My lil maxim

[Jmillxs400maxim]

Hi everyone new at forums so bear with me i recently picked up a gem i love the bike so far and have been slowly getting it to working order. My bike is a 1983 yamaha xs400kr maxim. Shes low miles garage kept 1 owner bike 556 miles to be exact. I first drained all old fluids changed the master cylinder as was clogged,then took off gas tank flushed it then removed carbs cleaned and flushed she fired right up like had never been sitting. I did have to order some things the tires where dry rotted fuel petcock flowed constantly instead of under vacuum carbs leaked around bowl seals small stuff really. I do have a few questions id like to remove the airbox possibly and run pods but seems to be a p.i.t.a. also fro t forks seem super soft to me but idk. Lastly id like to upgrade the fromt rotor and caliper but havent found much options if you have any ideas or suggestions id love to hear it.

 

[Lou Ranger]

My lovely wife is from Ohio, so I owe you one.
First of all, nice choice! I loved mine and only parted with it when I stumbled on a really nice 650 Maxim and couldn't resist.
Second. I never tried pods and decided not to after reading all the horror stories. It ran great and I wanted to ride more than tinker all the time.
I once saw a fake set of pods on a bike that had the proper, Japanese-engineered air-intake system. He liked the look but didn't want to ruin a well engineered masterpiece.
Front forks probably need fresh oil but no parts unless they sat dry for 40 years.
If you can't get the paraphernalia off at the top, don't panic. You can empty the gas tank, take out the battery and hang the bike upside down with a rope through the front wheel and then fill the forks with the right amount of oil using the drain holes.
Unless you're a big guy, you might enjoy switching the front sprocket to one with one more tooth. It shaves about 400 - 500 rpms off highway cruising speed and, except for starting off from a dead stop on a up-slope, I never noticed any real performance difference. Once over 3,000 rpms, it was all the same in terms of acceleration.
Best of luck!

 

[JPaganel]

id like to remove the airbox possibly and run pods

Is there a practical reason for this? Pods are worse in every respect, except for looks. Cloth and wire mesh filters usually let a lot of dirt in, more than foam. Plus, you get the tuning issues with vacuum carbs. You do not get any additional performance out of them. Only more noise.

I can understand going that way if you have a modified frame and the airbox doesn't fit, but on a standard bike pods are pretty pointless.

fro t forks seem super soft to me but idk.

They probably are.
Remember, this bike was designed for the average Japanese rider of 40 years ago, who was probably smaller and lighter than you.

Service them with 15W fork oil. Factory spec is 10W. See how you like it when they are properly operating. If it's still too squishy, you can get heavier springs, these forks are not an uncommon size.

Lastly id like to upgrade the fromt rotor and caliper but havent found much options if you have any ideas or suggestions id love to hear it.

I don't know of a direct bolt-on. You might need to swap the fork for that.

I haven't really had issues with the brakes on these bikes, though. They are pretty light.

 

[Jmillxs400maxim]

Thanks guys the info deff helps i dont mind keeping the airbox if helps performance and reliability i reqlly wanna get the bike functional then if i wanna change it uo go from there im sure the forks need oil changed but seals look good no leaks so maybe thats how they are i look forward to posting progress pic

 

[JPaganel]

i reqlly wanna get the bike functional then if i wanna change it uo go from there

That is a good plan. Better than something like 3/4 of people who get an old bike...

im sure the forks need oil changed but seals look good no leaks so maybe thats how they are

Oil degrades over time. Also, you never know if they were filled right before.

Basically, if you personally haven't done a maintenance item, you can never be sure if the previous owner did it right, or at all.

 

[xschris]

I would keep the bike as stock as you can. The bike will have the best overall performance like this. I would go with a 20w fork oil for best dampening control. If you take them apart make sure to clean everything well. You would be surprised on how much gunk and crud ends up on the bottom of them. Time alone will do funny things to oil.

 

[Jmillxs400maxim]

Ok so a lil update i got to ride her today for the first time across town the replacement parts are subpar and i had to revert back to stock on most of them the stock petcock is vacuum controlled well it was leaking badly i got a rebuild kit still leaking so i used a combo of old and new but had to run a fuel shut off so it wouldnt leak past the floats the only issue im having is the bikes idle hangs after revving slighlty i did a bottom end rebuild changing the float screens needles jets all that however i could not get the pilots out stuck badly ill be doing a leak check tmrw but i honestly feel its that vacuum either at the petcock or my idle jets are partially clogged or air screw needs adjusted ugh she runs good except at idle i dont wanna burn her up being lean

 

[Jmillxs400maxim]

Also experience a slight bog at 1500-2000 rpms

 

[JPaganel]

Have you adjusted the valves to spec?

 

[Jmillxs400maxim]

Have you adjusted the valves to spec?

I have not the bike has only 556 miles but thats not to say there not outta spec when i was synching the carbs and was using an auxiliary gas tank the bike ran perfect, but when I switched to the original tank and reinstalled the backing line i noticed the symptoms of being lean

 

[Jmillxs400maxim]

Ok so another update took the carbs back apart to clean them once again rigged up a way to get rid of vacuum controlled petcock just on and off petcock bike runs decent however i did notice for w.e. reason the carbs idle mixture screws where set at 0 all the way down i tried them at 3.5 turns like the manual says and bike wouldnt start for shit put them back at 0 been riding all day am possibly having a vac leak im either gonna have the carbs professionally rebuilt or swap them also bike runs great on the needle and main jet so idk i would like more top speed it has enough power to climb a mountain but i found myself at 55 keep grabbing for 6th gear which isnt there lol any swap on the sprockets avail.

 

[Lou Ranger]

I''m not sure, but I think you're asking about what happens with a sprocket swap. Here's an old thread from when I tested my Maxim several different ways with a 16T front, and duplicated the tests with the 17T. The only difference that was really significant and which I definitely noticed was the drop in rpms at highway speed. I loved the difference.
http://www.xs400.com/threads/sprockets-does-new-bike-have-the-wrong-ones.7592/page-4

 

[Jmillxs400maxim]

I''m not sure, but I think you're asking about what happens with a sprocket swap. Here's an old thread from when I tested my Maxim several different ways with a 16T front, and duplicated the tests with the 17T. The only difference that was really significant and which I definitely noticed was the drop in rpms at highway speed. I loved the difference.
http://www.xs400.com/threads/sprockets-does-new-bike-have-the-wrong-ones.7592/page-4

Absolutely love to try a 17 tooth will check out your post