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sctrec · Joined: 14 Nov 2006 Posts: 16

wondering if anyone knows what denso ignition from other rotax products interchange with the fr125? I run in an open class at our club and before I invest in a sonik that turns 18,000 rpm, I would rather find a cheaper alternitave to making the rotax faster. I do realize that this is a sealed motor and am not interested in a tounge lashing from anyone that competes in the series for cheating, the engine is as illeagle as it could be with the big bore kit and a completly differant exhaust, so it would not even pass as a stock fr125. The reason for using the rotax as the experiment big bore is ist reliablity, as others are tearing down and rebuilding evry 4 races, I have only rebuilt once running 12 races, it is a great engine but I am tired of running 3rd. Any help would be nice.

jacksi · Joined: 14 Nov 2006 Posts: 40 Location: malta

hi i have a fr 125 and it has been giving me accelaration problems for the past 2 races i have change the complete piston and we have changed absolutly everything and still cannot find the fault for lack of accelaration.
now i am also looking into the sonik instead of the fr125 but am not sure whether to go with the delorto kit or the tryton carb, even engine the im not sure wich is better the tx125 r or the ktx 125 horstman clutch type.
any ideas?
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jacksi racing
malta

sctrec · Joined: 14 Nov 2006 Posts: 16

I think the tryton is easier to dial in and you can't go wrong with the hortsman

jacksi · Joined: 14 Nov 2006 Posts: 40 Location: malta

do you think with the correct jetting i can get more power out of the horstman?
the fr125 you have from std you did this upgrade?
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jacksi racing
malta

sctrec · Joined: 14 Nov 2006 Posts: 16

the hortsman will allow you to set the rpm ingagement. I have bored fr125, and the reason i am looking for a ignition modual is to advance the timing.

jacksi · Joined: 14 Nov 2006 Posts: 40 Location: malta

i will check with my mechanik tommorrow for you.
so do you race with other 125 racing engines?
what do you think is better the max or the sonik ?
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jacksi racing
malta

Andy · Joined: 28 Oct 2006 Posts: 376 Location: Surrey

Hi, a word of caution for you, the Max's Conrod does not like revving much more that 14,000rpm, could be an expensive mistake.

Something to bear in mind

sctrec · Joined: 14 Nov 2006 Posts: 16

you ask my opinion the max vs. the sonik, the max is a great setup for it's intened use...being a sealed motor racing other max's, now for open classes trying to be competive against the sonik, rotax would need to use a differant clutch with higher ingagment, use a more user friendly carb for jetting. The reason the max last longer is because it does not turn 18,000 rpm's and it shouldn't, good power can be made under 14,000 rpm's it is just finding it. The sonik will cost you dearly to own and race, they are a time bomb the minute they fire and will explode without notice. I race guys and they are going broke rebuilding the engine to stay competive, as where the rotax has been very affordable to race. hope that helps.

Kart4fun · Joined: 08 Oct 2006 Posts: 404

sctrec,
what carb are you using ? Dellorto or a diaphram carb ?
Ignition mods are available ( but i can't find the details at the mo') but you should be able to find the contacts from one of the Aprillia RS tuning sites.
Are you using a Pollini conversion ? I believe they have Ignition parts also.
Where do you race ?