NSR 125 acceleration problems.

[paul651975]

i have a nsr 125 (51 plate). now i have derestricted the bike following alanis guide. now i'm have some problem's with the acceleration, when i start my bike and pull away at about 5K it begins to sound like its spluttering and the acceleration is really slow and bike sounds awful, this continues up through the gears, it only seem's to clear if i push the bike past 8K then its ok until next time the engine is stopped for any length of time. this happens even if i leave the bike to warm up for 15 mins. i've cleaned my carb, air filter etc. checked the operation of my r/c that is hi on idle and lo at about 2500K. the marker on the barrel lines up ok. checked float high and just about everything else. any help would be much appriciated.

Oh the bike did this before derestriction aswell, had hoped it would be cured it.

[salty21]

does it also get louder and more throaty? then picks up dramatically at 6,500-7,000rpm
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04 NSR 125(sold) ---- 03 CBR 600rr(sold) ----90 pan euro ST1100 '' ----02 CG 125
94 CB400 Super Four ---- 2000 VTR SP1 (sold) ---- 08 ninja p8f(sold, meh) ----05 CBR600rr

[alains]

set the needle at the second notch from top
____________________
the worst day fishing is better than the best day working

[paul651975]

no it seem's to sound the same, but yes once it gets to about 7k it does suddenly pick up. my needle is already set on the second notch from the top

[dougon2wheels]

sounds to me like you still too rich on the needle............drop the needle(raise the clip)one more notch and see if that improves it.....

[paul651975]

won't i then run the risk of being to lean, and also once its cleared its self it runs fine. i can stop at a junction and pull away fine accelerating up through the gearbox. its only after the bike has been stopped for say a couple of hours. usaully involves starting the bike with the choke out.

[salty21]

im pretty sure its the powervalve being open, hold the revs at the point where it loses power(or around there if you cant hold it steady) then key off at those revs and check the position of the powervalve, it should be on low still.
____________________
04 NSR 125(sold) ---- 03 CBR 600rr(sold) ----90 pan euro ST1100 '' ----02 CG 125
94 CB400 Super Four ---- 2000 VTR SP1 (sold) ---- 08 ninja p8f(sold, meh) ----05 CBR600rr

[joop200789]

choke not sticking is it??

[paul651975]

ok i'll try that, but i have checked that they open and close, when in neutral if i rev the engine the servo turns and also the valves do move. altho at times i have heard the servo trying to move after the initial key on like its not quiet receched position proplery. 1 have replaced the choke assembly with a new one and that wound to minimuim as the bike struggles to start when set to 10mm stroke. (sounds like its flooding).

[paul651975]

just been checking the valve timing, when servo is on high the mark on the pulley lines up with the mark on the casing, but i have noticed that there is another mark on the pulley then when servo is in lo position this is near the mark on the casing but doesn't line up with it, should this line up if so how because there is no adjuster for it that i can see, only for the hi position.

[salty21]

its the barrel side that needs to line up correctly, the servo side just gives a rough idea, but if its not moving fully in each direction it would suggest the valves in the exhaust port have coked up or you have the wrong p/v control unit.
____________________
04 NSR 125(sold) ---- 03 CBR 600rr(sold) ----90 pan euro ST1100 '' ----02 CG 125
94 CB400 Super Four ---- 2000 VTR SP1 (sold) ---- 08 ninja p8f(sold, meh) ----05 CBR600rr

[paul651975]

i have taken the exhaust off and looked up the port and the valve look's not to bad, if i turn the valve manually it will goto both lines marked on the barrel casing. the servo moves freely between the lo and high marks, how do i set it up so i hit both marks as the adjustment is for the open setting.

[paul651975]

Actually the cable with the adjusters on connect to the side that is nearest to the lo setting on the barrel, altho i do have a french import, and according to alains guide thats correct. but if i alter these i can either get it to hit the lo setting or the high setting not both. i have a tv-78 fitted and a ci626 cdi unit

[salty21]

weird are you sure its a tv-78 as the restricted unit only opens the valves to about 70% which would fit your problem perfectly.

only other thing i can think of is the red/white wire from the cdi, which tells the r/c control unit what rpm the engine is at which in turn opens the valve accordingly, so would be worth checking the connections on that wire, also do you have an orange/white wire on your cdi box that has 2 connectors and and goes round in a loop back into the cdi?
____________________
04 NSR 125(sold) ---- 03 CBR 600rr(sold) ----90 pan euro ST1100 '' ----02 CG 125
94 CB400 Super Four ---- 2000 VTR SP1 (sold) ---- 08 ninja p8f(sold, meh) ----05 CBR600rr

[paul651975]

yes defo a tv-78, sorry tho my mistake my cdi is a ci639 with the shunt cut. so should i set the valve up so it hits the lo mark and then get a ci626 cdi.

[salty21]

yep the ci626 should smoothen out the revs too and give more power, will probably sort out the powervalve openings aswell, but dont hold me to that.

for the mean time, depending how you ride you can set the valves to be on hi or low, say if its dual carriage ways probably best on hi, if its town or city riding keep it on low.

make sure when you get the cdi it's a ci626 and not a ci626a as this one tops out at 10,500rpm and the normal ci626 tops out at around 11,500rpm which is well into the redline
____________________
04 NSR 125(sold) ---- 03 CBR 600rr(sold) ----90 pan euro ST1100 '' ----02 CG 125
94 CB400 Super Four ---- 2000 VTR SP1 (sold) ---- 08 ninja p8f(sold, meh) ----05 CBR600rr

[paul651975]

ok cheers for the help, i've set it up for the lo setting as mainly city riding, altho when it does go hi its only a fraction out anyhow (say about 1_1.5mm)

[salty21]

[robbo68]

You should get the C1626 cdi soon as possible because the shunt cut on the C1639 is rubbish and it dos'nt work fully change this and it should solve the problem just remember to swap the 2 wires on the 4 pin connector.

[alains]

exactly
____________________
the worst day fishing is better than the best day working

[paul651975]

ok so now have a ci626 and now my valve is hitting both mark's but i still have the same problem.

[alains]

did you cross the green and the black/yellow at the 4 wires connector going to the CDI ? if not stop immediatly and cross the wires . you've got the chat on my file NSRtips.doc
when running at 7500 rpm , what shows the pulley arrow (must be fully on HI) ?
____________________
the worst day fishing is better than the best day working

[paul651975]

Haven't managed to check that coz neighbours moan about the noise. But it goes low and hits the closed mark on key on. And on starting the bike it goes high and hits the open mark when idling. Yes i have got your guide and i have swapped the wires around, just another question tho when i cut the hole in my airbox i cut a 2cm x 4cm hole and covered it with mesh, is this the right size? would this cause my problem?

[robbo68]

Hi, as for the hole in the airbox that sounds small mine has a cutout about 3inch x 5inch this could mean you are starvin the carb of air but l think you have another problem some where try what alain's said and let us know the out come.

[alains]

could be the problem , too much air . what shows the plug ?
but the main thing when running at 7500-8000 rpm , does the pulley go fully HI ?
____________________
the worst day fishing is better than the best day working