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Post by rooman on Nov 21, 2015 15:19:56 GMT -6
I'm modifying the spring compressor but until I get round to stripping the motor down again I have a question.  internet image, not my actual head The orange areas of the combustion "dome" are literally flush with the bottom of the head and not scooped out hollow like the rest of the dome. Is this deliberate squish shape or bad design that a little porting could improve? |
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Post by rooman on Nov 20, 2015 7:11:07 GMT -6
If you spend all day trying to get to the cam-sprocket bolts and end up needing to take off nearly all the bodywork, just make sure you have the right spring compressor when you finally have the cylinder head on the workbench. Mine was okay for car pushrod valves in the 80's but no go for this 2012 VS125 4-valve head. The inlet side is all gunged up and the exhaust side completely coked and I had to put it all back together to do another day! See photo of Sym h6t head from manual.  |
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Post by rooman on Oct 25, 2015 13:12:45 GMT -6
Thanks a lot for clear info.
My VS125 is 86mm center-to-center diagonally, on a rectangular pattern, clearly not a normal GY6 clone.
Many web vendors claim their BBK will fit but how to know when they don't give stud spacing?
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Post by rooman on Oct 20, 2015 12:04:27 GMT -6
That's logical, but which way? Some patterns are square, others rectangular: diagonal?
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Post by rooman on Oct 19, 2015 13:56:07 GMT -6
I admit I still want to find a bbk (for my vs125) but I'll have to do it the hard way.
What is the correct way to reference a cylinder bolt pattern? Measured outside to outside? Inside to inside? Centre to centre? Horizontal --, vertical l, diagonal /...?
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Post by rooman on Oct 5, 2015 6:45:00 GMT -6
Scooter Seals can not help. with these photos can someone say if there is a bbk available? center-to-center horizontal stud spacing 67.5mm, center-to-center vertical stud spacing 45mm approx inlet & exhaust valve covers 3-bolts    |
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Post by rooman on Sept 28, 2015 2:11:59 GMT -6
I'm having trouble identifying my engine.
On the lower left side there is a number DM809893 and on the cylinder head I see H6T.
Chassis N° RFG HV12WY CS00 6144
I'l be looking for a trustworthy on-line vendor either for a standard 150cc sym cylinder & piston or a BBK.
It's a 4-valve (two 3-bolt covers) head. Engine-bolt center-to-center not yet measured.
HV12W variant...?
Any thoughts (not forgetting re-jetting).
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Post by rooman on Sept 18, 2015 1:00:12 GMT -6
Hi all,
Wanting to get my scooter back to "like new" performance I've installed a digital rev counter (from Dr.Pulley) in my Sym VS125 (H6T version) to help tuning.
Refresh interval is stock at 0.5s, hot idle sounds steady showing approx 1580 varying from 1560 to 1610 and pulling a slight uphill at 60kph shows approx 6000 varying between 5700 and 6300 rpm each second.
These display differences seem big to me and I cannot detect any audible changes at the same time but my ears are getting dodgy I know ;-(
ps: the supplied cable was too short for fitting inside bodywork so I added 40cm of a similar two core cable by soldering. Readings were checked and found to be identical before and after hiding inside bodywork. I think that the only high voltage that can be detected comes from the coil->plug-cap cable so passing the rev counter cable near to the CDI should change nothing.
Are these readings in the normal expected range? If not what's to check and how? If I have dodgy high rev sparks, that could explain a possible top end power lack?
I'm not often at more than 60kph, strict town limits here but some hills, I climb from 400m altitude to 700m on my 4km home run.
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Post by rooman on Sept 11, 2015 1:24:19 GMT -6
Injector cleaner petrol tank additifs are the only thing available here in Switzerland and auto shops just do not exist. The official vehicle checks are so severe that nearly no-one touches their own bike or car! What are the most efficient and basic chemical ingrediants to clean a carb? I have access to industrial products but do nor dare touch the carb without advice. Are we talking acids, alkali or what?
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Post by rooman on Sept 8, 2015 5:35:58 GMT -6
Done easily, it literally came off in my fingers after one little tap with a cold-chisel, now replaced by a 6mm bolt same length.  |
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Post by rooman on Sept 6, 2015 12:09:43 GMT -6
The shiny thing right in the middle.  That's what I was thinking of myself, glad to hear someone agrees. But strange idea, is it anti-tamper? Cannot see why, not like obligatory emmission seals seen in some places. |
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Post by rooman on Sept 6, 2015 6:58:47 GMT -6
I maywell need to access the cam sprocket one day, but, the side cover upper bolt seems to be a round nut. Not rounded, but designed round, how is it meant to be undone to take off the side cover? Must it be destroyed (by a Dremel par ex) or is there another way? 4 valve engine (2 valve covers), HT6, Cam side cover black; see photo  |
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Post by rooman on Sept 6, 2015 6:46:37 GMT -6
Not the typical student really, I have ridden different small bikes and scooters for more than 30 years. I now have my second Sym vs125 since new, 5000ml/3yrs.
I use it for all year round 3 mile town commuting trips, putting on winter tyres from october to march. I have now corrected the valve cleatences and idle mixture, the clutch is starting to shudder a lttle so maybe dr.pulley clutch and sliders soon.
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