750 rebuild

Part one

Now I have sorted the lack of power problem on my 750D (exhaust gaskets!) I am getting set up to take the motor apart to fix No. 3 cylinder. Not sure what the damage is going to look like yet, but as I have a spare parts motor I am attacking that first to see what problems I may encounter and what condition my spare is in.

My spare is the original motor. It has done 129,000 Km. At some stage the cam chain has been replaced, only thing done to it by PO in ten years of use!

What I have found:

First, the large (30mm) nut that holds the clutch basket on is very hard to remove "on the floor", easyer to do it on the bike unless you have a large vice and sturdy bench (I don't).

Second, the bolts that hold the carb boots onto the head can break (flush) with almost no effort, leave them unless you have to remove them :-( .

Third, check valve clearances before taking the cams out (several were closed).

Fourth, the manual states you can remove the cams, chain, head and cylinder block with the engine in the bike. I would not like to try removing the cylinder block in this way as the block seemed to get caught on a stud thread and a locater on the block and required some manoeuvring to get it off, it is hard to hold the block dead even (without that vice and bench!). A job best done by three people, one on each side lifting and one guiding the pistons out. The amount of dirt etc. (lots!) that fell down from the studs where they go through the block makes the job worse, manual recommends removing the block upside down to avoid dirt falling into the crank.

I have got the motor to the point of having the pistons off the rods. As I only want top end components as I fear major damage to No. 3 in my "good" motor that is as far as I am pulling this one down at the moment.

Pistons, rings etc are original (marked 22n) and standard size (00). The primary (or starter) chain has a inch of play, the guide has had it, gears clunk but it ran well and used no oil.
After 129,000 Km the condition of the top end was not bad.
I have gone through the manual checking components for wear and within spec. The pistons are within spec, the ring groves are as well. The cylinders are within spec and will take just a debur and hone (at bike shop). The rings are out of spec with .4 mm end gap, spec is .35 mm so will need to be replaced. The cam bearings show lack of oil change with bad scoring.
Next job is removing the valves and springs to check for spec, I will not be using this head (because of the cam wear).

Now to go to the shop and find out what a gasket set and rings will cost.

Stay tuned for part two ;-)

 

Interesting story keep the narrative coming.
Primary chain will be errr "pricey' and there are NO alternates to the dealer. However it must be replaced, no choices there. Versah makes a decent gasket kit but they start at $100 and there are no oil seals included.
Yamaha Dealer cost is just usurious.
Rings and bearings ? maybe.. the same source /cost problem. Few actually 'rebuild' these motors (in the real sense, as opposed to a few bits and some fresh paint) as the parts pricings simply preclude it.
But in fairness you have gotten yr moneys worth /use out of it.
G'luck.

 

Excellent information coming from you, Danilo.

I have always preached about those Intake Manifold Cap Screw's snapping-off. It's a crying shame the Head threads or the Cap Screw threads weren't given some treatment to prevent that from ever happening.

Aside from a pre-teardown pressure washing which might have limited debris from entering an area needing to be kept clean ... the safest method for preventing anything from falling into the workings is:

"Cover and Stuff"

Cover the whole area with something clean and lint-free if you can.
Stuff cavities and areas where a dropped - "Anything" - could get away and really complicate matters.

(I usually cruise by a thrift store and get a couple of threadbare bed sheets. I cut-out sections to cover the work. I also cut a 3-inch wide and very-long section to use as the "Stuffer." Stuffed with clean sheet ... any void or section where a small part might escape too can be stuffed with linen. When you are done taking-down something or buttoning-up etc. -- You just grab the end of the length of linen you stuffed the cavaity with and pull ... easy as that.)

 

I have heard that you can have the chains made up for a reasonable price.

And as KiwiXJ750D is in NZ then a call to R R Fisher may yield a cheaper alternative.

I have heard of a place here in Aus that makes them as well. They are simply a HyVo chain and used in lots of applications. Guides ad tensioners will most likely have to be genuine yamaha.

