RS125 Speed Problem

[ooby]

G'day all,
I'm hoping someone will be able to help with me on a problem thats started on my Rossi Rep RS 125

We cleaned the power value as it was stuck and put it back in and made sure it was working, but now the bike won't go faster that 125 km/h.

In first and second gear I get good accelaration but up around 11,000 revs it struggles but will push through if you hold it but from third gear it will take a long time to get past 10,000 doing about 120km/h and just sit there - won't go faster or rev harder.
Knocking it up a gear will make it rev about 9,000 doing about 125km/h and nothing more.

It just started after we put it back together - we took it apart again and made sure the power value was still working.

Any help/ideas would be appreciated

[Kickstart]

Hi

Have you put it back in the right way up?

All the best

Keith
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[ooby]

Yep - put it back in the way we took it out. Flat side facing up

[Jamie.]

take the cover off it, if you can do that on an rs im not sure if its easy accessable, and when u turn the key ON it should do one full open and close, if it dosent, get someone to revv the bike while you watch to see if its opening all the way

[Kickstart]

[ooby]

-Jamie- Have done that. You can pull the tank off and run the bike. The value works as it should

Keith: Sorry - bad terminology. The longer side is facing up.


I think I'm looking at a rebuild. Will do a compression test on it first but I cannot see that helping much.

At least with a rebuild I can put a big bore kit in :)

It's done about 31,000 k's.

I've had it since 26,000 and all I have done to it is

1) New battery
2) New clutch cable
3) Clean power value x2

It needs new rings etc so I may as well go all the way

[Jamie.]

[Saint Matt]

It's not the frame and gearbox that will have any issues mate, it's the bottom end.

[Kickstart]

Hi

From the problems many people have, the big bore kit barrel / piston is unlikely to last long enough to cause problems with the rest of the engine.

Oddity with the compression would be that it is unlikely to suddenly have an effect after cleaning the power valve.

All the best

Keith
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[ooby]

Thanks for all the replies

Thought I'd give a bit of an update as I was able to do a bit of work on it over the break.


The compression test came back normal. It was reading at about 105-110 psi, so it doesn't look like that was the problem.
My friend had another look at the power value and did some adjusting - he didn't take it off or anything, I'm not 100% sure what he did - and it seems to be working a lot better now.
I'm able to pull through 11,000 now in 3rd and 4th and can hit 140-150 km/h without much effort.


The only problem with it all working properly now is that I'm not sure if I can be bothered with a rebuild yet. I was waiting for it to blow before I did it.

It was a learner bike for me - got my provisional license a few weeks ago but my wife is still on her L's so I'm not too concerned with the condition because I won't have it much longer (don't worry - I'll give it a proper service come selling time)

I am aware of the dangers of a big bore but my friend has a few spare parts so it's not too much of a hassle if it goes

Anyway, once again thanks for the help

[Kickstart]

Hi

The compression is probably a bit low, but not hideous.

I have heard that the big bore kits have overheating problems at the top of the exhaust port. Not sure I could be bothered with the cost of the parts and the hassle of running in for a short life expectancy.

All the best

Keith
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