1985 Maxim-X 750 Recommission - Putting it back together

I recently picked up an 85 Maxim-X 750 and am in the process of going through the checklist to get it back on the road. I was hoping I'd get further along in the list before I had to come looking for help, but here I am.

The first thing I did was check the valve clearance and 10/12 intake valves were out. I got new valve adjusting pads and just put them in. After re-installing the camshafts I can't turn the crank.

I followed the instructions in a post here as well as the service manual.

Any ideas as to why it won't turn now? Did the chain come off the crankshaft maybe? I really hope not... I don't want to have to dig that deep into the engine.

A little back ground on the bike. It was not running when I bought it. It was not running when the previous owner bought it, but he did not get around to doing much to figure it out. The handle bars, fuel tank, and seats were already removed when I got it. My plan was to get the valve clearance back into spec, clean the carbs and fuel tank and see if I could get the engine to run. After that I would go on to doing the brakes, brake lines, sort out any electrical gremlins (lights and whatnot...), petcock, all that stuff, to get it roadworthy. I've been working on old cars with my dad for a few years but this is my first bike.

Any insight as to what I might have done while adjusting the valve clearance that is now preventing it from turning? It was turning fine before I took out the camshafts to adjust the valves.

Edit: I checked to make sure it wasn't in gear for some reason and it is not. Is it possible to get the chain back on the crank without ripping it all apart? Like can I take the camshafts out and fiddle with the chain from the top and try to get it back on? It feels like it wants to turn, but is binding on something. (Don't worry, I'm not cranking on it very hard, I know how easy it was to turn it before and don't want to wreck anything by forcing it.)

 

Re: Maxim-X 750 Recommision

If it was turning over before the valve clearance adjustment, you have to determine what is currently binding it up.

Did you tighten and torque all 4 cam sprocket bolts? Are your spark plugs in so you can be sure you didn't inadvertently drop something in one of the cylinders?

At this point, I would go back through the dissasembly steps outlined in the manual and start over. Remove the sprocket bolts, then loosen and remove all the cam bearing caps, then extract the cams after supporting the sprocket and chain. Remove the tensioner and be sure to note if anything was keeping the engine from turning.

Hopefully, at this point, you can rotate the crank and set it up at top dead center for the #1 cylinder, and then start over with the step by step reassembly.

Let us know what you find.

Tony

 

Re: Maxim-X 750 Recommision - Looking for help

Possibly the chain guide is not in the correct position. But yes, you can get the chain back onto the sprockets at the bottom by figuring with it. I have a couple x engines apart right now and the chain is slack but I can get it back on the bottom really easily......

I'd look to see if a valve is stuck down, or a shim slipped off and is jammed or something.

Yep, you're gonna hafta go back in as far as needed to find the problem----

 

Re: Maxim-X 750 Recommision - Looking for help

I wasn't able to get both the cog bolts in as I couldn't turn it to get at the other holes. The spark plugs are out, but I could turn it up until I had the cam shafts and cogs back in.

I will have to pull the camshafts and cogs again and make sure no pads are jamming up the works, and fiddle with the chain to make sure it's on at the bottom and try it all again.

Thanks guys!

 

Re: Maxim-X 750 Recommision - Looking for help

Loosen up the bolts on the cam caps until they are just more than finger tight. If the crank turns then, but tightens up when the bolts are torqued to spec, look for scoring on the journals.
Since the bike hasn't run for a long time, have a good look at the journals anyway and lubricate well as you reassemble.

 

Re: Maxim-X 750 Recommision - Looking for help

Should have also said, if you loosen the cam caps and it still binds, then most likely one of the pads has slipped out of position and is sitting cross-ways under its bucket. This is very easy to happen on the X since the pads are tiny and live under the buckets (where you can't see them) rather than on top of the buckets like all the other XJ's.

 

Re: Maxim-X 750 Recommision - Looking for help

I had the cam caps too tight. I loosened them off and it turned just fine. (at least as well as it did before...) I retorqued to spec and it still turned.

Glad it was a simple solution, thanks for all the advice. Valve clearances are now all in spec as well so I guess it's time to button it back up and move on to carbs and fuel tank and see if it runs.

