french xs400

made a few notes
JSAK was 142.5 mains needles 3 washers as shims for needle, 4.5 turns out on pilot
Jigm400 45 pilot 145 mains
mine 50 pilot 142.5 mains 1.5 turns on pilot screw (using a dohc carb though and on open exhaust and EMGO pods using the rubber inlets so I don't block the diaphragm vents)
 
this afternoon I did some test
I installed an old tachometer and I realized that my problem was not so simple.
With setting the most consistent I found I have watched the symptoms.

In fact the bike go over 6000 rpm on the first gears and more i go up the gear more the area where the bike can't go over is down:

i can't go over: 8000 in 4 gear / 7500 - 5 gear /6500 - 6 gear!!!

do you think it's really a carb problem? now i doubt...
what does it could be?
 
The bike is stock, the secondary reduction is 36/16.
in stock it was a 16" rear wheel and i put a 18" rear wheel with the same reduction.

could be down on power
Click to expand...
perhaps but the bike run very well, just at this rpm area the bike seems to have "cuts" and does not pass beyond

before i put a tachymeter it's seems logical it's was a carb or ignition symptoms but now that i've seen the area wasn't in the same area in each gear i don't understand!

perhaps vibration with electric material?? float level not really good ??
but the problem would not it be in the same rpm??!
 
You might try a 15 tooth sprocket on the primary side,as it's cheaper,and see if it helps a bit.You can always use it for short runs and change it for longer trips.This would help pin down your problem without throwing too much money at it. lha
 
What is the size of your front and rear rim? it's look like the same, is it from a XS or another Yam?
 
hello, the rims are 18" size.

the source of the problem is found for some time ...
finally there is not enough air has a certain speed.
it might not seem surprising without the air box, but it's real. I think this is due to the turbulence has some speed.

I remove the bmc pod and put Ramair foampod. it's better but still not great.
I think that I would have distant filters of carbs.

but the main thing is to have found the problem ...:)
 
Merci Niko je viens de capter que tu es français :)
but where do you get this 18" rim with drum?
 

Similar threads

G
XS400-something - identifying an Aussie Yamaha
Replies
7
Views
602
CaptChrome
CaptChrome
A
1982 Seca no spark after rainstorm
2
Replies
23
Views
6K
AlexH
A
N
'81 Back Running; Now What?
Replies
2
Views
614
JPaganel
JPaganel
Addison
Help finding the "beginners" thread?
Replies
3
Views
914
XSLeo
XSLeo
Dregles
Noob Mechanic
Replies
10
Views
1K
JPaganel
JPaganel
Back
Top