85 Maxim X Finally Back Together!

Hey guys, it's been about 4 months that I've had this bike and with little to no experience in working with anything like this. I finally got the carbs put back on after being cleaned, tank put back together after re-lining and rebuilding petcock, and getting my battery all prepped and charged. I put everything back together tonight and went to fire it up but no dice. I'm lucky enough that all my electrics work, can hear my relays clicking away, but still not wanting to fire up. It cranks fine, all new spark plugs, but I can't really seem to pinpoint where my issue is. I know I need to replace the vacuum line from the intake boot on cylinder #2 (and I have no idea how to remove it) but I am not totally sure if that would really be my problem? The carbs are getting fuel and I'm fairly certain I'm getting spark (I'll update on that later today), but one thing I noticed when replacing my spark plugs is that cylinder #2's spark plug had some sort of sandy gunk on the tip? When I put in the new spark plug it almost sounded like sand inside the threads. Looking in the cylinder it looks alright but this gunk was oil-colored and was like dry oil mixed with dirt. Any thoughts?

Thanks,

Medici

 

Sounds funky but you know a picture is worth a thousand words.
Can you upload a pic of the sandy gunk on the plug?

 

Could be PMP

Did you cover/seal your intakes when the carbs were off?
How long were they off?

 

The carbs were off for approximately 2-3 months. The intakes were loosely stuffed with rags but were left open for about 2 weeks. I have also confirmed that I do have spark and I will be getting a picture of the aforementioned spark plug later tonight or tomorrow morning. Could you clarify what exactly PMP is?

 

Take a can of starting fluid and spray two or three shots in each carburator body with the throttle wide open. Than try starting it with the throttle at least half way open. See if she roars to life for a few seconds. If it comes then you will know it must be a fuel issue or air leak and you can start tracking it down. If it doesn't start I would start looking at the spark or timing issue. Have you confirmed your valves don't need adjustment? If not, that's agood place to start. But try the starting fluid even bfore trying that. It's an easy no sweat diagnostic. Good luck.

 

Pulverized Mouse Parts.
Those buggers like engines . . . .

Were the carbs, bench synched and wet set?
What spark plugs did you use?

 

The bike has less than 12k miles on it and the previous owner said he maintained it to certain point, but I understand that should be taken with a grain of salt. I'm fairly certain my valves are alright but I'll most likely end up checking them anyway.

They were bench synched but not wet set. I did manage to get incredibly accurate float height measurements and set them all accordingly but another question I have is how far should my mixture screws be backed out? I'm currently at 2 and 1/2 turns exactly. We don't really have mice as an issue where I'm at so I'm sure that's not the case. To be honest I was in a bit of a hurry to get the carbs back on because it's taking me quite some time to get a lot of these tasks done (seeing as how I don't really know what I'm doing) so I'm taking it slow. I'll try the starter fluid method but I would really like to confirm integrity of the engine above all else. I have compression but other than that it's a mystery to me because most of the check I need to do I am not even aware of. Also I am using NGK D8EA spark plugs, exact replacements for what were originally on the bike. Just to confirm and cross-reference what should my gap be set to?

 

Hmmm, don't know the Maxim X specs. I know an 81 Maxim takes a different plug.
0.7 - 0.8 mm for a gap (again on an XJ Maxim).

Perhaps I'll just stand down, as I have been wrong to compare my knowledge of a particular Yamaha with different models.

Good luck and glad you don't have mice (although our dogs, cats and local avian/small mammals find them quite entertaining here!).

 

Gap won't be the issue. at less than 12k, clearances won't be the issue.

If you have spark, then that seems narrow it all back down to the carbs/fuel delivery

 

^^THAT^^

 

Well I finally got back around to tinkering and at full choke she fired right up! sounded pretty good but the previous owner had spilled some nasty oil on the side of the engine so it was smoking the hell out of my garage. Didn't want to idle but I suppose I should just richen my mixture and play with my idle adjustment and I'm off to the races!

 

Well done, always feels good bringing old stuff back to life.

 

Was applying full choke all that was needed for her to fire up? Or was there some other adjustment or change you had to make before it fired up for you?

 

We all would like to know.

 

Yes, sorry for the late reply. At full choke it started right up. I imagine the next logical step would be to synchronize the carburetors? If that is the case then I have a few questions about the process seeing as how from everything I've seen only applies to bikes with non-vacuum petcocks. This may be an issue seeing as how I have a vacuum petcock.

EDIT: It should be noted that upon startup all carburetors were bench synced (honestly needed almost no adjustment whatsoever) and sync/mixture screws were all backed out to the specified 2 1/2 turns.

 

are you able to gradually shut the choke off as the engine warms, or will it stall?

