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Discussion Starter · #1 ·
2001 jc22 unrestricted version
wossner piston
giannelli exhaust

when I got the bike it had a phbh-26
I've since got a standard unmodified phbh-28 from a uk model and jetted it to the recommended jets only a little larger main before I do plug chops (142)

so 142 - 42 - 65 as recommended by a few online.

my problem seems to be the 42 pilot jet. the air screw does not affect idle which points to the pilot jet being to large so I went back to standard size and I've a small rise in idle when the screw is almost fully in so this says the standard pilot jet is too large also.

the bike also starts without choke all the time. so something is wrong in my carb setup.

Can anyone shed any light on this.
Also has anyone a pic of the airbox mod. this might give me more air which could solve the situation in itself.
I don't want to randomly drill the airbox wrong and need to replace it.

Cheers
 

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I would take a look at the float level, it should be at 24mm. I do have the same setup with a pilot jet at 42 and for every air screw turn it makes a huge difference in how the bike idles.

Also, what do you mean starting without a choke all the time? Does it start even when the bike sits for 24+ hours? While we are at the choke thing, check the choke assembly. It may be old/broken or just set up wrong and it gives a little fuel all the time.

In terms of the airbox mod, it will make a difference for every jet you have installed. Take a look at the float level and choke assembly first. I'm also sending you an NSRTips doc by Alain, there is some information about the airbox mod and much more.
 

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Discussion Starter · #3 ·
I would take a look at the float level, it should be at 24mm. I do have the same setup with a pilot jet at 42 and for every air screw turn it makes a huge difference in how the bike idles.

Also, what do you mean starting without a choke all the time? Does it start even when the bike sits for 24+ hours? While we are at the choke thing, check the choke assembly. It may be old/broken or just set up wrong and it gives a little fuel all the time.

In terms of the airbox mod, it will make a difference for every jet you have installed. Take a look at the float level and choke assembly first. I'm also sending you an NSRTips doc by Alain, there is some information about the airbox mod and much more.

Cheers. I will take the carb back out and look at them things first.

yes it starts first tip with no choke even after sitting for a week.

I've a smaller pilot ( the original) back in it now and no difference
 

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Cheers. I will take the carb back out and look at them things first.

yes it starts first tip with no choke even after sitting for a week.

I've a smaller pilot ( the original) back in it now and no difference
Yeah sounds like a stuck choke or something. Take a good look at the carb and clean it well. Cheers!
 

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Discussion Starter · #8 ·
Yep. Definitely looks broken :p
so I fitted the choke cable, definitely runs better now and smoke cleared up nicely.
I went back to the 42 pilot jet.
no significant change in idle when I adjust the air screw still. it does rise a little at one point but not by much.

seems to be still very rich.
Carb and jets are all spotless. I changed the needle position from 2nd to 3rd notch from top and it seems to pick up a bit better but still boggy on wide open from idle.

reeds are good and top end is rebuilt.

would it be worth trying to the stock pilot jet again ?
I musta had the carb out 10 times now 😅
 

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so I fitted the choke cable, definitely runs better now and smoke cleared up nicely.
I went back to the 42 pilot jet.
no significant change in idle when I adjust the air screw still. it does rise a little at one point but not by much.

seems to be still very rich.
Carb and jets are all spotless. I changed the needle position from 2nd to 3rd notch from top and it seems to pick up a bit better but still boggy on wide open from idle.

reeds are good and top end is rebuilt.

would it be worth trying to the stock pilot jet again ?
I musta had the carb out 10 times now 😅
What does your air screw situation look like? How many turns? In my case, I'm at 2 1/4 out with idle jet 42. After you turn the throttle more than 1/4 then the needle /clip takes over. I would leave the idle circuit for now.
Mine bogs on idle with the wide-open throttle as well, but only when it's cold. Make sure you warm it real good, take it for a spin, then check again.
Also, wot is mainly controlled by the main jet. From 1/2 to full throttle the main takes over. Do you have your original main 138? I would try to experiment with that. Change your 142 to 138 and test it. What I found is that sometimes it's hard to tell if the bog is a "lean bog" or more like a "rich bog". Then again, warm it up real good and test it while riding.
Do you get a lot of spooge out of your exhaust? Sometimes this bogging means that it's actually too rich.
This post explains jetting really well: Beginners Guide to Two Stroke Jetting
This one is also awesome and you should take a look at it as well: Secrets To Jetting A 2 Stroke Dirt Bike [Guide] - Motocross Hideout
 

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Discussion Starter · #10 ·
It had loads of spooge but since I put the new choke cable in its cleared.
the back wheel was plastered in black dots

The air screw is about 2 1/4 or 2 and a half turns out to get the nicest tick over and response.
the main is big alright. I've a 139 there I could try but il take it out tomorrow and see how it goes. thanks for ur help
 

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Discussion Starter · #11 ·
so bit of an update and still no fix.

changed stator
changed back to genuine coil
all recommended jets fitted
float height set.
new plug

still bogging down. so bad I can't take it out now.
last thing to check is the fuel tap filter but I'm getting a good flow of I pull the pipe off the carb.

is it looking like my stator side seal is the culprit ?

it. Will go alright in the high revs but I'm not driving it now until its solved or il blow it up.

any help appreciated
Cheers
 

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so bit of an update and still no fix.

changed stator
changed back to genuine coil
all recommended jets fitted
float height set.
new plug

still bogging down. so bad I can't take it out now.
last thing to check is the fuel tap filter but I'm getting a good flow of I pull the pipe off the carb.

is it looking like my stator side seal is the culprit ?

it. Will go alright in the high revs but I'm not driving it now until its solved or il blow it up.

any help appreciated
Cheers
Hmm, you know you have a pretty difficult situation there. It's getting fuel, the reeds are ok, carb is ok, piston/cylinder is ok as well...
If the left crank seal is leaking, then the air would get sucked into the crank and make it leaner, so that might be the case. You would have to do the pressure leak test on your engine to know what's going on. I know that it won't make you happy and it's quite a job to do. Right crank seal leaking would mean a shit ton of smoke even when the engine is nice and hot.
Unfortunately, that's how it is with those old two strokes. I presume you bought it from someone, just like I did with my nsr. If you don't take care of them on a regular basis, then the problems will show up all at the same time. Maybe it's time to do the bottom-end overhaul. New seals, new bearings, maybe a new rod (although if it doesn't have any up-down play it should be ok, side to side play is ok but the manual states acceptable values), new gaskets, new water pump sealing.
You know I had done all of that. Brand new nicasil cylinder, new wossner piston, new connecting rod with all new bearings, seals etc., and yet I'm still leaking transmission oil on the left side. Tomorrow I'm heading back to my mechanic cause the needs to fix that, I presume he did something wrong there...at this stage, we should just learn how to work on two strokes and overhaul them by ourselves.
 

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Discussion Starter · #13 ·
yea maby so. just do the bottom end now and be done with it. I have it about a year but never drove it. it would be a nightmare to build the bottom end and the original problem still exists 😅
 

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yea maby so. just do the bottom end now and be done with it. I have it about a year but never drove it. it would be a nightmare to build the bottom end and the original problem still exists 😅
I really hope that the bottom end will help you. I think that the left crank seal should be replaceable without the need of taking out the engine. Just remove the left cover, remove the flywheel and you should be able to see the left crankcase seal.
 
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