preparing for war

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James P
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Re: preparing for war

Post by James P » Sat Aug 23, 2014 2:12 am

JanBros wrote:I think you are thinking way too big. this is just for fun, not to pour money in :lol:
is forced air cooling, big fan on the flywheel with a cover that goes from the fan from one side of the cylinder over the head to half the other side.
my main goal for the first race is to have my engine opened up for inspection, to make sure it's a 50cc, than I will have done a good jod :D and you would be right about the massive performance increase 8)
I even don't have a clue about the compression ratio (too lazy to calculate :oops: ). I stick to 10cc heads for my KR, so that makes 4cc for a 50cc moped.
about the ignition : first need to find out if the rev's are limited or not, than I'll thinck about the rest.
:lol: :lol: Fair enough Jan, although you have obviously spent a lot of time on it so far, even if very little money! Keep us updated.

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Re: preparing for war

Post by JanBros » Sun Aug 24, 2014 10:58 pm

squish is set (0.7, wanted 0.60 but difference is not enough to bother, not for what it's ment to do -> get beaten up :mrgreen: )
put the engine in the frame and tested it for running with original carb and exhaust, and it does :)

made the hole in the frame for the exhaust to pass trough, welded in a strengthening bar between headstock and rear frame and started on the exhaust :

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Re: preparing for war

Post by JanBros » Wed Aug 27, 2014 11:00 am

exhaust is finished

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just need to make a bracket between stinger and frame bar to support it, but it also needs to make a circular movement as the engine moves forward compared to the frame when the rear suspension is pressed in.

wanted to hear how it sounds, so sprayed some brakecleaner in the carb (like on the picture, without throttle) and it immediatly jumped to high rev's screaming :mrgreen:
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Re: preparing for war

Post by JanBros » Thu Aug 28, 2014 7:51 pm

too bad you guys can't smell the Denicol oil :mrgreen:

http://youtu.be/7uCMKHrV1uY

hope it isn't too peaky. good news : it rev's as high as it can, so no rev-limiter 8)
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Re: preparing for war

Post by Luders » Thu Aug 28, 2014 9:28 pm

Hahaha that sounds keen Jan, good effort. I've not been commenting on this much, but am enjoying your updates on the thread, so keep them coming :D

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Re: preparing for war

Post by 500bernie » Thu Aug 28, 2014 9:55 pm

Hi Jan,
I hope you will be posting some videos of the event
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Re: preparing for war

Post by JanBros » Sat Aug 30, 2014 9:34 am

first run yesterday : it did run, that's all that could be said about it :mrgreen:
but that was with stock clutch and vario, and of course not enough power in the bottom rev-range to "make things happen"

started playing with clutch springs (bought a set with 3 different springs , engaging between +/- 5.500 and 8500 rpm) and vario weights and comming down on my test-track (it's slight uphill) finaly most of the times it could get into the powerband, and when it did, it was awsome :D kept pulling from about 30km/h up to I estimate 80-90 which is more than enough for MX I guess 8) , untill .... the plastic fan mounted on the crank broke off , went through the plastic engine cover and hit my leg pretty hard :shock:

had calculated the exhaust for max power at 13.000, so started making a new one for 11.000.
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Re: preparing for war

Post by JanBros » Tue Sep 02, 2014 12:24 am

new exhaust made (forgot to take picture), as engine just goes into the powerband, clutch kicks in and the rear tire just throws up everything underneath it and the moped takes off :D

only did one run, as I noticed a strange sound on idle. opende the engine and the head gasket was already blown/burned :( after only about 6 runs down the street ...

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again extra work :evil:
cylinder + head is tightened down by only 4 long M6 bolts and I believe the bolts are stretched too much under power. took some 12.5 M8 Alen bolts and put M6 thread at the end (not enough meat in the cases to get a bigger thread in them), and drilled out the holes in the head + cylinder. Hope these can take the presure. middle one is an original for comparison.

