82 Maxim and Coil Interchangeability

Hi guys,
I just picked up an 82 maxim that wasnt supposed to run. Well I got it home and got it running just fine except after it warmed up it would immediately start fouling the plugs.

So I took the carbs off today and took the bowls off. I cleaned everything in there and honestly it wasnt real dirty. So I put it back together and now only the 2 inside cylinders fire. The outside cylinders get spark, but it seems to be kind of erratic in its intensity. I pulled the plugs off of the outside 2 while the motor was running and it didnt change anything so they arent firing.

First, does one coil control the outside plugs and one control the inner? Second, are the coils from the same year seca interchangeable?


I appreciate the help.
Chuck

 

The coil for plugs 1 and 4 are the same as are the ones for 2 and 3, so yes the same coil controls the outside ones. As for the coils being interchangeable I would think so if they are the same engine size. I have traded a couple of parts off of a SECA 550 and put them on my 550 Maxim just fine, so I don't think that would be an issue. Others with more knowledge than me will be along later to either tell me I am right and fill in the blanks where I most likely missed something or to correct my newness to the world of motorcycles and XJ's

 

Well I appreciate your reply, I just really want to get this thing running so I can start riding to work and let my poor car sit.

 

Your original post seems to indicate all four were firing before you got into the carbs. If so, I think you need to look at the carbs again.

Before you do, switch the inner plugs to the outer cylinders and vice versa. Did your problem move to the inside?

Do the outer two fire at higher RPM? If so look at you mixture settings and synchronization.

Are the float heights set correctly? Fuel getting into all the bowls?

Of course you may have caught a wire or loosened a connector removing/installing the tank.

 

They were firing before since all were fouled evenly. I dont understand how the float height would be any different I just took the pin out, the float off, and pulled the needle valve out and cleaned them. I have done this many times before on my mopeds and they have all ran fine. How would I adjust the float height there arent any shims or anything. But I might have knocked a wire loose or something.

Are the coils under the tank? If so maybe I knocked a connection loose when i put it back on.

Ill check to see if the bowls are getting fuel today by opening the drain screw on the bottom, but I dont see why they wouldnt. I checked all the floats before I put it back together to make sure they moved freely and they all seemed to be just fine.

 

I'd try moving the inner plugs to outer and outer to inner first. Real easy to foul plugs so it won't fire. I pulled a perfectly running bike into the garage once for some unrecalled reason. Went to re-start and only 1 plug firing. Cleaned them up and everything was fine.

Coils are under the tank. The connectors should have locks on them to keep them from coming apart. However, in the past 25+ years it's possible someone has damaged the lock tab.

 

I am having the exact same problem with my 1982 maxim 650. Outside cylinders not firing, inside cylinders firing great. I suspected a bad coil so I swithched the coils and now the other coil is not firing. Coils are fine. I am now thinking maybe a short in a wire somewhere? Or maybe (and I don't know anything about this) whatever tells the coils when to fire (pick up coils?) is not making a connection somewhere. SOMEBODY PLEASE HELP! DRIVING MY F150 EVERYWHERE IS BREAKING THE BANK!

 

ahah no kidding im driving my 350z everywhere and its killing my bank, not to mention putting wear and tear on the car.

 

Pickup coils are located behind the left side point cover. Check the connections to and from them. They send their signal to the TCI and it controls the timing of the coils based on them. Check the resistance of the pickup coils with a multimeter, 700ohms +or- 20% at 68 degF.

 

Alright I am getting pretty frustrated with this thing


All coils fire, but the thing runs so pig rich the plugs foul in a matter of seconds. I dont understand how so much fuel is dumping into this thing.

When it does run its more of an on or off.

At 3k rpm and below it is really slow to go, but after hitting 3k rpm its like nitrous kicks in it just takes off.

 

Which Maxim?

1) Make sure the enrichment valves go completely closed when the "choke" lever is pushed all the way to off.

2) Check to make sure air filter and rest of air intake isn't plugged. No mice or wasps nests in there?

3) Check float level (again, which Maxim?).

4) Check pilot mixture screws not too rich (about 2.5 to 3 turns on Hitachi carbs).

