85 Intruder No Start Condition

[SLANDRO]

Hi guys. Looking to this community for help on getting this bike running again. I have an '85 Intruder 750. To my knowledge, it is all stock. The bike has sat for about 15 years. It was running before it was stored with no issues. Due to it sitting for so long, the bottom rear carb was stuck from the fuel getting gunked up. I went ahead and removed both carbs, bought a rebuild kit, cleaned them and put it back together. The bike will only run with the choke on. And it runs poorly. As soon as the choke is let go, it shuts off. I have pulled the carbs off a bunch of times trying to adjust the floats to the specs that i have read online. Still the bike wont run. I also replaced all fuel lines and vacuum lines. Didn't replace the plugs, but i pulled them, and cleaned them with some gas, made sure the gap was correct at (.035). I also replaced the fuel pump and made sure that the pump is actually pumping. So i am wondering if there is something that i have overlooked but mainly the specific float height specs as i feel that this is where my problem might be. Any thoughts or other info needed? Thanks

[Herb]

When you have it idling are both cylinders getting hot at the same rate?

Check is to make sure the carb balance is as close as possible. If the throttle plate is opening a lot sooner on one cylinder than the other it can cause the engine to bog down.

Did you replace the air filters?

I would also see about a new set of spark plugs as an increase in compression pressure can cause a bad plug to misfire.

[hillsy]

You need to clean the carbs with carb cleaner and compressed air. All the fuel circuits need to be blown out. 15 years sitting will mean they are probably gummed up.

[Designer]

Since you say you already cleaned your carbs when you rebuilt them, I say do what Herb says first;

When you have it idling are both cylinders getting hot at the same rate?
Check is to make sure the carb balance is as close as possible. If the throttle plate is opening a lot sooner on one cylinder than the other it can cause the engine to bog down.

Did you replace the air filters?

I would also see about a new set of spark plugs as an increase in compression pressure can cause a bad plug to misfire.

It makes little sense to go through all that cleaning/rebuilding you already did all over again without doing the simple, sensible things he outlines first. That's what my friend who is a Professional Mechanic recommended for you. Makes sense?

[hillsy]

Bike only runs on choke. Your carbs are still dirty.

Or you could do a bunch of other stuff first.

Let us know how you go.

[Designer]

For one thing, the bike hasn't fully warmed up, add in a quite possible very off-set Carb Balance,... both together could be the problem.
Even though the carbs might be dirty, it still makes sense to work with what you have where you are now, before going through Yet Another carb rebuild,.. as my Professional Mechanic says.

[hillsy]

Any thoughts or other info needed? Thanks

OK - how did you clean your carbs? Did you remove all the jets and the idle mixture screws? Did you use carb cleaner and compressed air (100psi) to blow out all the passages?

If not....they are not clean.

[SLANDRO]

Thanks for all the responses. So I'll go down the list.
1. Can't check the heating up of cylinders because I can't get the bike to idle. When I choke it, it'll run and it runs like sh*t (what I suspect to be a rich condition) and once I let go of choke it shuts off. I know that the carb sync is next but I need it to idle. I actually found the DIY mano meter method here in this forum, but i need to get the bike idling first.

2. Did not replace air filter. Just pulled them, Blew air through them and cleaned the air boxes as best I could. I will replace but I wanted to get the bike to atleast run.

3.The cleaning was done with carb cleaner and compressed air. I took it apart as much as I saw I could. Pulled all of the jets and little parts. Left them sitting in a bottle submerged in carb cleaner, bought myself a carb cleaning brush kit on amazon to properly clean all orifices on carb body. Rinsed with carb cleaner and blew out with air. Im pretty confident in the cleaning I did, but I could be wrong.

Is there any way to check the balance on the carbs without the engine running. I wouldn't be surprised if the sync is out of whack with all of the
movement. I removed them both again so that i can have access to them as we tackle the mystery.
I will go ahead and replace the plugs and get the filters and see if that helps.

[Herb]

You can get the balance close by putting your left hand on the throttle lever for the front carb and watching the lever on the rear carb while turning the throttle off the stop. You should feel the lever on the front carb start to move at the same time you see the back one start to move.

While you are at it check the throttle cable splitter, make sure both carb cables are properly seated and it is mounted solid. The first time I cleaned the filters on my 87 I forgot the remount the splitter box and the bike ran like crap. Also make sure the cables are properly seated in the adjusters. it is really easy for them to get cocked a little and not be completely seated.

I doubt your problem is a rich mixture if it runs with the choke on but not with it off. The "choke" on these is actually an enricher circuit and adds fuel to the carb.

Check that the slide diaphragms are in properly and the vacuum holes are clear. Make sure the needles on the slides are properly seated in the main jet. while you are checking the diaphragms hold them up to the light and look at them closely checking for pinholes. If there are a few you can patch them with a VERY thin coat of red RTV.

When you cleaned the carbs did you replace all of the O-rings?

How many turns out are the idle jet needles?

[SLANDRO]

Ok. So since I took the carbs off, I will double check the things you mentioned on the carb first. Once I reinstall them I will make sure all the other things mentioned are in order.

