Another new owner of a 1984 Maxim 400 (XS400K)

Hello everyone. I recently picked up a used 1984 Maxim 400 from a lady who parked it outside for the winter (with all fluids) and ended up getting something bigger come spring.

I'm hoping to get it running soon so that I can learn to ride the darn thing and get my motorcycle license.

 

Re: Another new owner of a 1984 Maxim 400 (XS400L)

Well you have some work ahead of you. Lots to do to get that bike running smooth. Everyone here will help you out.

 

Re: Another new owner of a 1984 Maxim 400 (XS400L)

Thank you. I have gotten as far as getting the engine to backfire through the air intake. 8O

The bike is 99% complete and ran all last summer.

The first thing I changed was the battery since the old one tested bad.

Imagine my disappointment when there was still no power.

I traced the issue to the ignition and after fixing that up power was restored.

I couldn't check compression until there was power since there is no kick start. Luckily compression was good.

I changed the spark plugs since the old ones were pretty black.

After cleaning out the gas tank with POR-15 Prep & Ready and Evapo-rust I tried to start it, but the best I could get was a few back fires.

I tried to clean the carbs, but didn't do a great job, so I took them off again last night and soaked them in Pine Sol. Today after work I will hose them off and see how they look.


TrueG

 

Re: Another new owner of a 1984 Maxim 400 (XS400L)

Thats not a good way to clean them. Do a search for church of clean. You need to take them fully apart. Back fires are from a lean condition. you'll need a colour tune to get the mix right after you vac sync the carbs. Chacal has the rebuild kits and colortune. And if it's YICS you'll need the tool to get the vac sync right.

 

Re: Another new owner of a 1984 Maxim 400 (XS400L)

NOT a good idea. There are throttle shaft seals buried in those carbs; soaking them can cause more problems than it might solve. DO NOT submerge whole carbs unless you plan on replacing the throttle shaft seals, in which case they would be removed first anyway.

"Cleaning carbs" isn't a reference to how shiny you can get them "looking" on the outside, they need to COME APART and have all their little internal bits cleaned, inspected and renewed where necessary; their floats properly adjusted, etc. Plus, you may discover you now also need to replace the throttle shaft seals.

How many miles on the bike?

 

Re: Another new owner of a 1984 Maxim 400 (XS400L)

There are around 56 000 km.

 

Re: Another new owner of a 1984 Maxim 400 (XS400L)

Hmm, I spent hours reading dozens of threads about using Pine Sol to clean carbs before making the plunge. Is it these carbs in particular that are not a good candidate?

http://xjbikes.com/Forums/viewtopic/t=1 ... nesol.html

http://www.advrider.com/forums/showthread.php?t=560117

http://www.xs650.com/forum/showthread.php?t=8898

http://ltd454.proboards.com/index.cgi?b ... hread=2559

http://www.hondashadow.net/forum/72-tec ... -more.html

http://cx500forum.com/index.php?/topic/ ... h-pinesol/

 

Re: Another new owner of a 1984 Maxim 400 (XS400L)

Your not cleaning all the little holes and pathways inside of the carb with a soak. It has to come apart to clean those.

 

Re: Another new owner of a 1984 Maxim 400 (XS400L)

They are referring to PineSol to clean the castings. That's fine. But you can't submerge them with fragile rubber seals trapped inside. You can use PineSol to clean "naked" castings, not to submerge fully assembled carbs in.

If you read the thread you linked from this forum closely, you'll find the quote "stripped of all parts." If they haven't been "stripped of all parts" (which includes the throttle shafts and their seals) then submersion is not a good idea, for the reasons I mentioned.

 

Re: Another new owner of a 1984 Maxim 400 (XS400L)

I cleaned my bodies with carb cleaner and elbow grease.

 

Re: Another new owner of a 1984 Maxim 400 (XS400L)

Understood.

