1981 XJ650 Midnight Maxim Restore - (Picture Heavy)

Since you're going to get new coils, and considering what you've been doing to/for the bike, I'd highly recommend spending the money ( iI know that's not what you want to hear) and get a set of Dyna-Coils. You'll NEVER have trouble with them again, and the ignition will also be much stronger.

You could get a set of known good used coils and use those.....I've never heard of the coils causing the tci to blow. In my experience, blown tci's come from a regulator ceasing to work which causes an overload of electric and burns out the tci as well as other fuses, lights, etc...... My experience is that the coil burns out and you're stuck with a dead coil til you replace it.

Think seriously about the dyna coils.

Dave Fox

 

I was leaning towards the Dyna Coils already. I know Len has them for over $100 cheaper than the OEM ones. Granted there is also the mounting kit, cables, and cable ends that would all be needed but would still be cheaper than OEM coils.

I checked around and cannot find used Dyna Coils anywhere. Len sent me a list of available coils/wires/caps available through him as well as the gaskets I will need to replace the head gasket.

I now have a bit of reading and decision making to do, and I expect I will start taking the engine apart down to the head gasket and do a thorough inspection mechanically of the internal components. I am sure you will be seeing a few more updates and pictures this weekend as I get down through each level of the engine.

Thanks again guys for your help, I probably would not have gotten this far this fast without your help!

 

Gawd, that thing is gorgeous! Nice work, man!

 

Ill have to check but I have a couple of side covers if I have a right one i could sand it down and you can have it (its red) what all exactly do you need because most all of the extra parts I have are already on my bike so I have no use for them. I dont think it has the maxim symbol on it though but the one on my tank is falling off.

 

So today was SUPPOSED to be a motorcycle work day, but in total I only got in about 30 minutes of touch up paint work done on the frame. I got sucked into a family house project for the day, but it is a small price considering I have taken over the garage almost every weekend this year for the work done so far.

I did have a chance to start to sift through the information Len sent me about coils, caps, wires and so on (all 37 pages of the email printed - and damn is it thorough), and I have YET to decide on my exact replacement coil/wire/cap combination.

I also NEED to spend tomorrow tearing into the engine and removing the head so I may thoroughly inspect the valve seats, cylinders, clean up the head for a new gasket, clean up my intake and exhaust manifold mating surfaces, check for timing chain wear and guide wear, and check for any other issues I may run into BEFORE I place my order for parts to Len.

I've wisened up in the sense that I will NOT give an estimated time when I expect to be able to ride because as soon as I say 'Okay, riding tomorrow' I discover a new problem TONIGHT or even worse AS I am getting on the road (or attempting to). At this point I have come this far and only really painted the bike, done some light body work, completed my front brake maintenance, and done some LIGHT upgrades but not touched the engine aside from an oil and filter change. Clearly I should have planned to spend as much time INSIDE the engine as I have spent on things away from it.

On the bright side, since I will have the head off the engine I think this will be a PERFECT opportunity for a fresh coat of paint (I can feel my wallet cringing as my fingers type those 'famous last words').

If there is anything to be taken away from this for anyone else looking to do such a rebuild on a bike that has sat for any length of time it is to make a checklist and NOT ignore any problems you had before. Secondly TAKE YOUR TIME and DO NOT CUT CORNERS as I attempted to with cheap paint and no topcoat on some engine components.

Thanks but thanks to Dave F. I have a side cover already painted and installed to replace the missing one.

 

Not a problem but the funny thing is I didnt realize this thread had 6 pages and I thought we were just on the first still. (facepalm)

 

I might have missed it ... what is the gloss black finish you used on the carbs and have you had fuel on it yet?

 

That black gloss paint is high temp engine ceramic paint I purchased in an aerosol can from Advance Auto Parts. It was a primer and paint that then had to be baked onto the parts.

