Resend my activation email : Register : Log in 
BCF: Bike Chat Forums


Aprilia Rs 125 Rs125 Re-jetting

Reply to topic
Bike Chat Forums Index -> The Workshop
View previous topic : View next topic  
Author Message

twotakt
World Chat Champion



Joined: 25 Oct 2007
Karma :

PostPosted: 18:47 - 14 Nov 2007    Post subject: Aprilia Rs 125 Rs125 Re-jetting Reply with quote

Hello all,
Im changing my standard exhaust (with catalytic converter) to a full arrow system on my Aprilia Rs 125. I just wondered what size main jet I need to fit to my 28mm carb? Apparently its 120 but I just wanted to double check.

Thanks in advance
 Back to top
View user's profile Send private message You must be logged in to rate posts

stirlinggaz
World Chat Champion



Joined: 22 Jul 2007
Karma :

PostPosted: 19:17 - 14 Nov 2007    Post subject: Reply with quote

hi,
do you know what size is in at the moment?
as far as was aware, the standard carb came with a 125 main jet,
mine did.
im now running a 34mm carb with a 160 jet.
but will find out what others are using and get back 2 you.
im sure the 2 stroke experts out there will help!
cheers,
GAZ
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts

stirlinggaz
World Chat Champion



Joined: 22 Jul 2007
Karma :

PostPosted: 19:26 - 14 Nov 2007    Post subject: Reply with quote

Hi,
yes mines was defnately a 125.
what year is your bike?
anyway if youve put arrow on, im pretty sure you should be going for a jet with a higher no. than what you have in now!
so if you have a 120 in now, go for a 125.
if you already have a 125 (probably have) go for a 128 or 130.
i would just buy 2 or 3 different sizes going upwards from what you have in now.
& see what runs best.
trial & error.
let me know what jet you have in now.
hope this helps.
cheers,
GAZ
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts

Phil_P
Trackday Trickster



Joined: 10 Nov 2007
Karma :

PostPosted: 19:43 - 14 Nov 2007    Post subject: Reply with quote

If you buy a range of jets, start off with the BIGGEST and work down, not the other way round and do a plug chop with each. Running your two stroke at full chat with an over-lean main jet is a quick way to get a hole in your piston. much safer to start rich and work leaner.
____________________
It is not enough to win, others must fail.
Moto Guzzi 1100 Sport Injection '96
 Back to top
View user's profile Send private message You must be logged in to rate posts

twotakt
World Chat Champion



Joined: 25 Oct 2007
Karma :

PostPosted: 00:33 - 15 Nov 2007    Post subject: Reply with quote

Not sure what size jet that I've got on there at the moment; the bike is 2003 SBK replica. So the bigger the jet the richer it'll run?
 Back to top
View user's profile Send private message You must be logged in to rate posts

Kickstart
The Oracle



Joined: 04 Feb 2002
Karma :

PostPosted: 02:20 - 15 Nov 2007    Post subject: Reply with quote

Hi

Yes. Larger the number the larger the jet, so the more fuel it will flow (within reason). But it only controls the mixture on full throttle (or close to it), so you will likely have to play with the needle as well as it controls the mixture through most of the throttle range.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts

Phil_P
Trackday Trickster



Joined: 10 Nov 2007
Karma :

PostPosted: 15:33 - 16 Nov 2007    Post subject: Reply with quote

As kickstart has suggested, just raisng your needles a notch or two might sort it out.
____________________
It is not enough to win, others must fail.
Moto Guzzi 1100 Sport Injection '96
 Back to top
View user's profile Send private message You must be logged in to rate posts

stirlinggaz
World Chat Champion



Joined: 22 Jul 2007
Karma :

PostPosted: 23:47 - 16 Nov 2007    Post subject: Reply with quote

Phil_P wrote:
If you buy a range of jets, start off with the BIGGEST and work down, not the other way round and do a plug chop with each. Running your two stroke at full chat with an over-lean main jet is a quick way to get a hole in your piston. much safer to start rich and work leaner.

hi,
yes, sorry!
i should have added that.
i meant buy 2 or 3 different sizes up from what you have.
so if you have a 125, buy 128, 130, & so on.
but when fitting, try the biggest one you have first, then work downwards
but im pretty sure you wont have to go much bigger, just depends on what you got now!
so whip that jet out & let us know!
someone might have the jet you need, there only about 3 or 4 new.
I found, as others have said, that most improvement/difference happens when circlip is moved up or down needle.
took me a while but after rejetting & trying all the different positions on needle,adjusting idle & mixture screw, i must say it was worth the hassle.
cos bike runs great, all thru the revs, no bogging down.
the 2 stroke guys on here gave me lots of good advice(thanks!) listen to them!
cheers,
GAZ
ps - have you done the cdi mod yet?
best thing i done! (apart from bigger carb)
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts

twotakt
World Chat Champion



Joined: 25 Oct 2007
Karma :