 

Part two

Well today I went into town and got some prices.
I am using NZ$ which is about NZ$1=A$0.85=US$0.68

Primary chain $88 for a aftermarket one!
Head gasket $87
Rings $58 per cylinder
The seal that goes round the cam tunnel (long rectangle) $78!!!
Base gasket, base cylinder o rings, other o rings and top end seals (IE everything else needed for the top end) $100
All genuine Yamaha.

Total $585

A few above points answered, I am not doing up this motor and don't need the primary chain, the one in the bike is OK.
Yes cover and stuff and a bloody good clean! Some one else using a vacuum cleaner to suck up any loose dirt while lifting the block might help too?
Dirt and stuff tends to get into the head stud passages hard to remove with everything intact. I did not worry with this one too much as I am taking it completely apart. I will use a lot more care with the motor still in the bike, many rags and a couple of extra helpers!

I had a talk to the shop guy about a cheaper fix, it is just the No. 3 cylinder that appears to have broken rings on the engine in the bike. After we looked at the prices he said "While I would not recommend using second hand gaskets etc. if I take the other motor down to the same extent and swap the barrel, pistons and rings get a new bottom gasket and all the o rings and seals, reuse the best of the two head gaskets, apply Loctite Gasket Master and see what happens". He said he has heard of this being done (quite a bit with old bikes) and has reused gaskets in this way before himself, though not recommending this course of action!

Also i do not know how bad the motor still in the bike is, if the bores are OK in No. 3 I might get away with just putting rings in No. 3.

I know this is not the right way, but I could buy another XJ for the price of doing all the work. If I do this and it works, I will report back here, if not will look at the options and post here.

Total cost of Quick Fix $127.80 including a large tube of Loctite. It will take a couple of weeks for the parts to arrive, the barrel o rings have to come from Japan.

Indeed $585 not counting bearings is a lot of $ on something this old but the XJs are just soooo cool I don't want another bike!
I like old gear, my car is a "84 Holden VH Commodore (3.3l or 202 cu inch) 5 speed, real classy! My computer is a much modified '89 Commodore Amiga 3000 even my rifles are old a '42 .303, '68 TOZ .22, '40s Side by side 12g! Guess I'm getting old too '67 model New Zealander!

 

There's no shame in just doing the bare minimum to restore the problem with your #-3 Cylinder.

Everything depends upon doing the very best with what you have to work with.

I don't know if I'd swap the liners. I guess it would depend upon how much the service charge to press two -- Out ... and, press one -- IN.
Since most of the labor incurred in doing the swap is setting-up the PRESS.

You should also consider the option of simply having the 3-hole bored-out to the 1st Oversize and buy ONE set of Oversize Rings.

It is my own personal opinion ...
An unpopular one ...
but, my opinion -- never-the-less ...

Re-use the old gaskets IF they came off clean and nice with NO rips, tears or damage to the critical points of separation and sealing.

In the 30-years time that has passed since someone wrote never to re-use the old gasket ... there is a wide assortment off treatments and sealers available to be able to install the head on the block with just the new compounds or sealer and NO gasket.

 

Hi RickCoMatic,

Yeah, no shame but I do like to do things right. At the moment I have little to loose going down this track. When I get the o rings I am going to go to the Local Diesel specialists (who have the largest amount of o rings I have ever seen) and see which ones they stock. I will post here the results of that, could save others a lot of $ buying off the shelf o rings.

I am going to clean everything to a like new finish before I put it back together hopefully will lessen the chance of things going wrong. Also I have not taken the other (in the bike now) motors head and barrel off yet so I do not know what condition it is in or why it is using so much oil. I have done a bit more riding and have noticed that there is fuel (not very much several drips like) in the breather that comes from the crank to the air box, it doesnot seem to be coming from the sump. Also every now and then it stutters off idle. Would this be a symptom of a bad (inlet?)valve I wonder...

Not looking at pressing out the bad No. 3 liner am going to replace the Whole Block, pistons and rings off the engine in peaces now.

If I did not have a spare Top End I would have to be looking at a re-bore as I guess No. 3 and it's piston will be stuffed, then yeah I would think about just a re-bore on No. 3 but I would put new rings in the other 3 and do bearings as well, or just go the whole hog and see if I could get a cheap replacement motor?

