Maxim 400 Build Project

Hi all.

New member here. Bought a 1983 Maxim 400 two weeks ago and am in the process of turning it into a brat / cafe racer of sorts.

I have LOTS of questions but let me start with the simple ones.

- Can someone explain XJ / XS and where a 1983 Maxim sits in all of this. I want to understand better what parts i should be looking for when sourcing things. What works on what bikes?

Ok. See images attached on it stripped down. So far i have:

- Removed Seat / Rear fender
- Grinded off rear brackets
- Lowered front front forks
- Added clubman handlebars
- Removed all passenger pegs etc

I have a KZ650 tank i am going to fit instead of the stock. The next work i want to undertake is:

- Removing and lowering the instruments / light (can't really see how i can do this with the stock bracket...is it possible or do i need to remove them all and buy new ones?
- Removing the stock air filter and moving battery. Anyone done this on this bike before? What air filter can be used?
- Adding loop on the back for a flat seat.
- Rear sets?? -

 

YAY the grinder has come out already!
OK first off let's overlook the mechanicals (but we'll get back to it later) on the bike since you are only asking about aesthetics. For that, keep in mind that Brat and Cafe are two disparate styles, you kind of need to choose one or the other. Cafe bikes are typically styled to look "race-bikey", Brat bikes are more upright standards made to look utilitarian.
Cafe = Clubman bar, rear set pegs, , bump stop on the rear of the seat, maybe a small nose piece/fairing
Brat = Dirtbike bar, mid pegs, flat pleated seat

In both cases you would strip out the rear triangle of the frame and try to leave it "open", which means moving the battery, airbox and electronics somewhere. There should be pod filters on the market to stick on to the carbs to eliminate the airbox, the rest gets a little trickier. There are really small batteries out there which could be made to work, but remember the economic laws of electrical stuff: smaller = $$$. A small set of gauges would work better than trying to modify the bracket for the OEM monsters. Well, again the difference between a brat or a cafe comes up. Cafe would have both speedo and tach, for that you would want some mini-gauges, and brat would only have the speedo mounted high and centered so in that case you could use the OEM one but you would need to make a bracket. There are harder things to make than a speedo bracket, get a vice, a set of files, a drill and some bits, some stock metal pieces from a hardware store and start trying different things. There are tons of places nowadays making seat pans for either style saddle, so take your pic. You may even be able to use the OEM pan and have it re-upolstered by a local shop, but I am not sure what the stock XJ400 saddle looks like. At least in that case you wouldn't have to work too hard to get it to fit. Something to keep in mind if you are changing the tank is the tank/saddle contact point will change, so don't go to the upolsterer until you have test fit everything and determined whether or not you need to trim the seat pan a bit to make it work. Welding on a new rear loop should wait until you've got the seat pan sorted out, as well. You will assemble, measure, disassemble, grind, trim, reassemble, measure, disassemble, weld, grind, reassemble several times. DO NOT PAINT UNTIL EVERYTHING IS RIGHT!

OK, so you've got the look down and sorted out. Prior to any of this, did the engine run? If not, well there is a lot of sorting out to do. Carbs, valves and ignition are just the beginning but you must begin or else you'll never start (haha). Seriously, if I were you I would sort out the mechanical stuff, at least on the engine, first before I wasted a ton of effort on making a good looking piece of lawn art. Once the engine is running, the valves are set properly, the carbs will need to be totally taken apart and cleaned then tuned because you added the pod filters and presumably you will be cutting off the OEM muffler (because everyone does this). Then just when you think you are ready to go Beards-A-Popping! at the local coffee shop you need to strip the forks, wheels and brakes (master cyl., calipers, lines, drums anything and everything to do with the brakes) to make sure that the bike is actually safe to ride. New tires are an ABSOLUTE MUST. Shit for a proper look, either cafe or brat, you should really try to find some wire spoke wheels, cast rims look like an oversight and on a otherwise sharp bike. OMG I haven't even gotten into the electrical stuff, lights and charging system.