PostPosted: 14:43 - 21 Nov 2007    Post subject: Reply with quote

Thanks for everyone's help,
I haven't done the cdi mod yet. I'm going to give it a go in a minute providing I can find some silicone to re-fill it with. I'm still not sure what size jet I got in there at the moment.
I un-screwed the two bolts on top of the carb and took the slide out. Then un-screwed the choke cable and moved it out of the way, then loosened the the two jubliee clips connecting the carb to the inlet manifold and the air box and tried moving the carb around so I could get access to the bolt (14mm i think) which I'd unscrew so I could have a look at the jet. But after loosening the jubliee clips the carb wouldn't budge, I didnt want to force it in case I missed out a step in what I need to do to gain access to the jet.

Have I missed anything out in that process? Or is it just that I need to force it out a little?

Thanks again
 Back to top
View user's profile Send private message You must be logged in to rate posts

Kickstart
The Oracle



Joined: 04 Feb 2002
Karma :

PostPosted: 15:03 - 21 Nov 2007    Post subject: Reply with quote

Hi

First guess at the problem might be that the oil pipe (from the pump to the carb) is too tight to allow you to move the carb.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts

twotakt
World Chat Champion



Joined: 25 Oct 2007
Karma :

PostPosted: 17:13 - 21 Nov 2007    Post subject: Reply with quote

you were right kickstart, it done the job. the main jet size is currently 132.
With the information I got with my Arrow pipe it said that I ought to run it with a 120 main jet on 28mm carb. That seems a big jump from a 132.

thanks for the help
 Back to top
View user's profile Send private message You must be logged in to rate posts

Kickstart
The Oracle



Joined: 04 Feb 2002
Karma :

PostPosted: 17:42 - 21 Nov 2007    Post subject: Reply with quote

Hi

Rich is safer. Maybe get a few more main jets and play. But get it too lean and it is likely to seize, while too rich mainly just blunts power and fouls plugs.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts

stirlinggaz
World Chat Champion



Joined: 22 Jul 2007
Karma :

PostPosted: 00:55 - 22 Nov 2007    Post subject: Reply with quote

jackdim wrote:
you were right kickstart, it done the job. the main jet size is currently 132.
With the information I got with my Arrow pipe it said that I ought to run it with a 120 main jet on 28mm carb. That seems a big jump from a 132.

thanks for the help

Hi,
are you sure you have a 132 main jet in now?
as the standard jet should be 120 or 125, as far as im aware.
so if you have a 132, someone has been playing with it before you!
you would normally change your jet accordingly :
usually from 120 to 125 or 128
or 125 to 128 or 130.
so if you have a 132 in at the moment, was it running ok before?
not bogging down?
i would have thought a 132 would be too big for standard set up?
anyway, i would think 132 would be fine for full power & arrow pipe.
give it a try.
best thing i ever done to my rs was the CDI modification!
after some advice I followed pics on rs forum but cut too far & ruined my cdi!
but got another, cheap, & had another go (after some more advice & some worrying!)
10 minute job. just covered it up with duct tape afterwards, till i got silicone sealant from pound shop!
ran great, right thru the revs!
no more resistance/flat spot!
cheers,
GAZ
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts

twotakt
World Chat Champion



Joined: 25 Oct 2007
Karma :

PostPosted: 11:22 - 22 Nov 2007    Post subject: Reply with quote

Yup its definately a 132, apparently its so big because it's set to run rich with the catalytic converter in the previous exhaust.

I haven't even ridden the bike yet; its immaculate so I'm saving it for the summer. Just riding my yamaha dt125 through the bad weather.
Although I brought the Aprilia from my Dads mate and he said it was running sweet before.

Have you got any links on how to do the cdi mod? I've got some information but I'd like to cross reference with the material you've used in order to make sure that what I've got is correct.

