XS400J Maxim 82/83 DOHC engine rebuild

I took the cylinder and piston over to Crossroads Cycle for a second set of eyes. They said everything looks good, some surface rust but nothing serious. Some of the rings are stuck to the pistons so I'm giving them a bath with the valves in marvel mystery oil. Should free them up and break up the carbon.

 
I was fortunate with some persuasion the stuck piston rings came free without damage. The MMO bath really softened up the carbon on the valves and pistons. To free the rings I mounted the pistons in a vise and gently tapped them loose with a small flathead screwdriver:



The parts still have some carbon on them so they're taking another bath now:

 
Kind of stabbing in the dark at this stage. Manual isn't very helpful. This is the base gasket I received:



I could only assume the 'o-ring' portion is meant to go down facing this channel:





That Berryman's did such a nice job cleaning the carbon off the pistons. I got the cleaned up pistons on the rods:



Shot of cylinders all cleaned up:



I started with hot soapy water, then I used Marvel Mystery Oil and white disposable shop towels for this.

I have to say putting the cylinders on wasn't fun. Mercifully there's a taper on the cylinder spigots to help guide the rings in. But compared to doing 1 cylinder/piston at a time like on my Harley, this is a bit more complicated:



Next up I need to lap the valves and re-assemble the head.
 
When I cleaned the cylinders I didn't know what these chambers were for. .apparently it's Yamaha's YICS (Yamaha Induction Control System). Sounds cool, here's more info on it: http://xjbikes.wikidot.com/yics . They had a bunch of gunk in them so I soaked them in carb cleaner:



First time lapping valves before. It isn't shop quality but it will work. Here's the products I used:









There isn't really a lot to it. You smear some compound on the seating area of the valve, oil the stem, insert into the valve guide and work it back and forth until you hear the grinding noise go away. Lift off, rotate, and repeat. You're not cutting new seats just removing some pitting allowing the valve and seat to make a better seal. You can go crazy here but I only spent a little time on each valve as I read not to overdo it. The important thing is to make sure you don't get compound on the stem (which would damage the guide) and to clean everything well with carb cleaner after. In the home stretch now. Still missing some fasteners and I can't locate an oil seal to go between the starter and the engine. It is not in the parts manual.
 
Project has been on the back burner a bit as I waited for stuff to come in. I can upload the step by step if someone chimes in they'd like to see them but this is where it sits now:



Heads fully assembled with lapped valves and new valve seals, cams are in and timed properly, tensioners torqued. It turns over smooth with a socket on the AC generator bolt. All that's really left to do engine wise is finish getting the baked on gaskets off the covers and reinstall. Then I have to focus on the carbs which will be their own project in themselves.

I've learned a lot working on this engine and even if it doesn't run (it should) I feel comfortable enough that when I do eventually get a bike from this era I'll know a bit more about what I want. I got an education in techniques to break free rusted out fasteners, how to walnut blast parts (that was fun), how OHC engines work inside and out, literally, how to work on cylinder heads, that was a first for me. I've looked at a couple twin cylinder engines and they all seem to share the same general design so I ought to be able to jump in if I ever need to again. I found the manual lacking in a lot of areas compared to what I'm used to with Harley but with enough time and thinking about how things should go together I was able to get everything back in place. I would probably go with a more popular model like the XS650 since it seems to have a lot more support. I didn't find much of anything out there when I looked for the Maxim/SECA models.

I hope someone following along has found this helpful. I can get the step by step from cylinders on to where it sits now if anyone wants, I took plenty of pictures.
 
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Oh please do as I have an 84 Maxim that I will rebuild the engine on this fall/winter.
Very useful thread;)
 
Not to hijack this thread but, maybe you can answer à simple question as you have the 84... I find everything from piston rings to gaskets and so forth for 82-83 Maxims....do these fit our 84'?
 
That'sounds what I assumed, started ordering gasket kits, pistons rings etc...for the engine rebuild this fall assuming just that...live and learn I guess
 
Oh please do as I have an 84 Maxim that I will rebuild the engine on this fall/winter.
Very useful thread;)

I second that! Looking to do a rebuild come fall.

A1 buddy im rocking the 84 as well

Ha the threat of not finishing the post and all the silent watchers come out of the woodwork.