All that being said, please do not think I am trying to discourage you, rather I am trying to help you set your expectations and encourage you to make a plan and work toward a goal. For reference, read a few of Wizard's build threads, he starts with a hum drum bike and slowly but efficiently works on it one part at a time until he makes a friggen masterpiece.

Good luck!

 

Thanks for the reply!

Yes - I am planning on taking it in stages. I know there's a lot to do. I say Cafe / Brat because i want a hybrid look - cafe tank / handlebars, with long seat - not the cafe single seater - a seat like this https://s-media-cache-ak0.pinimg.com/736x/4e/3d/cb/4e3dcb2d69cfdc172f3a3a636889fe82.jpg

1) It's running great - no engine work needed - tires and brakes are good too, don't need work.
2) Before the winter hits i want - Seat / Tank / Instruments sorted.
3) Over the winter it'll be the airbox / carbs / rejets etc and hopefully spoked wheels

So, the stock seat pan isn't going to work - it's a real cruiser stance. I have seen lots of people just make a seat pan, so will try that.

Will a speedo like this work on the bike? Not sure how specific it needs to be for this model

http://www.dimecitycycles.com/2-5-i...with-white-face-and-led-indicator-lights.html

for the headlight i was just going to get a simple bracket

http://www.ebay.com/itm/Universal-B...Cafe-Racer-Bobber-Chopper-Style-/221773478308

I tried to find some examples of maxim builds like this on the forum, but search wasn't helping much

 

For reference, that bike is the epitome of Brat style which I happen to prefer, but the douchey glasses make my brain squirm.

Oh man, before the wolves get to you, please please please take the time to go through each of these items and verify by your own hand that this statement is true.
-Because it runs well does not mean its running right. Check your valves, check your fluids, get it back into OEM specs.
-Because it stops well does not mean the brakes are safe. That bike is 32 years old and probably has original rubber parts on it. They need to be serviced and/or replaced.
-Because the tires have tread does not mean they are safe, either. There is a date code on them, anything older than 5 years needs replacement.

Yeah there are youtube and instructables on how to make a seat pan, give it a try. The worst thing you'll do is learn a new skill (well, you could inhale a bunch of glass fibers, that would probably be the true worst thing). Google up the gear ratio of your OEM speedo, then cross reference it with the mini gauges. There are other vendors besides Dime City, of course.

 

Thanks! So, back to my noob question

- XJ / XS / Maxim 400 - is my bike a XS MAXIM 400 or an XJ Maxim 400? Or is it both?

 

You have an XS400 maxim. It's a two-cyl engine. The XJ400 maxim is a 4-cyl engine, and was a Japanese-market-only bike, not many of them made it to the USA.

 

thanks Hogfiddles!

I am now knee deep in wiring. I wanted to get a smaller headlight and speedo and move the wires under the tank / seat.

 

Ok - so i tore into the airbox tonight to remove it for a clean look. I'm looking into getting a small battery to hide under the seat.

Couple of questions.

- Will i have to rejet my carbs with the airbox gone?
- What replacement air filter should i look at attaching?
- There is a rubber hose that goes from the right side of the engine to the airbox, what exactly should i do with that if i remove the airbox?

Any help would be MUCH appreciated!

 

General petcock question for the forum - I bought a Kawasaki kz650 tank which looks great on the maxim - but i don't quite understand the petcock it has. It's just a threaded hole. I know i need to purchase something new to fit this - but i don't even know where to start looking, or what to search for....what are these called?

 

Do i need something like this? http://www.lowbrowcustoms.com/petcock-22mm-hd-style-straight-outlet.html

 

I assume i'll remove this threaded bung and replace it, not find something to go over this.

 

That's really the more common type of petcock mount, at least in my experience. Replacement valves should be easy to come by, check the Information Overload Hour for information on how to hook it up, basically you will need to plug the vacuum port on your carbs which would normally provide vacuum to open the OEM petcock diaphragm.
Does the inside of the rest of that tank look as bad as that bung?

 

Thanks BigShank - where is the vacuum port i should be looking for, and how do you bung it? Is this the common replacement type? http://www.z1enterprises.com/ItemDe...k+Pingel+Single+Outlet+3/8+NPT&item=TU03-0505

The rest of the tank is rough, but not as rough as the bung. I am planning on a full rust removal process - starting with apple cider tonight...

