Cam Chain Tensioner Failed

[ViperRon]

New cam chain Tensioners

The new cam chain tensioners are foolproof however not failure proof. There are things that you have to keep in mind. These bikes are old there is gum and varnish that builds up no matter the millage. They also have rubber impregnated cork fiber clutch disks that wear. Also for the bikes that have not been driven for a long time the disks tend to build up rust and corrosion. This means there is a steady amount of contamination that can get into the oil which drips down and settles in the teeth of the newer designed tensioner. If it builds up in the next slot over a long period it can keep the teeth from solidly latching when it ratchets to tighten chain from stretch and wear. You can have a situation under high rpms where it can slip. So every now and then take it off and clean it and now you are fail proof.

[Schming]

The new cam chain tensioners are foolproof however not failure proof. There are things that you have to keep in mind. These bikes are old there is gum and varnish that builds up no matter the millage. They also have rubber impregnated cork fiber clutch disks that wear. Also for the bikes that have not been driven for a long time the disks tend to build up rust and corrosion. This means there is a steady amount of contamination that can get into the oil which drips down and settles in the teeth of the newer designed tensioner. If it builds up in the next slot over a long period it can keep the teeth from solidly latching when it ratchets to tighten chain from stretch and wear. You can have a situation under high rpms where it can slip. So every now and then take it off and clean it and now you are fail proof.

With the first hand experience, that many of us share, of digging into these and other internals of vintage engines, I've come across a product about a decade ago that I've used in all my vehicles that safely works on removing the filth inside the engine. A bit costly but it works.

Heres a link, if nothing else an interesting read:

https://www.auto-rx.com/

P.S. YMWV if you decide to use this additive, mine did

[jennings2309]

Alright, sort of.

Good things that have happened: the bike is back together and running pretty good. On the stand, she revs from 1k to 7.5k without stumbling.

On the road, all systems work well: lights, brakes, trans, shifting (no 2nd gear issues), battery charges well. Road manners are good and that thing is comfortable to ride.

No so good: she stumbles revving from 4k up to 5k, and will not really rev past 5k when under way. I looked at the spark plugs and the color looks like the 'good' pics in the manual.

Keep in mind, she has new rings, spark plugs, and spark plug wires, all the valve clearances are in spec. I running stock air filter, air filter box, carbs, carb-boots, and throttle cables.

Could be fuel flow, or something like the timing. I welcome your ideas.

[Radioguylogs]

Ideas

Sticky carb slide(s)?

Vacuum advance hose is attached in the correct place and has a good seal?

Gas tank vent?

Don't know which model you have, but octy or vacuum petcocks opening correctly?

Kinked fuel line?

Corrosion in main jet(s) or emulsifiers?

[motoman]

Alright, sort of.

Good things that have happened: the bike is back together and running pretty good. On the stand, she revs from 1k to 7.5k without stumbling.

On the road, all systems work well: lights, brakes, trans, shifting (no 2nd gear issues), battery charges well. Road manners are good and that thing is comfortable to ride.

No so good: she stumbles revving from 4k up to 5k, and will not really rev past 5k when under way. I looked at the spark plugs and the color looks like the 'good' pics in the manual.

Keep in mind, she has new rings, spark plugs, and spark plug wires, all the valve clearances are in spec. I running stock air filter, air filter box, carbs, carb-boots, and throttle cables.

Could be fuel flow, or something like the timing. I welcome your ideas.

Initially, I highly suggest with engine warmed up, set idle mixtures FIRST then sync carbs. Then with motor off, blip and release throttle several times to seat mixture screw threads. Re-start motor and follow same initial procedure again finishing with a carb re-sync. Use a typical box fan in front of motor for cooling during running procedure!

[bikerphil]

I running stock air filter

I would remove bottom of airbox, remove the air filter and then take her for a quick test ride. I have run into cheap quality replacement air filters that restrict air flow not allowing the engine to rev high RPM under load.