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going to make a 1mm thick copper head gasket, but that also means 0.5mm has to be taken from the head , and I had planned to have the engine finished last WE so I could do the rest this week and have a trial-run next WE.

picture of the 19mm Dell Orto I putted on. What bended handlebars are good for .... :D

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Re: preparing for war

Post by JanBros » Wed Sep 03, 2014 9:35 pm

nearly there :D

http://youtu.be/_zAzqu1snLc

only after a couple of runs, then engine won't pick up after comming down to a slow speed. Feels like the clutch disengages at too low speeds so the engine drops out it's powerband.
Last edited by JanBros on Thu Sep 04, 2014 6:25 am, edited 1 time in total.
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Re: preparing for war

Post by 500bernie » Thu Sep 04, 2014 12:41 am

=D> =D> =D>
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Re: preparing for war

Post by Luders » Thu Sep 04, 2014 8:25 am

Seems to be flying along Jan

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Re: preparing for war

Post by JanBros » Thu Sep 04, 2014 11:47 am

Luders wrote:Seems to be flying along Jan
yeah, I'm happy with it :D more than fast enough for off-roading on original suspension :lol:

if you start from a standstill in dirt, you have to make sure there is no one behind the moped, as otherwise he might feel some pain from dirt hitting him :mrgreen:

problem with getting on the gas again at low speed appears to be from the rear vario, some sort of "coupling-torgue-grooves" in it that let go slowly. possibly I will need an aftermarket tuning part :(
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Re: preparing for war

Post by garye345 » Thu Sep 04, 2014 8:13 pm

Forget tuning parts Jan,just don't let it drop down the revs :P Sorted
I used to be so care less,as if i could'nt careless.

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Re: preparing for war

Post by JanBros » Sat Sep 06, 2014 10:36 pm

did lot's of work today together with my co-pilot, allthoug it may not look like that on the pics

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* made footrests, putted them further back for easier ridind and better weight distribution (co-pilot has lot's of of-road experience and says it's essentiel)
* widened the handle bars by about 8cm for more leverage
* made a "nut-protector" over the exhaust
* made a fitting for the vaccum-hose for the fuel tap
* put on MX tires , placed an aluminium plate inside the engine cover as the rear tire comes very close , so in case it should damage the plastic, the aluminium will keep the cooling air inside the cover. had to cut the side of the studes for the front tire to fit inside the forks
* did some more fine-tuning on the vario/clutch. almost solved now, just a 1-2sec delay in picking up speed from going very slow, but doable now
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Re: preparing for war

Post by JanBros » Sun Sep 14, 2014 6:41 pm

So yesterday was recaday, and all I can say is that it was the most fun I had on 2 wheels since the first race I entered on a racetrack some 20 years ago and that we won 8) BIG BIG FUN and already hooked 8)

When we arrived in the morning, made a simple testrun on wet grass and decided we definitly needed a front mud guard, so made one of what was available :lol: sme pictures before the moped was to be "destroyd" :

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first training first lap, the moped went very good, very fast compared to others.
second lap : problem's already started. When the transmission heats up, the vario opens a bit sooner, it's like starting in a higher gear so the engine is making less rev's and the clutch engages at lower rev's. I knew this from at home, but at home it was just a slight hick-up before it took of. But in actaul race-conditions, it began to become much worse and by lap five it was unridable :cry:

so we decided to just place an original cylinder on it, and I made an estimated guess on what clutch/vario springs to use and what weights t place in the vario and it was spot-on 8) . I you would in advance tell someone you were going to build an engine like that, they would tell you you are a fool and know nothing about 2-strokes, but somehow the expansion chamber still worked very well 8). We still had one of the faster mopeds :D

And that was about all mechanical problem's we had. We just had to straighten the steer ones after a jump hadn't gone as planned and it bent because of the weight of my co-pilot pushing on it when the moped hit the ground hard on the front wheel. And we shortened the footrests a bit and placed them higher because in the corners they where going through the mud too much. For the rest of the day it was just putting in gas and having fun :D

there was a trainignsession which would determinewho would race in rookies and who would race in pro's. When we wanted to swap halfway the 15min session, a guy from the organisers was telling us it was not possible and was surprised we wanted to and so after what seemed like 2 minutes in the pit's we understood it was the first 15 finisher's that would go through to the pro's and that it wasn't about fastest laptimes :o we still managed 13 , well done team-mate =D>

pictures of him :

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