Sipma intro and Maxim build!

[sipma02]

Hello ! I have been sneaking around these forums for a few months now, but I've been able to answer all my questions (and troubleshoot quite a few problems!) just via searching. However, I want a place to document my build and get some advice/critiques, so here I am! I am a sophomore (junior in the fall) in college, live in Minneapolis, MN.

I acquired my first motorcycle last spring - a Honda 250. I kinda knew I was going to like riding and working on motorcycles, and boy was I right!! I got it's for $350 as a mostly running, mostly working bike. Fixed it up and it's the bike I currently ride! Anyway, I love it, but it's a little small. With that said... I came across a 82 Maxim (XS400J if I'm not mistaken) for $100 without keys, title, taken apart and not running! I love stuff like this, and so I bought it up, and here I am working on it ! Actually, this site has saved me already many times, there is lots of good info on it.
This is the Honda. Tank has since been painted silver. Seat is still homemade and pretty rough... Someday, I'll remake it. Other than that, there's some sketchy wiring. I'm learning, that's for sure. I think the Yamaha will be much better.

I plan to document my build here. I'm doing it because I want an easy to read record, and also hopefully some critique (whether good or bad). Can't wait to spend my summer makin the yamaha work/look awesome!

Here it is with pretty much all the main parts just teetering on top of it. Sure looks more ready to ride than it is... :') I

End goal is a modular street-scrambler. I want to be able to put some bags or something on it for short trips, but also take them off for slimmer looks. hopefully going to make use of that monoshock to have some 'gap' between the top of the rear tire and the bottom of the seat. I really like that look. But first - to get it running

 

[sipma02]

Removed carbs, cleaned as best I could. Took airbox off and rear swing arm. Soaked carb jets and stuff in Purple Power, that's some strong stuff.

this junk won't really come off, I've tried all sorts of chemicals, including gas. Is that still a problem? I mean, material isn't coming off, so it shouldn't clog anything in the carbs ...

Also filled rear tire with air, cuz the bead was still set. Front bead isn't even on. Put the rear at 30 psi but it was flat by morning. Prolly need a new tire anyway. Might just go with tubes right off the bat. Is there any distinct advantage to tubeless?

 

[rshutchinson]

You will need to clean that bowl out. Try carb cleaner in the aerosol can and some steel wool. A set of dentist picks works well for getting small areas.

Those carbs are going to need a thorough cleaning anyway. You might even have to take the rack apart and dip or boil them in cleaner.

If that tire is not holding air it's likely very old, hard and cracking. What is the date code on them? I'd replace with new tires, not tubes.

 

[sipma02]

Yeah, I plan on replacing both tires. I was looking at Shinko 777 and 712. They seem fine.

Cleaned the airbox, but I haven't re installed it yet. I want to make sure the engine runs/carbs work. Spark is good (I mean, it's there? I don't really know how to differentiate good/weak spark) and starter spins when attached to a battery (my car). It'll pop over for a second when I spray starting spray in the intake with the carbs off, but I can't get the carbs to feed gas. They seem pretty clean...

Next item of business is the caliper bleed nipple is rusted in there - really bad. Other than that all bolts are loose. Going to try heat later. That and I have no idea if all the O rings and ect are still good. Planning on a rebuild.

Just ordered exhaust gaskets as well!

Triple trees are loose - I was worried about that, because I couldn't get them loose on my last motorcycle. Looks like I will need to replace fork seals. (There is standing oil) Is that a pretty strait forward operation?

 

[rshutchinson]

Remove the top caps, push down on the spring caps inside and remove the circlip holding them in. Careful cause the spring is going to be pushing on them.

Remove the springs and drain the oil. Pump the cartridge a few times to get it all out. Remove the allen head bolt on the bottom holding the cartridge in. Remove them and take note of everything in there in which order they go. Then clean them out. Replace seals and reinstall everything. Then fill with correct amount of oil. That's the jist of it. Just know you can't remove the cartridges until you remove the bolts in the bottom.