[MarkD]

I'm gonna be the first ( and one of the more inexperienced) XSer to suggest that the pickup coil wires are faulty. Upon acceleration, the vacuum advance moves, the wires stretch, become non-conductive, and cause breakup at 4500 rpm or so. Mine did this, as well as countless others. There are exhaustive threads on this, but it is an easy fix--replace the wires. There is a test, too. Physically 'test?stretch the wires to see if they 'give ' a little. At any rate, someone will jump in here and either support me, or correct me. Thanks, and good luck!

[jennings2309]

Thanks for the responses. This is a 1979 XS1100F. The original petcocks have been replaced with simple on/off petcocks (the octopus was missing when i bought it).

[MPittma100]

Thanks for the responses. This is a 1979 XS1100F. The original petcocks have been replaced with simple on/off petcocks (the octopus was missing when i bought it).

If it is an XS1100F (Standard), there was no octy. Octy was only on the XS1100SF (Special). Verify the integrity of your pickup coils and go from there.

[motoman]

I'm gonna be the first ( and one of the more inexperienced) XSer to suggest that the pickup coil wires are faulty. Upon acceleration, the vacuum advance moves, the wires stretch, become non-conductive, and cause breakup at 4500 rpm or so. Mine did this, as well as countless others. There are exhaustive threads on this, but it is an easy fix--replace the wires. There is a test, too. Physically 'test?stretch the wires to see if they 'give ' a little. At any rate, someone will jump in here and either support me, or correct me. Thanks, and good luck!

Normally would support that suggestion, but normally if that were the case one or other of those exhaust would let out a heck of a backfire. Just for grins though, pulling on every inch of those wires would be worth the quick check.

[cajun31]

my experience

I just recently ran into this very problem after letting my bike sit for a while. I thought I had done enough preventative maintenance and stored the bike properly. Ethanol ... that evil component of most gas you get today was the problem. I completely drained the gas tank... filled it with ethanol free gas. I also put about a half a can of seafoam in with the new gas and then primed the carbs. Let that sit over night then started the bike. It started right up and idled good. Took it out on the road and it stumbled at higher rpms. I could literally not go over about 55 mph. Would have been great if it was 1980 when the bike was built and the speed limit was 55mph. I stumbled back home and stripped the carbs off the bike. Took them apart and removed all the jets minus the pilot circuit and gave all those a turn in my ultrasound cleaner. Used a solution of distilled water and cleaning vinegar. You could see the deposits fly off the jets as the ultrasound did its work. Re assembled everything … put the carbs back on the bike and she runs like a bat out of hell again.

[jennings2309]

Hi Jim,

Thanks for the post. I wonder if cleaner carbs might me the solution. It starts great (Two hits on the button at the most!)

I think that will be the next step...David

[motoman]

Hi Jim,

Thanks for the post. I wonder if cleaner carbs might me the solution. It starts great (Two hits on the button at the most!)

I think that will be the next step...David

Would definitely be my next option jennings2309. After removing ALL jets, inspect inside of those pilot jets carefully using a magnifying glass and good light. Their atomizing orfice is at top of jet and internally they DO have a bit of a taper, which unfortunately WILL trap anything besides fuel from passing by under vacuum draw. Upon inspection internally, a lot of times, a tiny,tiny piece of foreign matter will block normal fuel flow as rpm comes up. This scenario happened to one of my four carbs. I had to use a tiny straight pin, going in at bottom of jet, catch the tiny debri and drag it out. After which running correctl issue was resolved. JAT to consider checking along with making sure all other internals are clean, orfices,etc. BTW, those piot jet orfices are so small that not even a point of a straight pin can be inserted in them.

[LoHo]

A guy can spend a lot of time trying to fix problems that are caused by stretched vacuum advance wires...just sayin'...

If it only happens occasionally, usually in the middle of a ride, when the throttle seems to have little or no effect, then kicks in again, it is the VA wires.

[LoHo]

Also, I have a good cam chain tensioner retrofit that I know works (I have its mate on my bike, after adventures with a wrong version), that I will give away for the price of postage.

Does anyone need a 1980 head (no valves)? I bought one for the valves and hate to just toss it.