So far this has been a great learning experience and I am really excited to keep going. I only hope I can get it back on the road before winter, heh...

 

Re: Maxim-X 750 Recommision

Carbs are all apart and soaking. They were gummed up pretty good. Might have been anti freeze or something, or some kind of additive because it's all green. Comes off fine tho.

 

Re: 1985 Maxim-X 750 Recommision

Glad to see that you got it figured out.

Make sure you change the throttle shaft seals while you're at, especially if you're soaking the carb bodies. And, while you've got the carbs off, swap in a new set of o-ring seals for the intakes. Rubber that's nearly 30 years old needs to be replaced so you can eliminate any potential source of a vacuum leak.

Tony

 

Re: 1985 Maxim-X 750 Recommision

That's a good point. I'll see if I can get those parts ordered tomorrow. Is there a way to check if the current ones are still fine? Nothing is brittle or even weathered at all.

 

Re: 1985 Maxim-X 750 Recommision

As far as the throttle shaft seals go, you'd be doing yourself a favor just putting in new ones while you have it torn down. They may still be good, but you don't want to be chasing a vacuum leak after you get it all back together.

There's a good chance the intake o-rings will still provide a seal. But on the same note, no telling when the old rubber is gonna shrink and dry-rot to the point of creating a vacuum leak.

Most of the time it seems like you can get away with re-using old parts, but I'm sure you'd rather have a safe and reliable ride, and not constantly have to tear back into it replacing parts that should have been replaced previously.

I know the pics below may be an extreme example, but these are what mine looked like a couple of years back when I refreshed the 750X that I imported from Canada:

 

Re: 1985 Maxim-X 750 Recommision

if you have the carbs apart, do all the seals and o-rings NOW. Otherwise, you'll end up right back here again soon......saying to yourself "doh--I shoulda done these when I had the carbs off before...."

Green stuff in the carbs----nope, not anti-freeze.....that's waaaay old fuel. get that out quick, cuz once it hits the open air, it'll harden up quick. It is also quite acidic and can really do some damage if left in there, too.

In the snowmobile world we call it "Green Disease"......LOL

Dave Fox

 

Re: 1985 Maxim-X 750 Recommision

How do I get the diaphragm of the pistons? I don't want to rip them...

 

Re: 1985 Maxim-X 750 Recommision

Well if it's not one thing it's another... I took the carb bodies out of the soak after a few hours last night, wiped them down, blew out all the passages and they looked great. This morning after they dried out, they are now covered in a white residue of oxidation... I thought the solvent I used was fine but I guess not.

I just tried some vinegar to neutralize it but I'm not sure it worked. I'll find out once they dry again. Any advice on what I can do about it? They were looking so good last night... ugh. Didn't have this issue when I did the carbs on an old Triumph car.

 

Re: 1985 Maxim-X 750 Recommision

Yeah, the vinegar did not work...

What's weird is, they were all soaking for the same time, yet they are not oxidizing the same. 1 looks fine, 2 is a little worse, 3 a little worse yet, and 4 is the worst of all...

If I clean them off and then coat them in something like WD40 or a light oil of some kind? I really don't want to watch these rot before my eyes... They looked so good after getting all the gunk and varnish off them.

 

Re: 1985 Maxim-X 750 Recommision - Carbs oxidizing post cleaning

Just brush the white powder off with a toothbrush and wipe them flea with a rag. You can also rinse them off wi hot water and dry them quick with a hair dryerif it makes you feel better

 

Re: 1985 Maxim-X 750 Recommision - Carbs oxidizing post cleaning

Or simply give them a once-over with Scotchbrite, and then a good rub-down with WD40 (one of the few things it's actually good for.)

 

Re: 1985 Maxim-X 750 Recommision - Carbs oxidizing post cleaning

I wasn't getting very far brushing them off, so i scrubbed them down with wd40 and a toothbrush. So far they look pretty good. I'll see if the white comes back in a few hours and if not it's time to reassemble.

 

Re: 1985 Maxim-X 750 Recommision - carb assembly

I've got the carbs all clean and free of oxidation, just wondering if there is any torque specs or certain number of turns to use for the jets and needles and stuff. I haven't seen any in the shop manual or any of the guides, so do I just tighten them until they're snug?