Thanks again, Jack
 Back to top
View user's profile Send private message You must be logged in to rate posts

stirlinggaz
World Chat Champion



Joined: 22 Jul 2007
Karma :

PostPosted: 12:55 - 22 Nov 2007    Post subject: Reply with quote

Hi mate,
ok stick with the 132 for the time being, probably about right.
i take it you no longer have the cat? & have FULL arrow system?
not just the end can?
cos thats definately gonna make an improvement!
the cdi stuff was on the aprilia forum,
im no good at this pc stuff, so dunno how to post links,but if you cant find it let me know! & i will send what i have to you in pm/email.
as i done it quite recently, i can honestly say its piss easy!
& well worth doin!
cheers,
GAZ
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts

twotakt
World Chat Champion



Joined: 25 Oct 2007
Karma :

PostPosted: 16:57 - 22 Nov 2007    Post subject: Reply with quote

Got the full Arrow system (expansion chamber and silencer), the CAT is gone!
Just can't wait to ride it now; I'll do the cdi mod on the weekend when I'm fitting the Arrow pipe.
I was considering at some point getting it dynojetted. There is a place on the other side of Bristol which is called Tim Blakemore's racing which is probably where I'd get it done.
To the best of my knowledge they adjust the carburettor settings in order to gain the best performance out of the bike. Is this right?
Anyone had it done? Is it worth doing?

Thanks for the help, Jack
 Back to top
View user's profile Send private message You must be logged in to rate posts

Phil_P
Trackday Trickster



Joined: 10 Nov 2007
Karma :

PostPosted: 18:10 - 22 Nov 2007    Post subject: Reply with quote

Any dyno tuner is probably worthwhile if you have substantially altered the bike from stock.

Using a dyno and a fuel/air meter, they can tell if your bike is running rich or lean and hopefully re-jet it to get it right. Usually best power output coincides with best fuel air (stoichometric) ratio, or at least, pretty close to it.
____________________
It is not enough to win, others must fail.
Moto Guzzi 1100 Sport Injection '96
 Back to top
View user's profile Send private message You must be logged in to rate posts

Kickstart
The Oracle



Joined: 04 Feb 2002
Karma :

PostPosted: 19:51 - 22 Nov 2007    Post subject: Reply with quote

Hi

As above, but make sure it is someone used to doing 2 strokes.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts

twotakt
World Chat Champion



Joined: 25 Oct 2007
Karma :

PostPosted: 00:51 - 24 Nov 2007    Post subject: Reply with quote

Hi, phoned the bloke earlier and he said hasn't got the dynojet kit to do it for an Aprilia Rs. Anyone know of somewhere near the Bristol area where I could get it done?

Also went to do the cdi Mod earlier but its already done! Happy days.

Just a quick question; I got a new woodruff key (gianelli key) which came with my Arrow Exhaust. In the instruction manual it said that I need to replace the stock woodruff key with the new gianelli key.

Is this a hard job to do? It is worth doing?

I know you have to remove the flywheel cover and the woodruff key runs laterally along the crankshaft. However I don't know where the flycover is! (I think its on the gear change lever side)

Also I wondered what would be the best method of removing this cover?

Thanks in advance, Jack
 Back to top
View user's profile Send private message You must be logged in to rate posts

Kickstart
The Oracle



Joined: 04 Feb 2002
Karma :

PostPosted: 01:02 - 24 Nov 2007    Post subject: Reply with quote

Hi

The flywheel you need to remove is on the brake side of the bike (on the RS) under a plastic cover. However you will need a puller to remove the flywheel.

I take it you have got some odd offset woodruff key to adjust the ignition timing slightly.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts

twotakt
World Chat Champion



Joined: 25 Oct 2007
Karma :

PostPosted: 13:16 - 25 Nov 2007    Post subject: Reply with quote

Do you think that I'd definately need to replace the woodruff key?

The reason I'm asking is because I don't want to pay 50 for the rotax puller.

http://www.skydrive.co.uk/sd_to_rs.asp

Thanks for the help, Jack
 Back to top
View user's profile Send private message You must be logged in to rate posts

Kickstart
The Oracle



Joined: 04 Feb 2002
Karma :

PostPosted: 13:26 - 25 Nov 2007    Post subject: Reply with quote

Hi

Suspect it might give a bit more performance (might also mean using super unleaded to avoid serious engine damage). Depends exactly what it is there for. Possible it is there to retard the ignition to take account of the exhaust effectively shoving more mixture back into the engine and encouraging detonation (unlikely), but without the details I cannot say.

All thebest

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts
Old Thread Alert!

The last post was made 6 years, 336 days ago. Instead of replying here, would creating a new thread be more useful?
Display posts from previous:   

Post new topic   Reply to topic    Bike Chat Forums Index -> The Workshop All times are GMT + 1 Hour
Page 1 of 1

 
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You cannot download files in this forum

Read the Terms of Use! - Powered by phpBB © phpBB Group
 

Debug Mode: ON - Server: peanuts (www) - Page Generation Time: 3.76 Sec - Server Load: 0.48 - MySQL Queries: 17 - CDN Objects: 35 - Page Size: 125.71 Kb