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Discussion Starter #1
hi there i have a cl350 and after getting it running i have never been able to get the bike to run right.
i have watched you tube vids ,read about problems and float highs ect. and asked questions on forums ect . and after maybe 15 rebuild attempts on and off over 6 months i haven't gotten any ware.

i have checked compression, its good on both sides.
changed the rubber manifold boots
re build the carbs using different kits, one cheep one expensive [ both had correct jets]
new cable
tried with difrent float hights, meany times both on a flat surface and also holding carbs at an angle
changed and checked the fuel line inc valve
on the chance of letting air in the fibre washer i have tried to add a little oil. and sucking it in to the seel it [no difference]
and even took it in to a local classic bike shop. now it did run better after that for 3 miles. then the plugs were coked up, but its because the choke was fully on [ they said it worked in reverse ]
so they had my pants down there.

but nothing has had much difrence. and im the point of maybe selling the project on at a loss.
im missing something , and i dont know what it is .
is there any one that can help. i can either come around if your not to far, and have a look [ after lockdown has has ended] or if your far away. i could post them on
any help would be good
as i just feel totaly gutted after making no real progress
 

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I'll suggest that you go thru your ignition system closely. Coil resistances, voltage supply, plug caps, point, condenser, timing next. Carb and ignition symptoms are very similar to one another.
 

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Carb and ignition symptoms are very similar to one another
What he said . . .

I know you've said you've not managed to get the bike running right - and I know what follows isn't going to directly answer the question you've posed about UK carb specialists - but you haven't explained what problem you're trying to fix. Unless you're absolutely sure everything else is fine and the only thing that could possible be wrong is the carbs, you might end up spending a load of money getting the carbs rebuilt only to find nothing's changed when you fit them to the bike.

There's lots of folks on here who can offer advice and guidance, so don't be shy explaining the symptoms the bike is displaying - and what steps you've taken outside of the carbs to identify the problem(s) you're fighting with. As Jim says, what you may think are carb issues may very well end up being something completely different . . .
 

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I feel your pain saxby. I went through a similar experience with the carbs on my 450. I'm a couple of hundred miles away from you - but on the other side of the Irish Sea alas, or I'd be glad to offer to help in person.

The main problem I had was that there were a number of 'more unusual' problems on my carbs which combined to create symptoms that made it nearly impossible to do a simple straightforward diagnosis. Fwiw In my case the unusual issues were a bent/poorly fitting throttle plate, a rung screw in one of the four holding the carb top to the body, an internal passageway that remained blocked despite several home ultrasonic cleaning efforts, an errant little rubber particle that escaped down the the fuel line when I was trying to ream out a slightly too small fuel pipe which intermittently blocked the needle valve, and one of those little felt throttle spindle washers you mentioned earlier, being missing altogether. Couple those to the more 'normal' things like dodgy aftermarket carb rebuild kit sets, a poorly routed fuel-hose (entirely my fault), which airlocked causing fuel-starvation under full throttle and the ever-present doubt as to whether the issues were actually fuel system related and not electrical / ignition.. and it was a recipe for some serious head-wrecking :)

I did get them sorted in the end and the bike running sweetly though - through a combination of sheer mule-ish stubbornness, genuine mechanical curiosity, and pointers and help from the guys on here and a local mechanic who pro-cleaned the carbs for me in his shop.

In general terms, the approach that finally worked for me was to try to figure out (a) which cylinder was playing up (and later when/what part of the rev range) and then (b) use a process of subsitution, ie switch parts between the working side to the non-working (or problem) side for both the electrical and fuel systems progressively until I got the problem to move. Once you've established whether the problem changes sides following a change of electrical or fuel components - you then know where the main problem lies, and can further swop and change individual components (in my case in the fuel system) progressively until you have narrowed down where/when the problems are occurring and why.

** edit - just read your other thread on the carb problem there, and I see you've already taken the substition approach, albeit with an entirely different set of carbs off another bike :) Not sure if I've read your description of the current problems properly - but I think you said its running ok over 3000rpm, and poorly below ? If that's the case, and the compression is fine - I'd be focusing on the low-speed fuelling - wrongly size/poorly sealed jets and fittings or blocked internal passageways.

Anyhoo - if you were willing to get stuck on again, here's what I would do in your shoes:

(i) Check the points and timing as far as possible to make sure everything is in spec and functioning properly - use a strobe light to confirm the timing is working as it should be.