Edit: nevermind I found it... 2 1/2 turns +/- 1/2 turn for the pilot, the rest just snug I guess.

 

Re: 1985 Maxim-X 750 Recommision - carb assembly

The diaphragms are not meant to be removed from the slides. Although, if they are torn, there are ways to fix it.

If I remember correctly, the Maxim uses a similar carb slide as the Venture, Virago, and V-Max. You'll have to remove the metal retention lip to get the plastic retainer washer removed.

Here's a video I found. Be careful not to destroy the washer as you'll want to reuse it. Also, go slow as the metal can heat up quickly.
https://www.youtube.com/watch?v=84DRVc9J5GQ

I've also used RTV, let it cure, and that has worked for quite a while. It is a surprisingly easy and stable temp fix.

If you want to replace the slide diaphragms, check out: http://jbmindustries.com/
http://jbmindustries.com/Dimensions.html
They have some very tough products that are less expensive than OEM.

 

Re: 1985 Maxim-X 750 Recommision - carb assembly

Thanks! The diaphragms are fine and I was able to get the needles cleaned off without having to soak everything. The slides seem a bit varnished but I'll see if they still slide fine before worrying about it. I saw somewhere on here where someone suggested sanding/polishing them with some high grit wet/dry paper which I could do. (I think I have up to 3k grit for restoring/polishing straight razors)

 

Re: 1985 Maxim-X 750 Recommision - carb assembly

Putting the floats back in the bowls and I'm wondering if the PO installed new floats but didn't adjust them at all. The tangs on all 4 are perfectly flat and way out of spec. I'm actually having a tough time getting the first one bent to where it should be. With the carb upside down, the shop manual says to bend the tang (no easy task, they are very stiff) so that the top of the floats ate 17.5mm from the mating surface without gasket. They are sitting at around 19mm or so.

I'm tempted to go straight to measuring the fuel level in the bowls to see how far off they actually are using the tube in the drain hole.

 

Re: 1985 Maxim-X 750 Recommision - carb assembly

Make sure you are bending the correct tang! It should not be very stiff at all.

The float "down stop" arm is quite stiff, but it never gets bent.

See page 5 and 8:

http://www.xj4ever.com/setting%20fuel%20levels.pdf

 

Re: 1985 Maxim-X 750 Recommision - carb assembly

The middle bit that the float needle hooks onto, yes? That's the one I was trying to bend and it was quite difficult, like to the point where I was worried I would start bending and twisting the whole float.

 

Re: 1985 Maxim-X 750 Recommision - carb assembly

They are easy to bend... Hold the float and press with a flat screwdriver, keep in mind that a TINY bend makes a big change in measurement ...

 

Re: 1985 Maxim-X 750 Recommision - carb assembly

That's what I thought, but it is not bending easy and curls up instead of bending nice.

 

Re: 1985 Maxim-X 750 Recommision - carb assembly

Then pull the pivot shaft and use needle nose pliers

 

Re: 1985 Maxim-X 750 Recommision - carb assembly

Double-checking --- you haven't put the floats in upside down, have you?!?!?

 

Re: 1985 Maxim-X 750 Recommision - carb assembly

Tried that as well, that's how I got the end to curl up. Not enough room to grab the whole length. I'll try it some more but was curious if what I was experiencing was normal.

 

Re: 1985 Maxim-X 750 Recommision - carb assembly

Over the last couple weeks I cleaned the fuel tank, cleaned and rebuilt the petcock and cleaned the fuel level sender.

Today I checked the fuel level in the carb bowl using the hose tool attached to the drain and it checks out in spec, so that's good.

After wrestling the carbs back onto the bike, tightened the clamps on the manifold... Go to start getting the air cleaner boots on and there's something missing... one of the drain hoses from the carbs. That's odd, it was there a minute ago. Search around and find that it on the ground, the T junction broken off... Not very impressed with myself. I was so hoping to see if it would start, but now it looks like I'll need to order a part and remove/reinstall the damn carbs again.

Oh well...

By the way, where do the 2 drain hoses from the carbs go? They were disconnected and the bike partially disassembled when I acquired it.

