Bike just dosent want to pull away

[keithr]

After along break for building a new garage the old girl came out of fathers.
I have still been having issues with the running of her.

1982 import 350lc

There is a set of 4LO 00 carbs these have had the mod as there is a brass ball bearing in the original holes
27.5 air
220 main

Running a set of short can all speeds

All set up as per the manual, starts fine & ticks over throttle response is good no smoke sounds good.
When ou go to pull away the engine just starts to die, if you give plenty on the throttle then it will pull away, not the best idea i know.
There is a set of after market coils fitted, these came from norbo.

Engine has been completely rebuilt after a full bike restoration as it as not used since 1998, replacement crank again from norbo.

any thoughts would be a great help.

If not any ideas where it can go to get fixed as not many around devon any more.

cheers

Keith

[stasky]

your way too rich bud, your drowning it,standard main jet is 160 for your bike ,have u standard airbox, ?? as 220 is way too rich, allspeeds work on standard jetting/standard airbox ,maybe 170 , safe side,your pilot is a ok, not set up as per manual, because your main jet is way off,ps dont put it to a garage as they will charge u an arm + a leg , and most wont have a clue about 2 strokes, carbs off ,change main jet, you will be ready to go

[keithr]

Ok will change the main jet now i have a set of 190 thats the smallest at the moment will have to order a set of 160 & 170.
Every thing is standard except the all speeds. the manual says from 100101 engine onwards that the main jet is 220 for a 350 but before that the main was a 160, do i have to set it up for the early engine due to the carbs that i have.

cheers

[stasky]

u need to check all your other parts in the carb,to see what set up it should be, check your needles see if they are 5k1 or 4h16, then youll get an idea of how to jet,deffo sounds like its drowning,doesnt matter what 4l0 engine it is,any carbs will work if set up properly,i usually use 31k carbs(240 main jet),on all my bikes,5k1=220 main jet , 4h16=160 main jet for your bike, everything else good on the carbs ?, balance pipe in place,slides not mixed up,choke side has 2 slots ,?90% of problems ive ever encountered always comes down to carbs,youll get there in the end

[keithr]

Right just pulled it all to bits again.
Carbs turn out to be 4L1 00
The original parts fitted to theses are
needle 4N10
190 main jet
20.0 pilot jet

these are the correct ones for the 250.
Bike never ran well before it seized on the left hand main.

Complete rebild using all new parts mostly from norbo.
did use a yambits carb rebuild kit as needles looked very worn.

What they sent me
220 main
27.5 pilot
y184 needle this is considerably bigger than the original now that i have them next to each other.

Can i just replace all the insides to be able to use these on the 350 ?
If so do i just have to replace the needle or the needle jet itself.

[stasky]

now your getting somewhere,yes u can replace all the internals,u can use the 250/4l1 carbs ,but will need all 350/4l0 internals,dunno what needle that is,u can get the 5k1 needles from allens peformance,got them before 5k1 needle requires 220 main jet),and also dunno about your needle jet,when your buying carb repair kits,buy the ones from japan,they are the ones i found best, i would also consider buying another known good set of carbs,31k carbs are a good choice for 4l0 ,with standard 31k settings, would deffo say somethings not right with them carbs,im assuming u set float height also ???all carb passages blown out with airline,

[keithr]

The needle came in a set from yambits it is supose to be a 350lc repair kit.
I have just ordered a set of repair kits from japan that come with the needle jets.
Will look at the 5k1 needles now.
Also looked at a set of 31k carbs, do these have to be the ones with out the extra pipe on or can any ypvs ones be fitted.

cheers
Keith

[keithr]

Yes the carbs were sent away for cleaning, then they were completely blown out with the air line all holes have been double checked, float height has been checked and correct.

[stasky]

good,u just need to sort out internals of carbs mate, i know its frustrating,but will be worthwhile in the end

[stasky]

dunno what u mean by extra pipe ,f2 carbs have a powerjet, with extra pipes on the side of carb,these are harder to jet,hence 31k more popular,31k/31w are the early ypvs bikes, be wary of buying second hand,as most are for sale because there gubbed

[muttsnuts]

See below full specs for each type of carb for a 350LC

350LC 4L0 Later Type (4L0-01)
Main jet 220
Air jet 0.8
Needle 5K1
Clip from top 3
Pilot jet 22.5
Air screw 1.5 turns out
float height 1.0mm

350LC Early type (4L0-00)
Non-Modded - ID 4L0 00
Main 140 or 160 in some cases
Pilot 20 or 22.5 in some cases
Needle 4H16 Clip 3rd from top of needle
Air Screw 1 1/4 turns out
Float Height 21mm +/- 0.5mm
Air correction circuit open in bell mouth

Modded type - ID 4L0 00
Main 160 or 170 for high speed running
Pilot 25 or 27.5 depending upon location and climate
Needle 4H16 Clip 3rd from top of needle
Air screw 1 1/4 turns out (tends to work better with 0.5 to 1 turn out with 25 pilots fitted)
Float height 21mm +/- 0.5mm
Air correction circuit blocked off in bell mouth and 3mm drilling into air correction circuit completed

[keithr]

There are some 31k/31w on ebay but description says that the came off a 350lc that they could not get running correctly.

Carb repair kit on way from Japan as we speak.
5k1 needles should be here tomorrow.

The carbs have the brass ball bearing in the right hand hole as you look into them, i cant see where there is a hole drilled in the side of either of them.

