Cobra2
Forum Replies Created
-
Posts
-
Nothing wrong with HF681, the most important thing is to change the filter.
Personally, I change with every oil-change, or once every year…
Old and grumpy,(?), have fairly wide engine & tuning experience, "restoring/resto-mod" on cars & mc, worked as electronic tech. (retired).
GT125R - sold. New (used): 2012-GT250R-efi (sold)+ 2017-GV-125C (sold) - got my old 2018-GT-125R back... 🙂
You should check float-valve / float-level. easy with some transparent hose. Should be similar to this… just slightly open the drain-screw, till it stabilize, then compare carbs, front/rear.
Old and grumpy,(?), have fairly wide engine & tuning experience, "restoring/resto-mod" on cars & mc, worked as electronic tech. (retired).
GT125R - sold. New (used): 2012-GT250R-efi (sold)+ 2017-GV-125C (sold) - got my old 2018-GT-125R back... 🙂
Yes, but have not found anybody that can do/and that I trust… (and afford)
Old and grumpy,(?), have fairly wide engine & tuning experience, "restoring/resto-mod" on cars & mc, worked as electronic tech. (retired).
GT125R - sold. New (used): 2012-GT250R-efi (sold)+ 2017-GV-125C (sold) - got my old 2018-GT-125R back... 🙂
SMD/surface-mount leds are no particular voltage…(taken care of in the circuit) so any type within size & color is ok (remember they are polarized-only works one way)
Old and grumpy,(?), have fairly wide engine & tuning experience, "restoring/resto-mod" on cars & mc, worked as electronic tech. (retired).
GT125R - sold. New (used): 2012-GT250R-efi (sold)+ 2017-GV-125C (sold) - got my old 2018-GT-125R back... 🙂
I have a somewhat different solution to the problem… -nobody seems to think about; icing. I have no definitive proof yet, ( need a remote camera & light-source inside the filter-box), but I believe the carbs freezes over…after a minute or 2, they thaw, and you can drive again. Several other bikes have heating-elements built-in the carbs, to prevent this…
Old and grumpy,(?), have fairly wide engine & tuning experience, "restoring/resto-mod" on cars & mc, worked as electronic tech. (retired).
GT125R - sold. New (used): 2012-GT250R-efi (sold)+ 2017-GV-125C (sold) - got my old 2018-GT-125R back... 🙂
The vacuum-piston seems stuck open on one carb….? Dirt? Broken spring?
Old and grumpy,(?), have fairly wide engine & tuning experience, "restoring/resto-mod" on cars & mc, worked as electronic tech. (retired).
GT125R - sold. New (used): 2012-GT250R-efi (sold)+ 2017-GV-125C (sold) - got my old 2018-GT-125R back... 🙂
GT 250-efi-SM-2009-v1
https://mega.nz/file/eEMUQLaK#r2zvMJXv8UlyUMl0P5Q0RrSeEfChRCCRIo2Sp64Z9DU
Old and grumpy,(?), have fairly wide engine & tuning experience, "restoring/resto-mod" on cars & mc, worked as electronic tech. (retired).
GT125R - sold. New (used): 2012-GT250R-efi (sold)+ 2017-GV-125C (sold) - got my old 2018-GT-125R back... 🙂
🙂 – new tyres fitted last winter, F: Bridgestone T32, R: Michelin Road 5. Total: close to £300 (winter-price).
BIG upgrade from the “bakelite-rings” the bike was born with…
And compared with previous small bikes, the Hyo is so stable & “planted” on the road, it’s almost boring 😉The positioning, however, is for the younger, so I drilled the triple-top and mounted steering-bar insted of the clip-ons.
Old and grumpy,(?), have fairly wide engine & tuning experience, "restoring/resto-mod" on cars & mc, worked as electronic tech. (retired).
GT125R - sold. New (used): 2012-GT250R-efi (sold)+ 2017-GV-125C (sold) - got my old 2018-GT-125R back... 🙂
Agree, your plug-example looks about right.
