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Post by midlifecrisisrd on Jul 2, 2020 13:21:32 GMT 1
Just finished an LC motor and want to roughly set the timing
Not got a manual and as I've always done ypvs builds this is new to me
Idiots guide for ball park setting
Can be sorted by strobe once the bike is finished
Steve
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Post by flames on Jul 2, 2020 14:03:37 GMT 1
Will check Haynes tonight but think it's 2mm btdc tho some set to 1.8mm, then align the line on stator plate with line on flywheel.
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Post by midlifecrisisrd on Jul 2, 2020 16:31:29 GMT 1
Right so I take it I need to find Tec on the piston then go back 1.8mm then get the timing mark on the stator to line up with the flywheel mark
Steve
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Post by muttsnuts on Jul 2, 2020 16:35:51 GMT 1
Right so I take it I need to find Tec on the piston then go back 1.8mm then get the timing mark on the stator to line up with the flywheel mark Steve correct, TDC, turn flywheel clockwise for 1.8mm to 2.00mm, then align the mark on the flywheel to the stator by moving the stator plate to align, lock the 3 bolts up, turn engine over 360 degrees, check marks still align, job done
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Post by stusco on Jul 2, 2020 16:36:58 GMT 1
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Post by midlifecrisisrd on Jul 2, 2020 17:09:09 GMT 1
Cheers guys
Every days a school day ๐
Steve
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Post by midlifecrisisrd on Jul 3, 2020 15:06:10 GMT 1
All done ๐
Put the depth measuring end of my vernier down the plug hole and turned the engine over till it went past tdc
Locked the vernier then reset to zero, unlocked then adjusted to 1.8mm.
Then inserted down plug hole and rotated engine till the piston just kissed the end of the vernier
Adjusted, locked stator then checked 3 times by doing a full revolution then checking measurements and alignments
Steve
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Post by flames on Jul 3, 2020 16:12:07 GMT 1
Nice one. You still going to double check with strobe light?
I always like to just to b doubly sure.
Shame I don't make doubly sure on squish...... might make my pistons last longer than 300 miles.๐
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Post by nobby62 on Jul 3, 2020 16:12:10 GMT 1
I would double check it with a dti if you can get access to one, more accurate method.
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Post by midlifecrisisrd on Jul 3, 2020 16:26:16 GMT 1
I'm building the engine for a mate so I won't see it again lol
I have recommended he strobe it to check ๐
The squish is safe
Never measured it but used some 1mm solder and it never touched it ๐คฃ๐คฃ๐คฃ
That will do me
Steve
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Post by flames on Jul 3, 2020 18:01:45 GMT 1
I'm building the engine for a mate so I won't see it again lol I have recommended he strobe it to check ๐ The squish is safe Never measured it but used some 1mm solder and it never touched it ๐คฃ๐คฃ๐คฃ That will do me Steve I'm going to stick a log in mine and make sure it doesn't touch. Won't bloody detonate this time!!!!
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Post by damiensk on Jul 20, 2020 16:12:41 GMT 1
going to do the timing on my 4LO, understaand the principal, and was going to use a timing gauge, issue is there doesnt look a lot of room to install the gauge, between the head and the frame, dont want to buy one, to find out i dont have the room. i have seen this from a venhill engineering which i know will go in, which they say is about 110mm from the base of thee threaded body to the top of the main body, so that is fine. www.venhill.co.uk/timing-gauge-tool-14mm-vt22.html i would of prefered to buy with a gauge, so has any body managed to get one that will go in the space? if so can you post a link? thanks
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Post by Tobyjugs on Jul 20, 2020 19:10:07 GMT 1
going to do the timing on my 4LO, understaand the principal, and was going to use a timing gauge, issue is there doesnt look a lot of room to install the gauge, between the head and the frame, dont want to buy one, to find out i dont have the room. i have seen this from a venhill engineering which i know will go in, which they say is about 110mm from the base of thee threaded body to the top of the main body, so that is fine. www.venhill.co.uk/timing-gauge-tool-14mm-vt22.html i would of prefered to buy with a gauge, so has any body managed to get one that will go in the space? if so can you post a link? thanks If i understand your question right it is possible to buy small DTI's with a maximum range of 3mm. Which is what i mostly use for timing my engines when built up. The picture below shows you the size.
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Post by bare on Jul 20, 2020 19:38:33 GMT 1
Small factoid: DWELL .. can make precise MM settings into a shot inna dark... at best. Klever to determine exactly Where inside of that Dwell.. TDC actually is. Be sure that most everybody has a different take on it.
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Post by oldbritguy on Jul 20, 2020 20:03:36 GMT 1
Yup Pondered over that one myself as I have always timed engines on degrees relative to TDC and not mm before. I took the view that because of the small dwell at TDC where the crank still turns for a few degrees when the piston has actually stopped, getting an accurate 1.8mm before top was not going to happen. I set the timing with a slight retard at 1.5mm then used a digital strobe to dial the timing in at 1.8 once running. With a comfortable squish and ensuring the carbs were tuned fine I was then happy to rag the t*ts off it without fear of melting something inside. However, every lc motor I built as a spotty yoof back in the day, I used the Haynes method and never worried about a thing. Worked then so should still work now, irrespective of my middle age anal obsession with fettling with anything mechanical ๐ฎ
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Post by reedpete on Jul 20, 2020 20:15:40 GMT 1
TDC is the mid point of plus and minus 1mm.....easier to measure those and define TDC reference.