I'm going to have to grind off the inside mounts from the tank to fit on my frame, so once that's done i'll post a pic of it in place.

 

Hey, keep us posted on how the cider vinegar goes ... curious to know if the acid is strong enough. Others have suggested muratic or phosphoric acid.

 

Yeah - i Will. I'll post some pics of before and after too of the inside.

 

Actually I wouldn't even swear to the XS400 needing a vacuum operated petcock so I don't want to lead you up the wrong path. To whit, I have no idea where the vacuum port on your carb would be, if in fact it is there at all.

 

Maybe to simplify, you should go with an on/off valve, and just cap off the vacuum port on the carb. Important to remember to shut it off when you're done riding, but otherwise there's no issue.

 

Thanks - I think i'm going to get this

http://www.lowbrowcustoms.com/petcock-22mm-hd-style-right-hand-outlet.html

 

I own a 400 Seca and that is what I did to mine it works like a charm.

 

Can you take a picture and explain this better??

 

Wha I did is took the back of the peacock off took the plastic spacer out and made a square piece out of aluminum and then I made a gasket to fit and screwed them onto the peacock and put a shut off valve that came off of a ski-doo snowmobile. I hope this helps.

 

What I did is I made a square plate out of aluminum and a gasket to fit and then I took the back of the peacockoff and then the plastic block and replaced it with the gasket and the aluminum plate. The shut off valve came off of a ski-doo snowmobile. I hope this helps .

 

oops sorry for the double post I didn't think that the first post was showing up.

 

Ok - So i could basically find a way of attaching a hose to the threaded tank, and then create my own shutoff valve before it enters the carbs. No real petcock? And no prime - just off and on?

I have very little room for a petcock with my new tank installed (see picture) so will have to do a DIY version that's small. I just am not sure if you need an actual petcock, or a cutoff valve would work instead.(This is my first time not using a stock petcock.

Time to start thinking about a back hoop and creating a seat (notice from the pics i have a mock in place to test sitting on it)

Also I am thinking about either new risers for the clubman bars, or clipons. Thoughts?

Here's the new tank installed and some other pics. (Still need to clean the inside of the tank)

 

I kept the stock petcock because I wanted to have the reserve.

 

Still no luck on finding a petcock that will work with my new tank.

What options do i have in terms of a rubber attachment that i could put a hose and on / off valve on? Anyone done that before?

 

I ran an old Suzuki TR90 with that setup because the OEM petcock had failed after only 45 years of use! I will never buy another Suzuki again because of such a poor quality part.
Seriously, I just left the old petcock alone, ran a length of fuel line to a lawnmower-style shutoff valve then another length of line to the carb. Worked fine. Looked pretty much like chickencrap, but whatevs.

 

I need to get the petcock fitted first, before i wire up a valve solution. I have the tank full of vinegar right now. Got the airbox and rear inner fender removed, time to rejet the carbs and find somewhere to put all the electrics and battery......

 

Update. Vinegar seems to be working - below shows before shot inside, and a shot of inside the tank now (vinegar still in there). Also a shot of the bike, which now has no airbox

 

Vinegar worked great. I filled it up with 5 gallons and left it for three days. Emptied it. Rinsed it with baking soda and distilled water. Then used a hairdryer to dry it out. Then sprayed a mist of wd-40 in about 4 times.

 

So I've the new tank fitted but the bike won't start. It cranks with the starter but won't go past a few seconds on idle. I think it's because I now need a manual petcock setup. How do I plug the vacccum? I can't find where I should plug it?

 

Do you see a small nipple? Big one is fuel outlet, little one is vacuum, supplied by a tube coming from on one of the manifold boots. If there is no tube, make sure both manifold boot vacuum ports are capped. On the carb, a simple temporary cap is to take a short section of correct-size tubing and stuff a bolt or a BB into the end. The put that onto the petcock vacuum port.

 

Ok. One is capped. The other just tied. Needs an actual seal? Also the last pic shows the hose that did connect to the airbox. What should I do with that?

