko:

I would think the guy(mick) will find the problems with this bike before anything i would come up with,only to say although two strokes are very simple engines,setting up and running to the way someone's needs are is the hard bit.The three main things that govern how a modern sports two stroke functions are the reed valve,the exhaust valve,and the biggie the the expansion box.I don't know but if this bike has had a race set of expansion box's fitted? this will alter very significantly the rev range of the power band and also the fuel consumption,as most racers unless at a track that has a lot of very slow corners where you can't use the high corner speed of a sports 250,would prefer as much top end speed and will sacrifice a bit or even a lot of drive off a corner and would prefer to try and carry this speed through the corner.Hmm 17 lite tank(about three and a half gallon) 65 miles-- not that far off the mark for flat out all the time i think.As you know the RS engine is the Suzuki RGV 250 bottom end with Aprilia's own top end which was a lot more highly tuned compared to a standard RGV even down to the cylinder head squish band which gave a much higher compression which could make it susceptible to detonation if to low octane fuel is used.But small alterations to a two strokes can make big differences,and sometimes make them near unriderable,a bike say set up for the TT will be set up for flat out like this bike, as corners are not the problem,but would be totaly useless on the road for daily use,.Am sure your man will soon put his finger on the problem. KC :tongue:  

[This Reply has been modified by the Author]

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oscarthegrouch

Joined:

Oct 05

Posts: 2997

Thanks for the reply mate .....

Turns out my mate called mick today to see how progress was going and it turns out my mate had re oiled the air filter a little too much so he has washed it out and is going to re dyno it in the morning ........ so fingers crossed

cheers guys :biggrin:

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oscarthegrouch

Joined:

Oct 05

Posts: 2997

Fixed

Dyno run :biggrin::winkie:

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