 

[sipma02]

Well, got a little done this long weekend. Started making a seat for my other motorcycle

On the Maxim, I Welded up a small box for the wiring, and also a riser so the gas tank sits a little higher.

I plan for the seat to sit higher (I have long legs), plus it'll look way sweet I think. Also makes for a good place to stash wiring and hopefully a battery. (Obviously batter won't go on the box). Still need to make a top with some weather flashing. Won't be waterproof, but should eliminate direct contact with water. Isn't that pretty, but hey that's the price of stick welding. but it'll be covered by the seat, so I'm not super worried. Paint is drying as I type.
Anyway, the Maxim was moved to a different garage (we hosted my friends grad party over the weekedn) and I just trued to start it agian tonight, and it didn't turn over. Nothing. Classic blown fuse. Checked and sure enough, main was fried. Replaced it, and blew another. I had been fidgeting the wires (trying to be careful, but moving them around nonetheless). So I'm not sure exactly what up. Worked fine before I moved it, but I fear that I nicked a wire somewhere and I'm shorting it out every time. I will be checking continuity on each wire hopefully throughout the week if I have time. Could also be a ground? I did disconnect some wires, hoping I just forgot to re ground soemthing. If there's anything I'm missing let me know. I just don't want to blow the ignition or rectifier or anything. As long as I am properly fused I should be okay, correct?

 

[sipma02]

figured out the electrical problem... Starter solenoid was bad! Went to a junkyard and found one that plugged right in. Starts pretty well now.

Re did the wiring. I honestly think I may be redoing it agian... I want it to be perfect, and if I'm feeling uneasy about the placement of it, I probabaly will even more so down the road. Since I raised the gas tank, I may put it under there? Not sure yet exactly.

Installed the exhaust gaskets. Planning on changing oil soon.

I also decided on 3 words to help guide my build. Classic, Modern, Reliable. Somewhat contradictory, but we'll see if I can make it happen. So everything I do to it is hopefully going to push it in that direction.. We'll see what happens!

Finally got around to opening the master cylinder, and it's all jellified in there.

I blew the lines out with brake cleaner, and I have a new caliper. I cleaned the master cylinder pretty meticulously, and the piston seems to be holding pressure. However, when I fill the resovior with brake fluid and pump the lever, it doesn't fill the line with fluid ! Is my M cylinder bad?

Lastly, I welded on some seat risers. This will match the height of the gas tank better and suit my long legs! I spent the better part of a day getting everything perfectly symmetrical. Sure looks good tho!

Another way to raise the rear of the motorcycle would be to get a longer monoshock. Anyone done this?

 

[rshutchinson]

Have you removed the plunger from the bore and cleaned it up as well?

You may need to bleed the master. Remove the brake line and place your thumb over the port. Keep pumping the lever, then bleed the air by moving your thumb just a little to let the air escape at the top and then cover it again. Keep doing that until it's just fluid and it's really pushing your thumb off. If that doesn't push fluid out then you need a new master. I wouldn't recommend a rebuild as the bore does wear over time and can rust, just purchase a new one off ebay.

If you can bleed it that way then quickly reinstall the line. Then bleed the master again by pumping lever and loosen banjo, retighten banjo and then let go of lever. Do that a few times to bleed all air out of the master. Then move on to caliper bleeding.

 

[sipma02]

When I tried to cover the hole with my thumb, I can feel a little pressure when I pump the lever… But no matter how many times I pump it, no fluid comes out. Is it time for a new master cylinder?

 

[rshutchinson]

Have you taken the plunger out and cleaned the two ports in the master? There are two holes in the reservoir that are tiny and very likely plugged if the brake fluid went the way it did.

