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Re: preparing for war

Posted: Wed Dec 23, 2015 10:30 pm
by JanBros
maccas wrote:Jan,

That is awesome! Good work! Looking forward to seeing the results.

Dan
tnx, if the result is someone complaining it ain't a 50 no more, I'll be happy :mrgreen:

Re: preparing for war

Posted: Sun Dec 27, 2015 8:17 pm
by JanBros
made the hole for the cylinder :

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vieuw on the new intake :

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first time cyl at it's place :

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all just rough now, final preparation's are for when the cylinder sit's at the correct height.

Re: preparing for war

Posted: Tue Feb 02, 2016 9:47 pm
by JanBros
work had stopped for a while, as the conrod I had for a while appeard to be wrong. dimensions on the Mitaka website ain't always correct apparently, so always double check !
so had to find another one first, cause without the correct one the project is pointless. Managed to find a perfect fit (in Portugal from a Casal 401, google can not even find pictures of it :-k ), only 1mm shorter than what I had in mind, close enough 8)

closed the side of the cases under the carb again
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started on the intake. going to try a 19mm pumper carb (tillotson fom a chainsaw). pro's : lightweight, so floater jumping u and down, and easy adjustable. downside : normaly only good for idling or WOT (IBEA makes them with adjustable midrange for carting, but too pricy for this toy), but as the moped mostly consists of either throttle open or closed, should/hope it to be ok.
made a teflon part to fir between carb and intake to isolate the carb from heat, and turned a "trumped" to go on the intake side.

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took out the choke valve and sealed it's axe openings so it can not hamper flow. starting cold can be done with brake cleaner 8)

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and then a flexibel tube to the air filter

Re: preparing for war

Posted: Thu May 19, 2016 7:26 pm
by JanBros
spent the whole day on the dyno, getting to know it, find out how to wotk with it, and get the settings right.

first I measured the MOI (cord arround the wheel, pulley, bucket of water, ...). got a MOI of 9.78kg/m². so changed dimensions for the roller in the program to get the same MOI.
did some runs, put couldn't get any usable power figures (only like 0.00xx BHP).
so started changing dimensions/weight of the roller and finaly got a figure of about 2.5/3 BHP (moi was than about 2kg/m²).

next up : excluding the vario. blocked it in the short gearing position, but than a run lastet hardly 2 seconds
so blocked in in the longest gearing position. Only to face a new problem :( : because the clutch comes after the vario, it now spinned at a much higher rpm, making it come on at very low engine rev's. too low for the engine. Putted the stiffest clutch-springs I had in it and the engine just managed it :wari:

http://nl.tinypic.com/r/11r3qr8/9

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very pleased with the result, now the real work can begin

:beer:

Re: preparing for war

Posted: Mon May 30, 2016 11:35 pm
by JanBros
been playing for 2 days, happy with the result \:D/
full line is result, stripes is what it was, numbers on top bloeng to where the vertical line is. only thing that changed : other cylinderhead and programable ignition.

about 20% more power (graphs are with vario working) and on average over 5km/h faster after x seconds 8)

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Re: preparing for war

Posted: Tue May 31, 2016 2:26 pm
by DougB
=D> =D> =D> =D>

Bet it's great to start getting you own results through, nice work!

Re: preparing for war

Posted: Wed Jun 01, 2016 3:30 pm
by DeadHammer
Nice one Jan! Am really enjoying this thread!

I raced in the 'Moped Mayhem' series for around 10 years. Starting on air cooled RD50's and then progressing (?) to a DT50 supermoto (with an RG125 front end) and then on to a water cooled Motorhispania supermoto with a Minarelli AM6 engine (which I still have). I can honestly say I've never had as much fun on a bike of any size as I've had on 50cc mopeds! Brilliant! :D

Re: preparing for war

Posted: Tue Jun 14, 2016 4:49 pm
by JanBros
last sunday was raceday.

My moped worked like a charm, one of the faster ones and ran flawless all day.
My sons bike had sprobably some clutch problem, as it was accelerating lesser and lesser over the day out of slow corners.

We finished 7th, but that feels at least like a podium in the fictional "non MX riders class" 8) , and by the end of the day I had the feeling that I actualy knew what I was doing :mrgreen:
my son and his mate finished 23, out of 45 ?

