dead rear cylinder... now what?

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joeConnectALL
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dead rear cylinder... now what?

Post by joeConnectALL »

Hello everyone- I have a problem with a ‘dead’ rear cylinder on my 1987 Intruder 1400.

The bike was in a high-side crash in 2014 and has been sitting since.. with about ¾ of a tank of Premium gas (with StaBiL).

After the crash, 2 days later, I trailed it to my garage- I assessed the damage. I was able to start the bike and it sounded very good. The foot pedestal was broke- the rear brake pedal twisted, rear master cylinder damaged, gas tank with my nephews knee print in the middle of the tank plus a lot of right side cosmetic damage. All fixable given the time, desire & resources.

Three years later - and I decide to get her going again. I first tried to start the bike- it barely started and sounded very weak, It pops, crackles, backfires- you name it. Obviously, bad gas. StaBil / StarTron are great but they aren’t 3 year gasoline preservers. I drained the tank- replaced the bad gas with fresh gas. Pretty much the same symptoms. Dirty carbs more than likely. I removed BOTH carbs. Took out the sliders, removed the float bowl cover, removed and cleaned the pilot and main jets, screwed them back in. Backed out the A/F screw- cleaned under there as well. I screwed them back in all the way and then backed out 4 turns to get me running when the time comes. Removed the little round cover with the 3 screws, cleaned under there too.

From all the carb cleaner I used- I think I got everything but maybe not. I DID not replace the jets- just cleaned them, There definitely was tarnish in there- I’m pretty sure I got everything out. As far as the sliders- I cleaned inside, cleaned the plunger and made sure there was no resistance inside the chamber.

Anyway- I put everything back together- fixed the dent in the gas tank, repainted it and mounted it back on the bike. Started the bike- SAME thing- really weak. Front cylinder is fine. I think I got all the cables and linkages set correctly. I can visually see the choke slide the front carb arm and I can ‘hear’ the rear choke cable actuate inside that round opening.

There are no gas leaks and I can hear the fuel pump work. I also backed out the bleeder screws on each curb and yes- I got gas flow.

So then I figured I’d check compression, and make sure I got spark. Compression is 130PSI on both cylinders- not the 150 I want but for 89,700 miles without anything but gas & oil over the years- 130 should be plenty. Spark looks fine- tested with a light- it’s there. I changed the plugs too.

While the bike is running- if I remove the rear spark plug wire- there is hardly any change. If I remove the front spark plug wire- the bike immediately stalls. This tells me the rear cylinder is just along for the ride- not helping at all. I don’t know what to do now. My next move is to go back into that rear carb and hopefully- I missed something stupid like I usually do.

I’ve been scouring this forum and reading everything and anything to do with carbs. All great stuff and I’ve learned a ton. You guys man… unreal. Anyway- if there’s anything you think I missed or should try next- I’ll try / do whatever. I AM going to purchase a carb rebuild kit and actually replace the jets and o-rings, and gaskets… like I probably should have done when I had those things out. What a pain in the ass. Those friggin sync cables ??? PITA bigtime.

Any help would be appreciated. Ride safe everybody.

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WintrSol
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Re: dead rear cylinder... now what?

Post by WintrSol »

Start with the most basic: is the float chamber properly filled? You can check with a bit of clear tubing connected to the drain, and turned up along side the carb (no kinks), then open the drain. The fuel should rise to 17.0mm +/- 0.5mm from the reference mark (equal to the sealing surface of the carb body to the bowl). Are you getting spark? Hold a spark plug tight against the side of the engine and crank it over, and watch for spark - you may need an extra hand for this.

If that is good, the next location is the outlet ports at the throttle plate; there are a few, and they are fed by the pilot circuit, which includes the idle port. These ports are rather small, and feed the fuel mixture at idle, and as the throttle is opened. If you take the bowl off and remove the pilot jet, you can spray cleaner into the chamber above; some should spray out the air jet, the rest out the ports on either side of the throttle plate. If the latter doesn't happen, you will have to let the cleaner soak through, which works best with the engine side of the carb hanging down, and spraying the cleaner into the pilot circuit so that it fills the tubes. After some time, the cleaner may start to drip out the ports, indicating they are opening up.

BTW, when you checked compression, did you have the carbs off (or throttle held open wide)? Squirt a little light oil into the plug holes first?
Florissant, MO
CB450K3, GL1500CTValkyrie

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joeConnectALL
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Re: dead rear cylinder... now what?