 

It'll die if you shut off the choke but I never had it running long enough to really get it warm because some concern over the quality/age of the oil. I'm gonna be getting my oil filter in the mail soon and do an oil change and we'll see then once it's warm. To be honest though I don't think it will change anything. The idle screw wasn't set whatsoever when starting this first time.

 

Glad to hear. Bench sync may not be enough. This will only make the carburetors equeal but not the engine. Not all four cylinders may be peforming equally. The compression can be different between different cylinders due to wear of the rings walls or valve adjustement/seating, etc. Vacuum balancing will balance the engine power to conpensate for these variables in cylinder perofrmance. You may able to use the bikes own tank as a fuel source while sync'ing. You can see I was able to do so in this video in the link below. Different bike, but gives you an idea.

http://www.xjbikes.com/forums/threads/xj550-seca-carburetor-balancing.58149/

It has a vacuum petcock as well. But if you set the petcock on prime, it effectively becomes a gravity feed fuel source. I used some blocks of wood to raise the tank and was able to get at the adjuster screws. You may not be able to get away with doing so without taking the tank off. In wich case you can try setting the tank above the carbs on a small table or what ever. And have some extra fuel hose to extend the reach to the carbs. Or, use some kind of other auxiliary tank. By the way, you should be able to get the filter from Advanced Auto Parts. They may have to get it for you from their warehouse. But I think the sell them for around $12 or so.

 

^^^ yep, running vacuum synch
block of wood under tank, switch to prime.

 

Where does the vacuum line outlet on the petcock attach in relation to the manometer/carb sync tool setup? An explanation of the system would be appreciated because I cannot seem to work it out in my head.

 

Stumplifter recommended "switch to prime" because you can remove the vacuum line going to the petcock and attach your manometer.

 

You have a Maxim X - what I know about pertains to an 81 Maxim - I do not know for sure if they are apples to apples but . . . .
Traditionally the vacuum line for the petcock runs to the vacuum port on carb #3. As you already know it needs to be removed so that a manometer can be attached. As XJOE550 said the Petcock set to PRI will allow it to function without a vacuum source, so just pull the vacuum line off of which ever carb it is attached to and let it dangle.

I use a ho-made two bottle manometer so when synching 1 to 2 one of my vacuum port caps has to go on to #3 since it was exposed after removing my petcock vacuum line. Point being - all vacuum ports should be covered during the synchronizing process, whether they are all attached to 4 hoses like on a Morgan Carbtune or 2 connected to a two-bottle with the other two ports then getting capped.

Good luck and keep asking questions until it makes sense to you.

 

Stumplifter the vacuum line is on the engine-to-carburetor boot (the one that connects to the petcock normally). When you are referring to the vacuum port caps are you meaning those on the boots I just mentioned? or is there something on the carb body itself that gets connected to a vacuum line? If not what's the best way to get those little vacuum caps off the boots? I tried to do it when the boots were off but out of fear of tearing them I decided not to.

 

The caps just need to be pulled off. If you need to use pliers, then use pliers. If they tear, no big deal; new ones are available at any auto parts store for a few dollars.
The only vacuum ports are the ones that you see on the intake boots. None should be left uncapped, or unhooked, while the engine is running.
The only vacuum line is the one that goes to the petcock.

This video should clear up how to hook up a manometer for a running synch.

 

Yes those boots have the vacuum caps/ports.
As Kmoe said use whatever it takes to get them off.

 

Stumplifter so my final question is what is going to be connected to the vacuum side of the petcock while I'm running the sync?

 

You won't need anything to be connected there while sinc'ing because if you put the petcock selector on PRIME, the fuel will be gravity fed, then no vacuum is needed to open the petcock and let the fuel flow.

Actually you may use any auxiliary source of fuel with a manual valve during the process, as long as it is connected to the carb fuel intake

 

I use a snowblower gas tank when I sync.

Sync screws are different than mixture screws.

Bench sync is only so you can get the bike to warm up SO That you can do a running sync. It is the base starting line. It may be darn close, but it's still not dialed in. You might think it is, but it ain't.

 

Lawnmower fuel tank for me !

 

I just carefully balance the regular tank sideways on the frame.
I am also an idiot.
A lucky idiot.

 

I made my auxiliary tank from a universal radiator coolant overflow tank I found at the parts store for about $9. Just added a metal coat hook to hang it on the handlebar and a shut off valve. It's clear so easy to see the fuel level.