Hay some people find my personal opinion unpopular, I'm a cynical old sod! ;-) :-D :-D If it works who cares if others rhubarb it

The first head gasket came off clean, the base gasket disintegrated and so will be replaced.

The guy said he "swears by" the Loctite Gasket Master product and if it is that good I have lots of other uses for it. Been reading up a lot on sealants on the web, not manufactures but end users discussion. Carefully applied and following manufactures directions all should be good. Been working on cars for years so a bike motor is not a problem. I have the manual and good selection of tools.

Thanks for all your input guys, will keep posting as I find out more.

 

Wow! I'm impressed .
You found a Primary for less than $150 (us) ??
That the flat thick Hi Vo one?? Even the North American distributor for DID could not access that specific chain as Yama has reserved production and sale.
IF.. the same one or type, ensure that the thing does not flex enough to touch itself when laid flat on a table... it's garbage if it does.. no if's and or buts.. or you will be opening it up again surprisingly soon to 'fix it'
Versah makes a complete set including Valve seals (sans oil seals tho) gasket kit that is 95% of the quality of Mr Yamas .. usually $100 complete (ebay)
Micrometer the Valve guide holes... guides are cheapish and fairly easy to DIY.
Not so sure one actually 'could' press out the liner.. Yama Casts it's cylinder blocks around the liners.. they (on other Yamas for sure) have ridges in the outer liner tube.

 

Hey Kiwi... What part of NZ are you in?

I have 2 650 motors in bits in Auckland... PM me if you are nearby and need a hand or need some bits... I have the odd 750 part as well

 

There is currently an XJ750 on Trademe that I went and looked at last weekend... Its de-regd but pretty much all there and running... the guy wants $400NZD for it.

There was also a motor in Ch-Ch advertised recently on there that was last offered up for $350 and it had 14km's on a complete rebuild. I don't think it sold and I reckon he may relist it when he gets back from holiday.

 

Yup NZ$88 not OEM at a local (Timaru) shop. Not sure of the brand, I'd guess NZ has different trade agreements than North America.

Good info about checking the chain, I checked the one in the motor that is in pieces by the fact that one could move it so much that it touched the engine cases!!!
I've got a good one in my "new" motor so not getting it at this time, but I might do up the spare motor as time and $ allows. Will check up next time I'm in town as to the make of the aftermarket chain.
$100 for a gasket set is cheap compared to buying Yamaha ones here!

More good info, lucky I have a spare good cylinder block eh? ;-)

 

Hi Alive!

I'm in South Canterbury, place called Waimate so a few Ks away, but I do hope to get up to Auckland this year (on the XJ of course!) to catch up with some of the old man's family. Got a few spares, will keep in mind if I need anything else though cheers!

 

Is that the one (grey with a red painted motor?)whos wife made him sell it as he had too many toys?

Oh, did not see that one! Is that only 14 Km? Why was he selling it? Would have cost way more than that to rebuild!

BTW, there is a XJ750D EFI with only 50,000K on TradeMe in Auckland for $2,500, looks to be mint condition, wish I had the $! Another 2 might be coming up for sale locally here soon too! Need to buy that Lotto ticket /me crosses fingers!

 

Know it well... I'm on loan to Auckland from Dunners

 

Yea the grey one... Motor is a good runner even though its got red paint all over it....

The guy with the 14km motor has wrecked a complete bike so my guess is that it couldn't be re-regd or had some damage... Either way it was a really sweet deal. Oh and it was in New Plymouth.. May have sold in the last offer... http://www.trademe.co.nz/Browse/Listing ... d=80956584

Have you got the link for the 750D? The only one I can find around that price is in Wellington.

 

Yeah I did see that one, shipping is too much for my pocket, if it was Christchurch I would have considered it, still a lack of $ in my wallet though.

Doh, brain said Wellington, fingers typed Auckland, happens too often lately!

 

I hear you man... It's broke time of the year in my wallet too

 

What are the chances that one of you from "Down-Under" could investigate the possibility of finding the larger block they put on the Cop Bikes Down-Under.

