Cobra2
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Do you have any way to check; fuel-pressure? (regulator & fuel-filter) , Temp-sensor? , O2/lambda-sensor(s) ?
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... 🙂
From the sm:
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... 🙂
YSS – MZ366-300TR-55
https://www.suspension-store.com/yss_MZ366-300TR-55
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... 🙂
If you touch the exhaust-outlets (close to heads) with a very wet rag, or squirt water on the manifolds, do they seem similar hot?
(a compression-test will tell more…)
BTW, as far as I know… NO Hyo with carbs have a rev-limiter… other than floating valves, and crashing them into pistons, if you try hard.
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... 🙂
Check compression on both cylinders…
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 may use almost any master you can fit to the handle-bar….differences to check for, are; internal piston diameter, hose-connection/angle, fluid-chamber angle, brake-light switch connector…. -the first (piston-size) will be the most important.
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... 🙂
epay unit fitted within same top-bracket, same hose-coupling. (it did have an additional bracket on the underside…hacked away on picture. And it was raw-alu-color, I gave it a dash “radiator paint”)
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 did uprate oil-cooler last year, but I think the 250-cooler takes away much of the access to front spark-plug, so while experimenting, I found a cooler just in between the 125 and 250.
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... 🙂
We still have 98 octane (without “E”)… -the 95 octane may have up to 10% garbage in it. Ethanol-mix is not for engines… not even good for the environment.
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 outlet… cut the tube loose, divorced inner/outer tubes, welded the larger back. Gives enough sound so you don’t hear the gear/chain, but the engine.
I can live with the modified muffler, but it still is much too heavy. (Living by Colin Chapman (Lotus) famous words: “Simplify, then add lightness”
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 changes to the stock muffler: De-cat, + removed inner (smallest diameter tube) from outlet.
With / without cat. Needed a lot of elbow-grease to get there…
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 already had filled a handfull holes in the “dB-killer” with pop-rivets (just shy of half the total holes). Not much difference. I guess the muffler is sized for much larger engines.
BTW, if jetting is right, NO (4-stroke-) engine will ever make more power with restriction in the exhaust-system.
Part-throttle/mid-range can change, due to cam-overlap.
90/92,5 was on the lean side with stock muffler (lightly modified) and BlackWidow pipes. On MY bike…(with the mods earlier mentioned).
I do not like running AirFuelRatio in 15+numbers at high rpm-wide open throttle…most engines likes AFR round 13 for best power,-also to control temperatures.
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... 🙂
Dyno-session
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... 🙂
Mods:
K&N-airfilter
BlackWidow exhaust & manifolds (largest round can with “dB-killer”)
EGR-delete
Honda Rectifier/regulator
520 chain/gears, with 13/46-tooth. (GT250=14/46)
NGK plug-booths & upgrade coils
Jetting:
Float-level (carb upside-down): 7-7,5mm
Front: 95 Rear: 97,5 (Proper jets from 6SigmaJet-kit) Pilot: 15 (stock). Needles at upper level/clip at lower.
AFR was very stable at WOT , within 12,5-13,5 from ~4500-11000rpm
I had hoped to find another pony or two, but the butt-dyno thinks it may be less than one…hard to say without a dyno-test as bone stock…
I also need to find a better silencer, acceptable under 6k, but gets LOUD at speed.
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... 🙂
Dyno-result: 13,2Hk/10 000rpm – at rear-wheel, translates to 15Hk from engine.
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... 🙂
But…talking about lobes…intake cam is pretty mild. If i had plenty of parts, to experiment, I would have tried the 250-intake-cams.
Back to jetting. Seems I need to save up for a dyno-session, or a wide-band lambda.
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 the outcome is the same… why did they not print the lobes like in the 650 manual? -would have saved me a lot of time… -see pic…
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 index-lines I refer to are the (faint) line at cam itself (not the sprocket). Should be like circled in green, mine are close to the red line… The sprockets align (blue circles).
Cams are correct placed, IN/EX marking between lobes. Cams are bolted in similar to picture…
Will maybe bolt on a degree-wheel to crank and check timing figures tomorrow. Front & rear should however be the same… -and they are not.
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... 🙂
Rear: (with the magic of mirrors, I could just see the lines pionting up)
The way the cams pointed up/inwards, alarmed me to check…
No wonder there is a lack of power…actually a wonder that it did as well as it did.
This seems like a factory-error?
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... 🙂
Clearances are spot on; on both cyl, intakes, a .010 slides in, a .020 dont. and ex: 020 slides, 030 dont.
However… the plot thickens …
Seeing the camshafts, I noted a strange difference… and checked with the manual. Alignment is off! On rear cyl, both index-markers points straight up, and not to each side… (see pictures !!!) Front:
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... 🙂