About mine; this was after 1 hour “city”-driving, never above 6000 rpm, never above 1/2 throttle.
(mixture gets richer at wot, and higher rpm)
And…please delete the double-post, probably had a browser-glitch…Old and grumpy,(?), have fairly wide engine & tuning experience, "restoring/resto-mod" on cars & mc, worked as electronic tech. (retired).
GT125R - sold. New (used): 2012-GT250R-efi (sold)+ 2017-GV-125C (sold) - got my old 2018-GT-125R back... 🙂
Todays color…after 1 hour city-riding (slow), = white…
I have “touched up” the rear intake. Fuel-injection / micro-squirt, or similar is tempting, if I can find the funds…(and cheap parts).
The reason for larger jets, in a smaller engine, is the “signal” the carb gets is smaller. Same carb on a Harley, may be way too rich…
And pilot-jet size is mostly (by factory) determined by emission. I tune for drivability. My little contribution to a warmer world…is less than what comes out of a pigeons back. (Yes, tried 17,5, and 20. still too lean; evidence: when you can turn mixture-screw a full turn in or out from “best” setting, and engine-rpm changes less than 50-100rpm, jet is to small. Same rule goes on a 2-stroke, a 2,0-SOHC, a 5,0-V8, and so on…)
Old and grumpy,(?), have fairly wide engine & tuning experience, "restoring/resto-mod" on cars & mc, worked as electronic tech. (retired).
GT125R - sold. New (used): 2012-GT250R-efi (sold)+ 2017-GV-125C (sold) - got my old 2018-GT-125R back... 🙂
Todays color…after 1 hour city-riding (slow), = white…
I have “touched up” the rear intake. Fuel-injection / micro-squirt, or similar is tempting, if I can find the funds…(and cheap parts).
The reason for larger jets, in a smaller engine, is the “signal” the carb gets is smaller. Same carb on a Harley, may be way too rich…
And pilot-jet size is mostly (by factory) determined by emission. I tune for drivability. My little contribution to a warmer world…is less than what comes out of a pigeons back. (Yes, tried 17,5, and 20. still too lean; evidence: when you can turn mixture-screw a full turn in or out from “best” setting, and engine-rpm changes less than 50-100rpm, jet is to small. Same rule goes on a 2-stroke, a 2,0-SOHC, a 5,0-V8, and so on…)
Have you heard the story about the farmer that tried to change his horses habits? After a couple of months, he was devastated, all the horses died, and worst of all, it was just before they were “rehabilitated” to not eat at all. So close… 🙂 .
Old and grumpy,(?), have fairly wide engine & tuning experience, "restoring/resto-mod" on cars & mc, worked as electronic tech. (retired).
GT125R - sold. New (used): 2012-GT250R-efi (sold)+ 2017-GV-125C (sold) - got my old 2018-GT-125R back... 🙂
Well, carbs & jetting…changes all over the world…based on temperature and air-pressure/height above sea…
I’m located “sea-side”. (South-west-coast).
With 15 and 20 jets, and 2,5 turns out, it would run, but the “needle”-screw did not give much response, could turn a full revolution in before it stumbeled, and died. Could also turn a couple of turns out (from “ideal”) without change in rpm. With 30 jets, it started to respond on the screws, still best at 2,5 turns out, with 40 jets, response was good, -best at 1,5 turns out. Idling with AFR=14,5/Lambda 0,99
Many good hints on jetting here:
https://pilotodyssey.com/BillGivensjetting.htm
(40-pilot-jets actually came in the 6sigma-jet package)
Old and grumpy,(?), have fairly wide engine & tuning experience, "restoring/resto-mod" on cars & mc, worked as electronic tech. (retired).
GT125R - sold. New (used): 2012-GT250R-efi (sold)+ 2017-GV-125C (sold) - got my old 2018-GT-125R back... 🙂
2-stroke have haunted my thoughts… as Cagiva Mito, Aprilia RS, and Honda NSR is getting cheaper – but also harder to find good parts for. A Yamaha TZR125, or Suzuki RG125 is high up there…but rare here, and also overpriced.