If there was a chance for me to "Super-size" the 900 engine I have, here, for my spare. I just might consider the upgrade for the extra few ponies and persuade myself to build and install it in place of the 750 in my Max.

Whatever info you might have ... appreciated.

 

Hi, as i understand it the New Zealand Police Specials are XJ750s, Dave has one on his website but there is not much other info on the net. From the model number he lists there I now have a Police motor (24L) in my D and yes it feels like it has more go. Maybe they used larger displacement XJs in Aussie? Can you give more detail about the Police bikes?

The first XJ I remember seeing was a Police bike, I was talking to a Officer once and giving him a bit of cheek as the XJs were being upgraded to BMWs at the time and I asked him why he did not have one. He said that the BMWs were nowhere as good (pig round town and slow) as the XJs and he would rather keep the XJ!

 

I don't know much about them either but I'm more than happy to keep an ear out for you

 

Part three.

Spent today pulling down the (24L motor that is in the bike) engine, ring end gap is .6 to .7 when limit is .35 and the bores look "bad", kind of discolouration (grey/copper/blue) and "ring" markings on them, mate who helped said looks like it was overheated at some stage. So as my original D motor's bores are fine, pistons are fine and the rings are at .4, she did not smoke and compression was good, looks like the way to go. Waiting on some gaskets.

Will post some photos to the gallary when done as am taking a few as I go.

Oh well back to it!

 

Part Four.

OK, I have all the parts! Got a new head gasket and also a new set of rings. It has been such fun that I decided I do not want to do this again.
Also got a oil cooler and have all the fittings (bonus).

Key on parts reused 1=original 22n motor and 2=spare 24l motor.

Cleaned up every thing, removed the carbon from the pistons 1, combustion chambers 2 and valves 2. Lapped the valves and reassembled the head 2 (easy part).

Got the block 1 honed. Cleaned the crankcase 2 gasket surface carefully and avoiding getting anything into the crankcase, time consuming.

Installed rings, pistons 1 onto the rods, got the No. 2 and 3 pistons to TDC and eased the block 1 onto the middle pistons. Method used: One person on each side holding the block and feeding in one piston each into their bores. We had to kind of wiggle the pistons back to front to get the rings into the bores while pushing down on the block, looking at the block you hold the piston skirts with the tips of your fingers while your thumbs are on the top of the block (if you get what I mean?). Then bring No. 1 and 4 piston to TDC without pulling No. 2 and 3 out and repeating the "wiggle" method! Be careful to feed pistons in level and that the rings are completely in the lead-in of the bores before wiggling the pistons in.

Placed the head on and torqued down, went to install cams and found the cam chain had come off the crank. Had to get it back on with the motor together, you have to guide the chain down the back tensioner it did not want to be pushed or pulled sideways. Bit tricky but OK when you Sus it out.

Left to do, replace valve top cover, install exhaust, wiring and EFI gear the bodywork, oil change, connect battery, hit starter button, Friday awaits.

 

Your moving along nicely, your patience will be rewarded with a successful renovation. Pictures of the unit/process available?

 

I want some Police-Bike parts; too! I suppose I could send-out my Cam's to Isky and have Iskenderian do a little number on them to give me a couple more ponies.

Nah ... I'm keeping the toolbox locked until I see a Robin pulling-up a worm, outside.

Pictures would be a great addition ... even if you have to create an off-site album for them ... like my Cable Company provides. Free; too!

Although, the process to open the service, upload the pictures and get it all organized for a decent presentation of photographs, properly sized, in the correct chronological order and captioned in the allowable 25 characters is challenging: "This part broke so I fixd"

 

Hi Robert,
It is getting there! Mainly lack of $$ has been holding things up! It is a job that requires patience and being really clean. Been working on older model cars for years so am confident all will be well (fingers crossed) main thing was setting up the valve timing right! Well should be able to press the starter button on Friday, am busy tomorrow.

I have taken some pictures but not on the reassembly, will take a couple with the spares engine (will put it back together to save loosing parts) to illustrate the piston Wiggle (TM) and the cam chain engagement the rest is well covered in the manual.

