NSR 125F CARB AND JETTING PROBLEM

[bouncerdove]

Hi all. I have purchased a swiss import for my son. but have a headache of a problem to sort out.
The bike smoked like anything when ridden and smelt strong of petrol, also would not tick over nicely, or rev above 7k unless you shut back the throttle to about half then it would rev through to 8k then take off again right round to 11k.
I removed carb and cleaned out then refitted, Made no difference.
I checked for wire link which was already removed (put a link back in just to test, and servo stopped operating, so removed as before)
Changed plug. still no better.
I still felt it was a fuel problem so removed carb again to check jet size and this is what I found.
No inlet restricter fitted
carb is a PHBH28/FS.
SLOW JET 52
POWER JET 70
MAIN JET 132
NEEDLE 99x
Adjusted float height to 24mm and put back together and the smoking seems to have stopped completely but still hangs at 7k on full throttle.
Have cut expansion chamber in half to check for blockages etc all ok so rewelded together (no restricter fitted).
Have also checked piston, rings, and cyl. no signs of problems there either
Bike is a 1995 NSR 125FL JC20
CDI is CI589B
CV is TV78
Carb is PHBH28/FS
CHASSIS NUMBER is 213905
The CI589B has two orange/white wires exiting it as well as the two plug connectors I dont know what they are for (any ideas)
Like I said any help would be very helpful
Many thanks bouncerdove

[bouncerdove]

Hi again. Have now been on a 100 mile test. I get the impression that some form of electronic restriction is causing the bike to cut out at exactly 7k revs. At 6.5k it is fine, 7k dies if throttle opened above 1/2 way, 7.5k it kicks back in and accelerates like expected.
any help appreciated.
Although bike is a 95 model it has only done 11000 miles and is in immaculate condition, So it must have stood a while somewhere but I dont think this is a cause of the problem
Regards bouncerdove.

[bouncerdove]

Hi all. Problem sorted. The CI589B CDI unit is not opening the RC valve at 7k. In fact it part opens then closes then part opens continuously.
Regards bouncerdove

[Mikey CB500]

Hi buddy, for a start is it a late registered JC20? As they stopped making them in 93 and you say yours is a 95. Or is it a JC22 foxeye? You need a fully derestricted CDI unit, depending which model of bike depends with CDI you need

The swiss bikes a restricted by having a different powervalve servo, different powervalve control box, different CDI, exhasut restrictor, the plate between the manifold and the reed block and as far as i can remember they are also running a lower jetting than the other european bikes

[bouncerdove]

Hi. Now I am confused as to what the bike really is. I purchased it as a 1995 swiss import ( I have the swiss log book ). It is a twin round headlight model. There was no restriction in either the exhaust or inlet, The RC valve control unit is the unrestricted TV78, But the CDI CI589B is a restricted unit.
I understand from other peoples posts that the HI - JC20 on the frame number means it is a Japanese model, which this one does
Any information on this please.
Regards bouncerdove

[anthony_r6]

[Mikey CB500]

Thats definately a twin round headlight gold frame alcast JC20. Not sure the TV78 is even the right RC valve unit for the JC20 I know it is on a JC22.

Ill give my buddy in france a ring later, hes a nsr expert lol

[bouncerdove]

Hi and thanks for the reply. Heres another picture.
regards bouncerdove

[alains]

i suggest :
1) have a compression test (results under 125PSI are indicating a loss of power)
2) buy a CI572 instead of your CI589
3) buy carbon membranes for the reed block here https://cgi.ebay.de/JOllify-Carbon-Membrane-Honda-NSR-125-R-036e-/120762901399?pt=Motorrad_Kraftradteile&hash=item1c1e07a397
4) change main jet with 145 , power jet 70 , idle is OK see https://www.dellorto.co.uk
5) fit BR9EIX plug (a lot on ebay uk)
and the most important use only fully synthetic 2 strokes oil (do not use mixing oil)
____________________
the worst day fishing is better than the best day working

[bouncerdove]

HI. And once again thanks for your replies. I have done a compression test (132 to 136 psi). I checked piston and cylinder anyway and there is no problem there.
I have purchased a CI626, will this be compatable. ordered the upgrade jets from Dellorto (all awaiting delivery).
I also have the option of a CI 572. What is the better.
Reeds will be changed as well (Boyson i'm going for).
Already use synthetic oil and plug.
Regards and thanks again bouncerdove

[alains]

CI626 is made for the JC22 (foxeye) so drop that,CI572 is made for JC20
boysen are not suitable for the JC20 they are too thick and havnt the 3 petals as my link shows . i run the forum geneva-racing.ch and nearly all members bought those and are fully satisfied
those are about 20quids inc p&p , boysen will be around 45
____________________
the worst day fishing is better than the best day working

[st3v3]

What is it with people demanding the use of synthetic? Really?
____________________
Roger wrote: Women don't get damp for clingy puppies. Get some better happy pills, hit the gym & buy a medallion the size of a dinner plate. Job done

[bouncerdove]

Hi. Lets go back to the beginning. Could you please tell me what CDI unit, RC controller, And RC Servo is required to fully derestrict this bike. Please see various photos attached in earlier posts as to what the model is.
I am getting more confused as to what the bike is with each post.
Your help is really appreciated.
Regards bouncerdove

[alains]

none except the CDI unit CI572
____________________
the worst day fishing is better than the best day working

[bouncerdove]

Hi AGAIN. I have fitted the jet upgrade and the CI572 cdi, But still the bike bogged down at 7k (unridable like this). Stripped and cleaned all the connectors to do with cdi, rc controller, and rc servo. Still no better.
As a test I disconnected the rc valve cables and temporarily locked in the high position. The bike now drives fine, right through the rev range perfectly (it's like a different bike but without quit the punch low down).
Any ideas what to change next, The TV78 controller or the Servo unit. One of them must be faulty I think.
Your help is still much appreciated. Regards bouncerdove.

