Ray's Mongrel Engine Build

LTGTR

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As mentioned in previuos posts, I have purchased a motor to rebuild.
The most important thing to me is that I learn something - and at the end of it I have a rebuilt motor that I can use in my 77D.
The word 'Mongrel' is because this motor seems to be a bitsa - everybody and his dog has had a go. I am finding this frustrating and I may have ended up with the wrong motor to learn on.
Firstly, thank you to those members who responded to my Engine Stand" post about a month ago - I took all the advise and built myself a rotating stand and it works brilliantly.
What I know so far :
Engine No. 3G0 - 007987 - refering to Skulls charts - US Model 650G - 79-80.
The little bit I have done so far seems to show it has got lots of bits that dont relate to a G model from 79-80.
It has points - this could happen from the factory - but - only 2 bushes fitted in the cam - no labyrinth seal (bushes), just the 2 plain bushes - one each end - indicating points not factory fitted.
It has normal Generator (no TCI trigger) - the stator screws are well used and the wiring is jammed horribly behind the gear shift protection plate - indicating not factory fit.
It has a C type Cam chain tensioner - 1975 - B model.
It has a B model engine breather fitted.
It has very short arm type clutch worm fitted - indicating early model worm.
At this stage Im a bit worried what else I will find when I open the motor up.
I would like to ask for some help/advise at this stage relating to the mismatched parts I have found so far.
Cam chain tensioner - refer photo - the 2mm thick damper washer is missing - if it was installed the plunger would be flush with the end of the adjuster - I beleive this is what Im looking for - is it okay to use this tensioner (with copper washer fitted) ?
Clutch worm - refer photo - why would somebody fit this early type - it only has 30mm distance from pivot point to cable pull point - the clutch seems to be good (visually) and a late model clutch fitted (6 friction/5 steels with cushion plates, no wear on basket fingers, all washers/ bearing in place). Would you recommend fitting a new worm ?
Can I fit a G model engine breather - are there any internal bits in the breather that I have to consider ?
I could not do this without the this forum. I am trying to help myself by studying hundreds of pages of info from the forum so far and will continue to do so, and I appreciate any help you guys give me.
Regards Ray. 210725 stand.JPG 210725 cam chain tensioner.JPG 210725 cam chain tensioner 2.JPG 210725 breather.JPG 210725 clutch worm.JPG
 

650Skull

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Hey Ray..........For curiosities sake, is the area on the engine case above the front sprocket square or round.
P1110357.JPG
 

5twins

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Yes, you would want to fit a 2mm thick copper washer to that type C tensioner if you plan to use it. But you may encounter clearance issues between that large cap and the bottom angle bracket that ties a linked carb set together. I would be on the lookout for a complete type E assembly.

The late model single breather housing should swap right on but I would be sure to get a complete assembly that included all the internal baffling. I'm not sure the baffle plates would swap between the two, probably not.

That early short arm worm give slightly more pushrod travel and clutch plate separation but at the expense of a harder lever pull. I think you'll want to change it. Many of us have switched to the "1L9" worm assembly from an XS400. It takes some minor modding ( a little sanding) but it's pretty easy. Details are in post #65 here .....

http://www.xs650.com/threads/200-special.51454/page-4
 

650Skull

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Something pretty strange on that engine. All the indications are its an early engine around 73-75 and with the Clutch actuator, breather, square side case corner and the cam chain adjuster just doesn't match the engine #............ That engine case having a square fit changed to a round. (as can be seen in the pic i posted), mid way through 75.
 
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LTGTR

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Skull and 5twins - thanks for your reply.
Just for the record my cover is 306-15411-0 with a little 2 under the part number - square corner - no oil hole - no gear change pattern - made in japan is on it - no screwdriver slot. In your link it is the same as one that Too Many shows in post no. 40. It seems to have an early worm fitted so as a guess it is an early 75.
That link was amazing - great reading - who would of thought there would be so many changes and the confusion it caused.
Going back to my problem with this bitsa motor:
Why would a motor have the following changed on it - breather, cam tensioner, LH case, points added (missing bushes), possible generator changed (from tci). This is whats giving me the shits - I dont know whether to keep this motor and keep digging into it. I would be interested in your advice please.
I understand all the above can be changed to 79 period parts, its just a bit scary what the rest of the motor will be like.
Thanks for your help.
Regards Ray.
 