 

I've got a wiring question. I don't think the stock controls (for run, off, start) are what is on the bike as the plugs do not match. I am wondering if the 2 red/white wires coming off it are unique in any way? I want to change the plug to match the bike but am wondering if I can just match up either red/white wire with the other side or if they are somehow unique. I've looked at the wiring diagram but can't make any sense of it.

 

I just got the bike back from the local bike mechanic this week. Last summer I had done the valve spacing, carbs, battery, spark plugs, and fuel tank. The engine would run but would leak fuel everywhere. I took it to the local shop a few weeks back and now it runs great! He put new tires, did the brakes, brake lines, syncd and tuned the carbs, and generally went over the whole bike making sure it was good to go on the road.

I am so pumped to finally be riding this thing. It's a blast!



Got a question now tho, what should the RPMs be at in 5th going around 60mph? It seems high to me but I'm used to cars. It's around 4500 rpm.

 

That sounds about right. 65 MPH is seen at 5,000 RPM. You're right in the midrange of the engine and can run like that all day long.

 

Learn to enjoy the sound of it whining like that.... It's supposed to--- and YOU'RE supposed to

 

Oh I enjoyed it, just wanted to make sure it was normal. I've only had out up to 6k, easing into it. Lol.

 

6k.... You're juuuust starting to get into the powerband. Once it comes in, you're gonna feel " the X factor"

 

Yah I figured I was about 1k from the real bike. It's my first bike and my third day riding, figured I'd take my time. Heh

 

DO more than ease into it. Get thee to a beginning rider's course. There is a huge skillset required of a motorcyclist if you want to remain an uninjured/non-deceased motorcyclist for long. You might also benefit from getting a copy of David Hough's excellent street skills book, "Proficient Motorcycling."

 

^ +1 on Hough's book and the beginner's class . . . .just do it!

Bought it three years ago and usually finding myself re-reading it every winter waiting for spring.

 

Thanks for the tip, I'll check out that book for sure. Unfortunately there's no course locally but there it's one a couple hours down the road.

edit: Just ordered that book, thanks for the tip!

 

So I noticed while warming it up to go for a rip this evening that there was some arcing between one of the spark plug boots and the cylinder head. I assume I need to replace the boot, but is that possible or do I need to replace the whole coil assembly? Also, how serious an issue is this? Do I need to keep it parked until it's sorted? There are no misfires and it runs great.

 

Are you referring to the large/thick orange boot at the base of the hard plastic resistive PLUG CAP, or the small black boot at the top of the hard plastic resistive PLUG CAP, where the spark plug wire (from the coil) enters the PLUG CAP?

 

The caps and boots are replaceable, and the man above has them in stock.
Start her up in a dark room or after sundown and check the state of the wires. They can be replaced too, but it's a bit more work since they are moulded into the coil body.

 

It was arcing here, at that round notch in the valve cover.



But of course when I went to take a little video of it this morning it was not doing it...

 

OK order new plug wire caps and the rubber boots. They screw on/off of the plug wires.

 

While waiting for the new cap assemblies to come, can it still be driven? What if I give the arcing cap a few wraps of e-tape? I can wait until next week when they come but I just want to ride! But I also don't want to cause a bigger issue by doing so...

 

I've read that it's not good to power the TCI when there are no spark plugs attached (for example, disconnecting all you spark plugs when doing a compression test) but I would think as long as the coil is discharged and the spark has somewhere to go the risk of damaging anything electrical is minimal.

Now depending on how bad the arc is, you'll have the associated performance problems, possible fouled plugs, un burnt fuel entering the exhaust. etc.

That said, I'd patch it up and ride.

 

As long as there is an arc to ground the TCI won't be harmed. Vynal electrical tape will not insulate voltage that high. You can wrap the caps with a self-amalgamating tape (often sold as miracle tape), which will insulate that.

 

Cool thanks guys. Should hopefully have the new caps this week.

 

Can anyone tell me if there is a colant overflow/recovery tank that will work on this bike? Mine is getting brittle and cracking a bit but it doesn't look like there is an OEM or aftermarket replacement available... If there is nothing that can work, I guess I'll just have to try to plastic weld it or something.

ETA: also, how can I go about testing that my fan comes on at the right time? I haven't ever noticed it come on and it's gotten pretty high on the temp gauge a couple times...