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c_dug |
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c_dug Super Spammer
Joined: 04 Sep 2007 Karma :
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Posted: 11:54 - 14 Aug 2017 Post subject: 2 stroke maintenance and tuning - RS125 |
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Hi All,
I own a relatively rare Tuono 125 2 stroke, it looks a bit like this one:
https://2.bp.blogspot.com/-CKiGV4OMp24/Uaxl8Vo2tfI/AAAAAAAACRk/sG2_tte8vVw/s1600/Malaysia-Aprilia+Tuno+silver.jpg
It's essentially an RS125, with a different fairing and bars.
I originally bought it for my other half to learn on, but I've since realised how rare they are, and also quite enjoyed riding it, so, it's mine now
It runs okay at the moment, but I'm aware that its due a top end rebuild around about now. It also bounces hard off the rev limiter at 80mph in top gear, which would suggest it's probably been at least partially derestricted at some point, a cursory glance would suggest the front sprocket has dropped a size or two too.
I know these are capable of outputting high 20s bhp, low 30s at a push, and I'd like to get it towards those figures. I can work a set of tools, but I don't really have the knowledge of tuning two strokes, and I'd rather not learn the expensive way when it can be avoided!
As far as I'm aware, it's virtually standard at the moment. Where do I start?
Sporty barrel?
Bigger carb?
K&N filter?
Sporty pipe?
How do I work out jetting for the above?
I'm not intent on keeping it bog standard to eek every penny out of it's value in 15 years time, I'd rather enjoy hooning around on it now, and showing it off down the ace (It gets about as much attention as my old TDR250 did!).
All advice appreciated,
Thanks! ____________________ I am a bellend, I am a man of constant sorrow, I am a gummy bear, I am a rock. |
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Robby |
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Robby Dirty Old Man
Joined: 16 May 2002 Karma :
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redeem ouzzer |
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redeem ouzzer World Chat Champion
Joined: 06 Oct 2015 Karma :
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RhynoCZ |
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RhynoCZ Super Spammer
Joined: 09 Mar 2012 Karma :
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Posted: 12:52 - 14 Aug 2017 Post subject: |
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I was gonna say keep it stock, that it's not worth the money and worse MPG with short service intervals..., but then I'd like to see you fitting a RS 125 engine with big bore kit in it. ____________________ '87 Honda XBR 500, '96 Kawasaki ZX7R P1, '90 Honda CB-1, '88 Kawasaki GPz550, MZ 150 ETZ
'95 Mercedes-Benz w202 C200 CGI, '98 Mercedes-Benz w210 E200 Kompressor |
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stevo as b4 |
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stevo as b4 World Chat Champion
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c_dug |
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c_dug Super Spammer
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Kickstart |
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Kickstart The Oracle
Joined: 04 Feb 2002 Karma :
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Posted: 18:35 - 14 Aug 2017 Post subject: |
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Hi
It isn't so much the pipes were restricted, rather than they landed up with all sorts of rubbish in them as time went on to get through noise and emissions tests. Early bikes had better pipes, and with later ones potentially quite a bit of power from a decent pipe.
After that, later carb, played with barrel, played with cdi unit if you want.
All the best
Katy ____________________ Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing |
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c_dug |
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c_dug Super Spammer
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Kickstart |
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Kickstart The Oracle
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ScottT |
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ScottT Scooby Slapper
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Kickstart |
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Kickstart The Oracle
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stevo as b4 |
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ScottT |
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ScottT Scooby Slapper
Joined: 17 Sep 2014 Karma :
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Posted: 20:00 - 16 Aug 2017 Post subject: |
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stevo as b4 wrote: |
I don't know how many two stroke bike engines Scotty has tuned or stripped, but do you really think on all relatively modern two strokes, that there are huge casting obstructions in the transfer ducting and where the liners meet the crankcase?
Also everything you have said even if there was some some small casting imperfections and mismatch between gaskets and port entry areas, is very minor in restriction to air flow. The manufacturers would get it perfect if they were losing any noticeable or easy to get at bhp.
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I didn't say huge obstructions, little ones will not allow the fuel to flow exactly as the engine was designed to do.
Given that most gaskets are stamped out on a machine with a die cutter, which will wear out. Do you think gasket 1 will be exactly the same size as gasket 10,000?
Lets say a company is producing a 20hp 125,they build a prototype or 2 and its got 20hp, then go into production they check the bikes coming off the production line and they are producing 19.6 to 19.8hp, do you think they will stop production and go looking for that 0.4 to 0.2 hp or will they just carry on. Or lets say they find the missing HP and realise its going to take another 4 or 5 hrs in labour to sort each engine.
Ferrari or Rolls Royce might think its worth the effort, but a mass produced bike in a competitive market might not want to add extra costs.
stevo as b4 wrote: |
So best case scenario is that your so called blue printing is going to gain a few fractions not masses of power. |
It's not just fractions, its all about getting the engine right before you start tuning it, perhaps blueprinting was to strong a word, but getting it back to standard is the way to start.
Look at it this way, a 20hp 125 bought new, thrashed everywhere from cold, used cheap oil in the premix, serviced with the cheapest ebay parts, a few years or 10,000 miles later how much HP will it have? 15? 12? less?
Then the owner sees an advert for a expansion chamber, has a chat and is told he can expect about 20% more power, so he buys it and wow the bike is now much quicker, that was money well spent, except now its still producing less power than it did when it was new.
Or he could have got the engine back to standard, then added the expansion and now he has 24Hp.
Tuning a worn out engine will never get as much power as tuning a standard engine
stevo as b4 wrote: | Tuners don't generally go for the tiny time consuming details if there's much more noticeable and dramatic gains available elsewhere. |
So which bike would be quicker? The one with only the "noticeable and dramatic gains" done
or
the one with the noticeable and dramatic gains and the tiny time consuming details done?
stevo as b4 wrote: |
I don't know how many two stroke bike engines Scotty has tuned or stripped
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Owned, rebuilt, tuned, worked on, raced and competed on 2 strokes from old Villiers engines, production racing LC's, full race spec Kart engines to fairly modern trials engines. |
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Old Thread Alert!
The last post was made 6 years, 254 days ago. Instead of replying here, would creating a new thread be more useful? |
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