Post by joeConnectALL »

When I checked compression- carbs were installed but throttle NOT wide open. I'll definitely do a more exact test on the float level. All I did was open the 'bleeder' screws until I saw gas dripping- I just wanted to make sure gas was getting there. Now- is there enough flow to keep the bowl filled ?- your test suggestion should clear that up.

Thanks so much for talking the time- I'll try and get to it tonight.

One thing that's bothering me- when I tested for spark, I definitely get spark but it's not 'Fat blue'- it's yellow / orange and it isn't all that bright. The spark quality looks the same on the front which is firing fine. ???? I used 3 methods to test, the screwdriver in the plug hole test,the ground the spark plug to the engine test, and the timing light test. Each method seemed to indicate the coils were at least sending the electrical signal to the plugs.

Anyway- I ordered a carb rebuild kit and a set of coils just in case. I'm the original owner of the bike so after 89,000+ miles- new coils can't hurt and replacing the jets makes sense at this point.


Thanks again- MUCH appreciated.

Forge
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Re: dead rear cylinder... now what?

Post by Forge »

Your jets are probably fine and don’t need replacing if you cleaned them. If something is plugged, it’s probably the passages. Soak them and make sure to blow them out with compressed air.
Arthritis sucks!

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WintrSol
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Re: dead rear cylinder... now what?

Post by WintrSol »

I agree with Forge - jets don't wear, and as long as you don't damage them, will last forever. If your carb is filling properly, odds are you still have some blocked passages.

An orange spark could just be from the battery Voltage sagging when you crank it; a booster battery should keep it up higher, and give a better idea of spark quality. You can (carefully) use jumper cables to a non-running car or truck.

FWIW, a compression test is normally run when the engine is warm, with the carbs wide open. A squirt of light oil will make it more like a warm test, if the engine is cold, but will still yield lower numbers; the rings expand with heat, providing a tighter seal.
Florissant, MO
CB450K3, GL1500CTValkyrie

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hillsy
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Re: dead rear cylinder... now what?

Post by hillsy »

Forge wrote:Your jets are probably fine and don’t need replacing if you cleaned them. If something is plugged, it’s probably the passages. Soak them and make sure to blow them out with compressed air.
Yep ^^^

If you dont blow out the passages with compressed air you havent cleaned the carbs.

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joeConnectALL
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Re: dead rear cylinder... now what?

Post by joeConnectALL »

I'm on my way to my garage now - I'll definitely run air through the ports. If this is all I missed and if this works- how do we get to together so I can buy a couple of rounds ? :)


I'll keep you posted.



Be well- have a good night.

Forge
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Re: dead rear cylinder... now what?

Post by Forge »

As Wintersol said, make sure you soak the passages well with carb cleaner before blowing them out with air.
Arthritis sucks!

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joeConnectALL
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Re: dead rear cylinder... now what?

Post by joeConnectALL »

Just to give you guys an update: I removed the rear carb, took it apart again: slider, float bowl, A/F screw, throttle valve, plot and main jets, float, float valve. Anything that could be removed- I removed it. Sprayed everything with carb cleaner and blew 120PSI of compressed air through anything and everything.

So I noticed a couple of things- there was definitely a couple dirt particles flying out of the little holes where the butterfly valve is… small but large enough to inhibit gas / air flow. Which is more than likely my problem. So whoever pointed out that "if you haven't blown air through the carb- you haven't cleaned the carb"... nailed it. I also noticed that the floats look ‘dented, kinda/sorta crushed’. Not completely but they look weird. I checked for pin holes- didn’t see anything ??? I also noticed there is a tear in the boot of the throttle valve. NOT the big boot on the slider but that little boot under that cover that’s about an inch in diameter I’m not putting it back together like that. I’m going to wait and get a new float, float valve, and new throttle valve components. I’m going to pretty much replace everything in there except the butterfly and the slider components. The slider moves nice and smooth and the spring and boot look good.

I’ll update this when everything comes in and I got it assembled and reinstalled. Thanks again for your guidance and interest.


Be well - Ride safe.

Forge
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Re: dead rear cylinder... now what?

Post by Forge »

Those transition ports that you blew out can make a major difference in driveability. I don’t know if you did already, but check your air filters. The oem are foam that has a tendency to break down over time and can plug up the air jets. The filters are often neglected and should be checked regularly.
Arthritis sucks!

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Re: dead rear cylinder... now what?