PS I now have a CI626 CDI unit for sale if anyone is interested

[alains]

it seems that your powervalve servo is not working (could be stocked)
try this :
- dismount the servo-motor from the bike
- apply 12VDC (2 seconds) on the white & white/black , then reverse polarities
if the motor turn , your controler (tv78) has a problem or you have a loose contact
report to me i will help you
____________________
the worst day fishing is better than the best day working

[bouncerdove]

Hi. The rc valve works fine at 2k revs (goes from H to L okay) so I do note think it is the servo motor. That narrows it down to the controller. Do you agree.
Regards bouncerdove

[alains]

yes i agree but it could be also the potentiometer inside the motor which be worn .
if you buy one be carefull at the model :
- JC20 (as your's) has a very short loom with 2 connectors of 5 & 3 wires
- JC22 (foxeye) has a 10" loom with 2 connectors (different) of 4 & 3 wires and a wild wire on a round terminal
____________________
the worst day fishing is better than the best day working

[bouncerdove]

Hi. Anyone got a working link for a good set of reeds.
Regards bouncerdove

[alains]

all my mates in geneva-racing had those and are satisfied
https://www.ebay.de/itm/JOllify-Carbon-Membrane-Honda-NSR-125-R-036e-/120762901399?pt=Motorrad_Kraftradteile&hash=item1c1e07a397
cheers
____________________
the worst day fishing is better than the best day working

[bouncerdove]

Hi. Two questions to alains. 1) The link for the reeds is not English and the Ebay site will not accept my password. Also the site says the reeds are 1998 to 2003 JC22. My bike is 1995 jc20.
2) The servo controller I have purchased is the one with the extra single wire (for the JC22). Is it just the connections that are different, As all the wires leaving the units are the same colour on both units, Or are the internals different.
Many thanks bouncerdove

[alains]

1) if you are paypal verified , no problem to order those and they are the same for all models since 1989 . also if your bike is 1995 it's certainly not a JC20 and even if it's a JC20 the year cannot be later than 1992
2) if your bike is a JC20 the JC22 rc/valves controler will not fit , you can modify it by taking off the 2 connectors of your old controler and fit wires one by one respecting the positions . for the wild light green wire you should find a spade terminal in order to fit it in the 5 wires connector
____________________
the worst day fishing is better than the best day working

[bouncerdove]

Hi. Thanks for your reply. The bike is definitely a JC20. That means when it was advertised as a 1995 model imported from Switzerland it is in fact older. Have managed to sort the RC valve problem out (some previous owner had connected the cables to the valve round the wrong way).
Have ordered the reeds from the link alains posted.
I have posted pictures earlier in this thread of the bike so if anyone could shed some light on what year it is likely to be I would be very grateful.
Regards a very appreciative bouncerdove

[0ld_L4dy]

Hi.

I know that the last post is very old, but it seems that I have the same Problem with my JC20 from Swiss.

I got in contact with Honda Germany an they told me to change my jets to
- Mainjet 135
- Powerjet 50
- Starterjet 60

@Alains
- you always recomment bigger jets, that would also count for my Dellorto PHBH28 RD?


Electric stuff
- I changed the CI589B to CI572
(Is it ok, or do I have to change some cables?)
- And I have a TV78

Mechanical Stuff
- The exaust-pipe is fine!

Facts
- Engine turns up to 5000/min (while driving)
- Engine turns up to 11000/min (while standing or pulled clutch)
- Top Speed is 70km/h (~45mph)

What I want to check
- If the Servo works fine

@Alains
- In another thread "Solmon" wrote
"I have unrestricted mine this way!

Lift the tank, and look closely on the tray that holds the servo motor and on its left is the box storing all the cable connectors (all one piece). In the box with all the connectors, you will see 2 wires (1 Red/ white, 1 Green) connected by a 2 Pin connector. Simply unplug the connector and turned ignition key ON. This is the restrictor that stops servo, the servo should function correctly (open/close).

Now it opens and closes. To be precise, opens when Key ON, closes when 2K rpm then opens at 7K rpm. the power should also improve and the valves are opening."

Is it the same for my JC20?

[alains]

if it's a JC20 your carb is 28PHBH/FS (S means screws on the left)
for the JC22 it's a 28PHBH/FD (D screws on the right)
the genuine jetting are:
- JC20 145,45,70
- JC22 132,38,60 (Fr,De,Sw) or 135,42,60 (UK,IT,SP)
(in order : main,idle,power)

to be sure : is you tank can be switch after undoing the bolt in front & underneath ?
is it this model ?
____________________
the worst day fishing is better than the best day working