5) Carb slides sticking? (RickCoMatic "clunk" test).

6) Float valves leaking?

7) PO put oversized jets in?

8 ) Are you sure it's fuel fouling and not oil? (Reading Spark Plugs)

 

1) Valve does seem to shut all the way off when shut

2) Air filter area is spotless nothing in there

3) Is a maxim 750, honestly dont know how to do this as I didnt adjust anything when I took them off, afik they should be the same.

4) Where are pilot mixture screws ill bet thats my problem

5) Do you mean go full throttle, let off and listen for the clunk of the closing butterfly's?

6) These could be leaking but they all seemed fine when i removed them not cracked or anything.

7) Pretty sure po didnt do that as he bought it from original owner and just rode it, it ran fine for him until one day it just started doing this.

8 )I know its fouling its heavy black soot on the plugs no oil whatsoever.

Thanks for the help though Ill see if I can find those pilot screws in the service manual.

 

pilots should be on the front at the top in front of the top covers. They may still have a brass plug in them, which means you will have to drill that out and adjust them to 3 turns out.

A lot of "pretty sure" and "could be" statements should be verified. Read the jets to check their sizes. Just make sure all the easy things are checked first.

The clunk test is something RickCoMatic had written up a while back. When you remove the top cap and the springs on the insides of the slides, you lift the slides up and let them go. They should just drop with NO resistance back into the carbs. They will land with a big clunk. If there is any resistance whatsoever, grab some 1500 grit sandpaper, and lightly sand the inside of the slide passage while using WD-40 on the paper to lube and catch most of the sanding dirt. Then clean it all up with carb cleaner and repeat the drop-test. When they all drop freely, you are good to go.

 

Hitachi carbs. Fuel level 2-4 mm below the bottom lip of the carb body, where the float bowl attaches. Mixture screws 2.75 turns out to start

They are on the top front of the carb just before the intake manifolds. Centered over the bore, next to the enrichment valve. May still have the brass plug on them. If you have the plugs drill a small hole in them and catch them with a screw to pull out. Be careful not to drill too deep as many a mixture screw has been ruined. If the plugs are still there this is probably not your problem. If the plugs are out, gently bottom the screws and back out just a hair shy of 3 full turns.

 

alright so I turned the screws all around 2.5 to start then to 3 then to 4 and really dont notice a difference in anything.

What do these do exactly?

Also when I got to them they were fully closed.

 

They adjust the fuel mixture.

Out = richer. In = leaner.

Someone already tried to fix your problem by screwing them in.

They are having no effect because you already have way too much fuel getting into the mixture.

If you're 100% absoultely sure that the enrichment valves are closed it's time to check the fuel level in the bowls.

 

They provide an air and fuel mixture to the cylinders when you are at idle and just off idle before the carbs have enough vacuum present to pull fuel and air through the main jets. If they were fully closed, then it shouldn't idle at all. There is something else wrong. If it runs pig rich with the pilot screws closed, that tells me there might be an issue with the float levels being too high. Keep the screws at about 2.75 turns and move on to the next thing.

 

whoa....MiCarl...we posted almost simultaneously about the same thing...

 

Were the plugs still in the carbs? Or were they exposed? If plugs were in then I would say you drilled a little too far down and hit the tops of these screws. This is easy to do. If not then some one had tried to repair the problem and failed. Floeat levels are next to check. Put a clear rubber tube over where the fuel comes out when the drain fuel drains are open. The small tube from when you fill a battery works well if heated a little and pushed on to the nipple. Any way with the tube installed, open the fuel drain screw. fuel should run in to the tube. Hold the tube next to the outer part of the carb. Fuel level should be 2 to 4 mm below where the bowl mounts to the carb body. Repeat this on all four carbs. I am betting that your fuel level is high. If not then it is time to remove and tear into the carbs.

 

Ok,
Ill give this a shot today. So say my fuel level is too high, which Ill bet it is. I take the carbs off, pull the bowls off, take the floats off and bend the mounting tab on the float just a hair right? When I get done modifying the levels can I test the height with them off the bike? I have heard that they need to be tested at the same angle the bike sits, but that should be damn near horizontal when its riding from what I can tell.