I took them apart about as much as I could before soaking. I removed the bowls, floats, float pin and main jet. I couldn't get the pilot jets out and I could not get the top cover off.

 

Re: Another new owner of a 1984 Maxim 400 (XS400L)

That top will have to come off; the diaphragms and slides are under there and if PineSol got in there you'll never get it out (without taking the "HATS" OFF.)

Sorry, but all you've done so far is make things a bit worse. Don't worry about the throttle shaft seals right now; the carbs won't work at ALL if PineSol/water/whatever is trapped in the diaphragms' air chambers. You've got to get the "hats" off; if you reinstall them right now you run a risk of sucking a bunch of PineSol into your motor, plus the diaphragms, slides, needles, etc., are going to need to be carefully cleaned to remove all traces of PineSol and/or water.

 

Re: Another new owner of a 1984 Maxim 400 (XS400L)

Well hopefully I will have better luck getting the top cover off after the soak. The screws were starting to strip trying to get them off before.

 

Re: Another new owner of a 1984 Maxim 400 (XS400L)

Screws tend to strip because these bikes don't use Phillips screws, they use JIS screws which only LOOK like a phillips. A "real" phillips screwdriver bit is too "pointy" and bottoms out in the JIS screw before the flutes fully engage the slots. Take one of your phillips screwdrivers and file about 2mm off the point; square it off a bit so it FITS the screws.

 

Re: Another new owner of a 1984 Maxim 400 (XS400L)

I use a vicegrip to add leverage to the screwdriver.

 

Re: Another new owner of a 1984 Maxim 400 (XS400L)

Thank you for the tips.

I will try that when I get home.

 

Re: Another new owner of a 1984 Maxim 400 (XS400L)

Question: Previously when I tried to remove the pilot jets, they just seemed to spin in place (both jets). Is there a trick to getting them out?

 

Re: Another new owner of a 1984 Maxim 400 (XS400L)

use the proper screwdirver (flat) make sure its snug as a bug in a rug and turn left

 

Re: Another new owner of a 1984 Maxim 400 (XS400L)

OK, well I got the carbs all cleaned up after soaking. I was able to blow through the main and pilot jets, so they should be clear.

The starter goes, I feel puffs of air out of the exhaust and I get the occasional backfire, but it doesn't want to start.

I guess I will have to look at the timing next? How do you check the timing on a non-running bike?

 

Re: Another new owner of a 1984 Maxim 400 (XS400L)

The timing is not your problem. It also isn't adjustable.

Your problem is still the carburetors.

You need to get the pilot jets completely out. The pilot screw and the spring, washer and o-ring under them need to come out. They need to go back the same number of turns from bottom as they came out. The caps might still be on them. This is all detailed in the write ups in the XJ FAQ Suggestions forum.

In the front of the float bowl there is a well that a tube from the carburetor body sits in. At the bottom of the well is an orifice to the float bowl. That orifice is called the starter jet. It's the first thing that plugs up and that is likely PART of your current problems. This is where the fuel comes from when you turn the "choke" on.

In the XJ FAQ Suggestions section you will find a detailed, illustrated write up from Schmuckaholic. Follow his tutorial each and every step and your motorcycle will start right up.

You should have the service manual which will give you the float level. That's the only thing that might be different than the write up I referenced.

 

Re: Another new owner of a 1984 Maxim 400 (XS400L)

you are confusing the pilot jet with the pilot screw. The jets have nothing under them, the screws do. Leave the screws alone. Get the pilot jets out and floss them clear with a wire from a wire brush

 

Re: Another new owner of a 1984 Maxim 400 (XS400L)

Well, I'm not sure if I will need to worry about the jets, but I will need to check out my floats.

Yesterday after work I decided to look at my plugs. Originally the bike came with a D8EA plug on the left side and D7EA on the right. I replaced them with DR8ES-L plugs as per the service manual.