650Skull

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At the end of the day it doesn't really matter. The only thing to make a difference is if it is a 256 motor or a 447, if or when you need to rebuild. That you cant tell till you open it up and it will be written on the con-rod.

All m\y information is the gear select no's was introduced on the 74 model. It doesn't have the screwdriver dent to prize off the clutch adjuster cap. if the engine side cover is original then i think the engine would be a 73TX650

Some new information come to light recently, i posted in this link regarding the con-rods in the early models, the change in the Euro models and the US and other countries models. Info on the model code that relates to the year/country
https://www.xs650.com/threads/xs650...workshop-manuals-and-other-information.30569/
 

Jan_P

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OK ..short comments
I don't think it is that strange to find a bike with various pars ..
Back in the day there was no internet .Many owners was young and not everyone was interested in the
Mechanical aspects .getting oil on their fingers some did not like mess up the Hairdo and switched to cars instead
they just wanted a quick fix getting out on the road.
Warm up before opening the throttle was unheard of and Oil changes could be rare and not done.
Not always a Competent Mechanic in town and certainly not always the factory documentation service manual and such
So what could happen was that more or less the Village Blacksmith was given the task getting the bike going.
I have met one such blacksmith in my life .That had an Awesome reputation When His name was mentioned it was as if Jesus Christ himself was involved
and had an enormous talent getting things to work. But not that much with " Modern " motorcycles " it was more oriented to farming equipment.
In many not to say most cases a solution could be found and when it came to Brit Bikes and before that was the norm.Perhaps a telephone call and there you go -over revving into the sunset again

Now in this case .There are parts and engines out there
If you were into Ferrarri Daytona spyders and had an engine .Then that is the one since there are few and they are valuable

In this case the "Black smith repairs " sends signals that this can be a bike that has seen " Action "
So I wold look into wear of the Big parts Crank / Gearbox before getting into the other small stuff.

As with the Ferrari anything more or less can be repaired .. But if the crank is gone + gearbox
here it can be an option to look for another engine if money is a factor. the grand total
Not followed the pricing but something like that

https://www.xs650shop.de/en/crankcase/1008/crankshaft-447-at?number=39-5326

So what can one do mainly
a ) Chuck it in a frame and start it .Se what happens
b ) Take it apart and do the job.

That decision can be tricky and depends on aspects not known for me now
Pictures if it appears taken hits / does it turn / compression test / Boroscope

Personally i tend to do as little as possible until it is necessary. Postponing the not essential ..But then i do it.
I have seen to many open up engines and newer getting them together again.

But again it depends Some do it for getting it perfect takes a long time others for getting a bike that barely makes it to the cafe 3 times a summer
200 miles tops

So i am leaning towards a ) if nothing can be found on inspection trying to start it --- if that don't work Swear and take it out and do b)
or find another engine
 

LTGTR

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Skull - thanks for your reply. I dont understand why you think the motor could be a TX650. The engine number clearly stamped on it is 3GO - 007987. Referring to your charts its a 79-80 XS650G USA only. It would be more likely that the outer engine cover would be changed rather than the main engine block. The cam chain adjuster is a 447 type - would that fit if it was a 256 motor. The person I bought it off says if its not a 447 motor, he will make it right. He also assures me the motor came from USA with a container of other motors and parts. (you would have worked out who Im talking about by now). My phone number is 0425846684 if you want to ring me - I value your knowledge.
Jan P - thankyou for your input - your description of what can happen to these motors over 40 years is pretty right.
Regards Ray.
 

