550 Maxim Carbs

Got one of the local members bikes over at my place. The carbs were the typical PO stripped screws and lots of screwed up adjustments. The original complaint was the bike would have hanging high idle at times. Well after taking the carbs apart I could see why. So after a good clean and adjust float levels and a handfull of parts from xj4ever. I got the carbs back on and it won't start. I bench synced the carbs and I wet set the floats.
The battery went dead and I have the charger on it but I did have spark and the float bowls are full. 2.5 turns out on the mix screws. I should try to run the idle screw up just a tad and see if I can get alittle more throttle opening. It ran before and I'm not sure why it won't fire up. I did check the plugs and they are not wet or anything
I do plan on checking the valves and a compression test but untill then I think it should at least fire up. Thoughts?

MN

 

Petcock on PRI to fill the fuel bowls first. Verify there is spark then try turning the idle screw.

 

You're using full "choke" until it fires?

Was cleaning/inspecting the enrichment plungers/wells/tubes part of the carb service?

 

The carbs were completely pulled down to nothing. Every part was cleaned, all passages blown probed and sprayed through. Reassembled with new throttle shaft seals, blade screws, o- rings & washers on mix screws. New needles & seats, gaskets. Replaced all damaged screws/ fasteners.
I filled the carbs on prime and verified there was gas in them. I hit the start button and no fire. Checked spark and I had spark on all four cylinders. Plugs were dry and could smell slight gas on them. The battery died and I put it on the charger. I am going to pull the battery and see if the water level is low. More than likely the battery is on the edge of being junk.
I did set the choke lever all the way over and tried it but the power was down.
The next thing I will try is I'm going to adjust the idle screw up and give it a shot. Maybe it will go . Report more later

MN

 

You need two things or it won't start:

FRESH plugs. Brand new, properly gapped NGK D8EA. Gap on the 550 is .024"~.028" so I set them at .025.

And a freshly charged battery. Also put the bike on the centerstand if possible.

For both of my 550s the starting routine is the same: Petcock on PRI for 30sec or so to fill the bowls, then back to ON; full "choke" and without touching the throttle, hit the button. Once it fires, you can give it a quick 'blip' to clear it out, and then when it settles down, use the enrichment (choke) lever to hold it to about 2K as it warms up. That's how it should work. The main point is NO throttle until running.

Trust me on NEW plugs and a fresh battery. It should light right up. If the idle screw is down too far, you can try giving it a TINY bit of throttle; if you crank it WOT it won't light.

 

OK the idle adjustment was all the way out so we were not getting any air from the carbs.
However once it started I tried to adjust the idle and was having a hard time getting it to idle. I reset the mix screws to 2-3/4 out and got it to idle somewhat. Did the propane test around the carb to head manifolds and there is a serious vacuum leak between 3 & 4.
I guess we stop right here and see how much more the owner wants to spend on this unit.
I'm sure the carbs are close but I can't do anything else. I'm going to suggest new manifolds and gaskets. But I'm afraid we could snap a intake bolt.
Also the petcock needs to be rebuilt since it won't let fuel in. It only works on prime.
Looking the bike over I see the fork seals are starting to leak and I'm sure he has not even looked at the back brake. He did join this forum and I hope he can scrape enough money togeather to get this one on the road again.

MN

 

The intake bolts are LESS likely to snap on a 550. The bolts on a 550 are "blind" (the holes don't go all the way through) and they can't rust from behind.

I'm not saying you won't snap one; just that it's less likely.

Make sure your vacuum leak isn't simply the vac port caps or petcock vacuum line. And be sure the brass "spigots" aren't loose in the manifolds.

 

Maybe it only works on prime(extra fuel) to compensate for the extra air you have coming in between number 3 and 4 carbs. Make sure you have the caps on the manifolds as bigfitz said, sometimes they fall off when taking the carbs in and out.

 

After checking and using a mirror to find this bloody leak , I finally found exactly where it is leaking.
It is for sure the #3 carb manifold to head gasket is leaking. As the engine warms up the leak slowly leaks less. The manifolds are cracked and hard as a frozen Snickers bar. I informed the owner and he is going to stop by and check it out. He is looking at it from the standpoint he is inside out and upside down and feels he will never recoupe his money on this bike. I don't think he has the commitment to see it through. It's too bad because it's not in that bad of shape and would be an easy restore. I guess I can't get everyone to love these bikes as much as I do.

MN

 

He's more than halfway into the woods already so he's already coming out the other side-too late to quit now.

You can soak those intakes in a fast drying paint thinner (60%) and Wintergreen oil (40%) to restore flexibility-the solvent will dissolve and carry the 'W' oil into the rubber where it will intercalate the polymer. If they are cracked you can coat them with por-15 or some other solid based flexible paint. I've also seen inter-tubes with liquid rubber used to reseal them.

I might have a set of 550 boots in the garage that are decent. I will look tomorrow and let you know what I find.

BTW I know you know this but none of us will ever recoup the money we spend on our bikes. The only way to do that is find a collectible bike that some sucker is selling for a song and then spend 3 months restoring it and make a few grand. Wiz probably makes a little on his projects but he puts PLENTY of time into each one.

I'm betting he's just really frustrated and the first time he gets to ride the bike when it's 'right' he will forget about the money.