Rs125 Problem at 6000-8000 Revs

[Stefan RS50 Wood]

Right Ive bought a cheap rs125 £500
New power valve kit

OK so the bikes starts first time every time, seems smooth at up until 6-8k revs makes loud splutter noise's.
I only know the basics about bikes, so any help on what this would be would be appreciated.

Thanks

[Digitalize]

does it rev past the 8k?
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1998 CB600F Hornet

[N cee thirty]

the jetting could be out,do a plug chop
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'00 Aprilia RS50 > '92 Honda CG > '99 Yamaha Fazer > '91 Yamaha RXS > '79 Suzuki X5 > 01' Honda Cg > 07' Honda Cg > 82' Kawasaki Z200 > suzuki gsxr 400 gk73a > honda vfr 400 NC30 Mod 2 Passed 09/06/2011

Jewlio Iglesias wrote: I actually did vote BNP once

[Syris the Indomitable]

I sold a lad one of these fully restricted and never reved past 7000 revs.
It looks like the APRILIA RS125 1996-2006 sport pro.
Just because the power valve solenoid actuator has been fitted it doesn't mean it de-restricted.

1. There will be a catalytic converter in the exhaust check to see if it's been welded or if you have a totally different exhaust fitted other then the standard exhaust.

2. Check the air box, the nozzles may have a tube blocked up, just remove that blockage.

3. cdi, under the rear seat, is a black box, in the back of this black box is a silicone patch, dig the silicone out, and there is a little circuit board. snap it and remove it. this gets rid of the little restriction, also known as a environmental dip.

4. You want a br10es for a unrestricted bike.

5. Power valve, you will need the rave unit, solenoid, pv cable and pv blade and pv housing.(You Have this fitted already)

6. The carburettor set up on these is absolutely crucial, it will need changing or up-jetting, see a specialist about this or maybe someone will tell you exactly how to up-jet the standard car on these. If your able to do this your self it will turn out to very cheap.
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In Greek mythology Ichor is what immortals have in the place of blood
Those that mind, don't matter...Those that matter, don't mind. Do you agree with this?

[Stefan RS50 Wood]

[Syris the Indomitable]

K. Good luck. Hope it works well without having to remove the catalytic converter because removing/replacing the exhaust on them is a nightmare; I had to grow muscles to replace the springs on mine, and had to cut an Alan key down to a stumpy to tighten the bolts at the manifold end.
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In Greek mythology Ichor is what immortals have in the place of blood
Those that mind, don't matter...Those that matter, don't mind. Do you agree with this?

[N cee thirty]

k&n filter ain't worth it,only makes your bike louder
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'00 Aprilia RS50 > '92 Honda CG > '99 Yamaha Fazer > '91 Yamaha RXS > '79 Suzuki X5 > 01' Honda Cg > 07' Honda Cg > 82' Kawasaki Z200 > suzuki gsxr 400 gk73a > honda vfr 400 NC30 Mod 2 Passed 09/06/2011

Jewlio Iglesias wrote: I actually did vote BNP once

[Kickstart]

Hi

The cdi mod has no effect outside the 5k to 6k range (it bypasses a massive amount of ignition retard between those rpm which is there to cause a large flat spot). If the problem you have is from 6k to 8k then the cdi mod will have no impact. I would leave it alone for now until you have found and fixed the real problem.

Check to see the power valve is actually open. It should also be open below 2500rpm.

All the best

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

[Stefan RS50 Wood]

Thanks all the cdi looks abit nakerd, all cut up and everything, i have ordered a new 1, if that isnt the problem then i have no idea because, when its in neutral or the clutch is pulled in it will rev to more than 8000, when riding everythink is smooth but as soon as it gets to about the 8000 mark it wont go higher

[N cee thirty]

maybe the exhaust is coked up,mine did this on my rs50
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'00 Aprilia RS50 > '92 Honda CG > '99 Yamaha Fazer > '91 Yamaha RXS > '79 Suzuki X5 > 01' Honda Cg > 07' Honda Cg > 82' Kawasaki Z200 > suzuki gsxr 400 gk73a > honda vfr 400 NC30 Mod 2 Passed 09/06/2011

Jewlio Iglesias wrote: I actually did vote BNP once

[Stefan RS50 Wood]

[N cee thirty]

well you could use caustic soda to get rid of the carbon,type it in on the search function on the top,a few threads about it

wait till Keith comes along to see if he thinks this is worth doing though
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'00 Aprilia RS50 > '92 Honda CG > '99 Yamaha Fazer > '91 Yamaha RXS > '79 Suzuki X5 > 01' Honda Cg > 07' Honda Cg > 82' Kawasaki Z200 > suzuki gsxr 400 gk73a > honda vfr 400 NC30 Mod 2 Passed 09/06/2011

Jewlio Iglesias wrote: I actually did vote BNP once

[Stefan RS50 Wood]

Just took the bike out for a spin, as soon as it hits around the 7k revs it just splutters, but sometimes it will like it happened twice in 30mins and that was in 1st gear, power seems fine when it gets past the splutter, noticed it backfires as well when letting off the throttle

[Kickstart]

Hi

I would check the jetting (someone may have done something silly with the jetting when derestricting it previously).

Also check the power valve is in the right way up (common issue, but really only knocks about 5mph off the top end).

Check the power valve operates smoothly (opens at just under 8k).

Check the air filter is clean.

All the best

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

[Stefan RS50 Wood]

[Kickstart]

Hi

On the 28mm carb the main jet should be around a 120 (give or take a few). Not unknown for people to get confused and fit a ~150 main jet (about what the 34mm carb uses).

All the best

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