 

Right, I understand that I will have to run the vacuum sync. The sync screws are the 4 brass slotted screws on the fronts of the carbs sticking straight up sitting in the posts? To be honest I don't really see any other screws, I did hear a lot about the regular maxim (non-x) having only 3 sync screws so you have a baseline to sync to. I do not see this on my mikunis as I have the maxim x. I have a question regarding syncing in general though. I understand the concept of keeping the fluid level in the manometer equal across the carburetors, but with the usage of a common 4-pillar manometer you can have an equal sync but the pressure (or rather vacuum) level can be at 22 cm/hg but can also be at 24 cm/hg. If one carb is adjusted will it naturally pull the other vacuum down to equilibrium? And if I'm using a diy/bottle manometer (let's assume two bottles) and get the fluid levels to stop moving with respect to each other is that a complete sync? or should they equalize out level? I understand these questions may be somewhat complicated but for my sake I feel that I should know.

 

Good questions, cause you want to know for sure before you start.

The synch screws (on Hitachi) are 'connected' to the butterfly valve shafts, they slowly open/ close the valves to fine tune the bench synch. Not being familiar with Mikunis it sounds like you may be talking about the air/fuel mix screws. ?

With the 4 pillar models, equal is equal, no matter what value. Two bottle, I was told no movement is equal, being the anal, over-thinking-it-again kinda guy, I got my two bottle very close to even and equal.

Note on two bottle construction; if your connecting tube between the two bottles is too narrow, the device will work like shite and you will say nasty words! < fact

 

The four screws on the top of the carbs are the MIXTURE screws.

The sync screws are down between the carbs at the ends of the butterfly shafts. Thee are 3 of them. 1 is between carbs 1 and 2. The second one is between carbs 2 and 3. The 3rd one is between carbs 3 and 4.

The screw between 1 and 2 balances those two to each other. The screw between 3 and 4 balances #4 to #3.. The screw between 2 and 3 balances the 1&2 pair to the 3&4 pair.

There is no adjustment for 3. They all get adjusted to #3. Idle speed is maintained with the idle screw in the rear middle.

For all the hassle of trying to build a manometer that actually works correctly, and consistently. I chose to do the simple thing--I bought the Morgan Carbtune Pro. I"d recommend that over anything........buy it, wait for it to arrive, never have any trouble again.

Dave

 

Here are the three sync screws.

 

That's where there are-------just realize the screws are on the top, of course........springs and supports are on the bottom

 

So I'm assuming all of these screws (in order from cyl 1-4) control carbs respective to cylinder 1, 2, and 4? 3 is essentially the "vacuum baseline" per se?

 

3's butterfly is controlled by the idle screw, not really a vacuum baseline per say . . . You don't measure 3's vacuum and match the other carbs to it. I believe the manual says you synch 1-2 then 3-4 (3 is not adjustable per say, so you synch 4 to 3) and finish synching the 'left bank' with the 'right bank' .
Some members start with 3-4, this can help prevent a condition where your idle needs to be adjusted to keep the bike idling properly while you synch all 4. . . . .

I don't think I am being very succinct with my explanation. . . long week.
A 4 line manometer (as Dave mentioned) really does make the process easier.
This may help, he offers good tips, like not pressing on the screw driver.

 

As I said

 

With the air cooled XJs it is important to run a big fan in front of the bike during the process. The engine has to be fully warmed up before you start to sync the carbs, but then you need a fan to keep the engine from getting too hot, because the process may last several minutes.

Your Maxim-X is liquid-cooled, so theoritically you don't need an extra fan, unless you know for sure your cooling fan doesn't work properly or the thermo switch won't kick the fan on at the right time.

 

Don't let Hogfiddles fool you... While he is the finest carb wizard around, the real magic he possesses is the half of a music stand that he uses to hold up his auxiliary fuel tank.

 

Is lectern the right word in English for a music sheets stand ?

 

The part that holds the sheet music is removed. The "stem" is perfect for hanging your fuel tank from the hook and getting it close to the side of the bike while tuning. I loved Hogfiddles' repurposing and had to have one for myself. It's great!

 

No it is not. Lecterns are for lecturing.

 

Wouldn't podiums be used for lectures, though?

 

Sometimes. A podium is the platform upon which one stands during a lecture, or a conductor stands upon during a performance.

 

Well to get back towards the topic at hand, I am going to be doing an oil change today and I was wondering the best method for a bike that sat for this long. I was gonna do a cold drain first then fill it back up with good oil and to the warm with the old filter still in and let the old/bad mix drain before replacing the filter. Is this the accepted method?

 

Drain the old. Add the proper dose of Seafoam to the new. Ride for a 100 miles or so. Drop the oil and filter. Replace with new oil and a new filter. The goal here is to get rid of most of the sludge that's in the oil pan.

Preferred method? Oil...the endless debate.

 

Funny you say that, a buddy o' mine got into a right hot squabble about cold vs warm oil changes recently. Not trying to pick up that scrap but thought it was entertaining.

 

Some have suggested heating the oil with a hotplate under the bike for the"cold" drain. Never tried it, but it seems that it would make the oil more viscous. I don't think it would do much to the sludge, but it might... anyone tried this?