 

Hi RickCoMatic,

I guess the cams are "hotter" she feels like she has more power but the 750D is only a 70 hp motor other model XJs I have seen listed on the net go to 81 hp depending on model. With all the talk of 4 into 1 exhaust and pod filters, some hotter cams and flow work on the head would finish the job off nicely.

I am working on the pictures side of things, will add a page to my website and put the info from the threads I have here cleaned up and on one page (and illistrated).
While I do not seem to have much spare time lately and most of that is spent working on the bike) I have a really slow net connection which makes uploading pictures a pain, plus I hand code HTML and test it on several browsers on different operating systems too. I will post a new thread when I have something online!

 

Part Five

All up and running!

Went for a ride into town and at first all ok, but started to hesitate and splutter just off idle all else ok though.

Got it home, went well, reported upto 24Km/l at 103Km/h.

Letting all cool down overnite, but had a look at the breather hose from the crank to the air box. There was a fair bit of water in it, enough to wet four fingers held under the pipe, about 3 or 4ml (as tested by using a 5ml teaspoon full of water and dripping it on my hand).

Will check the fuel (empty it all into a contaner to check for water), and take the plugs out to check for signs of a dud plug.

Anyone got a idea of where the water is comming from?

 

Still keeping an eye out, but they are pretty hard to come by these days

 

Nice one Kiwi.. Sorry can't help with your current problems... But i'm sure someone else on here will have a couple of suggestions

Oh and dump the dialup and go to the $30 Broadband 8)

 

is sweet just that slight off idle burp! Will have a look now then go for another blat, before it rains again!

Dials phone, Hello how can we help?
Hi I want broadband.
Sorry can't get it in your area, cant tell you when, don't care either.
8O :evil: :roll:

 

Plugs look fine, empty gas tank fuel had no water.

No rain (middle of summer n all it does here is rain!) so will go for a spin.

 

Nice job Kiwi, Enjoy that ride and all the others that follow..
Enjoy that fruit...... of all that labor!

 

Thanks! I did!
100Km under the belt now.

Popped in to see Dave and borrowed his carb sync tool (job for tomorrow), he said the water is blow by from combustion getting past the rings and will stop when they are bedded in properly, I think the burp off idle may be caused by water being sucked into the chambers as it does not always burp. 8O

After I have the throttles matched I will take a ride to drop the tool back (any excuse to ride the XJ).

Economy was better than before, cleaning all that carbon off the valves, pistons and chambers helped and she seemed to just want to go faster (with the economy better at 115Km/h than at 105!). Comes "on cam" at just past 5000 rpm.

Need to get her run in so I hope to be zooming around a lot next week!

Many thanks to all who helped me get to this stage and to Dave for the use of his gear and the rings he supplied.

 

Damn... Keep ringing them about once a month because the more calls they get from your area, the sooner it will become available... Supply and demand

 

Good stuff... I'm extremely jealous as I'm a couple of weeks off completing the 900 and REALLY hanging out to ride the beast 8)

 

Don't worry the weeks will go fast (pun intended).

Re Broadband, cost them too much to actually Fix the cables first (old, buggered, water filled, non grease filled plastic insulated from the early '70s) let alone bother with broadband (and I know what is involved former Telecom Lineman here). I don't ring them I write letters and demand they reply in writing, even send the letters in their prepaid envolopes :twisted:

Part Six

So not being one to wait, I have just about got the throttles balanced. 1 and 2 match and 3 and 4 match just have to finish off balancing 2 to 3 in the morning, they are close but not quite there yet (was getting a bit late tonight).

The throttles needed balancing as they were all out. Wow does she idle smoother, it really makes a difference and brings a big smile to your face and I have not finished yet! So easy with the correct tool.

Oh and no more water in the breather. NO OIL LEAKS 8) ! Mmmm...and thanks to my quick reactions today on the way back avoided a speeding ticket 8O .

 

Part Seven

Got the throttles balanced.

I did this without using the YCIS tool.

Cooling was by a 12 inch fan off a car rigged to a 12V car battery.