Post by WintrSol »

joeConnectALL wrote:I also noticed there is a tear in the boot of the throttle valve. NOT the big boot on the slider but that little boot under that cover that’s about an inch in diameter
That sounds like the Transient Enrichment Valve diaphragm, commonly called the coast valve. The diaphragm is #31 on this diagram: https://www.partsoutlaw.com/oemparts/a/ ... retor-rear

It operates on vacuum directly from the carb outlet, so if it is torn, you have a big vacuum leak, which would make the mixture that much leaner.
Florissant, MO
CB450K3, GL1500CTValkyrie

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joeConnectALL
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Re: dead rear cylinder... now what?

Post by joeConnectALL »

I ordered K&N drop in Air Elements... you have to slighty modify the air box covers... no big deal. As far as the coast valve boot... oh it's torn- big time. I'm quite confident between the extra debris I got out of the ports and replacing this coast valve boot.. there WILL be a happy ending.

Do you guys know anything about women ?? ;IDunno:



Take care everybody- I'll post when I got it running.

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Herb
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Re: dead rear cylinder... now what?

Post by Herb »

joeConnectALL wrote:I ordered K&N drop in Air Elements... you have to slighty modify the air box covers... no big deal. As far as the coast valve boot... oh it's torn- big time. I'm quite confident between the extra debris I got out of the ports and replacing this coast valve boot.. there WILL be a happy ending.

Do you guys know anything about women ?? ;IDunno:



Take care everybody- I'll post when I got it running.
Thank you for keeping us updated.

As for women, after 49 years of marriage, I still don't have a clue about them. I have learned how to, usually, stop an argument. Yes dear does it almost every time.

:Umm:
I can't seem to win the lottery. I think I have used up all of my good luck riding motorcycles.

Forge
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Re: dead rear cylinder... now what?

Post by Forge »

I know that women don’t seem to appreciate or think it’s funny when you fart under the blankets and wave them around their head. They’re just strange that way.
Arthritis sucks!

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Re: dead rear cylinder... now what?

Post by Spacecoast »

Toilet seat being up seems to be another issue they have.

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Herb
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Re: dead rear cylinder... now what?

Post by Herb »

Spacecoast wrote:Toilet seat being up seems to be another issue they have.
Yeah, I always have to put the damn thing up, but she won't put it down...
I can't seem to win the lottery. I think I have used up all of my good luck riding motorcycles.

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joeConnectALL
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Re: dead rear cylinder... now what?

Post by joeConnectALL »

Just an update:

I got all my parts in; I'm going to see if I can 'sneak away' for a few hours and get that rear carb back in the bike with all the new innards.

I'll report back.


Take care - Have a great weekend.

Forge
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Re: dead rear cylinder... now what?

Post by Forge »

joeConnectALL wrote:Just an update:

I got all my parts in; I'm going to see if I can 'sneak away' for a few hours and get that rear carb back in the bike with all the new innards.

I'll report back.


Take care - Have a great weekend.
Looking forward to hearing good news. Make sure to check the float heights while you are in them.
Arthritis sucks!

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joeConnectALL
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Re: dead rear cylinder... now what?

Post by joeConnectALL »

further update...

I'm a bit disappointed, ordered a new float assembly for the REAR carb... received a float assembly for the FRONT carb. I'm keeping the front float- I'll replace it ... whenever. I re-ordered the rear float- expedited delivery on their dime- won't be able to get to it until this weekend. I'm changing the float along with the float valve because the original float looks really bad. Almost looks like it's 'imploded' a bit and I noticed 3 pinhole leaks- one of them near a crease where the float looks bent. THIS, along with the torn boot on that smaller sized diaphragm, HAS to be the root of all evil here.

I'll know for sure when that thing purrs like it used to.


Take care everybody; Merry Christmas / Happy Holidays / Happy Hanukkah / Seasons Greetings / Ho-Ho-Ho / Lady of the Evening - Lady of the Evening - Lady of the Evening / etc, etc.

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Re: dead rear cylinder... now what?

Post by stillrolling »

I had a very similar situation. A couple of months after my wife died, I rode like I had a death wish and did lay her down. It was in storage for about three years. I experienced similar problems. I went through everything for about nine months. Nothing seemed to respond. I finally replaced the o ring around the float screen/seat. It was letting gas by even though the accelerator wasn't pulled and the float was closed. That gave me a rich situation and made it backfire. I have since done the same thing to about three Intruders. It seems those little o rings go after sitting for several years and seems to be a common problem on these intruders since most of them are starting to be 15 plus years old. Check it out.

Good Luck.....

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