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son :

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Re: preparing for war

Posted: Tue Jun 14, 2016 5:00 pm
by pookie
You guys got some good 'air' there, well done =D>

Re: preparing for war

Posted: Wed May 17, 2017 10:11 pm
by JanBros
time to get some more work done on the engine.

finaly made it to my mate (lives quite far away) to have the longer conrod installed. could have send it to him but I wanted to see him do it all, as it is something I've never done. but my motto is always : what someone else can do, I can do to 8)

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on the left the original, on th right the longer conrod.
turned down the thread for the oilpump.

also turned teflon "bearrings", as the crankcase will need to be opened and closed a few more times and like this it's a lot easier,and the crank can still turn while mounted.

both crankcases need to be milled precisly again. already noticed they were'nt fully straight when I milled down the welds. gonna mill one side some more and weld a thicker plate on it and then mill both sides to the correct size so the are perfect in line again.
so I also turned a no-crank-shaft to use for this, better to keep the crank sealed in a bag than to use it for this .

Re: preparing for war

Posted: Thu May 18, 2017 7:52 pm
by jarno
Great post Jan

For a moment I thought you wanted to make a 2 cilinder by looking at the picture

Re: preparing for war

Posted: Fri May 19, 2017 12:32 am
by JanBros
welded the hole for the oilpump

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and filled in the gap on the inside

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milledan extra 3mm from one crankcase half, and made a plate rougly in shape, 6mm thick. made longer "fitting bushes" (you know, those tubes that keep the halves in the correct position. how are they called in english ?)
assmbled evreything with the fake crank and when I tightnned the bolts, it didn't turn over by hand, kind of what I expected. when I loosened the bolts for about 3/4 turns, it spinned nicely, so the crank is still aligned, only need to weld the plate and mill the crank halves to the correct size

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Re: preparing for war

Posted: Wed May 24, 2017 8:06 pm
by JanBros
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milled the mating-surface for the cylinder, that concludes the "big" works on the crankcase, only flowing and cylinder-matching to do.

Re: preparing for war

Posted: Wed Jun 07, 2017 9:32 pm
by JanBros
matching cylinder to crankcase by use of a spacer :
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and at the end, you have a spacer to draw perfect gaskets from 8)

thought I could finaly start on the cylinders, but aparently the big-end outside diameter of the new con rod was bigger and touched the cases, so had to widen it.
before :
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after :
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Re: preparing for war

Posted: Sun Mar 24, 2019 11:02 pm
by JanBros
after having bent 3 frames already, a major suspension update was needed. frames bent from crap suspension :evil: or crap riders who think they can jump :oops: :lol: (either a very hard spring that can handle jumps but is like concrete everywhere else, or a soft spring that can handle normal off-roading but bottoms out on jumps, and because that force is only transmitted from the left to the frame the frame bends leftwards-up, or a spring somewhere in the middle that does nothin well).

no space for a mono-shock because the cylindre already sit's there. IF the suspension bottoms out, the forces should be transmitted evenly through the frame, and it should be progrssive.

So how can we do that ? just put a hard and soft spring in series. so I came up with progressive-linked twin soft and hard shocks 8) :

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made a right-side swing-arm, so IF the suspension still bottoms-out, it is transmitted to the frame from both sides.

both are linked through arms connected to an axle that can turk inside bearrings and both push against each other.

first, the soft one (yellow) will be compressed, while the blue one will not. but off course the blue one will also go up, so it will push against it's arm and make the axle turn. because of this, the arm on the other side will also push down on the soft spring. so the soft is being compressed from both sides. the amount of compression can be set-up by changing the length of the arms. for example : longer arms on the blue hard one will make the axle turn fewer degrees for the same raise of the rear wheel, making the yellow softer. I f you make the arm of the yellow shorter, the degrees will be changed into less compression. all because of the relation between turning degrees and the amount of circumferrence the comes with the length of the arms.
when the yellow is fully compressed, it acts like a pushrod. if the swing arm goes up further, obviously the blue spring is being compressed, but the yellow will make the axle turn opposite direction now, and also compress the blue one from above.

so I can play with different springs (have 2 different softs and 2 hards at the mo), pre-load on each spring, the length of the arms and I could even make different axles with different angles for the arms. I think that should be plenty to find a good set-up :P