I really appreciate your guys' help on this so far this is an awesome community.

 

Oh yeah my buddy was tempting me pretty hardcore last night when he rolled up on his 03 R6 he bought yesterday, alls I could show him about mine was that it could spit and sputter lol.

 

I usually set the tang on the float, then put them in the engine side carb boots to hold them at the correct angle, then put the thank on and check the levels. If it isn't right, I drain them and just pop them out of the holders to reset the levels. They do lean a bit towards the front. The manual I have says to check the levels with the engine warmed up and running, but I see no difference doing it cold and not running. The level reads the same either way on my bike.

 

You can set up a bench style tester. I get the angle with the carbs on the bike with a digital angle finder with the bike on the centerstand. A regular one works just as well. Make a jig to hold the carbs at the same angle. A bench vise works just as well. I then take an old 90w bottle with the cone shaped applicator on it. And bend a coat hanger so as to holt it up side down above the carburetors. I generally hang this from the shelf above the vise. Put some gas in the 90w container and hook the end to the fuel line coming from the carb. You may need to put a longer hose on there so you can make this happen without driving you nuts. Hang the bottle upside down and test the float levels. If the float levels are off then drain the cars in a suitable container remove the bowles and adjust. Keep going until the levels are right on. Simple yet time consuming. Took me about 2 hours to get my carbs set. Reinstall the carbs, Replace the fouled plugs and go for a test ride. Ist it wonderful to say you did it yourself.
As long as the bowles removed to adjust the levels, make sure the emulsion tubes are all the way seated. and the washer is under the main jet. If there is no washer(seal) then the bike is getting too much fuel also. The washer acts like a seal around the main jet and the emulsion tube. There is lots to look out for while doing the carbs but the end result is a finely runing bike that will fly down the road without wings.
Keep the posts coming and we will answere the questions as they come. Have fun.

 

Thanks for the advice guys.

I am about to win an auction for a used ignition box and set of coils. I am going to replace these first before I start messing with the floats since thats a major thing to get into imo.

It is getting spark but I am wondering if its more or less sparking randomly and not when it needs to or as powerful as it needs to be.

Once I get them installed ill see if that fixes the problem, if not onto the floats it is.

Once again thanks for the help.

 

Hang on to your old coils, they might still be good. I'm still thinking of a quick test rig for them so stay tuned.

 

I think those are the same carbs as on the 650 Maxim.

With the carbs inverted set the floats so the bottom is 9/16" above the surface the bowl screws to. This put mine right at 3mm.

 

Thanks for the tip that will make it a bit easier if I have to do.

Well i bought the coils but got outbid for the ignitor so I am kinda mad about that oh well Ill see if the coils help my problem.


Also can someone tell me if these bikes are 6v or 12v, I am pretty sure its twelve but just making sure.

Thanks,
Chuck

 

They are 12 VDC primary. Have at!
A small thought:
I used cheap rubbing alcohol to check my float levels today. Inexpensive, helps clean the carbs, and your not worried about getting any on you. Just be sure to drain the bowls when your done! Something about the word carcinogenic that just gives me the willies...

 

The only thing about using alcohol (or anything other than gas) is that it does not have the same density or specific gravity so the float adjustment won't be exactly the same would it? Maybe it is so small as to to be basically insignificat.... after all the spec is 2 - 4 mm

 

Good point. I set everything up to 3mm so if there is some varience, I'll hopefully be in the ball park. I'll check once I've got the machine running again.

 

Specific gravity of water is 1.

Gasoline .74

Alcohol (propyl) .80

So, Mr. Science Guy sez:

Fuel level of gasoline will be a bit (EDIT) HIGHER than alcohol.

Fuel level of gasoline will be significantly higher than with water.

 

Thanks for the tip! Hope I am still close enough when the fuel flows in. I'd hate to have to pull and redo the carbs, what a pain.

 

Alright coils should be on the way and made a deal with someone locally to get their used ignitor and a new set of mirrors from them for 40 total, not a bad deal I think, so hopefully ill be one step closer to solving my problem soon.

