POSCPI

[mikeyboy]

Piece of shit Chinese pig iron
Got a call the other day from a local chap trying to find someone to look at the engine on his sj 750.
Jap bikes aren’t my thing says I.
It’s chinese says he ,1970 it was made.
Definitely not my thing says I.
Eventually I realised what it was.
It’s a military style sidecar outfit that these two chaps take to re-enactments.
Any ways he was riding it and it started to lose power and didn’t sound quite right.
I pulled the heads off while the engine was in the boot of his car.
What have I let myself in for

 

[mikeyboy]

Found this in the LH tappet adjustment chamber.
Mebbs need to find where it came from

 

[mikeyboy]

Can anyone spot something missing

 

[mikeyboy]

How ,,,,
Did that get in there
Certainly wasn’t me

 

[mikeyboy]

Should be an interesting conversation tomorrow.
Crank big ends have a bit of wear,
Gudgeon pins as well.
Strangely the pistons look new,,ish
Hope he has deep pockets,
I was hoping for a quick rebore ,jobs a goodn.
Shouldafuckingknownfuckingbetter

 

[ShakeyGS]

Howlongpin

 

[mikeyboy]

A better shot of the barrel.
Poor winter storage or an existing problem ,,who knows.
The owner certainly seems to have a good sense of humour,
Guess you have to have if you spend your weekends dressed in ww2 German uniform

 

[theoneandonly]

i was talking today, with 2 other mechanics, about a particular punter , that we all have in common ( despite us being 50 miles apart)

it's all about managing customer expectations....... but you know that ....

you know the quote will be to your standards , not their's . if they don't like it , they can walk, it's your reputation .

the bill is going to be £1500 for a £1000 bike.

 

[Deleted account 220427001]

honing tool on that mike

 

[mikeyboy]

i was talking today, with 2 other mechanics, about a particular punter , that we all have in common ( despite us being 50 miles apart)

it's all about managing customer expectations....... but you know that ....

you know the quote will be to your standards , not their's . if they don't like it , they can walk, it's your reputation .

the bill is going to be £1500 for a £1000 bike.

Indeed,
Guess the bikes worth more than that though.
I’ve a suspicion it’s gonna be buggered.
Already evidence of someone being at it previously (not current owner,they haven’t touched it)
I have some not very fond memories of this and later vintage bmw motors ,they can be a right pain as the replacement parts are a bit nohow and may need a little re-engineering

 

[mikeyboy]

honing tool on that mike

Bit more than a light hone.
Need to remove the valves and take a look at guides and seats

 

[Nin]

I seen it. More than £1k ...

It’s an interesting bit of engineering mind, a study in how to make something very simple and very cheap, and very difficult to fix.


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[mikeyboy]

A question for those that might know,
I’d have thought there should be a piston ring in the top land.
A question for tarka perhaps,I think he has some experience of these beasts.?
Or the Russian variants

 

[Deleted account 220427001]

Broken part I think part of a collet


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[mikeyboy]

Broken part I think part of a collet


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My thoughts as well,
There appears to be no way that a fragment that big could have got to where it was resting.
But the collets fitted appear to be intact.
The truth will out eventually

Edit
The area where the debris was found has only a small oil drain hole,
But in order to remove the valves I think the barrel would have to come off,
So has someone just left it there after a failure of some kind?
Or maybe prized off the collets and replaced valves in situ.
Some bodgery going on.

 

[Deleted account 220427001]

My thoughts as well,
There appears to be no way that a fragment that big could have got to where it was resting.
But the collets fitted appear to be intact.
The truth will out eventually

Edit
The area where the debris was found has only a small oil drain hole,
But in order to remove the valves I think the barrel would have to come off,
So has someone just left it there after a failure of some kind?
Or maybe prized off the collets and replaced valves in situ.
Some bodgery going on.

Unless it’s the collett retainer broken or part of valve guide inferior metals metallergy


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[Santa-2512]

Piece of shit Chinese pig iron
Got a call the other day from a local chap trying to find someone to look at the engine on his sj 750.
Jap bikes aren’t my thing says I.
It’s chinese says he ,1970 it was made.
Definitely not my thing says I.
Eventually I realised what it was.
It’s a military style sidecar outfit that these two chaps take to re-enactments.
Any ways he was riding it and it started to lose power and didn’t sound quite right.
I pulled the heads off while the engine was in the boot of his car.
What have I let myself in for

Thats an interesting patina on that barrel

 

[Santa-2512]

A question for those that might know,
I’d have thought there should be a piston ring in the top land.
A question for tarka perhaps,I think he has some experience of these beasts.?
Or the Russian variants

I thought that odd too,

possibly removed due to step at the top of the bore / wear?

Certainly looks like a lot of combustion blowback deposit build up in that area?

Can't the big ends have (i can never remember which way it goes) over size shells fitted? or is the crank that far gone ?

Sounds odd, but thinking outside the box, could the customers frame be modified to accept an off the shelf refurbed BM unit? providing the drive end is the same

may be a cheaper alternative for them if this is going southbound

 

[mikeyboy]

One mans patina normally means shite,rust and dirt to me

 

[Tarka]

Chang Jiang.

Usually "flat head" side valve engines but they also make OHV ones.
Flatties are Chinese copies of the Ural M72 which is a Russian built licensed copy of the BMW R75 (actually, it was the predecessor, the R71)
Tony Jones in the Cossack Owners Club is your Chang Jiang man with real world knowledge of them.
Also Mick Cross of the former MPC Ural near Lutterworth....he used to sell them...I don't think the MPC site is active anymore, but if you need it I can let you know Mick's mobile number....he may well have a load of Chang bits in his unit.

Urals are my "thang, maan".