xs1100r problems

[hazza2508]

gday. have recently been rebuilding an 81 xs1100r only to get it all back together and find it's not running very well at all. basically the problem is as follows:
there is significant pressure variation in the carbie maniflods - when i hooked up the synchoniser it was all over the place for all cylanders.
i took off the timing cover and had a look while it was running - the vaccum advance is also all over the place. unhooking this makes it run better. hooked up a timing light and it's firing perfectly.
the only thing i could put it down to was intake valves opening too early or closing to late.
i took off the cam cover etc and checked the timing marks - perfect.
got a light down the sparkplug hole and watched the piston move up and down relative to the valves closing / opening. it appears the intake valves are opening to early and closing too late. to me (very much a rookie) this would suggest insufficient valve clearance. the clearance is perfect to the specs in the manual i've got which states that the clearance should be .11-.15mm for models past 1980. i cannot find clearance specs specific for the "R" - also known as the sport and am thinking it might be different. can anyone tell me the correct clearance / suggest any other factors that may be causing it. have put a lot of work into this bike and now seem to be up that proverbial creek without a paddle. cheers.

[tw1980]

If your vacuum advance is moving all over the place you may have the vac advance tube hooked to the manifold.It plugs into #2 carb.Welcome aboard mate.

Terry

[Guy_b_g]

Check the connection of the vacuum advance, is it connected to the vacuum port of carb#2?

If it is instead connected to a an intake manifold boot vacuum fitting that will cause the vacuum advance to jump around, unless you greatly restrict the vacuum.

[Guy_b_g]

Too slow...again...

[Ken Talbot]

basically the problem is as follows:
there is significant pressure variation in the carbie maniflods - when i hooked up the synchoniser it was all over the place for all cylanders.

That's exactly what you will see when the carbs are out of sync. The whole point of synchronizing is to adjust the three balancing screws to eliminate the differences. Use the screw between #1 and #2 to balance those two carbs to each other. Use the screw between #3 and #4 to balance those two to each other. Finally, use the screw between #2 and #3 to balance the left pair to the right pair.

[fredintoon]

gday. have recently been rebuilding an 81 xs1100r - - -

Hi Hazza and welcome,
so where in the World are you at? Your profile don't say. Indeed, it don't say much at all.
Revealing your home city and adding your bike model to your signature line will not bring you floods of spam
offering you drugs and equipment to enhance your sex life but it will let fellow XS riders help you better.
Does an '81 still have the vacuum advance? I disremember if they upgraded past that in the '81 model year.
As has been posted, if you got one, it's gotta be hooked up to the #2 carb, NOT one of the four manifold connectors.

[hazza2508]

cheers fellas. like i said - bit of a rook. anyway the only nipple coming out of the carbie bank is the one out of number two that the hose from the fuel shutoff valve setup doovie was plugged into. unplugging this and hooking up the vac hose to it makes everything go pretty well for a bit then it starves for fuel and cuts out. what exactly is this hose and where is it meant to plug into? hooking it to the manifold nipple doesn't work either. tried once again to sync carbies and the reading still varies a lot (for each dial - moves about 1/4 of the dial per fire). is this normal? never synced carbs before. think i got them about similar - this increased the revs by bout 1k, backed the idle off and runs quite well at idle, however still got nowhere to hook up the vac advance except the nipple where the fuel hose thing goes in. do i need some kind of double adaptor thing here to take both hoses? had never run this bike prior to rebuild so don't know if it was all hooked up correctly prior. cheers.

[Guy_b_g]

The vacuum hose to the ignition vacuum advance goes on the #2 carb. The one to the fuel Octy, (or the 2 to the petcocks if you have a standard) go to the maniold vacuum nipple (or nipples for a standard). Any of the manifold nipples will work.

You may need to damp the vacuum in your guages with the damping valves, or (if it doesn't have them), install some adjustable aquarium air valves, one for each vacuum tube on the guages to damp out the variations in vacuum as each cylinder goes through its firing and exhaust cycles.

It may be that you have a vaccum leak in the octy, consider removing it if the above does not help, or if you have no octy, try running the petcocks on prime if you still have problems. If either of these things work after moving the fuel vacuum hose (hoses for a standard), then you need to rebuild the octy, or (for a standard), the petcocks.

[MindWebs]

some ideas!!

