What do you think

funky

XS650 Junkie
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Hi chaps hope your well :thumbsup: Those of you who know and read my posts are aware that i am running in my engine I have done 51 miles so far, the engine was rebuilt by a professional H Smedley of Smed Speed London and did a great job. The reason I have stated this is to negate the engine from the equation ...:shrug: its not cam chain tensionners or bad rings or what ever other fault :Dthis is pure Carb issue :thumbsup:

What i want to know is am I right or wrong in my diagnosis of these two picture :thumbsup:
left side Plug
IMAG1473_zpskmqggclt.jpg

Right side Plug
IMAG1475_zpseeltdxru.jpg

Both plugs are the same irridium 7 came with pamco i voltage kit :thumbsup:
Diagnosis rich mixture
Cause Neddle jet set to low need to move clip one notch up :confused: or adjust mixture scres from three turns out to maybe 4 :confused:
Im not sure if i am on the right track here What do you Chaps think :bike:
All the best Funky
 
You seem to have foam float BS 34's, What jets and air filters are you running?
Float valve o-rings known good? If it seems to be running well maybe just get some miles on get the rings seated, RPM restrictions off, then you can open it up and see how the plugs look with some full throttle runs, so you know if the mains are right, before you change the needle settings.
 
Hi gggGary All standard ,airbox, jets, air filters ,floats brass, set at 27mm +-1mm. Engine is now 707cc pamco hi voltage fitted timming spot on drives well no back fire.
Am I right in thinking that if i adjust the mixture screws that will only effect idle circuit or does it change all of them ?
Thanks for reply:thumbsup:
 
This chart is for US carbs

CarbSpecsReducedSize.jpg

Never hurts to check that your brass is right. With those "mufflers" you may end up going up on the mains and pilots a size or two. Did you replace the float valve o-rings?

sounds like you have the floats set right.

mixture screws; out is richer. I like 5twins theory that 3.5 turns is about it, after that no difference and time to bump the pilots a size but you are thinking you're rich, Sure that's not just some break in oil on the plugs? :shrug:
Might set your floats near the high end of the spec that will lean it a bit.
 
my reading of those plugs is your pilot circuit is too rich

under the soot I can see that there is a nice biscuit brown colour of a good fuel mix which is being masked by the rich sooty mixture at the end of you ride at low revs.

I've forgotten what your pilots are but if you have run out of adjustment on your air screw you could try the next size down .Otherwise you might need a colder spark plug which will burn it off better.
Its probably mostly as a result of your low throttle runs at the moment
 
thanks for all the responses. if i weaken the mixture screw would this help ???????
probably not ...the air mixture screw governs the amount of air for closed throttle situations .Its not just for idle setting its also important for deacceleration where a weak mixture could cause seizing on a new engine.


It depends where your air mixture screw setting is ?. If the air screw needs to be nearly all the way in or all the way out to get the mixture right then you need to go up or down on your pilot jet.
 
If you're starting the bike using the choke, what you're seeing may be normal. Running with the choke on for a minute or so during cold starts can do that to your plugs. It may take 10 or 20 miles riding afterward to burn them clean again. Check the plugs after a ride. Then, to check idle mixture, re-start the bike while warm with no choke and let it idle for a minute of so. The plug check you get right after a ride will likely be indicating mostly midrange settings as that is the range you usually cruise in.
 
funky,

I would suggest that you use stock spark plugs until you get this sorted out. Those iridium's are expensive. :eek: Also, the ignition system is a wasted spark system, meaning that one of the spark plug wires is a positive voltage and the other is a negative voltage. The iridium relies on working with a negative voltage because it works by having a very hot tip to "encourage" the electrons to make the jump to the relatively cold ground electrode. Electrons are negative, so they are only available on the negative wire, so you are only benefiting from one of those expensive spark plugs! :wtf: It's also possible that that difference accounts for some of the difference in the appearance of your plugs. :doh:

How could this be, you ask, as these plugs are touted to be great for all applications? :shrug: Well, the older distributor type of ignition system uses a coil with a single output that is negative. Ford Motor company and perhaps others actually use a different spark plug in the negative and positive wires of their wasted spark systems, which virtually all cars are now with three coils for a six cylinder engine, four for an eight and two for a four cylinder.

However, many cars now, including my little Mazda Miata,
miata.jpg

have a coil - on - plug system (COPS), so we are back to having the preferable negative voltage for the spark plugs and in that case the Iridium's are beneficial. :thumbsup:
 
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Thanks pamcopete intresting reading you are an authority on such matters and find this facinating :)
:confused:When does the wasted spark activate. At what part of the 4 stroke cycle .:confused: I ask because my 360 degree engine and the silmultainious recipricating motion of the both the pistons leaves me wondering how its wasted,:shrug: Thinking about it:confused: it's got to be the exhaust stroke:doh: as it cant be induction or fuel will be ignited:D Compresion and power strokes is when the spark is needed:laugh: that leave the final stroke EXHAUST im guessing...:confused:

P.S What plugs do you recomend Pete ?????????
All the best Funky
 
:DHey 5Twins thanks for the reply the bike starts without any choke never had to use choke since rebuild:thumbsup: I see what you are saying I have adjusted the mixture lean it half a turn I will see how they look tomorrow :thumbsup:
 
Well, if you don't require the choke for cold starts then you are way rich somewhere or somehow. These bikes usually require the choke for cold starts even in hot weather, although you don't leave it on long in the warm weather (10 to 20 seconds). The bike tells you when to take it off. The motor will start stumbling and running rough, stalling even if you don't give it some small throttle blips.