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Post by yamark on Jul 20, 2020 20:26:39 GMT 1
Small factoid: DWELL .. can make precise MM settings into a shot inna dark... at best. Klever to determine exactly Where inside of that Dwell.. TDC actually is. Be sure that most everybody has a different take on it. Not sure if it's the same across the pond. Dwell in the UK is the angular measurement of the closing of points (although programmable transistor ignitions some times set up dwell). It affects multi cylinder engines when the points aren't closed long enough for the primary windings to build up a magnetic field.
Capacitor Discharge Ignition (CDI) is best set with a dial gauge to check the timing marks are accurate. This is when the pick up coil will signal the SCR to allow the capacitor to discharge through the primary windings, inducing a high tension pulse to the spark plugs. The timing is static on the LC, so no need to use a strobe to check the timing. 1.8mm is safer with modern fuel.
Cheers, Mark
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Post by Tobyjugs on Jul 20, 2020 20:33:25 GMT 1
Bare is talking about degrees and this is nothing to do with the method explained in the Yamaha manual.
It is difficult to go wrong with a linear measurement and very accurate. When the piston will not travel any further up it is in it's top position (not TDC) when it is 1.8 to 2mm lower it will be in the correct position if you're fly wheel is correctly positioned using the key on the taper. Dwell does not come into it.
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Post by saigonmark on Jul 20, 2020 21:00:01 GMT 1
I use a piston stop on my Lambretta. Put a degree wheel on the crank, rotate the engine clockwise until it hits the stop. Then mark the degree wheel at that position. Then rotate the engine counter-clockwise until it hits the stop. Mark the degree wheel at this location. Top Dead Centre is half the way between those two locations you marked on the degree wheel. The same principle can be applied to any engine.
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Post by damiensk on Jul 20, 2020 23:06:36 GMT 1
evening gents, i have seen this on line
but its 13cm on the main body and clock, which makes it tight between the hole that the spark plug goes in and the frame of the bike just under the tank rubber mounts.
ive looked around and cant seem to find one thats smaller, that will fit in the space. suppose i should have done it before i put it in the frame, but dont relly want to take the engine out again!!!! the one that tobyjugs has got looks a decent set up. hence why going for the venhill gauge i know will fit in that gap. unless some one knows of a gauge that fits??? and lastley, is 2mmm or 1.8mm BTDC? i know haynes says 2mm, but reading other posts i see 1.8mn come up a few times? will i be fine with either, and going for 1.8mm, will that up performance?
thanks
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Post by oldelsieboy on Jul 21, 2020 6:56:50 GMT 1
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Post by damiensk on Jul 26, 2020 14:37:21 GMT 1
thanks for the link oldelsieboy, checked it out, its the insitu size thats a bit vauge. 12cm would be fine, bit doesnt take into account the plug thread.
will e-mail yambits to find the overall lentgh,
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Post by Jethro5 on Jul 27, 2020 0:25:12 GMT 1
Mine definitely can be used with motor in frame. It is 80mm overall length including gauge and adaptor but not screw thread. I donโt think a longer gauge will fit with motor in frame.
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Post by oldelsieboy on Jul 27, 2020 18:51:02 GMT 1
This fits fine, approx 115mm OEB
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Post by damiensk on Jul 27, 2020 23:15:10 GMT 1
thats what i need, you dont live anywhere near north Mancheter by any chance!!!!
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Post by damiensk on Jul 27, 2020 23:49:56 GMT 1
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Post by JonW on Jul 28, 2020 2:20:00 GMT 1
That looks like the one I have Damien. Works well if it is.
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Post by bare on Jul 28, 2020 3:43:44 GMT 1
Yes Dwell in degrees is what I was on about Piston at the top of the hole isn't overly accurate... as you will note that as the piston stops, the crank still turns/rocks back or forward more than a wee bit Stuff in a piston stop contraption ie; repurposed/modded Spark plug Or a Locked Dial gauge can be made to work. Stick a degree wheel onto the Alternator and read it ! You might notice that The top of stroke (TDC) position is Fairly wide ..Lots more than the alleged 0.2mm difference suggested. Dependant on How long ago the crank, rods and pistons were replaced...assuming it was done capably (not always assured :-) Difficult to consider that the difference betwixt 1.8mm and 2mm is real, replicable OR even accurate positioning. Yess it does all work reasonably well regardless.. Remembering 99% of these engines are rebuilt by / for old gits who will at best go shopping, or gather in self interest groupings, crowding obscure car parks and wax eloquent on each others bikes, Likely as the things' most strenuous usage. Nonetheless it's a sloppy setup techniqueIMO. Quick 'n easy being it's main benefit. Fit a degree wheel, then choose to use whichever portion of the Dwell that.. you.. think best :-) BUT be consistent, as in always reusing the ..same.. arbitrarily selected TDC dwell point. Accuracy is far more important at 9000 rpm than when sitting on yer bench or in your drive. Marking a fresh reference line on the Flywheel would be Klever.
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Post by damiensk on Jul 28, 2020 23:58:40 GMT 1
bare, the cranks had a full re-build, with re-bored/pistons etc done by grampion motors, so im hoping they haave done a decent job
see how it goes when my gauge turns up
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Post by damiensk on Aug 11, 2020 0:17:37 GMT 1
got my timing gauge delivered today, fits in the spaace no problem. timing was spot on anyway, but glad that i checked to be on the safe side. timed at 2mm BTDC
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