 

[sipma02]

Yes, I previously removed the plunger and cleaned it. It seems to hold pressure, but it may need a rebuild kit. I can see the 2 holes, one is definitly plugged, one is open (I can see the plunger cycle). The one on the right is plugged, but it seems to be purposely plugged... Like there is metal in the bottom of the hole. Is this correct?
Edit: now with picture

Another edit:
Upon investigation, I re opened the barrel/cylinder and it seems as thought there is only one hole (from the resovior) that leads into it

 

[rshutchinson]

That second hole on the right is small, but it does lead into the bore. If you can't unplug it then a rebuild will do no good. I wouldn't recommend a rebuild anyway as the bores do wear and could be pitted/rusty.

 

[sipma02]

Nice, that was the ticket !! Thank you so much! I let some brake cleaner sit in there and blasted it out with compressed air. After fighting with them a while I got them bled and they seem to work good. I suppose you can only tell once you start riding..

 

[sipma02]

Havent updated in a while! Things are looking good... really good. I will upload some pictures soon. I finally got it running on the street! It was awesome to ride around the block for the first time.

Sadly, I came back with the engine smoking. It was a little bit on the exhaust (from some oil I spilled earlier) and above the engine. Seemed to be some plastic burning that I forgot to attend to, it smelled as such. the motor was very hot, along with the exhaust pipes - way hotter than they shouldve been. It also didnt pull well at all, and that is an understatement. It barley accelerated. I assume its running very lean? It wont idle unless I have it fully choked, and even then its a very weak idle.

Anyway, I havent adjusted the carbs at all. I assume Ill need to play with the air screws.. thats the one on top, right? Im running the stock airbox, new filter, and what I think are the stock jets. Nothing to prove that. Ive heard that the XS400's had an assymetrical airbox - meaning different sized jets were used. Perhaps I have them switched? Also, i havent balanced the carbs.

 

[sipma02]

Alright! spent alot of time in the past few days investigting things. I think I got it figured out, sort of. Basically, the CDI was bad. I tested coils, (Primary was 3.5ish, secondary was 17k ish), recleaned the (clean) carbs, switched main jets, made sure all other wiring was good. Wasnt getting spark on the left cylinder. I have the DOHC, so the coils are deep inside the frame spine, but when I switched the connector from the right coil to the left and vice versa, i could get spark on the left or right, but not both.

So I figured because there is 2 coils, the CDI must put out 2 signals for spark (one when one piston is high, one when the other is low) or something like that, to balance vibrations. Which also means there must be 2 circuits within the CDI. I figured (hoped) one circuit was bad. When I replaced the CDI, it worked! I got home from the junkyard, and started it up, seemd to run good! Revved it up and down between 2-5k rpms and shut it off. Now, it wont start. I checked spark... no spark on the left cylinder agian. I think I blew this new CDI box... which is really not good. What causes that?! Any ideas?

 

[16VGTIDave]

To start, it's a TCI module, NOT a CDI module. That is a very important distinction. Yes, it has 2 separate circuits, one for each cylinder. TCI modules are VERY susceptible to mishandling, which includes dead firing the ignition - having the spark plug wire disconnected and unable to discharge back to the engine. The 30+ year old power Transistors (the T in TCI) don't take well to the feedback. If the left circuit is dead again, I'd be replacing the coil, wire, and plug cap when I replace or repair the module.

I'd suggest you perform the full testing of the ignition system as detailed in the service manual. Then fully and properly clean every terminal of the connectors before coating them in di-electric grease to prevent any corrosion. It is possible that the TCI module is fine and that there is another issue.

Good luck!

 

[sipma02]

Good to know. I have been pouring over the service manual, and did notice it denoted it as a TCI not CDI. Thanks for the correction! I will do that, and report back. Lets hope for the best!

 

[sipma02]

Well this is about a month of frustration condensed into one paragraph, but I went through all the connections, confirmed all the grounds, and everything seemed to be in order. Still kept blowing fuses. One of my friends suggested the reg/rec, so i replaced that. That did the trick! Ridden about a hundred miles so far with no issues.

Still lots to do, but its coming along nicely! (just in time for winter )