(ii) Swop the colts/plugs and plug leads from the left cylinder to the right cylinder to see if the problem/slow warmup, lower exhaust temp moves:
- If it does then you have an electrical problem in the high voltage side, swop or replace the individual components between each side to identify which or replace the whole side affected.

(iii) If not, then if it is possible - swap the left and right carbs over, and again see if the problem moves:
- If it does then I'd do a very close visual inspection to see if there was anything obvious astray between the two. If there's nothing obvious visually, then try progressively swopping over the Jets/seals/needles/float etc to see which causes the problem to move from one side to the other again.

It's a bit more laborious of an approach, but should give you a better chance of identifying and targeting the problem areas to hopefully sort the thing once and for all.

Alan
 

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What problem are you having?
If you have 'pods' (particularly cheap pods) you will have an issue around 3,500~4,500 rpm.(and maybe another at ~7,000)
I have heard that CB160 needle and emulsion tube will work.
Needle needs to be dropped which is contrary to ALL the advice online (and elsewhere)
The 3 jet carbs have a major issue at transition point when slides start to lift, it goes rich instead of lean as you would expect.
Fitting larger secondary main jet (to get full throttle mixture right) compounds the problem.
Mikuni's are no better as the 'cheap' sets don't change primary choke for emulsion tubes and have totally wrong slides fitted 'stock'
I've used RD350 or RD350LC carbs with very little modification, (not YPVS)
They used to be easy to get hold of (1989~90) but may be difficult today?
Triumph 500 Mikuni conversion should work fine out of the box but could need pilot and main jet change?
That will probably be expensive proposition (around £500 through TOC)
 

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Discussion Starter #7
thanks for the replys.. i read them all and this is were im at

i had a bit of time yesterday. and stated from scratch fitting an different set . it was rubbish so i checked everything inside, the jets are clean and i set the float highs to 23mm
the floats arnt full of fuel or anything. but they do press down on the spring loaded float valve. so i set t eh height holding the carb at an angled with a tube blowing down the fuel intake till till the wight of the float shuts off the supply. and that was my point witch i set the hights.

[with the carbs now sitting upside down on my bench the spring loaded float valve is quite far in . and the floats them selves sitting v low. almost bottom out in the carb. but as i say the right way up. were they should cut the fuel supply, it should be spot on .

following this set up


i then want throw setting up the carbs one at a time while the bike was on. after warming it up a little. and also checking the points were correct on the timing

with the coil off on the right. working on the left , i set the tick over to 1k and then adjusted the misture screw in till the bike started to die off and then back it off a little . [about 1 full turn out in total]

same on the right hand side. although turning the screw in it didnt seam to die off. the revs increased a little . and backing it out again to the 1 turn out point . makes the bike die.

sort of running out of time . i settled for that as it was ticking over at 1k mark but it was behaving difrentley to what i expected

the rest of the cable set up is prity normal and the bike now ticks over . anthow still problems

now i have had these carbs off so meany times now i do just have the pod filters on them .

reading what you say crazypj [and yes they are particularly cheap pods ]

i didn't think it would make a difrance at this stage .. i thought that it would have been a case of getting better performance when riding the bike , or more power? but i can always try again with the main stock filters on
and also choke postion...once the bike is hot , my choke has postion has 3 postions
and this next question has sort of already been asked



Picture 1 - Lever to the right.[on the middle notch just to the left point on this photo] [ there the bike runs and revs to around 3k before boging down ]
Picture 2 - Level down.[ bike runs and revs fine ] but if im right its a bad idea to run the bike like this ]
and if i try the bike exactly on the same place as Picture 1. the bike dies off almost instantly

as for outher isues longdistancerider and the chauffeur
it could be.....
just with a good compreshion. checked [ and re checked the valve clearances and timeing again] im not sure how it could be
checking the plugs there is a good spark from them . as for what is happening when the bike is running i dont know how i can check that ?
but i would have thaught a problem with ignition it wouldn't resolve its self by simpley putting the choke on and running the bike rich
with the leaver fully down it sounds and runs fine

1- there is some blockage / isue in the mixture screw on the right hand carb. witch is why it didnt behave like the left when setting up.
2- i didn't think the pods would have had that much affect, but i can try again with the orignols on,. it was me being lazy as the high cl350 exhaust gets in the way a bit. but in hte past it had no major efect
3- the float heights are totally wrong .
i have set and re set them lots of time on the outher set of carbs, sitting flat on the bench, at an angle. [as i did yesterday], with different jetting kits [although there stamped the same thinking that maybe the was a defect some ware]
witch is why i simply wanted to start again in my head wit the new carbs. and also maybe have over thaught the set up of the hights

i can do a clip and put it up on you tube if it will help ?
 

