carb swap

[SmokinXS]

Air screws set to about 1 and half turns out. Im trying different settings also. Screws are new.

I even had my bike at a local service nearby and yes, i know the screws can be broken easilly - they did it on one carb (another story ). But i etched it out with HNO3 carefully. It works as before. If it didn't i can swap it for another carb at my disposal.

I can't measure my compression right now - a one-way valve on my compression tester leaks air so its not accurate, but i think i don't need it right now so i didn't bother.. Maybe next time i will be in the shop if you are interested in readings...

By the way - using acid to get broken screws free from aluminium material is nice and clean way for the threads. It takes longer to get rid of the broken screw, but it pays-off as it has always a good endig unlike other extraction methods

 

[xschris]

I would start with three turns out. It will help with starting. If your compression is under 125lbs it will run and start poorly. New is about 155+

 

[SmokinXS]

just to post some picts you wanted. Now its partly stripped for testing purposes.



sidenote: original thread is about swapping carbs for some aftermarket ones. Although i'm glad someone is trying to help me with stock ones, i think it is sliding somewhere else

 

[SmokinXS]

Now i have re-seted my ignition timing with a strobe light supercorrectly, did carb sync (with carbtune tool) and adjusted idle mixture with the help of colortune transparent spark plug on engine in operating temperature.
Still no luck with starting my bike cold... it just WON'T start without spraying some gas directly to the mainfolds or so...
Outside temperature is around 25 degree in the shade (20 in the garage). A short vid of fire in combustion chamber below:

 

[16VGTIDave]

Are you sure the engine is at operating temperature before you are tuning? Is the oil above 80ºC? Yesterday it was 23ºC here and it took over 20 minutes of brisk riding for me to get the oil to 80ºC. The idle speed and quality changed noticeably once warmed up, it became slightly faster and smoother.

The number of turns on the Pilot screws is nothing more than a starting point to get the bike running. After that, proper tuning is required. I personally set my idle mixture slightly rich so the bike doesn't get too hot when stuck in city traffic, and so it idles a bit better when cold. Cold starts always require the use of the "choke" and no throttle.

 

[xschris]

You need to tune the bike with the air filters on the bike!! It will run very lean without them. Color tune is NOT a sync tool but for fuel mixture. Make a manometer for that. They are cheap to make. If the bike is hard to start cold it may have low compression.

 

[SmokinXS]

Filters on/filters off - it does not matter. I did both. Not much of a difference. Im simply too bored to put em on and off milion times so on the vid it runs without em.. Anyway it should start and idle nice without em when right mixture is set. According to the vid i think it has the right mixture, or Im very near to it.
You made me laugh, xschris I know what is colortune for :-D No offence, really. I had synced my carbs before with another tool (actually carbtune). I was using connected bottles back in the days but i realised im soooo rich i can afford something more compact and readable.

16VGTIDave: it should be in operating temp. I have no thermometer installed, but it was running few minutes (something around 1 beer).

Thats the problem - i think my choke is not working well on both set of carbs. Am I just out of luck? Or is there a ghost inside my choke passage?
just to prove i have a nice compression i will get my compression test manometer working and provide you with numbers.

Thank you for your time and advices even if they are a bit pathetic to me - there can be always something i could miss, so double checking - in my case 10 times checking - is required i think.

Now just for fun... i was synchronising my carbs this way back in the days:

..worked well

 

[16VGTIDave]

As pathetic as my comment sounds, read again my description of operating temperature and what it takes to achieve. I'm going to say your engine was barely warm, so your tuning efforts were wasted.

Dirty carbs are a common complaint with these bikes. It often take multiple cleanings, using different chemicals, to get the small passages open.

 

[xschris]

Excessive idle time will foul plugs making starts more hard.

This works well for syncing. A member made this one. It's a bit large but easy to make. I use mercury stix for my bikes.

 

[SmokinXS]

I can ride it few minutes 16VGTIDave ... But as you could see, the fire was nice-colored even if it was not correctly warmed as you think. Assuming that, it might be slightly more rich then it should be. Than it would start nicely when cold using choke or half choke or even no choke, but it won't. Alright alright, enough theories, i can try it one more time, its not that time consuming compared to how much time i already gave to my "junk"
Carbs might be cleaned very well... sprayed it milion times (2 different cleaners), they were in ultrasonic bath twice and i made myself a "pressure washer" from older car's petrol pump. With hose attached to it i have flushed all the passages with technical petrol feeling output flow on my fingers and then again cleaned with carb cleaner and compressed air... Who on earth has cleaner carbs? )
Yeah, another way of syncyng, xschris..

 

[Jeff0133]

Filters on/filters off - it does not matter

Well I think it does matter...depending on the type of filter you are using, on stacks...or not.
Tuning or trying to tune without the filters on is wasted time IMHO because the air flow will change once you put them back depending on the way the air makes its entry into the carbs...(turbulent vs laminar flow)
I have been fidgeting with two bikes same filters, one on stack on the other straight on the carbs and I can tell you for a fact that the one with stacks run a hell of a lot better, which made me fit stacks to the other and it improved it's running two fold. Fluid dynamics is a bitch...

 

[SmokinXS]

Jeff0133: why then i had correct mixture in the combustion chamber with no filter? Why then it refuses to start cold with the same setup (still no filters)?

I dont know whether there is a big difference between air movement shape with no filter/direct filter/stock filter and how that potentially affect mixing condition inside a carburator - but there definitely is a difference in a weight of the air sucked (and mixed with fuel) in.
So yes.. without filters in my case its a raw setting, but it should at least start and idle nice when conditions are met for it (as you could see). Final tuning with everything installed is certainly required and a matter of few minutes... compared to 10times a day putting on and off filters after this mod and that mod... it weakens one's nerves : ))

 

[Jeff0133]

I agree with what you are saying here...was just underlining the need to tune again when putting filters back on.
Now,did you ever do that compression test you where referring to earlier as that could be just it.

 

[SmokinXS]

I will.. jist need the right fitment for my compression gauge but didn't make it to the shop yet. Still im quite sure the compression is nice with cylinder freshly rebored. Could be that rebore process went wrong though. But the propability is low.