I managed to get them close to each other, the adjustment is very sensitive and the throttle balancing adjuster does not require much movement. It would be easier to use the YCIS tool as every time I did 1 all other readings changed slightly enough that it took a few goes to get it right. They are spread within less than the 2cm/Hg range, 1 and 3 are matching spot on and 2 and 4 also match each other. The difference between 1 and 3 to 2 and 4 would be just over 1cm/Hg, close enough for this Kiwi.

Well no rain again today so off for a test ride. If I have got rid of the splutter off idle then I know I got the balance right

 

THANKS FOR THE UPDATES!

 

You're welcome, here is another!

Well I went for another ride to drop back the carb sync tool and ended up helping to install a FJR1300 motor and of course it rained while I was riding.

Bike is running better than ever and will not be too long before it is run in. Lots of speed changes to avoid running at constant RPM and some hill work thrown in, have to keep an eye on the speedo as she wants to go faster

I am really happy with the results, the XJ is just so cool. Have even got rid of most of the "chicken stripes" off the almost new tyres!

 

rIGHT oN!!!

 

hi Kiwixj750, we both hail from the same country were abouts are you in NZ. How is your bike going. I am a newbie I have a 1982 xj750 rj and a xj750rj 1981 ( i think that is the correct type and year).

 

Hi,

Just asked the same of you in your clutch thread

Waimate South Island. Moving to Timaru soon!

Bikes running really good (so it should after all I have done to it). XJs rule

 

Welcome Southern... Born and bred in Dunedin here... Just on loan to Auckland right now :lol:

 

Hi Alive and Kiwixj great town Dunedin iam a born and bred dunedinite as well. Currently living in Invercargill,cant get much more southern really. Have the both of you had a long association with xj's

 

I'm from Christchurch but have been here 19 years now.

I had a Midnite 650 16 years ago, local guy still has it. Had the 750D for 3 years now. Always had Suzi trail bikes before.

 

What made you do the move to Invercargill?? Most people I know that escaped Dunners, went north for the warmer weather :lol:


No... A friend got a 550 last year and I did it up for him and it got me hooked.

Now I have a stunning 900 and 5 650's that I'm rebuilding 2 from... It's a bit of a mission but i'm getting in to it.

 

moved to invervegas about 15 yrs ago for work, cant seem to get away. trying to restore my xj to get out off town...heh heh this is my first ever road bike and first ever project. iam a little lost but making a good plan off attack. The biggest issue I have is due to the age of these bikes things just seem to break etc real easy eg I wanted to replace my oil filter but the oil filter cover bolt would not budge so I used some crc 556 but it would not budge. lLast night I tryed again and the bolt head sheared off so now iguess I will have to use a extractor to remove it. have you got any ideas or is this just what you can expect.Should I be more cautious. sounds like the 900 is a great ride. I also purchased a second xj 750 to use for parts but it is almost to good for that so I guess I have some decisions to make

 

This is a common problem with the oil filter bolt, primarily because they are over-torqued when installed. Proper torque for that bolt is only 11 ft-lb (15 Nm).

An extractor would not work in this case because the bolt is hollow only a few mm down. (See link below.) Best bet is to shear off the top of the bolt, without damaging the filter cover, so that the cover is able to come off, along with the filter, spring and washer. What you'll have left over is a headless, hollow bolt sticking out which you can use any number of methods to remove.

Here is a replacement bolt, from a company I like doing business with:
http://www.z1enterprises.com/detail.aspx?ID=1642

Z

Please use the My Signature feature, under My Profile Information, with information on your bike.

 

hey thanks for that, great suggestion makes sense when you think about it. Have a another bolt from same model so I will check to see if it will fit first.Its a real shame that I re filled her up with oil again i surpose it will require a drain and replacement again. cant hurt really. Thanks WeAreZilla

 

Hi Guys
I'm from Whakatane, got a low k's 750D- awesome bike! Get a lot of fun from it. Went to Woodville and return Anzac day (ok, back the next day) 860ks 9hrs riding +-, sore bum but what a brilliant ride...went past 1 cop who was pointing down at my wheels- must have been something wrong with them...but I couldn't see anything wrong...! any suggestions?