Hi group,

I am a huge XS1100 fan, and have owned, maintained and restored several 1979 XS1100s. I like the 79 model because of its reliability, styling (decals) and kick starter (for praticality rather than machismo).

My current XS11 is a 1979/80 hybrid. Two years ago I bought a running 1980 bike primarily for the engine, seat and tank, and had it fully serviced, including carb overhaul and cam chain replacement before I totally dismantled it, and have spent two years building up a fully restored machine pulling together the best parts of several bikes.

The roblem is that since I finished the rebuild, the engine runs out of steam at about 110kms. The strange thing is that the machine goes like a scolded cat up to that speed, but then feels like it has run out of gas. The local Yamaha dealership have been working on it off and on for three months, and have thrown in the towel saying that they just can't pin-point the poblem.

I have fitted new inlet manifolds, new carb diaphragms, carbs overhauled and balanced more than once, plug caps changed and timming light shows seemingly correct advancement.

It idles nicely with good throttle response, and the drop of the clutch is as exciting as ever, especially with the sidecar attached because the home-made wheels are considerably smaller than the standard 19" alloys and the altered gearing easily lights up the tyres.

But as soon as I get to the outskirts of town and my speed increases to around 110kms, the engine loses power and I am forced to pull over and wait for revs to rebuild before I can continue. The engine doesn't miss-fire or blow smoke, and has good compression across all four pots. The engine is in good condition and set up as a sidecar has gone over 170kms/hour and has been timed at 15.5 seconds quarter mile (with out second gear). There is something very simple preventing this engine performing as it should, and the local Yamaha dealership and I have run out of ideas...can any one help?

From your info, sounds like fuel starvation at higher revs.

Recommend checking if the black rubber hoses underneath the tank (to equalise air pressure in the tank as fuel is used up) are nipped/kinked under the tank, if you have a fuel filter clean it, if you have an in-line fuel filter check that it's not blocked or too small.

Lack of misfire/backfire intimates that not electrical problem/HT leads, but lack of fuel (as it would detonate on hot exhaust if not burnt in the cylinder, but no backfire means no fuel present at the time.....)

At least, that's what I think.

Paul

Hello,I notice you have a 1100

I have a 1979 Yamaha 1100 XS

Was told at a cycle shop that the 1979 Yamaha 1100 xs

is the only Bike Yamaha ever made thats pushing over

309 Horse power.

too me This engine looks like a 4 cylinder car engine

strapped to a motor cycle frame. One heavy bike.

Talking about feeling the power between your legs I'm telling ya!

This is the bike.

I was wondering if you can give me some feed back?

I'm looking for some photos on the wiring on this bike.

They say pictures say a thousand words.

I need to know about the (Ignition Unit)

The Ignition Unit is the Black Box mounted under the seat.

Has two Plugins one big & one small 4 prong plugin.

I need to know where the small 4 prong plugin goes?

Does the 4 prong plug go from the Ignition unit too the Distributor thats near the gear Shifter

(Distributor is located on the side under a cover next & above to the gear shifter.)

Thanks for any help you can give!

I think it is fuel starvation also.

Check that the air can get into the tank when the fuel is used, as this could cause fuel starvation.

Likelyhood corrossion or cud blocking fuel strainer, or clogged fuel valve. Or alredy checked?

Try taking off the fuel cap at 100 kmh and see if that helps

Hi

Has it a fuel pump as I had a similar problem with my FJ12, the fuel pump relay was U/S would run fine and then it appeared to run out of juice. Turned it off then on again all was fine for another few miles and then it happened again.

Adam.

Hi group,

I am a huge XS1100 fan, and have owned, maintained and restored several 1979 XS1100s. I like the 79 model because of its reliability, styling (decals) and kick starter (for praticality rather than machismo).

My current XS11 is a 1979/80 hybrid. Two years ago I bought a running 1980 bike primarily for the engine, seat and tank, and had it fully serviced, including carb overhaul and cam chain replacement before I totally dismantled it, and have spent two years building up a fully restored machine pulling together the best parts of several bikes.

The roblem is that since I finished the rebuild, the engine runs out of steam at about 110kms. The strange thing is that the machine goes like a scolded cat up to that speed, but then feels like it has run out of gas. The local Yamaha dealership have been working on it off and on for three months, and have thrown in the towel saying that they just can't pin-point the poblem.

I have fitted new inlet manifolds, new carb diaphragms, carbs overhauled and balanced more than once, plug caps changed and timming light shows seemingly correct advancement.

It idles nicely with good throttle response, and the drop of the clutch is as exciting as ever, especially with the sidecar attached because the home-made wheels are considerably smaller than the standard 19" alloys and the altered gearing easily lights up the tyres.

But as soon as I get to the outskirts of town and my speed increases to around 110kms, the engine loses power and I am forced to pull over and wait for revs to rebuild before I can continue. The engine doesn't miss-fire or blow smoke, and has good compression across all four pots. The engine is in good condition and set up as a sidecar has gone over 170kms/hour and has been timed at 15.5 seconds quarter mile (with out second gear). There is something very simple preventing this engine performing as it should, and the local Yamaha dealership and I have run out of ideas...can any one help?

If not your gas line then probably your coil. Once the engine runs at higher rpm your coil cant supply the amount of current your engine is demanding thus make your coil very very hot. You can drive your beast w/o seats & check the coil if its getting hot. If it does, then, replace it w/ a new one.

Hi,currently own a 1980 xs 1100 that i am having a similar problem with. I am the owner of a motorcycle salvage yard and i have replaced and gone through everything on the bike. and yet still cant get it to run right under a load over 5,000 rpm? its a mystery to us and the only thing we havent replaced is the CDI box. i am currently trying to locate another CDI box to swap out mine and see if this solves the problem.

Did any of you guys ever figure this problem out? My xs1100 runs just fine up the about 5k RPM and then the front of the bike vibrates and it won't give me any more power. I'd love to know if any of you guys ever found an answer to the problem!

this is from 2007.

as you can see all one hit wonders,all no intro.

see the MO?