So I left off with the head needing to be assembled. I used a deep socket (I forget size, just be sure whatever you use only contacts outside of valve stem seal) and extension to push the valve seals on:





I was expecting a reassuring 'thump' when the seals seated but I didn't get that. I even smacked the extension with a hammer. Finally I took out my caliper and measured the distance from the valve stem top to the top of the seals on all 4 to see if they were equal (at least for exhaust to exhaust, intake to intake). Doing that I found one had a little more to go so I smacked it a time or two. I would've preffered to get some feedback installing these in the form of a positive slip fit but that just didn't happen.

Installing the springs and retainers with the keepers was a giant pain in the butt:



I had the tool shown at my disposal and I even splurged on the Lisle 36200 Valve spring installer/remover: https://www.amazon.com/Lisle-36200-Keeper-Remover-Installer/dp/B000P0ZJIS .

The Lisle tool was useless here as it just barely fits in the bore that the valve tappet fits into, and even then the head doesn't sit flat on the surface you're working on because there are 6 studs facing the cylinder for tightening down the head to the cylinder. So if you wanted to get leverage pressing on the Lisle tool you can't. If you're ambitious you could find some thick plywood and drill out holes where the studs are so the head can sit flat letting you press down on the Lisle. I had some 3/4" or 1/2" and it wasn't thick enough. I wouldn't recommend removing the studs.

Using the valve spring compressor shown (https://www.amazon.com/Amzdeal-Comp...12616&sr=1-1&keywords=valve+spring+compressor), I could get one keeper in but the second keeper always fought me. It was a struggle trying to keep the spring straight to the bore and getting the second keeper in. I don't really have any advice here other than to set aside some time and some cuss words. I watched plenty of Youtube videos but none of the 'tricks' out there worked for me. Also having a helper would have been useful so they could wiggle the compressor around to move the spring while you try to get the second keeper in.

For point of reference, this is what the keepers look like in the retainer before being installed:



And after install:



The gap means they're designed to clamp the valve stem keeping it from rotating. If there were no gap it would mean they're designed to let the valve rotate.

After lots of frustration:



Put the head gasket in place:



The other dowel was stuck to the head so I left it there. Just make sure both are in place:



Head on and torqued:





There are a total of 6 thick washers and 2 thinner copper washers for the head nuts. Oil the threads of the nuts before install and torque all the nuts in two stages following the manual. Basically you're clamping the head to the cylinder first by doing the bottom nuts, then tightening the whole assembly to the cases with the top nuts.

Next you're supposed to install the other side chain guide which I forgot to do until after the cams were in. Just go ahead and slide it into place.
 
:cheers:...this is very instructive indeed, did you, at any point use some kind of yamabond or liquid gasket? AND again, on behalf of the silent watchers out here...thanks
 
Go ahead and slide your valve tappets/cups into their bores with oil, if you can. I recall when I took mine out they were free moving. Going back in they did not want to go. That's how tight the fit was. Maybe try throwing them in the freezer for an hour before you try.

Then you put your timing cover on, set the front piston to TDC aligning the "T" to the line on the cover, take the cams with the sprocket bolts out and slip them under the chain:







The cam caps are E1, E3, I1, I3 and they must go on in the order and direction indicated in the manual (if facing engine from the left or ACG rotor side it would be E1 and I1 closest to you with arrows pointing away toward the right side).

Next you position the dot shown toward the top on the exhaust cam:



Do the same for the intake, as best you can. It won't stay perfectly vertical at this point because of the spring pressure from the valves. Torque the caps down at this point, alternating the bolts a few turns at a time.

Keeping the left piston at TDC, Exhaust cam pointing straight up with dot lined up with the line on the cap, you turn the sprocket for the exhaust clockwise removing chain slack and insert one of the sprocket bolts finger tight:



Now you need to take a spanner and force the Intake cam clockwise, compressing the valves and hold it there while simultaneously inserting a sprocket bolt finger tight:



While doing the above you may find it necessary to remove the sprocket(s) from the chain and re-align them to the chain to get it to line up. End goal, chain should be relatively tight and when you turn it over both dots should line up at the same time at TDC left piston. I had to redo it twice to get the Intake perfect.