On a whim I put the old plugs back in and tried to start it. Right away I could tell a difference because the engine was starting to catch. With a little extra throttle it started. It was a little rough at first, but seemed to even out. That's when I noticed fuel coming out of the air box and pouring on the ground so I turned it off. 8O (at that point I had to go to Karate)

Later I went back and tried to start it. This time with the petcock set to "on" instead of "pri" and the choke off. It started immediately. After about a minute a little bit of gas came out so I turned it off again. After another minute I started it again and this time it ran for several minutes without a problem. At that point my wife came out to the garage and gave me crap for running the bike so late at night (noise).

This morning I tried it again, and it started right up. I thought it was fine, but after a minute or so gas started squirting out of the carbs into the airbox.

I gather the floats are sticking and the fuel to the carbs are not shutting off?

 

Re: Another new owner of a 1984 Maxim 400 (XS400L)

And it begins.....
Could be ... improper float height, bad float valve, or just some crap preventing the float valve from seating properly....

I highly recommend reading all carb cleaning articles by Rickomatic...check in FAQ suggestions.....absolutely life saving..... AND Listen to Fitz ..... trust me,...

These little guys are fun once they get running.... mine was a mess and in pieces when I got it, .. been running it for over3 years as a daily commuter and she's only let me down once...stuck float on a rather nasty rainy day......

 

Yikes, my bad. It wasn't gasoline.

It was actually fluid from the crank case being blown out of the overflow. There is a hole just below the carb intake and that was where the fluid was coming from. I had never changed the oil and I guess there was too much fluid in there. I changed the oil (and filter) and problem solved.

I think I will need to rebuild the petcock though. I noticed it drips when the hose is off and it is set to 'on'. Even with the vacuum hose off. It seems to idle fine in 'on' but it feels like the bowls are not filling fast enough. There are no issues with hesitation when set to 'pri'.

TrueG

 

If the crank case is too full, I'd bet that if you pull the oil filler cap and take a sniff it's gonna smell like gas in there. That's cuz there IS gas in there due to a leaky petcock compounded by carbs that are leaking. Drain and replace the oil. If you don't and you actually do get the bike running, you'll blow it up soon after.

PLEASE listen to the rest of the guys when they tell you what are the correct things to do. Don't come back to us with the "well, I think I just need to...." and "i don't think I have to.......". Yes, you DO need to..... and yes, you DO have to........

We all do/did at some point. Stay the course and you'll get a nice running bike .

I'm going to be starting in on an xs400r shortly, too, in addition to the other projects. I'm supposed to pull that one home this coming week.

Dave

 

I'm in the same boat man. I've gotten to ride my seca about three short times. Good luck!

 

Take your time on the carbs. Search for "the whole nine yards" and "in the church of clean". Sounds like you got a few issues with the carbs. Check your valve clearances too. Know you want to ride, but riding is much more fun on a properly tuned bike. You are also going to avoid more problems later on with a properly tuned bike.

 

Re: Another new owner of a 1984 Maxim 400 (XS400L)

On Jap bikes I do this to the #2 phillips bit that came in my impact driver set. If you don't have an impact driver I HIGHLY reccomend that you acquire a set... See attachment for example. There was NO WAY I coulda got my carbs apart to clean them w/out my impact driver.

Jay

 

Re: Another new owner of a 1984 Maxim 400 (XS400L)

Agreed. These things are life savers when dealing with screws that are tight, or even starting to strip.

 

I ended up driving the bike around my neighbourhood for about an hour last night.

It seems to run pretty good. While riding I noticed that the speedometer doesn't work.

I have a lead on another 83 Maxim 400 that I plan to buy and use as a parts bike (since it doesn't have registration papers). The guy was asking $300, but I got him down to $150. Luckily, most of the parts that are rusted on my bike are good on the other one and visa versa. Between the two I should be able to get it looking pretty good.


TrueG

 

that's the way we do it!!

davve

 

Good score... hard to find a good parts bike... most that people try to sell here are no longer good for parts....

