I have a Victor 4-stroke (sprint 375) which is 8 yrs old. Never missed a beat until yesterday where the engine now revs, then almost cuts out, then revs, then almost cuts out etc. All 'obvious' components have been checked (spark plug, air filter etc) Any ideas?

The Victor GL was the first bike from the "Victor" series. The bike was loaded with 109cc 4-stroke engine, which was later known for its fuel efficiency and robustness. However the style quotient of the bike was a little low but TVS had compensated the same by launching the stylish "Victor GLX" later on with 125cc.

idle too low

four stroke

Giantco Sprint Sport 50 2009

if it is a 4 stroke then regular unleaded is good
make sure that there is oil in the sump
the fuel type is in the owners manual

Hi there Pauly 46 here

the basic settings for 2 stroke chainsaws are

Lo 1 1/4 turns out from lightly seated- this is base setting

Hi 1 1/4 turns out from lightly seated - this is base setting

note chain and bar must be on before proceeding as below


once engine running let it idle just below clutch engagement speed , then give the throttle a quick stab for 2 or 3 seconds - turn Lo needle out 1/8 turn at a time if it seems to stumble before accelerating

next you will have to sett the Hi speed this is done AT REV , with engine running at rev
ie top no load turn HI speed mixture out a little more 1/8 turn at a time until you can hear the engine 4 stroke at rev ( that is runn richer ) most saw top no load speed is about 10500 -11500 rpm
ball park

CAUTION Do no set the hi speed setting any lower than about 1 to 1-1/8 out from lightly seated
because if its set to lean and you bury the saw into the cut it will lean out even more
and the saw piston and rings / bore will be damaged

note use top quality 2 stroke oil if you are mixing @ 50:1 ratio

that is 20 mils of oil per 1.0 litre of petrol that you mix

cheers hope it helps

pauly46

Assuming that the bad fuel has been cleaned away, check the fuel filter, air cleaner, and muffler for plugging. Turn both jet screws CW to stops (lightly) then back out CCW 1-1/2 turns each. This is a basic setting which should allow the engine to start and warm up. After warm, pull the throttle full on and turn the H jet needle CW until the engine starts to speed up. Final adjustment is when the engine 4-strokes at speed unloaded, but immediately 2-strokes when cutting. Release the throttle and adjust L jet needle CW until the engine idles fairly well, but still allows the engine to 'follow the throttle'. Hope this helps!

Check the fuel filter, air cleaner, and muffler for plugging. Check the fuel lines for decay or other damage. Make sure the chain/bar is properly lubricated, sharpened, and tension adjusted. If no help, turn the H jet screw CCW a little so that the engine 4-strokes at speed unloaded, but immediately 2-strokes when cutting. This will give the most power and least heat. Hope this helps!

Sounds like the saw is running lean. Check the fuel filter, air cleaner and muffler for plugging. Check the condition of the fuel lines and that the fasteners on the carburetor are tight. If all ok, turn the 'L' and 'H' jet needles on the carburetor CW to stops (lightly), then back out each 1-1/2 turns CCW. This is a basic setting and the engine should start and run. Allow the engine to warm up, pull the throttle full on, and adjust H CW until the engine starts to speed up, but continues to 4-stroke. Proper adjustment is when the engine 4-strokes, but immediately 2-strokes when cutting. This produces the most power and least heat. Allow to idle and adjust L CW until the engine runs fairly well, yet will allow it to 'follow the throttle'. Set the idle speed screw til the chain stops moving, but keeps the engine running. Hope this helps!

ignition timing may be off slightly.

Remove the muffler and clean out deposits from the spark arrestor screen. Make sure the intake air filter is clean. If these two items are good, then the 'H' carburetor adjustment may be too rich--turn clockwise somewhat until the engine runs at full speed, but 4-stroking slightly. The engine should smooth out and 2-stroke with even a light cutting load. Make sure the chain is being properly oiled while running. Hope this helps!