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Honda states in the general service manual the carbs should be tilted to approximately 70 degrees's with shut off arm just contacting shut off plunger.
Float height should be at 26mm but 27mm is also fine and may be 'better' using modern fuel which ihas been 'designed' for fuel injected vehicles.
Choke lever will be 'horizontal' for on and 'vertical' for off.
It may be easier to just remove a filter and look at the choke flap?
Choke should be fully open for normal running after engine warms up.
To check spark when engine is running, you need a timing light. Probably not the safest method but having it visible during a ride you can see if spark fails. Majority of parts shops over here will loan a light if you don't have one and don't want to buy one for 'single use', Don't know if Halfords has something similar?
 

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Discussion Starter #9
Choke should be fully open for normal running after engine warms up.
just checking as might be getting mixed up here . my choke has 3 positions
after setting it up and a warm engine
no1 : i thought was choke fully on. and you shouldn't ride the bike like that [ seems to run best although i haven't taken it out ]


309159


no2: runs ok ish on tick over . but dies over 3k rpm [ did have only cheep pod filters on thow]


309160


no3: bike dies v quickley .-[checking that little paddle inside the butterfly valve it can open if needed to ]


309161
 

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You simply have #1 and #3 reversed - ON is closed visually, as in #3, and the bike is not intended to be ridden in that position. It's only for restricting the air flow to draw more fuel into the engine for cold starting purposes. #1 is OFF. Look closely at the word stamped inside the lever - the arrow points in the direction indicated by the word "Open"
309162
 

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Discussion Starter #11 (Edited by Moderator)
You simply have #1 and #3 reversed - ON is closed visually, as in #3, and the bike is not intended to be ridden in that position. It's only for restricting the air flow to draw more fuel into the engine for cold starting purposes. #1 is OFF. Look closely at the word stamped inside the lever - the arrow points in the direction indicated by the word "Open"
View attachment 309162
Don't I deal like a d-head .
With it saying open. And being the choke . I thaught it was running rich on that setting
 

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Honda has an actual choke, Mikuni carbs say choke but it's really an enrichener circuit built into carb.
Personally, I don't see any confusion in the Honda description?
If you choke someone your restricting the airflow, exactly the same with carb.
Choke on, airflow restricted, choke off you can breathe
 

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Discussion Starter #14
still having issues :mad:
i re fitted my first set of carbs setting them up the same way as in this video
but when it comes to setting up the fuel/ air mixture. it doesn't go the way it does in the video [2:30 on the you tube clip]
if any thing turning it in . adds a little rev and turning it out doesn't relay do much in any thing it make the engine want to die a little
now on my 2nd set of carbs the left hand carb worked fine . but the right did the same . but on this set of carbs. they both behave the same
i checked that all the paths and jets on one of the carbs at this point, and also removed the air/fuel screw inc the little O ring . everything looks fine ran some cand air in there as well. every thing was clear
after following the set up the bike runs best with the air /fuel screw in 0.75 turns out
but some thing is wrong. again there is some thing i have missed . witch is why ajustting the air screw isn't realy having any affect. i have done a vid on you tube showing the bike ideling .. the revs are up and down all on its own.

checked the fuel level and also that the hoses on both carbs there is a good supply to them

