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Discussion Starter · #1 ·
Just taken the timing cover off, to check the timing marks.
In Haynes and my workshop manual, the marks are:
Inlet and exhaust pinions one dot, lying in a valley.
Camshaft pinion dot under tooth.
Intermediate pinion one dot under tooth (exhaust), one short and one long dash on adjacent teeth (inlet), two dashes straddling a valley (camshaft).
But not on this T120V.
Both inlet and exhaust pinions have two dots spaced apart, marked A and B.
Intermediate pinion has one dot, two dots and a dot and a dash.
Camshaft pinion...no mark at all. Simlar to this:

Mmm, nice I thought...no way can I check this, doesn`t line up anywhere really!
But then I read the section B35 middle paragraph, above.
As I`m not inclined to rotate the engine 94 times, how do I check the timing?
Anyway, with no camshaft mark, I`d have to rely on finding the keyway, which is in what position?
 

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do you mean crankshaft pinion ?

if so the keyway should be at tdc


cheers , Woody
 

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not sure what bdtc is and i try to limit my answers to peoples questions to the knowledge at hand which are my unit 500 motors .

on the unit 500 cranks i have the keyway is at TDC top dead center and the dot on the pinion gear is inline with the keyway .

dot is at TDC on the crank pinion .

cheers , Woody
 

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Discussion Starter · #7 ·
Thanks for your replies guys.
I got a bit confused, the book says, "...the camshaft pinions are located by means of the keyway directly opposite the timing mark".
By `opposite` I thought it meant the keyway is the other side of the wheel in relation to the timing mark. (which is why I mentioned BDC)
Maybe it should read, the keyway is aligned with the timing mark?

OK, now I can find the crankshaft timing mark, now I still have the problem of which valve pinion marks to use...AA, AB, BA or BB.

BTW, I edited the picture above to show what I actually had.
I turned the engine so that, at least the intermediate pinion mark straddled a tooth on the camshaft pinion.
 

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Discussion Starter · #9 ·
Thankyou Plewsy.
I presume the `dash dot` on my intermediate wheel is equivalent to `long dash...short dash`.

This T120V, and I suspect others, are a mixture of various models.
Think I`ve said this before, a long time ago I was told to order everything as for a T140V except the engine. (not true!)
There`s no spares book for this model, needs a bit of detective work.
So, I`m not surprised if there`s 750 bits in the engine or 650 bits anywhere else.
But it is very confusing at times.
And I think people get a bit annoyed, when giving advice.
`Find X and set it up like this`. When I look of course I dont have X, so adjusting it is irrelevant.
Perhaps I ought to get a T140 workshop manual too.
 

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Discussion Starter · #11 ·
I found TDC and marked the pinions with white ink.
After turning the engine many times, I got this:

So, presumably its OK.
There are some drawings of the 750 timing gears in the back of Haynes. But they dont correspond to my 650...surprise surprise. (Except the TR65, I think)
The odd thing is the inlet pinion dot is not aligned with the long dash.
But it might, if I turn the engine another 50 turns.
I have lateral play on the intermediate wheel, should it be tight?
Also I can remove the small shaft by hand???
 

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Hi Caulky,
I'm had a look in my 650 workshop manual as it says the following:

1) Exhaust camshaft pinion dot aligned with dot on intermediate wheel.
2) Crankshaft pinion dot aligned with twin dashes on intermediate wheel.
3) Inlet camshaft pinion: Dot aligned with long dash.

It also notes that the timing marks will only align every 94th revolution.

So looking at your photo (if the manual is correct) your inlet cam is one tooth out.

There should be no play on the intermediate wheel, however I would guess the play is taken up once the timing cover is refitted. You can pull the intermediate shaft out by hand, it is a sliding fit.

Hope I've not confused you any further

Webby
 

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It looks ok apart from the inlet should be the "B" mark.
If you remove the nuts from the cam pinions you can see the key-ways they should point inwards to the dot and dash of the intermediate.
If the keys have been put in the wrong slot in the pinions there could be upto one tooth difference even though dots line up.
The three slots in pinion are for fine tuning the valve timing,
If I remember right each slot = 1/3 of a tooth either way.
Its a good pic just a touch too close,
do your pinions have a "B" mark?
the pin the intermediate gear sits on can be pulled out by hand the pinion should also carry two very thin shim washes, one each side (at least mine has some?)
 

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Discussion Starter · #14 ·
"do your pinions have a "B" mark?"
Yes, they`re just out sight in that photo, I did take another photo but the batteries were naff and it came out blurred.
I will persevere tomorrow.
Thanks for the info:)
 

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Discussion Starter · #15 ·
I have now turned the engine lots of times. The marks have lined-up on several occasions, always as before, always A to A. Incidentally, there are no dashes on the valve pinions, just dots on A and B.
Haynes differs from the workshop manual:

The marks are similar to the TR65T and the TR7T, according to Haynes.
But not the T140.
So now I`m no wiser. Either Haynes or the `72 workshop manual is wrong. Or perhaps mine is not a `72 type engine.
Given that I have a 1973/4 650 engine fitted with post 1985 timing pinions, it could be a Thunderbird engine with twin carbs... the mind boggles.
 

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How far are you going ,as far as strip down is concerned, with this engine mate? If you're just checking the timing but the bike worked well before, you could just leave it where it is. If you want to take the head off you could dial in the cams using a dial test indicator and degree wheel to set the cam centre lines or the opening and closing figures to the book or another setting that may be better performance wise. I know you can set up a DTI on the valves and leave the head on, but I found it easier with the head off. Of course I am doing a complete rebuild on mine. The trouble is that pinions get swapped about sometimes and not all pinions are quite the same. Some people do this to get closer to the timing degrees that they want.
John
 

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Discussion Starter · #17 ·
Well John, I`m trying to avoid taking the engine out and splitting the case. (no facilities, I`m working in my brothers garage...he`s already made noises about the clutter)
If I remember rightly, it used to run OK...ish, but I wasn`t really getting the performance expected. I was working abroad at the time, and it was in a local motorcycle garage most of the time.
It used to start-up easily, but the left cylinder was always smokey.
Then some nice person vandalised it.
So it sat in my fathers shed (for 20 years) until this rebuild.
The reason for all this valve timing checking is the clicking just after the exhaust valves have fully opened. [other thread].
This investigation has revealed: exhaust rocker-box misaligned with fixing bolts, inlet/exhaust timing pinions not standard `72 T120 type (TR65T?), the valve timing is correct according the the Haynes book, but differs to the `72 workshop manual.
The engine is stamped KJ- Sept 1974, but it was actually made in 1973, the reason for thinking it is a `72 type 650 engine.
 

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Well Caulky if you've got a non standard exhaust pinion is it possible the timing marks are not correct for your bike? Degreeing the cams won't require the engine to come out, just take the head off and I would imagine that even if the timing marks on the pinion are not right for your bike, not sure about that, the pinion itself would have the same number of teeth and so can be set up to run right. It's just a question of knowing where to set it.
 

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Discussion Starter · #20 ·
Thanks a lot Plewsy.
That could mean the inlet timing is way, way out, if the keyway is aligned for B.
GPZ noted from the valve timing data I reported, he thought the inlet cam pinion is incorrectly installed.
Further investigation needed.
Its a wonder it worked at all.:confused:
 
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