Plogged idle jets, I think

[Motofun]

Anything that stays in my "time out" corner for more than a year gets sold....well except for my '63 Riviera that's been there for 30 years.....Oh, and my trail 90....and I forgot the CB400F....

[Waiex191]

My FJ spent 16 years in the timeout corner!  But then my kids grew up.

[Waiex191]

You need to full investigation starting at the tank. If the tank liner has failed and there is now rust getting into the carbs, plugged idle jets for sure. The drop in milage could be leaking needles or seats or restricted jets causing you to use more throttle to maintain the same speed.

I had another one where the tank liner was getting in to the system as the filter was removed from the petcock in the tank.

I took my filter apart.  This is the outlet side according to the arrow on the filter.


Here it is unrolled, showing the inlet side.  Does not look too bad - definitely no tank liner degradation going on.


A closeup of the worst spot on the inlet side shows a little sediment - dark colored.  The Kreem liner is white.  It looks good from the top when I shine a flashlight in.


My thoughts are that it doesn't look too bad to me.  The filter seems to be doing its job.  I did notice some ugly corrosion on the fuel cap.  Not sure if anybody has seen this before or has a recommendation.


It took me a long time to get back to the FJ - I was working airplane issues.  I have those mostly sorted and am up to 5.1 hours now.

[Waiex191]

I weighed the 9 floats in my collection. Four of them weigh 8g, the rest 9g. The floats that came out of the bike are immersed in gasoline currently. I weighed them down so they are covered. I'll re-weigh them another time.

The inside of the carbs and bowls look pristine.

I took out all 4 pilot jets. I couldn't see through any of them until I blew through them. Just my own lungs, no air compressor or aerosol can.

Here is what my float needles look like:


The one on top is a new K&L.  The one on the bottom was new from RPM a year or two ago.  It looks pretty dirty.

Any idea what could cause that?
1) Alcohol causing corrosion or degradation somewhere?
2) Kreem liner making its way to the carb?
3) The pump making debris downstream of the filter?

[T Legg]

My guess is that scaly build up is caused by the alcohol in the fuel combined with moisture. The same thing that is on your fuel cap. The carburetors on my son's truck start to look like that in a couple months after cleaning. My motorcycle carbs look ok on the same gas. His fuel tank has a small slit from previous rubbing against another piece of metal and it allows water to enter his tank when it rains (rarely in Nevada) . I think the water reacts with the alcohol to cause that build up.

[Waiex191]

Thanks - I'll try a clean up and I'll only use alcohol free gas.  There are a couple of stations near me that offer it.

[Waiex191]

I finished pulling the carbs apart.  I've been working airplane issues so it has been a while coming. 


New seats & needles on the way from RPM.

[Pat Conlon]

Yep....Bad float needle seat o rings are the most common cause of gas leaks in our FJ's

[Waiex191]

Yep....Bad float needle seat o rings are the most common cause of gas leaks in our FJ's

Those were brand new o-rings from RPM just over two years ago!  This alcohol gas sucks.  My new parts should be here from RPM this monday according to tracking. 

I do love riding the GN400, but it is no FJ.  Hard to keep up with my kid when we ride together.

[Waiex191]

My new float valves arrived early - got them today.  Carbs are together and on the bike.  I'll chuck the airbox etc on tomorrow.

[Waiex191]

Just got back from a short ride.  Went to the gas station to get some ethanol free premium then a loop around home.  It's better, but not really good.  Still stumbly between 1000-2000 RPM then suddenly smooths out.  Also, as reported a long time ago in another thread, it is sort of wonky above 7000, like it is missing.

Here is what I'm thinking to keep trying stuff:
1) re-check the carb sync
2) Tweak the idle mixture screws
3) Maybe this is an ignition issue
    a) check the condition of the kill switch
    b) check the condition of the ignition switch

Anybody have any good ideas?  When I reported my miss at high RPM somebody had suggested the kill switch or ignition switch.  I never got around to that.

[fj1289]

Just got back from a short ride.  Went to the gas station to get some ethanol free premium then a loop around home.  It's better, but not really good.  Still stumbly between 1000-2000 RPM then suddenly smooths out.  Also, as reported a long time ago in another thread, it is sort of wonky above 7000, like it is missing.

Here is what I'm thinking to keep trying stuff:
1) re-check the carb sync
2) Tweak the idle mixture screws
3) Maybe this is an ignition issue
    a) check the condition of the kill switch
    b) check the condition of the ignition switch

Anybody have any good ideas?  When I reported my miss at high RPM somebody had suggested the kill switch or ignition switch.  I never got around to that.

Along with number 3)   Ale sure the battery and generator are both very happy - have experienced "ignition issues" that were battery related even though the battery would start the bike without issue.   Think it had a cell starting to go.

[Pat Conlon]

Hey Bryan, I had a dirty run/stop switch that caused an intermittent power interruption to the ignition box.
It happened around 6k rpm. After checking all the grounds, I found the culprit by running a temp jumper wire from the battery + to the ignition box power input and after a ride, I noticed the problem went away.
Intermittent electrical problems are a pain to track down.

[Waiex191]

Tonight I popped out my idle mixture screws. Blasted out with carb cleaner, WD40, and compressed air. Runs great. I did open them up another half turn from the previous settings for throttle response.  Why I didn't do this when I had the carbs out - I plead insanity due to a rough home situation.

Kookaloo!