Purchasing xj650

Yep these engine are really just air pumps. Sure there is a fire in there, but the air come in and goes out. How well the valves work (open to the right depth, time and then seal tight) makes the air pump work better.

 

Yes air pumps is what they are. Spinning an engine on the starter without fuel would just pump air. Add fuel and with all the other parameters correct they burst into life.

 

Modern cars actually have variable valve timing by having dephasers fitted on the end of the cams. Its all about maxmizing power and efficiency throughout the rev range.

 

Well that makes sense, cheers

 

Thanks to Chacal I was able to source I a new clutch cable here in the UK - the PO had fitted a 4K0 clutch cable that was far too short and didn't pass through the front forks.

This meant when steering left the handle bars were hitting the cable before the steering stops - that would be an MOT fail here in the UK

 

Nice find. Are you on yamahaclub.com? This is definitely the forum to be on for the XJ series. Work out the electrical before you start pulling cam shims. You may find something you don't want in the head, like cap galling or excessive lobe wear. If it will run and build compression I would not take the engine diagnostics much further just yet. Once you try tuning it and you find issues with compression or what-not then you can decide to either swap the engine or tear it down. I have a 650 head in the garage and it looks very similar to the 550, just with larger pistons, head and case.

 

Thanks, the bike is running fine at the moment (if you exclude the fact it's running rich). I've yet to split the carbs, ultrasonic clean and replace fuel o rings and butterfly seals.

New shims will be here tomorrow so will fit them asap and will then move onto splitting the carbs from the racks. Once all done, it's a syncing job.

I looked at the site you linked however xjbikes is dedicated to the xj series, the link you posted isn't.

 

Oh, we're friggin' dedicated! Some of us are so dedicated, we should be committed!

 

New shims are in and all valves are in spec.

Two questions:

1) Can the shims be saved and be reused at a later date?

2) Does anyone recognise these as being the original shims from factory?

 

Yes, just make sure you keep them in oil so they don't oxidize as corrosion will affect the dimensions of the shim.
I'm not aware of anyone that makes shims for these heads. Every shim I've seen is OE.

 

1. Yes. Hogfiddles runs the airhead shim pool, so any that you don't need can be sent to him as a donation.

2. The original shims will vary in thickness, and be ink stamped with a capital Y followed by three numbers designatng their thickness.

 

29mm shims are common. There are several manufacturers of them, both aftermarket and OEM for other brands (BMW for example).

The primary reasons for seeing mostly OEM shims when changing them is that hardly anyone does the maintainace as required, and back in the day most people had the dealership do everything.

 

Sorry I should have posted the pic.

The only issue is I'm in the UK so after postage and import tax its not worth sending over.

I'm currently in the process of stripping the carbs ready to be put in the ultrasonic tank

 

Another question... so my idle screws had the brass caps on so I'm assuming they have never been touched.

Once the screw is removed I looked down and noticed that only one of the slots doesnt have a metal disc on top of the rubber. If this is from factory, will it really make a different?

 

1. Those are the OEM valve shims. There is no definitive way to know if they are the shims that were in the machine when it left the factory, or if they were installed during a valve clearance check.

2. What you are seeing is the washer that protects the o-ring from the spring, and the o-ring.
They tend to get stuck in the bores. Take a darning needle, heat the tip, and bend a small hook into it with pliers. You now have a washer/o-ring retrieval tool.

The order of assembly onto the idle mixture screw (while holding the screw) is: spring > washer > o-ring. You will need to use new o-rings. The screws, springs, and washers can be reused (unless the needle tip of a screw is bent or broken).

3. Your macro-photography skills are quite good.

 

Thanks k-moe.

I cant take credit for the pictures, it's my mobile phone that does it!

I'm stuck on carb 3, I cant see to take this (see pic) off in order to get to the o rings.

 

The throttle plate is out, and tha'ts usually the difficult part. Have you undone the nut that's under your thumb?

It looks like there was some fuel leakage (and oil leakage). You will probably have to wiggle on the spring retainer (L shaped bit on the end of the shaft) to get it to come loose.
Since you're replacing the throttle shaft seals you could just go ahead and soak the carb body as it is now to help free things up.

 

Yes I removed the nut, gave it a wiggle and leverage with a screw driver but nothing budged. I'll soak it in the morning and see what happens.

I've already soaked 2 of the carbs with decent results - soaked for 20 mins at 80 Celsius

 

Thanks to everyone for the help with this. Over the last 24 hours I've stripped, cleaned, replaced seals and rebuilt my carbs. Here is some before and after pics.









