Dealing with the DT

[Easy-X]

Just for reference, if the pump is actually going in and out (stroking? is that the word?) it should move ~0.25mm at idle and 2mm full throttle.

If it is working (which seems to be the case) I just need to check the clearance on the throttle metering thingy at the two positions and add/remove/change the shim to compensate...

Assuming the tension has been set correctly (which I haven't done ) which is just a case of aligning the pin that sticks out with a mark.
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[WD Forte]

broad stroke rough guesstimating
1 intake is 175cc
at 14:1 air fuel ratio 175/14 = 12.5 cc fuel/rev
12.5/40 = 0.3125 cc/rev
1000 rpm is 16 strokes per sec or 5cc oil
As I dont know how many strokes the pump makes per rev
will guess say around twelvety sixpence and a bit
hth
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bikers smell of wee

[Easy-X]

I think I read somewhere it's a factor of 200 which I assume means at 2000 rpm it does 10 strokes a minute... in other words in and out every 6 seconds.
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Easy-X]

So today I went up and down the road a bit! Only in 1st gear

I added the mudguards front and back as the rear one has the number plate. Then I threw on the £15 Chinese seat:

https://i.imgur.com/TNI0lUx.jpg?1

"Wow! Actually this isn't too bad!!!" Might need some adjustment or a new bracket here:

https://i.imgur.com/ZSOfG1L.jpg?1

Not a major job but check the rear brackets:

https://i.imgur.com/CGX7oM1.jpg?1

Near perfect fit!!! I need to check the seat is resting on the frame properly (to take the weight rather than the mudguard) but other than a couple of cheeky bolts it'd be a done job

I had another look at the oil pump. First time I got the engine running it was dripping consistently - not much but it was doing something - and then I simulated full throttle (at the pump) and it was a bit of a dribble. So far so good. Faffed about with something else and came back to it... nothing, not even a drop Did "full throttle" again and some oil came out but not much. To be perfectly honest: I don't trust it

As the Chinese seat would fit nicely bolted down (not quite the right shape to hinge like the original) and the original, heavy metal seat pan is, to use the technical term, fucked and reproductions would be ~$150 from Vietnam...

Combine that with a suspect oil pump (which is the only reason you need a hinged seat: to get to the oil tank) and it's a pretty easy decision: blank off the pump and use the cheap seat. TBH the only downer is dumping out the gearbox oil to pop the crank case cover off.

Going premix isn't the end of the world really. Not unless I was going to rack up the miles commuting on the thing But it's probably better to have a tank of premix sitting than pure petrol considering this is an occasional use bike.

"So how was the ride?"

I'm glad you asked I dunno, seemed okay I was too busy making a meal of feathering the clutch to notice much which I suppose is a good thing i.e. the handling wasn't so off it drew my attention. Definitely need to reconnect the neutral light though as the gear box is very light compared to the Rebel.

Clutch works, front brake works, back brake needs some serious adjustment though. Might have put the brake arm back on the wrong spline position.

I was going to do the electrics but most of the clock lights are on the tacho I removed...

The tacho works most definitely (with the old tacho cable and an electric drill) but here's the thing:

It only registers if the tacho cable end is revolving clockwise but connected to the bike engine the cable is running anti-clockwise

WTF?
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Easy-X]

Regarding the tacho, it seems logical that the cable should rotate clockwise considering the needle sweeps clockwise but the bike is definitely anticlockwise!

Before anyone suggests it: no, I haven't put the gears inside the crank case the wrong way round as they can only go in one way

Having said that I shall pin this problem until the oil pump blanking kit turns up as I'll be having the whole side off and can scrutinise the tacho gear assembly.

If all else fails I'll have to get a tacho angle drive
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[stinkwheel]

[Easy-X]

Brand new shoes. Drums look good. I errrr... neglected to mark the original arm positions so it's probably in the wrong position.
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Sister Sledge]

My arse likes the look of that seat but it would look naff on my bike

I bet that short ride was like nothing you've experienced. 50cc scoots are like a polar opposite!
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CCM 404 DS

[Easy-X]

[WD Forte]

Stop!!
Get off you fool!!
You're not supposed to ride the bloody thing,
it'll get dirty!
Just stick it on Ebay as a rare/classic/cafe/bobber/custom
reluctant sale/so sad to see her go etc and ask for squillions of beer chits.
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bikers smell of wee

[Easy-X]

[WD Forte]

Seats the wrong colour too
shoulda got a brown one and took the mudguards off for
most fasterest speed
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bikers smell of wee

[WD Forte]

[stinkwheel]

Being frank, the rev-counter is just decoration anyway. If you can't tell when you need to change gear on a 125 2t, you're doing it wrong.