The carbs were together and in contact with fuel about 2-3 days after the paint was baked on. Keep in mind that the parts (while not being baked or painted) were stored in a non-temperature controlled garage between temperatures of 40-50 degrees F.

Given the conditions above, the paint DID come in direct contact with fuel when one of my carb bowls was not seated properly and leaked fuel. Unfortunately it ran right under the paint and the paint wiped off down to the bare metal.

The carb bodies still look fresh and have not been impacted by the presence of fuel VAPOR, and I did discover that once allowed to dry naturally the paint seemingly re-adhered itself to the metal (though clearly this is NOT a sign of 'fuel proof' paint).

 

Okay so quick update on the progress. My busy weekend gave me only this afternoon to work on the bike. I finally did get through the ignition system options from Len, and settled my mind on the Dyna Coils with all new plugs, wires, and the mounting kit.

I took the head off the bike today and inspected the various components and mating surfaces. Good news is the engine seems to be in good shape. Cam Chain guides are in good shape, cam chain looks to be good, pistons and rings are in good shape, and the carbon buildup on the valves will be easily taken care of once my head gasket kit comes in this week. I may be putting a quick coat of high temp paint on the uppers while I have them off the bike, time will tell if that pans out.

Some pictures of the engine from today's work. Most are from before I started scraping gaskets.

 

Got everything back together and I need some help. First off, let's start with the configuration:

Engine:
New gaskets from the cylinder head up, bolts torqued to spec
Timing dead on, all points match up, double and triple checked
Valve clearances in spec, double checked
Oil level appropriate
Compression readings: 1 + 4 @ 130-133 psi. 2 + 3 @ 118-123 psi.

Carbs:
Thoroughly cleaned, no blocked passages
New gaskets all the way through
Float levels set all at 3mm (checked with clear tube)
Bench sync'ed the butterfly valves
Idle screws set at 2.5 turns out. New washers and o-rings

So here is the deal:
With this setup, the bike will START and run for about a second or two. As soon as I try to give it a little throttle, it dies. Will not start again for at least 10 minutes, and then does the same thing. Idle is smooth until it dies, sounds to be around 1000 rpm, doesn't run long enough to get a good reading on the tach.
Will start with quick start sprayed directly into the vacuum ports on each carb-to-engine boot and will maintain at higher revs.. if I let it drop below 2k then it dies, and back to square zero.
The bike doesn't run long enough to get a good idea of which are firing by exhaust temp when started without assistance. I don't have an IR gauge, so determining pipe temp is difficult if not impossible. All pipes DO get warm by a 'back of the hand' test. Exhaust smells rich, sounds deep and appropriate.

So where do I go from here? Adjust idle adjustments?

I know I need to have it running to do a proper vacuum sync, and I REALLY want to avoid using quick start.

EDIT:
So did some extra testing on my own.. here is where I stand with the bike:

First off, given up ether as a starting agent. Switched to PROPANE gas pumped from a propane torch (NOT ignited, obviously) directly into the intake on the air box to get her started. I read a post on here suggesting propane to determine leaks in the carb-to-engine boots, so I thought it was a safe(r) alternative to quick start, though clearly NOT a long term solution - just for diagnostic purposes.

Moving forward, after the bike is STARTED with the propane, it WILL NOT maintain idle. Throttle must hold the engine over 2000-2500 rpm to keep the bike running, and it STILL dies below 2k after 30 seconds to a minute of revving when allowed to drop below 2k rpm.

Played with the idle adjustment screws. At 2 turns out, no firing. at 2.25 turns to 2.75 turns seemed to be the best result. 3 turns out was no better. Adjustments were done in 1/4 turn increments.

All exhaust headers hot, hard to determine which are hotter (or not), still no IR gauge or other accurate temp gauge. MAC 4-into-2 exhaust joins 1 + 2 before the muffler clamp, and 3 + 4 similarly.

Watching the fuel filter and with two extra sets of hands, confirmed fuel being pulled into the carbs when cranking/running.