I have looked at the pictures that are on the other technical page mine are different to the ones that are being shown so they must be the later ones ?

any advice would be a great help, i am hoping to be taking the bike to the isle of man at the end of August

[ianr4863]

Might sound daft but its not just a blocked / dodgy pilot jet is it ?
Are they genuine Mikuni ?

[keithr]

Right i am going to try to put some pictures on here of the carbs, looking at the other pages on technical that muts replied to those did not have the brass ball bearing inside, but then looking at the technical drawing where the 3mm holes were drilled there is another brass ball bearing.

so looking at the side with the markings 4L100 to the left of the adjustment screw is a small flat surface with the number 04 on it, not sure what this number if for.

[keithr]

www.flickr.com/photos/151330360@N02/shares/QM561R
www.flickr.com/photos/151330360@N02/shares/1Si319

[muttsnuts]

Ok, they are 250 carbs (not 350), ignore all the jetting details above, if you want those to work you will have to fiddle a bit with the jetting, think a few on here have actually done this so should have some settings


from the top of my head, you could start with

5K1 needles (mid clip position)
345-p2 needle jets (you must make sure these are correct)
200 Mains
25 Pilot, although you could easily end up at 30
A/S at 1 full turn out

That's where I would be starting from

HTH

[keithr]

I have read on the other technical page about removing the brass balls that are in the middle and making sure that it is clear, is that some thing I should look at.
Never heard about this before

[stasky]

i personally,would bite the bullit and buy a descent set of carbies,either 4L0,OR 31K/31W,

[stasky]

any progress keith

[keithr]

Right got my delivery from japan in 6 days.
Fitted new 5k1 needles set on middle slot.
205 mains as this is all i have here at the moment
25 air jet
brass ball removed cleaned out and new ball refitted

Started first kick let her warm up adjusted the tick over sounds a lot better.
Pulled away better than it did before, but when it got warmer it started to bog down & struggle.
I am going to change the air jet to 27.5 to see if that is any better.

Looking for a set of 350 carbs standard or ypvs ones, a chap in plymouth has a set of f2 on his 350 and he says that they are fine as long as the extra pipe that goes to the air box is blanked off.

[muttsnuts]

if its bogging down when it gets warm that sounds like the low side coils on the stator are on their way out, have you tested them when cold and warm to see what readings you are getting? on the plus side it sounds like you are moving in the right direction

[keithr]

Coil has all ready been done by westcountry windings.
I have managed to get a set of 31k carbs that are in excellent condition for £80

If any of you know what the set up should be that would be great.

So as soon as the other carbs arrive & hopefully work i have a set of 250 carbs in excellent condition to sell.

Just a thought is there any difference in the 250 & 350 reed holders, as i had a look through some photos of the bike when i first got her & the carbs were fitted to the rubbers & the reed holders by cable ties.

[stasky]

reeds are the same,and on any ypvs carbs i think that guy meant to block off the vacuum take off for the ypvs fuel tap, as the lc fuel tap has no vacuum,theres no pipe goes to the airbox
31k carbs are
240 main jet
5K1 NEEDLES
NEEDLE CLIP POSITION 4TH FROM TOP
PILOT JET 22.5
AIR SCREW 1 1/4 TURNS OUT FROM SEATED
FLOAT HEIGHT 21MM

THOSE 4L1 carbs should run with 220 mains + 22.5 pilots

[muttsnuts]

Aug 6, 2017 18:31:49 GMT 1 keithr said:

Coil has all ready been done by westcountry windings.

While I hear what you're saying, unfortunately that doesn't mean to say it is all ok, I've had them rewound before now and had them go down, so had to send them back for repair, I've also had pickups go down after the low and high side coils have been rewound, also, when rewound by westcountry, the resistance readings don't match the values in the haynes manual anymore, so you need to speak to Westcountry to find out what the new values should be

HTH

[rigga]

Fitting 31k carbs to a 4l0 work really well, but you might need to increase the pilot to 27.5, LC seems to need bigger pilot jets than the powervalves.

[keithr]

Right delivery this morning of carbs

Took apart to check they have the following
240 main
22.5 pilot
5k1 needles these are new

using the original slides as these are new & original tops

Starts & runs well nice & warm pull away great up to 5000 revs all but perfect, but after this the right hand side seems to be not running correctly as the exhaust goes really quiet, whilst the left is making a right din as it should.

Ease off the throttle a bit & the right comes back into action after a bit of coughing & spluttering.
Left end can is nice & warm but right is just tepid, both barrels seem to be about the same temp with the gauge sitting just before the half way point.

[midlifecrisisrd]

Aug 3, 2017 10:19:22 GMT 1 keithr said:

I have read on the other technical page about removing the brass balls that are in the middle and making sure that it is clear, is that some thing I should look at.
Never heard about this before

This along with checking your emulsion tube holes are still clear is your next move

Steve

[keithr]

Emulsion tube holes are where exactly.

Carbs are completely clear of any thing as i have used a airline to make sure all holes are free from any blockages.

cheers

[stusco]

Emulsion tubes are under you main jet ,remove the jet and washer refit the jet ,give the jet a tap and if your luck it will start to push the emulsion tube out,its a brass tube with very small holes that help to mix fuel /air,they will be full of crap air hoses/ ultrasonic can't clean them you need to remove them.
Also as Steve says you had better drill your balls

[midlifecrisisrd]

The emulsion tube is the brass bit that runs from the main jet up to the needle

Take the main jet out. Remove the washer then refit the jet and tap it into the carb body

The tube has some very small perforations in it that can block.

The air passage behind the brass ball feeds into that chamber too so it needs to come out to clean that anyway

Steve