I bench synced them using the little holes in the top method and I've hooked them back up to the bike. At first start up the revs didn't even soar and it idled at a steady 1100 revs but my preference is around 1400/1500 as the bike sounds healthier.

I replaced my spark plugs and instead of being carbon fouled, the the overhanging part (that creates a spark) had cleared up, a sign of running better perhaps?

So now I'm onto the syncing stage. I've been looking to invest in a Morgan carbtune pro however I've not done anything like this before. I searched the forum but couldn't find a how to on how to use it alongside the yics tool (which I already have). Can someone point me in the right direction?



Maximus.

 

1. Set your idle speed after the bike is fully hot. 1400-1500 RPM full hot is a good place to be.

2. You don't need to use the YICS tool to synchronise the carbs. You'll get 99% of perfect without it.

3. The ground strap should be fairly clean (greyish is fine), and the insulator should be grey to tan. There should be no grey bumps on it (a sign that you are too lean and the aluminum from the piston crown is melting). Nor should there be soot (a sign of leanness and of richness, but more typically richness).

4. As you synchronize the carbs you will be adjusting the idle speed again, and do a final idle speed adjustment after a 10 to 15 minute ride.

If you hear any popping on deceleration (as you rapidly close the throttle like you would coming to a full-stop) the idle mixture is set too lean.

If you have any concerns about your fuel mixture post pics of the plugs so we can have a look. Good light, neutral background, lined up left to right cylinders 4-1, insulator, base ring, and ground strap all showing.

 

2) I dont need the yics?? So I've wasted $50, great!

3) no grey bumps at all, if you remember from my previous post the plugs were carbon fouled and one was wet - insulator is black but ground strap is now grey... I'll post pics tomorrow at some point

I dont suppose you would know how to use the yics in conjunction with the morgan carb tune?

 

there are 2bolts, 1 on each side of cylinders at rear they are just below the level of the carb boots .
remove them clean the tunnel with gun solvent and cleaning rod then tool is inserted locked and then sync carbs.

some have tried to remove bolts and cracked/broke the passage. that is why I do not use the tool

bolt upper left

 

You can use it, but you don't have to.

The YICS manifold is just below the head on the back of the engine. Carefully remove the bolt and crush washer (the washer will have to be replaced or annealed before closing the manifold back up).
Insert the YICS blanking tool and tighten it to expand the seals.
Synch the carbs as normal. #3 is the master, everything synchs to it. Synch #4 to #3, then #1 to #2, and finally (using the #2 synch screw) synch the 1-2 pair to #3.

Here's the part where the overheating discussion matters. When using the YICS tool the engine can get hot enough to melt the seals on the tool (depending on who you bought it from and what the seals were made from). Using an electrical cooling fan blowing across the engine will keep the manifold cool enough that the seals won't melt and get stuck.

Following the synch, remove the tool and allow the engine to cool before installing and tightening the manifold bolt. Treat the bolt like it is a oil-pan plug. Tighten it enogh to crush the washer for a seal and no more. The reason for allowing the engine to cool, and taking care when tightening, is to help ensure that you don't accidentally cause a crack in the manifold (this comes up occasionally, and is difficult to diagnose since even a very small crack will result in a vacuum leak in a location that one would not normally expect).

 

No you didn't.... you bought a tool to show off at the next Carb Clinic you go to..... you show them what it is and you say "THIS is the YICS tool that everyone think they need to get. Look at it close. Memorize what it looks like, Cuz you'll never need to see one again".

BTW, I have one and it's still in the package. I show people at the carb clinic what it looks like.

 

Silly question but if I block off the left passage (sitting on the bike) would I be then be adjusting #3 & #4 or #1 & #2?

I thought the yics ports were to block off individual cylinders so imagined there would be 4 ports

 

The tool blocks off all of the ports when installed. The synch order will not change regardless of what side you insert (or do not insert) the tool into.

Sitting on the bike, cylinder #1 is on the left.

 

Well that just confuses me even more so.

Do I only need to insert the tool into one side to do the entire sync with the yics tool? If so why is there two ports?

 

Also, gunson colortune prior to vacuum sync with morgan carb tuner- yea or neigh?

 

yes color tune sync check color again if adjusted re sync

 

http://www.xj4ever.com/HCP5460 YICS tool.pdf

 

Thanks, do I need to use both ports or just one? I'm confused as to why there are 2 ports.

 

PLEASE PLEASE PLEASE PLEASE

RE-read the PDF. Especially the bottom of page 1, and the top of page 3

 

I have done, I even have the paper copy that came with the tool when I ordered from Chacal.

