FJRiders.com

Name Etc. wrote:I maybe wasn't clear. I was doing carb sync. 1 2 3 all normal. 4 like 12 cm

Okay....I continue to be confused...you said you lost "compression" in #4.....anyone would think that was in reference to cylinder compression. Are you actually trying to say that you have lost vacuum in the #4 throttle body?

clocklaw wrote:

Name Etc. wrote:I maybe wasn't clear. I was doing carb sync. 1 2 3 all normal. 4 like 12 cm

Okay....I continue to be confused...you said you lost "compression" in #4.....anyone would think that was in reference to cylinder compression. Are you actually trying to say that you have lost vacuum in the #4 throttle body?

Ya, that kinda threw me a curve too. Time to check the bands on the #4 intake boot or better, do a leak test. If that is good it's time to check the bleed screw and the 'never touch' throttle screw with paint to indicate if it has been moved. I won't go farther because you really want to have found the problem by now and don't want to think about anything beyond this.

true story. My problem is low vacuum on #4 intake. I know that it can be low compression but, I did have massive intake leak at the boot. I am hoping it just fixes the problem. you can't just tighten the bands because they are tight all the way from factory. against a spacer. so I ordered new boots. Those Never Touch screws. I badly wanna feck with them.

The low compression was just a MIND PANIC.

Low vacuum on one cylinder could be anything. If it was a Chevy 305 I'd immediately say its a flat cam lobe. However, I have not heard of a Yamaha that has soft cams to date. I bet its a leak post stream to the vacuum tap. You said you have the air system blocked off, check the gaskets there. Also a sniff of carb spray at suspect points can indicate a vacuum leak by a chance in engine speed. There are also electronic stethoscopes that can make a small vacuum leak sound like an F5 tornado, but they are about $100.

Sent from my XT1080 using Tapatalk

silverback wrote:Low vacuum on one cylinder could be anything. If it was a Chevy 305 I'd immediately say its a flat cam lobe. However, I have not heard of a Yamaha that has soft cams to date. I bet its a leak post stream to the vacuum tap. You said you have the air system blocked off, check the gaskets there. Also a sniff of carb spray at suspect points can indicate a vacuum leak by a chance in engine speed. There are also electronic stethoscopes that can make a small vacuum leak sound like an F5 tornado, but they are about $100.

Sent from my XT1080 using Tapatalk

This is indeed How I KNOW it has a vacuum leak between the TB and the motor. I sprayed the boots and the motor died. not just slow down. died. I am just panicky about the big things. I actually woke up in the middle of the night and said "shit, what if its compression?" My wife said What? I'm like "Oh crap, Nothing"... then I laid there awake for a couple hours.

Name Etc. wrote:This is indeed How I KNOW it has a vacuum leak between the TB and the motor. I sprayed the boots and the motor died. not just slow down. died. I am just panicky about the big things. I actually woke up in the middle of the night and said "shit, what if its compression?" My wife said What? I'm like "Oh crap, Nothing"... then I laid there awake for a couple hours.

Those damn biodiesel Yamaha's can be flaky sometimes!

clocklaw wrote:

Name Etc. wrote:This is indeed How I KNOW it has a vacuum leak between the TB and the motor. I sprayed the boots and the motor died. not just slow down. died. I am just panicky about the big things. I actually woke up in the middle of the night and said "shit, what if its compression?" My wife said What? I'm like "Oh crap, Nothing"... then I laid there awake for a couple hours.

Those damn biodiesel Yamaha's can be flaky sometimes!

Maybe it is my Method of Biodiesel.... It is way up on those damn shelves.

Name Etc. wrote:Maybe it is my Method of Biodiesel.... It is way up on those damn shelves.

That could be it....ya freak!

clocklaw wrote:

Name Etc. wrote:Maybe it is my Method of Biodiesel.... It is way up on those damn shelves.

That could be it....ya freak!

ha! If only everyone knew about my Biodiesel...

got half of the boots today. If anyone is Curious... The new boots are soft pliable Rubber the old ones are very hard and stiff. This is a problem. I am guessing this happens to all of them given enough miles and heat cycles.

Got all my parts, installed them several times(just be careful where all the connectors fall to is all I'm saying) for those of you curious types. New boots fixed my problem and she runs great. Old boots were hard. New boots where so pliable and thicker it was very hard to squeeze everything back into the rubber holes. I'm guessing the massive air leak was causing my hard acceleration ping as well. Also cleaning the TB fixed the sticking throttle as well. I recommend doing this if you keep your bike a long time. JMHO also the air box is the easy part.

I think the slow change in how the bike runs snuck up on me. Man she is smooth.... Hasn't felt like this in years I just forgot.