any idea what i might have missed to be causing this isue
 

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Someone has probably 'cleaned' the pilot jets with wire and they are oversize?
Do throttle shafts wiggle up and down? Could be the felt seals are dry? (after 40+ years they will be on any carb that uses them) The leakage will be tiny but can make a difference at idle.
Spraying levers with WD40 may 'fix' the problem for a little while as it soaks into felt but it will dry out again
3/4 turn (0.75) is within spec although I wouldn't worry about actual setting too much.
Anything between 0.5 to 3 turns out is OK, jet is flowing as much as it can by then so going further doesn't add anything.
It doesn't need much, I found 360 doesn't run right going from a 38 to 42, (350 is smaller at 35)
.You need a 0.35mm gauge wire to check.
In several years of working on 350 and 360 carbs I haven't found a pilot with accurate hole size (even genuine Kei-Hin are now slightly undersized)
You may be able to find high precision jets in correct form but they will probably be 'expensive', about double or more thew cost of standard jets (may only be available directly from Japan?)
If you have aftermarket kits I can pretty much guarantee the cross holes are undersize and the jet itself can be anywhere between 30 to 40. Cross holes on original jets are 0.80mm, number drills don't work as there isn't an exact match (even though several charts say there is an equivalent)
Compression is the same on both cylinders? (I forget if you already said so and too lazy to go back and look)
 

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Discussion Starter #16
Could be the felt seals are dry? (after 40+ years they will be on any carb that uses them) The leakage will be tiny but can make a difference at idle.
Spraying levers with WD40 may 'fix' the problem for a little while as it soaks into felt but it will dry out again
I heard about this . In the early days with this problem I had a 2nd set of carbs . And I had a go at taking them apart to access this felt washer . Not sure if I damaged the round disk getting it out .
It's a tight fit putting the disk back in , (out side of the carb body . ) But I could have a go. Here are some photos. Can you tell from looking at the felt ? As from what I can see online it looks ok
But I will try wd40 on the current set to see if it helps . .

By looking at all the difrent jets I have . They all look the same to the eye. But I haven't got any wire or any thing that presice to check with
Do you think I'm right in the fact that the air,fuel screw doesn't do anything means there is an isue. . And once the screw has an affect. It should be the elf to my problems . ?
As for compression. Ya . There the same on both sides . I think it was 170psi on both IMG_20200524_142412.jpg IMG_20200524_142352.jpg IMG_20200524_142342.jpg
 

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Discussion Starter #17
Had a go both with wd40 and then a few drops of engine oil on the 2 outer seals. It didn't make any difrence . But I will have a go at fitting new felt washers. It's really the last thing I can try realy . I'm not sure if I have the right jets or anything . But would you say it's worth me getting some more from " common motor " . As then there should be as close to stock as I can imagine being right . . After that .. I'm totally out of ideas.
 

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Discussion Starter #18
Got my self some hole punshes and some felt . The felt is more fluffy. Does anyone know the name of the type of felt to buy?
 

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The felt in the photo you posted looks fine. I replaced the washer on mine, but they were badly worn - thin and eaten away in places. If you already have the new ones made, then sure use them - but if not go with the originals, and just put some thicker oil in them to stop air leaking through them.

Your carb problems really do sound similar to mine. Essentially the carbs weren't working as they should due to a combination of the throttle plates not closing properly, and the little internal passages that the air-screw meters air into being blocked. The starting point for the carbs to work properly at low speed is you need the carb plates to close fully - and for the air-screw meter to be able to control the flow of air/fuel downstream of the plate when it is closed or partially open.

So ..

(i) Getting that disc to sit square and fit perfectly in the throat of your carbs is critical. Make sure that the edges of the disk and the bore section of the throat where it sits when closed, and where it slides open are clean and polished. Use metal polish if you have to - there could be decades worth of crud around the lip of the disk and the bore if it hasn't been seating properly. If it doesn't seat properly - on both carbs then the plate won't close properly and seal the main Venturi as it's supposed to - and you won't get the idle and slow-running to work properly.

If you are having problems geeing both throat plates to close fully - check (a) how they are mounted on the spindle they bolt to make sure they are centred properly and (b) check that the spindle itself isn't bent. Again - either of those will stop the plate closing properly.

Try this first - and once you have the plates closing properly - see if you can set up the carb and test whether the air screw starts to work as expected.

(ii) If not, and the air-fuel screw has no effect, chances are you have a blockage in the little internal passages in the carb-body.

I spent ages trying to get my carbs clean with a little home ultrasound kit - but it was a waste of time. They looked clean on the outside, but were blocked internally. The fix was to take them to a pro garage and get them to run the carb through a proper professional ultrasound and de-gas process. That sorted what my home kit couldn't.

HTH
 

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Did you bench sync the carbs? Also may be good to go over valves and timing to make sure that is correct. I focused on a carb issue with my cl350 and it turned out to be a loose electrical connection from the coils.
 
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