Rear brake and Enrichener

[Ccitis]

Hey All,

You good people got my 80 XS1100G online when it was not running. I have a few issues to iron out. On the rear brake, no matter how much I bleed it, the pedal bottoms out (mushy) and you can't lock the rear. The cylinder has been rebuilt... any advice? Could it be the line itself?

The other issue is number one cylinder stays offline on full enrichener. I had cleaned the carbs many times, could the enrichener circuit still be clogged? Anything else to look at? Once the enrichener is closed, that cylinder comes online. Bike runs well otherwise, albeit a touch lean and has some pops on decel.

Appreciate it.

[LAB3]

Hey All,

You good people got my 80 XS1100G online when it was not running. I have a few issues to iron out. On the rear brake, no matter how much I bleed it, the pedal bottoms out (mushy) and you can't lock the rear. The cylinder has been rebuilt... any advice? Could it be the line itself?

The other issue is number one cylinder stays offline on full enrichener. I had cleaned the carbs many times, could the enrichener circuit still be clogged? Anything else to look at? Once the enrichener is closed, that cylinder comes online. Bike runs well otherwise, albeit a touch lean and has some pops on decel.

Appreciate it.

Did you prime the master cylinder prior to reassembly? Put a finger over the outlet hole and pump the cylinder without the line attached until fluid comes out. I've gotten stumped more than once over the years by not doing this, after you do though it bleeds out just fine

[bikerphil]

As for the enricher circuit, make sure this passage is clear in the bowl. There is a tiny jet down in there, shine a flashlight thru one hole and to verify it's clear after cleaning...

[DiverRay]

Lab3 has your brake problem answered. That is it 99% of the time, as air bubbles will get trapped in the MC.
For #1 carb, pull the float bowel as phil's picture shows, and squirt carb cleaner through the tube that comes with the can through the large hole on the top edge. Point the bowel away from you, and wear glasses! You should see a nice stream shoot out the jet near the bottom of the bowel. If it dribbles, it's still partially blocked. A fine wire can help clean it.

[Ccitis]

Thanks all. I did not bleed the MC... Do you mean to say take the banjo fitting off the MC and then build pressure inside the MC itself? I will try with the carb bowl, thats easy enough that the whole bank does not need to come off the bike,

[DiverRay]

Yes, remove the banjo fitting and put your finger over the hole. Put something to catch brake fluid under the area, then press the rear brake pedal while you have your finger over the hole. after about three or four times you should not be able to hold your finger over the hole, and your done.
When you rebuild ANY brake master cylinder you should always "bench bleed". put the MC in a vise and use what is needed to push on the piston with your finger on the brake line hole.

[Ccitis]

Something I never knew! I will give it a go.

[Ccitis]

Someting is up with the MC, I can't build pressure at all in there with my finger. Taken it off and will diagnose on the bench.

[oldyam80sg]

Pilot jets controls the idling and it has got to be clean. Spray carb cleaner on it and also blow it out with air. I use a magnyfing glass to look at things to be sure they are clean. There is a little passage between 1+2 carbs make sure that is clean. Also make sure you clean everything thoroughly. There is no mechanic in a bottle. so dont put cleaner in and think it will be good enough.

[cajun31]

Someting is up with the MC, I can't build pressure at all in there with my finger. Taken it off and will diagnose on the bench.

You probably don't have the rubber parts seated on the plunger. If not installed correctly they don't function properly and won't build pressure. There is a thread here somewhere that shows both improper and proper installation of those parts on the plunger.

[bikerphil]

Ok, this is the order left to right...

spring/cupped washer/smaller rubber seal/thin washer/plunger rod/larger rubber seal. Both rubber seals have the cupped end facing towards the fluid side of the plunger rod.

That little washer goes behind the end smaller rubber seal by the plunger rod.

[Ccitis]

Brake seems a bit better. Still spongy, however, can lock the rear tire now. Cleaned out the float bowl on number 1 carb, carb fluid came through no issue. Still does not come online until the enrichener is closed...odd.

[bikerphil]

As for the spongy brake, block the lever overnite so it is fully depressed and that will bleed out the tiny air bubbles that don't come out with a normal bleed.

[3Phase]

It sounds like you have a clogged Pilot Jet. Remove the jet, then hold it up to a light and look through it.

The screwdiver slots in the brass jets are amazingly easy to ruin and they're in a deep well so they're hard to remove, especially if they've been in place for a while. I found an old screwdriver with the right length/diameter, then ground the tip square and narrowed the blade to fit in the well and stay square in the slot so it doesn't wallow out the jet.

For the rear brake mastyer cylinder, fill a small coffee can or something similar with clean brake fluid and submerge the master cylinder in it, then pump the stupid thing until it stops bubbling.
Block the outlet hole hole with a plastic plug or your finger so it doesn't lose prime after you take it out of the can and blot it off with a clean rag before you put the brake line back on and bolt it back to the frame.

[Ccitis]

Pilot jet should be ok... The carbs were cleaned a few times and were good inside. Still dealing with number one offline on enrichener... I would like to tune out the stuttering and popping while riding. The bike makes good power and ride fine, but definitely has a burble, stutter, and pop at certain RPM 3500-4500 ish. I assume float height is a touch lean (plugs are white so pretty damn lean)... and idle mixture won't make a difference.