 

Ok quick question. I was researching about replacing my petcock because it leaks a few drops when the bike is running.

When I leave it in the 'on" position and pull off the hose it will pour out. Could this be causing my rich condtion?

What I mean is gas forcing its way into the carbs overcoming the floats?

Its just a thought, and from my understanding you cant rebuild these things so ill have to order one or source one from someone.

 

What does it do on "RES"? Any difference in the flow?

 

Actually no, it was running just fine on reserve it seemed the other day.

 

What I wanted to know is does fuel pour out on RES too?

There is a rubber disc behind the fuel cock that seals it to the valve body. They wear out. $8.00 part at the stealership.

In the case of mine, petcock was fine on RES, leaked at ON. The rebuild problems we hear about seem to be related to the vacuum valve.

Might be worth a look at that disc. Pull the two phillips screws that hold the fuel cock retainer in place. The fuel cock will pull out. Disc is behind it. Make sure tank is empty or tipped as fuel will run out.

 

Ill have to check if it does or not, but the motor ran like normal on reserve so i am assuming the bike is getting fuel even while on reserve from the tank.

 

Take a peek and see if your oil level is overfull. A lot overfull. If it is that might be the problem. Check the air filter and housing as well. You may have fuel in there too. Have you noticed fuel disappearing from the fuel tank??

 

the oil is fine I think, the fuel isnt disapearing at all.

I turned the petcock to res today and no fuel comes out, also I am pretty darn sure its ignition related at this point since I was having spark troubles.

I think its the ignitor unit now because the one I have on there is used I found out and when I pulled the cover off I noticed that some of the solders on the front right corner were corroded possibly connecting themselves. I cleaned them off and it really didnt seem to have an effect.

The bike then got the plugs wet and then only the right bank was firing something is messed up.

 

Fuel should flow freely when the petcock is turned to res and pri. The only tome it should not flow is when it is on "on" position. Unless the engine is running or the petcock diaphram has vacuum to it. Sounds like there is a petcock issue as well.

 

Nope, the fuel only flows freely when in the Prime position.

When you are in the on or the res positions no fuel should leak out if you disconnect the fuel line.

If it does in either setting then you need a new petcock or to rebuild the one you have.

For some reason these carbs tend to flood if the petcock leaks-by. I thought the floats and their valves should be able to hold back the head pressure of the fuel but they dont!

You should find wet plugs and possibly a wet air cleaner, sometimes (more often than not) you'll find the oil level increases over night.

I replaced my petcock with a manual one.
Only bad thing is if you forget to turn it on you will run out of gas!

 

If fuel flows (engine off) on "ON" and not on "RES" the problem is the disc behind the fuel cock.

Go to your Yamaha dealer and get the $8 disc. Easy fix.

BTW. I have new needles and seats in my carbs. Accidentally left the fuel valve on "PRI". No measurable fuel got by them.

 

yeah, I left my manual c**k in the on position and didn't have any leak-by through my floats. So, if your floats are not holding, perhaps they need to be refreshed as well.

Regardless if a vacuum operated petcock leaks in the ON or RES positions, it either needs to be rebuilt or replaced.

 

Hey guys thanks for the reply's still waiting on my damn coils they shoulda been here by now err!!

Quick question how do I check the oil level on this bike and where is the drain and fill plugs, does the tranny and engine share their oil?
Thanks In Advance,
Chuck

 

There is a site glass on the right lower side of the engine case. Down by the brake pedal. The oil should read about 3/4 up the site glass. You will need to put the bike on the center stand for this reading.
The engine and trans do share the same oil.
oil drain is up front between the exhaust tubes on the front lower part. Just below the oil filter housing and a little back. Fill plug is on the clutch housing cover. On top.

 

Update..

Bought new float valve assemblies minus the new floats since they are fine. This threw the floats all out of wack so I had to adjust them.

I got them to a point I think they are ok. Put the carb back on the bike and its still doing the same stuff fouling plugs in a matter of seconds.

I have also replaced the coils as well to no avail.

Next stop is the CDI and after that I am completely lost.

 

Replaced the plugs yet?