 

Ya, I really lucked out it seems.

So far from my parts bike I pulled the gas tank, rear body panel and front wheel fender, handle bars and horn. The paint is not original but looks a lot better. I will post a picture soon. Oh, I also used the spedometer cable which allowed mine to work again and swapped the clutch lever.

I think I might switch the clutch cable since it felt a lot better than mine.

The old handle bars were after market and came with grip heaters. That's probably why they were all rusted up. I ripped out all of the wiring (for the grip heaters) and swapped the handle bars. They almost look new now.

 

Here is how it looks right now....

 

nice mudflap! LOL

 

Mudflap? My license plate?


Anyway, I swapped the carbs from my parts bike after thoroughly cleaning them.

In some ways it seems better. The bike doesn't jerk as much when I let go of the throttle and the choke seems to work better.

The only problem is I am now getting backfiring/misfiring out of the left exhaust pipe.

Ideas?

 

Well I put my old carbs back on and the backfiring/misfiring is gone.

I was hoping the new carbs would fix a problem I am having with the throttle.

It's not a big deal, but when I let go of the throttle the bike jerks and slows down really quickly. When I give it throttle it jerks forward and after that speeds up like normal. I can live with it, but it would be nice if I can get it to smoothly transition between throttle on and throttle off.


TrueG

 

mudflap...back of front fender

 

ahhh, yes indeed. The previous owner of my parts bike attached that. It appears that the fender underneath is partly broken. I was thinking of painting it black again as it looks like some yellow is starting to show through.

I would use my original one, but it's red.

 

My guess for the backfiring would be the carbs are out of sync
A good bench syncing should take care of that
The jerkiness... carb cleaning.....

Read Rick's Article.. "your carbs need to go clunk" that will smooth out the throttle issues
Hell, read all Rick's carb cleaning articles and get those puppies working great..
Easy as you have 2 sets to play with... no down time

 

Yes, I guess it could be that the carbs need to be synched.

I might have also mixed up the jets between the left and right. They looked the same but apparently the left and right are jetted slightly different on this bike.

As for cleaning, unlike my main set of carbs, I was able to completely disassemble this set. I've been unable to get at the diaphram or pilot jet on my main set of carbs (although I have no problem blowing through the pilot jet while installed).

With this second set, all of the jets and pathways were thoroughly cleaned. I was hoping they would be noticeably better because they are so clean. Perhaps I should try to synch them and put them back on.

****

The throttle jerkiness may have been because of the jerk controlling the throttle.

I've been really careful with my throttle control lately and the jerkiness is barely noticeable. I only really notice it when I completely release the throttle (by letting go). If I slowly release the throttle there is no jerkiness.

TrueG

 

Indeed, I had accidentally swapped the main jets. The left jet has a slightly smaller opening.

I also made sure they went "clunk", cleaned the enrichment pathway and bench sync'd them.

I put them on and they work great.

This weekend I think I will try and build a two bottle carb sync tool (as seen here....) and properly synchronize them.


TrueG

 

Adjust your valves first.

 

Ya, I thought someone might suggest that.

I was hoping to get by without doing that. I watched a couple of videos and it seems like a big task. That and I guess I would have to order some shims.

Synchronizing the carbs seems like a pretty easy task once you have the right tool.

 

You CAN'T get by "without doing that" it has to be done and periodically or you'll wreck the motor.

It's only a "big task" until you've done it a time or two, and it's an important part of regular maintenance on this type of motor. You will probably have to get a couple of shims, yes; but it's easier and cheaper than pulling the head to replace a burnt valve. Might as well learn the process; if you're going to be keeping and riding the bike for any length of time it will come due again.

You have to have the valves in spec to expect any good results from carb tuning, so get after them now.

 

Valves do seem like a daunting task but it is very easy really. Once you get in the motion, it goes by pretty fast