5twins

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My best guess would be that motor was blown up which badly damaged the cylinders, so a whole spare topend was swapped on. Not sure about the side cover, crash damage fix maybe? Or I suppose it's possible the motor was just assembled out of spare parts the guy had on hand. If it is a 447 I think I'd run with it. You wanted to learn some stuff and putting this motor right will certainly teach you a few things, lol.
 

LTGTR

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5Twins - thanks for your advice. The guy selling it is the 650 bike bloke here in Aus and he says he will work with me to swap over those parts to make the motor match up "period" wise. He also said he will make good if its not a 447 (as thats what I asked for). At this stage I will continue with it and you are right - its about learning first. Just feels like a bit of a shitty start. As mentioned, that C type cam chain adjuster will foul any linked carby's. I will start dissembly and will keep the forum posted on my progress and undoubtetly ask for help.
One other thing I dont understand - after I put a new post on the forum (through the Garage tab) - I cant find my post in the normal part to see if there are answers - I have to go back through the garage route to find it -could you help with how this works please.
Hope you liked my rotisserie - it was based on your design.
Regards Ray.
 

650Skull

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LTGTR

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Some photos of the RH engine case showing how the square part of the case doesnt match with the small radius of the crankcase. Other photos show the engine case part number, missing gear shift pattern and screwdriver slot for the clutch adjustment cover. Its clearly the wrong cover and the good news is the seller will swap it over for a period correct one.
Before I dismantel the top of the motor I want to do some "learning" exercises.
I have been practising finding TDC just by watching the piston through the spark plug hole - I can get it spot on each time, but I will buy a piston stop in the future.
I want to check my cam timing is correct - for learning/interest sake - I think my main steps are the camshaft pin perfectly vertical, cam chain tensioner correctly set to remove/compensate chain wear, mark on cam chain sprocket up the very top and TDC. If those line up, or are very close, would that mean the cam timing should be correct ?
I would also like to use a dial indicator to check my cam timing (learning/understanding sake). I have looked at dial indicators and magnetic base and so far I think a Moore and wright, metric, 10mm model - does this sound okay for the type of things I would use it on the motor. I have researched a bit on the forum and I think the opening/closing specs are measured with a set amount of rocker to valve clearance and the dial indicator would have to be positioned on the top of the valve spring area. Another bit I am unsure of is the specs for the closing of a valve mean the point at which the valve is completely closed and not when it starts to close.
Sorry about the amatuer questions. I could just dive in and follow my nose, but this is a great opportunity to learn and understand how it all works.
Thanks for any help - Regards Ray.
 

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LTGTR

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Is this cam okay ?.
The pitting is on the heel (opposite the high part of the lobe). Its the same place I noticed 2 of the rockers sittings before I dissembled the top of the motor.
Also - I may not be posting my queries correctly - after I have posted something it never seems to appear with other peoples posts.
Nobody answered my questions that I posted on the 1st August which may mean nobody is seeing them or I am not posting correctly or I'm giving the wrong person the shits).
The mongrel build is living up to its name - looks like I need a new crank - piston pin (gudgeon) is rocking up and down in the small end - bugger.
Thanks for any help.
Ray.
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gggGary

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That cam is pretty ugly/scary looking. I'm guessing it was a severely rusted/abused part that has been cosmetically "cleaned up" with harsh methods; sand paper, wire wheel, dico wheel or the like. You can see the scratching that isn't 90 degrees to the shaft. Given choices I would put it back on the shelf, and use another. This may be more educational than you intended it to be.
 

arcticXS

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That cam is pretty ugly/scary looking. I'm guessing it was a severely rusted/abused part that has been cosmetically "cleaned up" with harsh methods; sand paper, wire wheel, dico wheel or the like. You can see the scratching that isn't 90 degrees to the shaft. Given choices I would put it back on the shelf, and use another. This may be more educational than you intended it to be.
Maybe still useable for a regrind? Since the base circle is where most meat needs to be removed, in order to increase lift and/ or duration.
 
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