So, the Hyo stays. Need another 3-4 ponies and some torque…for going against wind & uphill… -so the hunt for 50-125cc more volume will be the next plan. I have anti-rust-oiled most of the frame-internals, and rear-swing, and most other modifications are for convenience and reliability reasons.
If I were rich…I would have used way too much on titanium parts, to save weight, maybe also lighter rims.
Single cylinder 4-strokes…I usually describe as lawnmowers… – not interesting.
Old and grumpy,(?), have fairly wide engine & tuning experience, "restoring/resto-mod" on cars & mc, worked as electronic tech. (retired).
GT125R - sold. New (used): 2012-GT250R-efi (sold)+ 2017-GV-125C (sold) - got my old 2018-GT-125R back... 🙂
The EBC will of-course be better quality than any chinese….
Old and grumpy,(?), have fairly wide engine & tuning experience, "restoring/resto-mod" on cars & mc, worked as electronic tech. (retired).
GT125R - sold. New (used): 2012-GT250R-efi (sold)+ 2017-GV-125C (sold) - got my old 2018-GT-125R back... 🙂
Have been tuning the carbs a little more…for drivability, response and low-rpm “cruise”. And can not understand the “religious” view of keeping the stock “15” Pilot-jets…
I had to raise the needle to lowest clip-pos. + add a small shim (~0,2mm), + increase Pilot-jet to more than “30”, and less than “40” -still some finetuning to do, but will end up with Pilot-jets @ ca “35-37,5”. – Makes the bike rideable in the 2,5-4000 rpm band without issues.
A wideband O2 has been a good help.
Old and grumpy,(?), have fairly wide engine & tuning experience, "restoring/resto-mod" on cars & mc, worked as electronic tech. (retired).
GT125R - sold. New (used): 2012-GT250R-efi (sold)+ 2017-GV-125C (sold) - got my old 2018-GT-125R back... 🙂
Seems similar:
Old and grumpy,(?), have fairly wide engine & tuning experience, "restoring/resto-mod" on cars & mc, worked as electronic tech. (retired).
GT125R - sold. New (used): 2012-GT250R-efi (sold)+ 2017-GV-125C (sold) - got my old 2018-GT-125R back... 🙂
Thinking the “advertized” 211 degrees of intake duration really restricts any power-increase… – witch makes 4 valves/cyl and dual carb a complete waste…
even my 1980 Honda CB125-Twin was rated 17,5Hp..! -from factory! (with slight variations, depending on marked, but has:2 valves/cyl, 2 x 22mm carbs)
Old and grumpy,(?), have fairly wide engine & tuning experience, "restoring/resto-mod" on cars & mc, worked as electronic tech. (retired).
GT125R - sold. New (used): 2012-GT250R-efi (sold)+ 2017-GV-125C (sold) - got my old 2018-GT-125R back... 🙂
And mixed:
Old and grumpy,(?), have fairly wide engine & tuning experience, "restoring/resto-mod" on cars & mc, worked as electronic tech. (retired).
GT125R - sold. New (used): 2012-GT250R-efi (sold)+ 2017-GV-125C (sold) - got my old 2018-GT-125R back... 🙂
Hoped buckets were the same, as they use same shims…?
Anyway: the difference:
Old and grumpy,(?), have fairly wide engine & tuning experience, "restoring/resto-mod" on cars & mc, worked as electronic tech. (retired).
GT125R - sold. New (used): 2012-GT250R-efi (sold)+ 2017-GV-125C (sold) - got my old 2018-GT-125R back... 🙂
650Fi -(2009-) sm:
https://mega.nz/file/vcs1XDyI#NJuh8MykclBv4gAMsVozb-OIPRWDPSCP3tpwPqGg0BI
Old and grumpy,(?), have fairly wide engine & tuning experience, "restoring/resto-mod" on cars & mc, worked as electronic tech. (retired).
GT125R - sold. New (used): 2012-GT250R-efi (sold)+ 2017-GV-125C (sold) - got my old 2018-GT-125R back... 🙂