From there all that's left to do is insert the other 2 sprocket bolts and torque all 4 sprocket bolts to spec. Insert the third chain tensioner in the middle, then install the tensioner that goes through the cylinder.

That's the abbreviated version any questions just ask.
 
:cheers:...this is very instructive indeed, did you, at any point use some kind of yamabond or liquid gasket? AND again, on behalf of the silent watchers out here...thanks

I only used gasket sealer on the cases (Permatex motoseal) everywhere else used new gaskets on clean surfaces. To clean the cylinders of gasket residue for this engine walnut blasting was a must. Even then quite a bit was left behind and against my better judgement I used a razor blade and a "Super Scraper" from Goodson tools. Both of these will cut into aluminum if not careful but I had no other choice. For the head gasket surface I recommend if it's bad to get it walnut blasted. .don't want to mess that surface up or you'll be in trouble. Luckily all the material here blasted off.
 
I forgot to mention use common sense when working on this or any engine. Don't install seals dry, use grease or oil..on clean surfaces or you'll be replacing them soon. If this is your first time in an engine take it slow, watch/read as much as you can. I skipped over some basic stuff that a beginner may not know about.
 
As I get closer to putting the covers back on I realized I need to get new cover fasteners. I found a tip online that seems to apply to most any Japanese motorcycle. In the microfiche if you look at any fastener, like this one:

upload_2016-8-5_8-37-26.png


It's #22 for the Clutch cover. Then go down to the parts list:

You see it calls for 14 of these screws:

upload_2016-8-5_8-38-10.png


Then click on the link and you come to the actual Yamaha Part #:

upload_2016-8-5_8-38-37.png


The last 5 digits are what we're concerned with. The 06 tells us it's 6mm and the 25 tells us it's 25mm long.

Traditional SS Allen head socket cap bolts should be direct replacements for these using anti-seize lubricant and by lowering the torque value.

Here is what I've come up with for the cover fasteners:

(14) 6mm x 25mm Clutch cover

(2) 6mm x 65mm Chain cover
(3) 6mm x 25mm Chain cover

(5) 6mm x 20mm Crankshaft timing cover
(2) 6mm x 30mm Crankshaft timing cover

The only one I'm not sure on is the ACG cover. It has a PN ending in 06570. It appears the bolt is a 6mm from the two I have here, not sure why they put that 5 after the 6.

Now all that being said. .if you're planning on replacing all your JIS screws it seems to me a kit from Alloyboltz might be cheaper than sourcing these elsewhere:

https://alloyboltz.com/catalog/prod...cts_id=2429&osCsid=drqecrssshbp0p81lqdncqggq3

$41.95 shipped to your door. Pricing just the cover fasteners from Fastenal is coming to $18 without washers. I need to replace the carb screws as well which aren't in the Alloyboltz kit so I might be going the Fastenal route.
 

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Aren't the screws for the gen cover real long? 570mm / 5.7cm / 2.25"?

I bought a kit of engine hardware off of eBay a couple years ago. I believe it was this kit. The price was better than sourcing the hardware locally, and I didn't have to do any homework. :eek: The only issue I had with the kit was with the tach cable retaining bolt. I had to take it to the bench grinder to adjust the tip to resemble the stock bolt. It took less than 5 minutes and has worked perfectly, so I didn't complain.
 
Aren't the screws for the gen cover real long? 570mm / 5.7cm / 2.25"?

I bought a kit of engine hardware off of eBay a couple years ago. I believe it was this kit. The price was better than sourcing the hardware locally, and I didn't have to do any homework. :eek: The only issue I had with the kit was with the tach cable retaining bolt. I had to take it to the bench grinder to adjust the tip to resemble the stock bolt. It took less than 5 minutes and has worked perfectly, so I didn't complain.

I have two of those screws here and I measure them 70mm long. 570mm = 57cm ;) Not 5.7.

I'm tempted to just order through Fastenal. It'll be cheaper for me since I'm not replacing the valve cover screws, those are already allen head I believe and are probably going to get painted.
 
I ordered a sohc bolt kit from Dime City.
Turns out they resell AlloyBoltz kits.
Great quality. All bagged separately and includes revised torque specs for antiseize.
 
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