The stock and recommended plug for these is the NGK BP7ES .....

CorrectSparkPlugs.jpg
 
Hi this is the result of moving the needle clip one notch up i have one more to go. in you experiance do i need to rejet or should i go to the top notch. bike runs fine no back fire pulls well for the RPM i am going to 3500 to 4000
IMAG1505_zpsiqaj0x2m.jpg

all the best Funky
pulled the plugs at 20 mile
I have put back the iridium plugs... the plugs in this picture are NGK BP7ES
 
good to hear that you can ride it at last :thumbsup:

If you refer to the chart I posted you'l see that the jet needle and needle jet is mostly responsible for the 1/2 to 3/4 throttle range together with the pilot circuit so that is the range you need to be testing in order to tune the needle jet and needle and read the spark plugs. The main jet is also becoming increasingly involved from 3/4 to WOT

When tuning you should start rich and work lean so start with the clips at the bottom of the needles and work up. If at the top clip position the 1/2 -3/4 throttle range is still too rich then you may need to change your needle jets and or needles or main jets

You need to mark the 4x throttle positions on the brake lever bracket so that you can see where the throttle needs to be in order to test the various jets and needle.


The part of the throttle that you are interested in at the moment is 3/4 to full throttle. In order to read the spark plug you have to ride at a steady 3/4 throttle for a couple of miles with the engine hot then pull the clutch in turn the ignition off and coast to a stop . That way you'll be able to see what the mixture was at 3/4 throttle and the plugs hopefully won't be covered in soot from low throttle cruising and idle as you pull up .

The part of the plug you read is the centre ceramic insulator

Before you do that notice how the engine reacts when after a steady throttle position run you close the throttle . Does the speed seem to surge ever so slightly ? indicating that you have a weak mixture at that particular throttle position ?

There are loads of carb tuning guides all over the net so there is no point in laboriously rewriting it all here.
I just wanted you to see how carb tuning needs to be tackled in throttle sections which test a particular combination of jets needles slides etc .:wink2:

http://www.iwt.com.au/mikunicarb.htm
 
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Thank you peanut I will attempt what you suggested great advise ... I must say I am a little lost on this, the issue I have is that i am running in the engine and do not think i am getting anywere near 3/4 to full throttle I am doing about 50 to 55 MPH in 4th or 5th gear and using engine breaking on the down hills to help the rings bed in.
As mentioned in my previous post I am now on the second notch from the top so only have one more notch to go.
I will do what you suggested thanks.
I also wanted to ask you about getting the next spark plugs up or down,, hotter or colder , i cant remember now,,, to get more heat to help this issue. what do you suggest Peanut .
Thanks again
All the best funky
 
What are your mains and pilot sizes? Or did I just not see it?

going to a hotter plug doesn't fix poor jetting. To rich and you'll wash the bores.
 
Sorry. Just read stock. Should need choke to start when Cold. Check your float level with clear tube method. Should be couple mils under bowl seam.
 
Thanks for the reply CDNTX,Peanut, and all You will all have to excuse my ignorance on this I am quite confused at the moment. :confused:
My current settings are Floats (brass) are set to 27mm +-1mm needle clip one notch down from the top notch and as far as i am aware the jetting on my carbs are standard for the the BS34cv carbs.:D
I will get all my jet sizes and post them today.:thumbsup:
Engine has been rebuilt to 707cc with standard down pipes but a reverse cone muffles which are basically strait through via a mesh screen tube with wadding around them .

I am thinking that I need to re jet as my plugs are comming out dark as around the central insulator as you can see. :thumbsup:
I am also thinking right or wrongly that I have to reduce my main jet sizes to lean off the mixture is this correct. :confused:
I have one more adjustment on the needle clip which will reduce or lean off a little more if this does not resolve the issue of too rich:shrug: I have to reduce the needle jet size by one or two sizes.:confused:

Also on starting:thumbsup: I do not need to have the choke on which tells me that the mixture is rich also I think.:confused:

I am running in the engine:thumbsup: so need to make sure my mixture is right for now and future performance.

I need confirmation that I am thinking the right way, Silly as it seems but i need to ask... reducing the jet size leans the mixture by reducing fuel atomisation:confused: increasing the jets size richens the mixture is this correct.:doh:

I have read the theory but what confuses me is that people are saying "i have fitted pods and strait through exhausts":thumbsup: and are being advised to increase jetting but theres no pictures of there plugs:banghead: Are they running rich or lean. :confused:
They seem to be changing there jetting based on the fact they have fitted pods on and an straight through muffle not on the condition of there plugs.:shrug:

I have a slight understanding of the theory and are aware of altitude differetials I am personally at about sea level compared to someone living up some mountain.
I am also aware that air pressure does what it does and that a good air to fuel miture is around 15 to 1 ratio:thumbsup: But i have no way of messuring this only the condition of my plugs once I have done a good few miles..


All the best Funky
 
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