 

Yes, do as Dave advised...just cut it down and add a bolt or bb. Auto parts in lawn care section should sell a proper diameter air filter to add to the relief hose. Hope this helps.

Gary H.

 

Gary - does that filter go on to hose or do I remove the hose?

 

Stub the hose and add it to that. Take the hose with you to buy the filter to insure a proper fit.

Gary H.

 

Thanks. I'll try that. I drained the carbs. If the bike still isn't starting what is the next step? Cleaning the carbs?

 

You're running pods. It's essential to establish a good baseline for re-jetting. It will be impossible to do this without impeccably clean carbs. Chacal has a very good write-up in The Information Overload Hour forum about pods. Might wanna check it out. Are the valves in spec? Got in spec compression in all four cylinders?
Pick-up and coils ohm out showing strong spark at each cap? Plugs gapped correctly? Battery fully charged?

Gary H.

 

Thanks Gary. Going to start with a fully charged battery. Last night I got it to idle but the bike would cut out when the throttle was touched. Which prob is a fuel supply issue? I'm going to charge the battery and try again. Leave it to idle for 5/10 mins and play around with the choke.

I will give that a read tonight and then regardless of whether the bike turns over I'll clean the carbs. I've watched lots of rejet videos and its daunting looking.

 

Definitely a "hat trick " to pull off with these carbs because they were not designed to run pods. Please read Chacal's xj specific write-up on this subject.

Gary H.

 

Have I made a huge mistake????

 

I wouldn't call it a mistake because it's doable.Question is...how much time and $ you want to spend trying to get as close to stock performance as you can without running it way too lean or way too rich? The collective advice is to start with the stock configuration then move to pods.

Gary H.

 

Which is what I have done. It ran great with the stock. I removed the airbox properly (no sawsall) so can add it back in if needed. I'll give this a few days of work and if it's a no go roll back. Carbs need cleaned regardless.

 

This may be helpful and/or encouraging:
http://www.xjbikes.com/forums/threa...-pods-and-4-into-1-exhaust.29381/#post-251972
Others have gone where you're going. I love the look of pods, but I have no desire to dink around with carbs and jets any more than I have too.

 

Drained the carbs of fuel and got some caps for the vacuum ports. Charged the battery and it started no problem. Left it on the choke for 5 mins and then turned it off and let it idle. Applied throttle and it now revs (it was dying before). Here's a short video of it running and throttle.

https://www.sendspace.com/file/j0h5dp

Now to get the front end electrics wired up and the battery placed so I can ride it and see how the engine is running!

 

Update. Got the headlight hooked up and the backend electrics secured so I could take the bike out. It ran great until I ran out of gas. No problems with the pods. Two things I noticed

- the front brake is always catching (I think it's because the front forks have been lowered and the hose is bent.) can you buy shortened hoses?

- when I squeeze the clutch the headlight flickers. How / why would that be happening???

 

Yes shortened brake lines are available. Get braided stainless ones.
When you squeeze the clutch, you remove the load from the engine allowing it to rev a little easier (cause it's not trying to spin the transmission). This can raise your RPMs slightly which in turn spins the generator faster creating a little more amperage which can cause the lights to flicker. Unless you are referring to a complete, momentary blackout in which case you got a loose wire somewhere.

 

Things are getting a little more involved. Any tips appreciated

 

Whopsie! I forgot we were talking xs400. Only 2 carbs, don't know if that pods link will be much help after all!

 

no problem. I thought there was good info regardless. The bike runs good - just takes it time to get warmed up.

I let it run 5 mins on choke then run it off choke. It then takes another 5 mins before the revs settle and it starts sounding like it's ready to go. I'll deal with that just fine. It's 30.

I'm going to clean the carbs and buy a jet kit if I'm feelin adventurous.

Something like this:

Yamaha XS400 XS 400 cc Special Twin Custom Carburetor Carb Stage 1-7 Jet Kit https://www.amazon.com/dp/B006QZEMUW/ref=cm_sw_r_awd_ZBMgwbGY7E7NN

Hope that will work on a maxim too.