Pictures!! I like pictures

OK, now..

the bigger line (outside carb) is the vac line to the octy.. The octy can be hooked to any one of the "SYNC" ports.

the smaller line on the second carb in is the Vacuum timing advance. It
must be hooked to that exact "nipple"



Ok, next. wwhat type of synchoniser are you using?
if it's a liquid type, then they are fine. (No calibration needed)
if it's a vac gauge type, then you'll need to calibrate them before use.
here's instructions for that. http://www.megaupload.com/?d=WC0A3044

Now, try to sync your carbs following Ken's instructions:
synchronizing is to adjust the three balancing screws to eliminate the differences. Use the screw between #1 and #2 to balance those two carbs to each other. Use the screw between #3 and #4 to balance those two to each other. Finally, use the screw between #2 and #3 to balance the left pair to the right pair.

these screws are located on the throttle shaft connecting the carbs to each other. Hint: they move with the twist of the throttle.

Sorry to write things out in the "simplistic" manner.
We help everyone here, sometimes they are expirienced mechanices of 40 Yrs
sometimes they are people trying for the first time. we usually don't know who is who, so we do the best we can.

Good luck

[hazza2508]

thankyou kind sirs. well synced my synchroniser then synced the carbs as instructed (using the valves - wondered what they were for). she purrs very well but still not growling right.
without vacuum advance hooked up it idles nicely, revs out quite well, and returns to idle without cutting out. with the advance hooked up:

still idles normally
the pickups start to flutter a bit at round 1200rmp
open throttle --> it moves but not very evenly , sorta jolts it's way around.
at around 4000rmp starts to backfire
cuts out as soon as the throttle is backed off.

i tried putting one of the valves of the sync in the vacc line - didn't work.
checked the advance system ovver and apppears perfectly functional - moves freely with good spring back. can suck the diaphragm and move it. it i push the planger back and cover the hole it stays there. makes me think it's something to do with the pressure from carbie nipple. just thought i should have hooked up a guage to that and seen what it was doing. what should i expect if i do this? what factors would contribute to abnormal vaccum in this port? i would expect clearance /timing etc but if this were the case would it idle right?

is there anyway to check the functionallity of the valve timing relative to the spark / TDC other than on the marks on the cam shafts? - have checked these and appear fine, but just doesn't seem like a very accurate test, and i have my suspicions.

alright. potentially stupid question: is there meant to be a centrifugal advance on the "R" / "sport". cos if there is i didn't get one with this bike. doesn't appear to be anywhere for it to go, but seems kinda strange if yammie left it out for one model. cheers fellas.

[hazza2508]

also have been told that the inlet valve gap is 0.11 - 0.15 mm only for the G and the SG, on all others it is 0.16 - 0.20. can anyone clarify this? if this is so then i've got the clearance set wrong. this is an xs1100R - i have also been told these don't exist, but this is whats stamped into the side of it. serial no. 5N5...etc

[DGXSER]

thankyou kind sirs. well synced my synchroniser then synced the carbs as instructed (using the valves - wondered what they were for). she purrs very well but still not growling right.
without vacuum advance hooked up it idles nicely, revs out quite well, and returns to idle without cutting out. with the advance hooked up:

still idles normally
the pickups start to flutter a bit at round 1200rmp
open throttle --> it moves but not very evenly , sorta jolts it's way around.
at around 4000rmp starts to backfire
cuts out as soon as the throttle is backed off.

Pick up coil wire repair is my diagnosis. Runs fine wiht out the advance, runs liek crap with it. Yep, the wires from the pickup coils can break inside the insulation. There is a tech tip on finding the break(s) and repairig them.

alright. potentially stupid question: is there meant to be a centrifugal advance on the "R" / "sport". cos if there is i didn't get one with this bike. doesn't appear to be anywhere for it to go, but seems kinda strange if yammie left it out for one model. cheers fellas.

In 1981 they eliminated the mechanical or centrifugal advance. They built the advance into the TCI box. Only has vacuum advance. However it was not just one year, they did it in 82 on the XJ also. But then they also eliminated the vacuum advance and put that into the TCI as well.

[petejw]

Hi Hazza,
I replied to the valve specs in your other post,
Ive got the same model bike as you,
where abouts in nsw are you, if your not to far away
I could give you a hand.

[hazza2508]

DGXSER - hit it in one mate. three out of four wires pretty much shredded. think i'll replace all from where they come out of the pickups to where they join to the normal type wires - gotta find some flexi wire and get some shrinkwrap first. am confident now to put it all back together tomorrow and then sort that bit out after i get to town (a little out in the sticks).
thanx for the valve cleaarance pete. good to know there are others out there with the same bike (and that it actually does exist.... darn yankies on facebook!). am near wagga / albury. thanks a lot for the offer of a hand but i think i may have it sorted now - everything ran so well other than when the vac advance kicked in. this was not hooked up when i bought the bike - now know why. also quick Q: there appear to be a lot of carb kits available, but none that specifically say they fit this bike. any idea / experience on which type fits / where to get one? cheers.