Letting the battery charge up some from my starting attempts, will start at my diagnostics again tomorrow (neighbors have middle and elementary school children).

Tomorrow going down to my local Yamaha dealership.. I've spent enough there on tires and various parts, I am going to ask them for advice OR to walk me through final tuning if I can't tackle this tomorrow on my own. Any advice and input before that point is VERY welcome.

 

I'm far from a carb expert but I know a bit and to me at least it sounds like you've got an issue with your enrichment circuit or pilot jets or possibly both. The way you describe it dieing out makes me think it's choking itself to death. Ether or propane will cause it to fire do to the higher volitility of the gas over gasoline. If it where me i'd start with the enrichment circuit.
Hopefully one of the carb guru's will chime in and give you more advice.

 

Okay so update on the bike after today's tuning work.

First off, pulled the carbs off the rack. Redid the bench sync them with 1/4" slips of photo paper. Carb 4 was completely closed, holding 1-3 open and causing high revs.

Pulled the carb hats off. Noticed a few diaphragms were not seated properly. Fixed this issue, double checked my work. Also had the piston on cylinder #3 not returning back to fully closed. Fixed this issue.

Reset the idle adjustment screws to 2 turns out.

Checked the alignment of the carb bodies to each other. All lined up, no issues there.

Carb jets all clear. Only change from stock is the primary air jet was changed from a 195 to a 205 in each carburetor.

Installed the carbs on the bike, began testing again. Bike would not start on its own. Used propane in the airbox, got her started. Running MUCH smoother, still doesn't want to start on its own.

Pulled the plugs after a good 7-8 minutes of idle to check fuel mixture. Plugs 2-4 are a light tan color, 1 is still running lean. Adjusted the idle adjustment screw for 1 and started the bike back up.

Took her for a spin with this configuration. The bike is running with WAY more power than before, at full throttle I had to really hold on. Overall VERY impressed with the power the bike has now, despite not starting.

Pulled the plugs after this and determined fuel mixture under load is lean. Exhaust headers discoloring at the head, plugs all very close to white. Picked up some brass washers #6, put one brass washer shim on each carburetor.

Did not have a chance to get back on the bike and ride after doing the throttle shims. I had two beers while working after my first ride, so safety first!

Tomorrow I plan on draining the remaining gallon and a half or so from the tank and filling with fresh gasoline before I do anymore work trying to get it to start. I suspect this could easily be part of the problem.

 

do what you can to get the carbs synced on the bke.

DaveF

 

John, Sounds positive - Just curious - Wy did you let more air into the mixture with larger main air jets? And how exactly did you "shim " the carbs?

 

dmcoach, I may be wrong, but isn't the pilot air jet the larger of the two? I agree on the size, 195 should be correct for the pilot air jet in stock configuration on an 81 650 Maxim.

 

Dave, I will certainly be doing my best to get the carbs synced on the bike today. Part of my challenge is NOT using a colortune kit right now and this week is going to be 70 F every day, so getting her running and STARTING on her own is definitely a priority.
A friend of mine who used to work in an independent shop servicing older Hondas told me a trick of turning the idle adjustment screws out on each carb until the engine starts to rev highest, then turn DOWN the overall idle adjustment until I get around 1050 revs. I will be attempting this today, results will come when I either am successful or get stumped.

Coach, in response to your first question the 195 air jets ARE stock on the 81 Maxim. The 205's are from an 82 YICS carb rack that I bought as spare parts. That particular air jet and the threading of the idle adjustment screw (fine threads on the 81, course on the 82) are the only difference between the model years as far as I can tell.
The way I shimmed the carbs was to take some thin (.5mm) brass washers I picked up from Lowe's, pull the piston / throttle needle, unscrew the throttle needle from the piston, drop a washer down into the hole where the throttle needle sits, and reassemble the carbs. This gives me just the thickness of the washer difference in the height of the needle in relation to the piston. The package of 12 brass washers was about $1.25 and means I have spare shims if I need to increase the fuel mixture more.

