atha
L plate rider.
Posts: 18
|
Post by atha on Apr 15, 2022 12:31:25 GMT 1
Hi, my RD350Lc from 1981 does not run with its full power... it only revs until 5k rpm and from there it doesnt want to rev any higer... the carbs have 4L0 00 written on them, they have standard jetting. Spark plugs have been changed yesterday (right one was darker than left one) but it didnt help with the problems. Here is a link to a video which should show how it runs:
i really dont know what to do... Is it the carbs or maybe some electrics?
|
|
|
|
Post by arrow on Apr 15, 2022 13:09:39 GMT 1
Could be the high speed windings in the stator. Not uncommon at this age.
There is a test. I'm sure someone will be along soon to describe.
|
|
|
|
Post by shaunthe2nd on Apr 15, 2022 13:32:48 GMT 1
Search on here for removing brass balls in carb to clean the air correction circuit. Also look up 4L0 00 modification and settings as Yamaha issued a mod for these carbs as original set up was problematic.
|
|
atha
L plate rider.
Posts: 18
|
Post by atha on Apr 15, 2022 16:48:23 GMT 1
ive got it to work, kind of... changed the main jet to 160 from 220 which i ran before that... runs ok except for low torque power... but now another problem appeared... the throttle seems to get stuck idk why the bike starts to rev very high for some reasons... i have the needle in position 2 btw
|
|
|
|
Post by zig on Apr 16, 2022 10:03:59 GMT 1
make sure you have the carb slides in the correct way , match them up in the carb windows from kickstart side of the bike
ZiG
|
|
|
|
Post by muttsnuts on Apr 16, 2022 20:13:46 GMT 1
if the carbs are 4L0-00 and unmodified then there are no brass balls on the air corrector, that circuit is open, the carb settinsg are
Needle: 4H16 (2nd clip)
Needle jet: 345-06
Main jet: 140 (160 optional)
Pilot Jet: 25 (27.5 optional)
Air Screw: 1.25 turns out
Check you have all of the right parts in the carbs, suspect you'll have the wrong needles fitted (probably 5K1 - no good with that needle jet), need 4H16's and I sold my last one today and not easy to hold of at the moment
HTH
|
|
|
|
Post by shaunthe2nd on Apr 17, 2022 9:48:11 GMT 1
Ahh forgot, Dave is right original 4L0 00 was open but modified ones were filled with araldyte although I have also seen them with brass ball too. Either way still worth cleaning the air correction passage.
|
|
atha
L plate rider.
Posts: 18
|
Post by atha on Apr 17, 2022 9:54:27 GMT 1
My specs are
Needle 4H16 on pos 2, also tried 3
Main jet 160
Idle jet 27,5
Air about 1,5 turns
|
|
atha
L plate rider.
Posts: 18
|
Post by atha on Apr 17, 2022 10:39:44 GMT 1
Why were the original ones open and What difference does it make if they re open or closed? If mine are closed, I’m only going to remove the ball or whatever to clean the tube and after I’m finished I’m going to close it again right?
|
|
|
|
Post by shaunthe2nd on Apr 17, 2022 23:59:20 GMT 1
Are yours modified per Yamaha recommendation already?
|
|
atha
L plate rider.
Posts: 18
|
Post by atha on Apr 18, 2022 10:20:53 GMT 1
I think they re not but I’ll have to look again the next days
|
|
|
|
Post by shaunthe2nd on Apr 18, 2022 10:58:57 GMT 1
If they not then I would consider getting them modified, if Yamaha struggled to get the originals to work well then most likely you will too.
|
|
atha
L plate rider.
Posts: 18
|
Post by atha on Apr 19, 2022 13:31:18 GMT 1
The problem tho is that my bike is the 46 hp version with the 1 on the cylinder… idk why I should drill them open I’ve never heard of this procedure
|
|
|
|
Post by arrow on Apr 19, 2022 13:54:43 GMT 1
The problem tho is that my bike is the 46 hp version with the 1 on the cylinder… idk why I should drill them open I’ve never heard of this procedure Yamaha struggled to get the early 350lc's to run correctly. I believe it was a bad flat spot/misfire in the mid range. The modification was done at the dealers via a service bulletin from Yamaha. To be honest, I'm surprised there are still unmodified ones still around in 2022! |
|
|
|
Post by shaunthe2nd on Apr 19, 2022 18:27:07 GMT 1
Search on here for the Yamaha 4L0 00 modification, it's all detailed and I even put some pics up. Yamaha published a bulletin which is also here in several threads if you search.
|
|
