carby diaphragms

[HMC]

Thanks Guys          I am happy with simple checks. I will go thru the list above. Cam timing Im happy with but will put it on the list to check.. I replaced the pickup coil with a good one so confident of the wires coming thru the grommet.
I have the original intake manifolds on so will check them and that advance canister, its working but I have not checked if its holding.Hole in filler cap - have not thought of that.
Also revisit float levels.
Once it gets over the lag it leaves your head behind with acceleration, so we're excited.
Any advice is appreciated,as I knew nothing about these things when we started except it was very heavy trying to move it with flat tyres.
Its got new plugs, will check what sort. Thought it also might be sticky slides as it has freed up a bit with use.

[excess.11]

What you are describing the problem is .......is that you can freely rev it and all seems ok.......but under load or sustained throttle opening your finding that there is a stutter or hestation when increasing speed from takeoff or cruising. What plugs are you running ?

[steptoe]

it has been a long time on the build, it might pay to pull apart and push back together a few times the plugs for the cdi box and the wires from the governor {if you haven,t already} also might pay to check how freely/far the bearing in the advance unit moves,
5  degrees at 1100rpm, have you taken it to 5000, it should be very close to 36 degrees, if not do you have a spare vacuum canister
from memory yours is a std no, the 2H7 boxes rarely cause hassles, you,ve checked the wires for breaks/stretching as they come off the timing plate and thru the rubber grommet

as Phil said the diaphragms don,t come into it unless they have holes and even then they have to be bad, what condition are your intake manifolds, have you sprayed ether or such over them while running

more than likely fuel, lagging before lift off usually means floats are a little low meaning there is to much fuel in the bowls and is to close to emulsion tubes,

they are a very simple machine but they like to be set up very close to spot on, it,s ALWAYS the simple things that are wrong

as for the air box being in the road, take the air filter off the bottom and you should have plenty {still small} but enough room for easy removal and replace, 1 thing that I do make sure of though is when I undo the clamps, I move them back behind their seat and do them up again so they,re out of the road and don,t get bent

how hard does it go once it gets over the lag if it does, maybe clutching at air, I know you and your team do engines, so I,m assuming new cam chain, tdc set to perfection, timing marks on cam sprockets are set with cams,{they do go 180 degrees}, and all line up,

sorry mate not making you out for a fool, just things we double/triple check all the time
ask Lou, {Beemeer 11} he rode his round for ages with timing a little out, he thought it was going alright to till he sorted it

check your pm

[excess.11]

To work blindly and not be able to dissect where the fault is is more than frustrating.
If you had a spare set of carbs that were proven on another bike would help point you in some direction.
Its all about breaking down the issue into areas to address.
When riding at altitude you would find even a well tuned and trouble free bike would struggle with idling and sluggish performance.
Check for air leaks on all vac hoses and check that the advance mechanism holds under vacuum and doesn t have a slow leak.
Air hole in filler cap is not blocked ....check all the simple stuff.

[HMC]

Yeah    Its more of a lag before it takes off. It was worse over Hotham. It idles like a gem and revs out fine so I reckon timing and valves are ok. If it was fuel then it would not rev out as well as it does. I know the carby circuits are clean as I tested them all. The only other part I have not renovated apart from the diaphragms is the cdi box. It did have major electrical dramas as I replaced the pickup coil, installed new dyna's, leads, plugs and the rectifier was dead also. Also did a fair bit of work on repairing the loom. Ignition box is going on my list of unlikely suspects - to the elephant cave!!

[pgnz]

carb balance is just for smooth idle and after a couple thousand revs a .03mm prod of a butterfly is of no consequence,  "can't get any midrange revs"  means definitely something waaay faulty somewhere, "normal" XS1100 = instant arm wrench and fast hurtling to horizon at any revs

[HMC]

I'm replying to myself,
I think I will put the carby balancer on and see if it shows any differences in the dead zone.
I only used it at idle. Looking for any diagnostics I can do without tackling that airbox again. 
Its only an issue under load though, which could make it interesting.

[HMC]

Thanks  The oil is from the fork seals which I have not replaced yet, although I do have them.
Has got new valve seals. Float heights checked with a clear hose and all within a miniscus.
New pilot jets and ultrasonically cleaned carby bodies x3. I actually have spare carbies if anyone is desperate.
Have set the timing with a timing light but cant remember , maybe 5 degrees at 1100rpm.
Valve clearances done three times, dont ask! mostly new valves.
All new electrics, pick up coil, coils, leads, plugs.
What is weird is that it had exactly the same dead spot before I did all the work on the top end, carbies and timing.
That's why I am considering anything I have not replaced based on the same logic employed in the chewbacca defence.
ie It does not make sense! 

[pgnz]

nah complete waste of cash replacing perfectly ok slide diaphragms unless the one's in there ACTUALLY HAVE got splits or pinholes, nothing will change, soggy midrange more likely dodgy pilot jet circuit(s) etc

[excess.11]

The question to be asked is "why are you getting oil over the front brakes?"
Have you done the valve seals?
Regarding the lack of midrange....there s a possibility there s an issue with the advance ...either mechanically or electrically.
I assume you ve set the float heights and have the correct jet sizes in the carbs.
Could the oil be causing a bad mixture giving you the flat midrange acceleration?
Double check valve clearances and set timing with a strobe light.
Fix the "Known" issues first ....such as the oil ....then see how things go.

[XSIIE]

you could try these.

http://www.ebay.com.au/itm/YAMAHA-XS650-XJ900-XS750-XS1100-CARB-SLIDE-DIAPHRAGMS-/381121415076?pt=Motorcycles_Parts_Accessories&hash=item58bc9b47a4

http://www.ebay.com.au/itm/CARBURETOR-DIAPHRAGM-B-CARB-CARBY-1980-YAMAHA-XS1100-XS-1100-80-/380768517924?pt=Motorcycles_Parts_Accessories&hash=item58a7927f24

[HMC]

Hi All         Any clues on getting new diaphragms?  I cant get any mid range revs and have cleaned or replaced everything else in there, The ones in there look ok but they reckon they can stretch and display such a symptom.      We took it to Omeo and Mitta with 140kgs of delicensed President on the back and it went ok but 2 into 1 exhaust manifold cracked through and have got oil all over front brakes.   Tempted to ditch the original pipes to neaten it up a bit.   Thanks