Now it is time to go get started on fine tuning the bike! First going to get some fresh gas for the bike, swap out the old stuff and see if that helps!

 

I hate to ask this, but I've read back through the thread (not super thoroughly, admittedly) and looked at your "done" list and I don't see...

Valve clearances. Are your valves in spec, prior to all this carb fussing?

 

Okay valid point. Let me recap the 'done' list in chronological order:

Tires, front and rear, done December 2010
Front caliper and MC rebuild, pad replacement (front and rear), done Spring 2011
Shocks front and rear, done Summer 2011
New Mac 4-into-2 exhaust system, done Summer 2011
Complete repaint / restore of ALL components including engine, done Winter 2011-2012
New steering column bearings, done February 2012
New seat, done February 2012
Full carburetor overhaul, new fittings, o-rings, seals, thorough cleaning, done February-March 2012
New braided steel brake lines (front), done March 2012
Head Gasket Replacement Kit, done March 2012
Valve clearances, timing, full inspection and all checked out, done March 2012
Fresh oil and filter, done March 2012
Fresh gas cap, tank lining, fuel lines, done March 2012
Carburetor tuning and throttle needle shims (brass, 1/2mm) installed, valves and timing double and triple checked, done THIS WEEKEND, March 10th and 11th 2012


So with that being said, let's get into how she runs, shall we? First off, let's keep in mind that I did NOT have access to a colortune spark plug kit nor do I have access to an EGA or a proper vacuum gauge set. I also had no accurate way of measuring exhaust pressure or temperature - the ONLY tools I used to tune were a few screwdrivers, a spark plug socket, and my hands and ears.

Once I had a decent bench sync completed, reset all idle fuel screws to two turns out, measured and confirmed throttle butterfly valves all set equally, compression test results all within normal range, and she started right up. Running was a bit rough at first. A plug chop showed only cylinder 4 at the proper fuel mixture after initial running. A bit of adjustment by ear and with the assistance of FEELING the exhaust headers and she started sounding MUCH smoother.

A quick side note on HOW I dialed in the fuel mixture and carb balance without the use of gauges or an EGA. To start, the bike WAS stationary, on the center stand with a box fan pointed at the engine head at full power. As the pipes warmed up, I checked them by hand (with the paper towel doubled over as a buffer) to see which pipes got hot quicker.

The basic principle was that under the assumption that with each cylinder was getting the same fuel / air mixture it can be safely assumed that a pipe that heats up quicker implies more airflow into that cylinder. With this basic assumption, I was able to adjust the screws connecting each carb throttle shaft until the engine ran smoothly. At this point I did a plug chop and used the plug color to fine tune the fuel mixture screws.

Needless to say that with this being my first time tuning a carburetor system by ear, but I am fairly certain I nearly nailed it. Improvements since before I started the teardown and rebuild include more power, stable idling, smooth acceleration, no revving up after coming to a stop, no need for quick start or other starting agents, more wholesome sounding exhaust, proper plug chop colors, and a MUCH bigger smile on my face when I get the opportunity to open the throttle.

 

I just acquired an 1982 Yamaha XJ650 which is basically the same bike. This is my first bike an I cant believe how much I learned about it in one day just from this forum post. This was a very enjoyable post and I am sure that I will read it again and again. Thanks for sharing!

 

Everything I posted here was compliments of the forums here. I have an advanced knowledge of auto repair (not certified but going to school for auto work this fall) which helped with the basics, but everything motorcycle specific came exclusively from this forum and the Haines manual (also acquired on this forum in pdf format).

Good luck with your project and I hope to see as much about your bike as you have seen about mine.


On a random side note, tomorrow when I get off work I fully intend to get a few shots of the bike in the sunlight now that the paint is (mostly) done. As everyone here knows you never are 'done' with work, but at this point I can finally proudly ride around on my bike knowing I am on a sound piece of machinery built over three decades ago.