I know that when I took it apart I checked the diapragm as you described because I did read that they are sensitive and expensive to replace. I will check them again. The slide moves freely and when I move it with my finger, you can hear the air being pulled as it moves back down. So I think they are ok. That was the main reason i rebuilt them, the bottom carb vacuum slide was stuck from the fuel gum.

Orings. I know for sure I replaced the orings on the little screen thing (forgot the name) and the orings around the choke fittings. However there are 2 tiny orings (1 for each carb) I couldn't figure out where they went. I still have them.
And, are the idle jet needles inside the carb or outside. Im more familiar with edelbrocks, first time messing with motorcycle carbs. I searched around for an idle mixture screw setting but couldn't find one.

[hillsy]

And, are the idle jet needles inside the carb or outside.

They are outside the carb (IE: not in the float bowl) and are set around 2.5 turns out as a starting point. If your carbs haven't been messed with before they might have a plug over the needle. There is a spring, a washer and an o ring under the needle - they are tiny. You need to fish out the o ring and washer (they will most likely be stuck in there).

[SLANDRO]

Yeah. Im pretty sure this carb was never taken apart. These are the orings that I am referring to. I will have some free time tomorrow and will look for this idle screw.

[SLANDRO]

This is the bottom rear carb.
Is one of these brass plugs covering the idle screw.

[hillsy]

Pic care of Lechy.....

[Herb]

See the little aluminium plug with a dot in the middle right above the throttle lever and under the bracket that holds the throttle cable? That is what needs to be removed to get to the idle jet needle.


The plug you have labelled as 10, turn the carb and look at the throttle lever assembly. there will be the same kind of plug between the throttle lever and the cable bracket.
This is the bottom rear carb.
Is one of these brass plugs covering the idle screw.

These are what need to be removed. On my first 1400, I drilled them with a small bit and then used a drywall screw to screw in and pull them. On the current 1400, I just used a dry wall screw and screwed it in with the power screwdriver to pull them out.

No matter which method you use be very careful because the metal is soft and you will go through it quickly. If you go too deep you will damage the needle jet head because it is soft brass. I learned this the hard way.

Since you ran carb cleaner through the passageways with the needles in it is a pretty good bet that the cleaner destroyed the 2 small o-rings. You will have to make sure that you have all of the pieces out before re-assembly.

Word of caution. There is a spring and small washer in there that are VERY easy to lose and hard to get.

When you put the needles back in run them down just until they seat lightly. Then back them out 2 1/4 turns. You can fine-tune them when it is running.

One other point of caution. If you use carb cleaner this time make sure you don't get it on any of the rubber parts. Carb cleaner will destroy them.

[Lechy]

Try the idle adjust (black knurled knob rear carb) 1/4 turn increments to get the machine started and idling then IF it idles without choke do a carb synch and AF adjustment look here for how: http://intruders-alert.com/viewtopic.php?f=32&t=4139. Might get you started, might not, but it's something that hasn't been addressed up to now.

[hillsy]

This is what the idle mixture screw should look like with the spring, washer and o ring....



The screw should come out easy enough but the spring, washer and o ring need to be fished / picked out. The o ring will probably be stuck to the washer.

[Designer]

These are what need to be removed. On my first 1400, I drilled them with a small bit and then used a drywall screw to screw in and pull them. On the current 1400, I just used a dry wall screw and screwed it in with the power screwdriver to pull them out.
No matter which method you use be very careful because the metal is soft and you will go through it quickly. If you go too deep you will damage the needle jet head because it is soft brass. I learned this the hard way.
Since you ran carb cleaner through the passageways with the needles in it is a pretty good bet that the cleaner destroyed the 2 small o-rings. You will have to make sure that you have all of the pieces out before re-assembly.
Word of caution. There is a spring and small washer in there that are VERY easy to lose and hard to get.
When you put the needles back in run them down just until they seat lightly. Then back them out 2 1/4 turns. You can fine-tune them when it is running.
One other point of caution. If you use carb cleaner this time make sure you don't get it on any of the rubber parts. Carb cleaner will destroy them.

SLANDRO. Thank you for clarifying that you meant Idling when you typed "Running" in your Symptoms description:

The bike will only run with the choke on. And it runs poorly. As soon as the choke is let go, it shuts off.

To most of us,. that means running beyond just Idle, hence the diagnosis of checking the Cylinder Heat, Carb Balance, Air Filters, Spark Plugs and such.

And thanks also for telling us you did indeed use Carb Cleaner and Air Pressure to clean all the Internal Passages. That made all those suggestions to do it again moot and a mistake.

If I may add my Experiences to what Herb said quoted above, Yes, the Carb Cleaner can ruin those "O" rings ,..am interested to see what you find.

And his word of caution about the spring and small washer in there that are VERY easy to lose and hard to get. I have found it was wise to disassemble carbs in a Cardboard box with High sides. So if something small falls or drops out, it is retained inside and not lost on the Floor.

[hillsy]

And thanks also for telling us you did indeed use Carb Cleaner and Air Pressure to clean all the Internal Passages. That made all those suggestions to do it again moot and a mistake.

He hasn't even taken the idle mixture screws out. He hasn't cleaned the carbs properly.

How about you stop leading him astray?

[Lechy]

Did you clean the pilot air jets?