My confusion lies with it being one or two passages - the instructions say to open up both sides of the port so I imagine it is just one big port and doesnt matter which side i open I put the tool in

 

I put mine in from the lest side and saw the end of it just inside the right side. You have to have the O rings lined up in the chamber to allow the tool to block off each chamber from each other. Unless you really want to use the tool to say that "you used the tool" go for it. As others have started, you can do a really good just without the tool. Cleaning the passage should be done as after yrs of running and sitting, those passages might get a little dirty.

As stated above and by the people on this forum that have done so many of these bikes, the tool is "over rated" and does need to be used.

 

There are not two ports, there are 4 (one per cylinder). The manifold has two ends to allow access for cleaning and was (still is) less expensive to machine in a production environment.

Envision a length of copper tubing with four equally spaces holes drilled perpendicularly into it. That's how the manifold is shaped. Now imagine that there are four tubes connected to those holes by o-rings. Those are the YICS ports that lead into the intake tracts of each cylinder.

 

Fitz is the man (still).
Behold: a diagram.
#8
The dark blue is the YICS system. Light blue are the intake tracts.

 

I think the reason for removing both plugs is so the tool can be aligned properly.

 

For what is worth then I may give it a miss at first but if it doesn't run smoothly after then I'll use the tool. Thanks all for the help

 

If you execute the sync and colortune properly you will have no issues with how it runs not using the yics tool

 

Got ya

Colortune should be here tomorrow followed by the morgan carb tune on tuesday

 

Silly question time.

So I was tuning in the air fuel mixture screws today (only had to adjust one) with a colortune. However on spark #3 the cable had broken inside the spark cover and so wouldn't give me a true spark.

Would this:
1) stop the cylinder firing
2) cause the bike to periodically sit at a higher idle?

I also have a spare one which is labelled 1 & 2 for sparks 1 and 2 but I'm not sure if this can be used to replace the 3 and 4 cables that are currently on the bike.

 

Yes to both questions 1 and 2.

You're confused as to what goes where, or things are mislabled on the spare coil.

As you sit on the bike the left coil provides spark for cylinders 1 and 4. The right coil provides spark for cylinders 2 and 3.
The only difference between the coils is the length of the plug wires. The plug caps are different, but only in physical form-factor to ease instillation and removal from the inner plugs.
You can swap them around so long as the wires are long enough to reach without putting stress on the wires.

 

Thanks k-moe I was getting frustrated as to why it kept idling higher... now I know!

I'll be swapping it out tomorrow

 

So I swapped the coil out for a replacement and tuned the bike using colortune and Morgan carbtune pro.



The bike runs very smooth now and revs as it should - I went up and down the street a couple of times to test it and it all seemed fine.

However (theres always a however), at one point the bike bogged a little and required more gas, upon inspection it had splashed some water from the exhaust. I then went to the bottom of the driveway (sloped) facing upwards and gave it some gas and set off - more water came out. I parked up and there was a slow drip from the exhaust where the muffler meets the pipe.

Can this be linked to my earlier (still there) issue with the white smoke/steam coming out? Maybe a sign of the cylinder gasket going?

Also (sorry) my right indicators flash much faster than the left one does, any ideas?

 

FIrstly, there is nowhere for water to leak from on an aircooled engine.

Secondly, condensation does collect in the exhaust system and will drip out/ steam out as the engine warms.

As for the indicators: check that all of the bulbs are of the same wattage and type.

 

That's what I thought, do you think the steam is where the bike hasn't been ran in a while? I don't think it's been used in 16 year... at least that's when it was last road legal.

It just seems odd that a collection of water or other unknown liquid built up and came out of the exhaust. It doesn't smell of fuel.

 

condensation happens quickly in humid weather. rain if bike is out side can blow into exhaust

exhaust has a little hole in bottom to let water out.

 

That would make sense, its rained most of the day and its been quite warm too. The bike however is stored in a garage and only came out for the tuning today and for me to ride up and down a couple of times

 

dew point is what makes it all happen

 

Anyone have instructions/diagram for the correct routing of the throttle cable for an xj650 maxim?

I've replaced it with a new one from chacal and whenever I turn the steering to the right it revs the nuts off of the bike.

I'm looking to book it in for an MOT and if they pick up on this they'll fail the bike.

Currently is is routed (sitting on the bike from throttle grip to carbs) to come in from the handle bars, under the tank and over the coils. It then goes under the frame where the main loom sits and connects to the carbs.