Go full hipster and use the tacho drive to wind a portable gramaphone.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Easy-X]

[Easy-X]

Learn something new every day! I didn't know 2-strokes can run backwards

So that's me nominated for "Top n00b 2020"

And guess what: to fix it (bad timing that is) I turned up a Tef post on this very forum from 2011. O.M.G.

Would make sense really. I've been dicking about no end with the thing. Sometimes it starts easy, sometimes it doesn't... I shall now scrutinise the tacho cable rotation when slowly operating the kicker with the spark plug out and see which way round it goes.

Good news is if it is bad timing (or busted woodruff key) I bought the correct puller tool for the magneto from Yambits a while back.
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[WD Forte]

Some old 2 stroke deisels were notorious for running backwards
at times
but think about it for a moment
If it ran backwards which way would the gearbox and wheels run
when you rode it ?
It would also kick back like buggery if tried to run backwards
when kicking it over.

Not sure what's in a yammie tacho
but mine works by driving it anti-clockwise from the back
when testing it with a drill so the needle sweeps clockwise from the front.

This means when you look at the drive on the engine with the cable removed
it should run clockwise as you look down into it.
If your tacho works when driven A/C from th rear like mine with a drill
then the problem has to be the gubbins down below in the gearbox/engine.

Mind you those inscrutable orientals may have devised some cunningly complicated
contraption inside to display engine speed contrary to cable direction
I don't see why they'd bother though when tried and tested methods like
the eddy current types on most bikes were cheap and easily available at the time of manufacture
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bikers smell of wee

[Easy-X]

Well it'd be my luck that I managed to get the engine running backwards when testing the tacho and then forwards after I pushed it out the garden
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Sister Sledge]

Ahh but if it ran backwards then you'd have more fuel in the tank at the end...

How could you get the tacho drive installed incorrectly? My brain doesn't compute with the idea of it - it's not like an old hay thresher where belts could be twisted half a turn..
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CCM 404 DS

[Easy-X]

I've looked at the parts diagram time and again and no, you can't get the bits in wrong No, more likely the timing is way off...

The other thing I learned: "oh no, it can't run backwards 'cos there was a big problem with this on DT100s & DT175s so Yamaha fitted a diode on later models." Yeah, really? I don see no stinkin' diode Either it never had it or someone deleted it way back.

BTW the DT125 of this era is an entirely different beast having a 12V system and a dynamo/starter motor. Electric start, on a dirt bike, in the '70s... wow! Learnt so much working on this bike
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[blurredman]

I had a case two years back where my ETZ250 kept running backwards. I had recently purchased an electronic ignition kit for it and since installing it was running backwards- And what is more, it would change direction even just idling!

I put it down to the magnets on the rotor/cam not being at 180 degrees like they should be, and instead being more like 45/90 degrees.

It was quite difficult to ride backwards though.. I did try!
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CBT: 12/06/10, Theory: 22/09/10, Module 1: 09/11/10, Module 2: 19/01/11
Past: 1991 Honda CG125BR-J, 1992 (1980) Honda XL125S, 1996 Kawasaki GPZ500S.
Current: 1981 Honda CX500B - 91k, 1987 MZ ETZ250 (bored to 295cc) - 38k, 1989 MZ ETZ251 - 49k, 1979 Suzuki TS185ER - 9k, 1973 MZ ES250/2 - 17k.

[stinkwheel]

[Easy-X]

[Diggs]

Could that be an in-line suppressor? In the olden days, electrical interference from engines used to affect radios....
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Now - Speed Triple, old ratty GS550, GSXR750M
Gone (in order of ownership) - Raleigh Runabout, AP50, KH125, GP125, KH250, CBX550, Z400, CB750FII, 250LC, GS550, ZXR750H1, Guzzi Targa, GSX750F, KH250 x2, Bimota SB6R and counting...

[Easy-X]