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Discussion Starter · #1 ·
Move along nothing to see, no fightering going on in here...








You still there? Fine...



So as some of you that`s been reading the random thoughts tread know I bought a moped really cheap a while ago so figured it`d be a good idea to document the teardown and rebuild, and if someone is actually willing to waste their precious time reading this feel free to chime in if I missed something or you got some insight on what something is or does, already got a few questions coming when I get the pitchers uploaded from me camera and phone to the puter and uploaded online.



The patient at hand is a 2006 model Derbi Senda SM, as in SuperMoto, and being a moped it quite naturally is a 50cc.

More pics coming in a jiffy, the SD cards are so full it takes half of forever to get them loaded...
 

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Finally got the garage cleaned enough today to start tearing down the moped.



First off I figured to try on a pair of mirrors I`ve had for quite a while now, snagged em from a discount bin years ago, and since they got indicators too figured to kill two flies with one swat since this is a no-budget build so everything is going to be done as cheaply as they can be properly done. Not exactly pretty IMO but they`ll do, the next owner of the bike will spill it anyway within the first week.



The entire moped is riddled with pre-teen bodges like these. The mask should be strapped to the stanchions with four rubber straps not "patent band" as I tend to call it.



Could at least have bothered to make the same bodge on both sides...



Just a reminder to myself what goes where...



Isn`t it fun to reach for a new tool for every screw?



Go figure, the coolant expansion tank is empty. What a shocker.



No wonder it feeled like it`s got a bad battery...



First positive surprise, the rad is in surprisingly good nick.



The coolant seemed to be in good condition. Both deciliters of it...



ya won`t be doing any cross-country trips with this thing... that is, if you`re not living in Liechtenstein. What is that, 5 liters max?



Was just about to go pour it into the Volvo when I remembered oh yea this thing is two stroke... Could be smoking just a tiny bit on the XC...



Cool can... gotta see if I can blag off something a bit tidyer from somewhere...



`ts not the original can for this model anyway...



Silicone glue to seal an exhaust after failing to make it hold by tightening the tits out of the bolts, I`m amazed the PO hadn`t managed to shear the treads off the cylinder as I was turning the bolts with such force that if they hadn`t opened I would have snapped my allen key in a few seconds.



Would probly help to make a seal if the pipe would be even remotely in the right position. Now I`m no expert on these things but I`m fairly certain that`s not the factory recommendation on how to fix the pipe in place...



Interesting. The coolant catch can is sub-pressurized via the airbox.



Well low and behold there actually is an air filter and it`s not that tatty either. Seems like someone had cleaned it up and oiled it fairly recently.



So there actually is a manual choke lever, missed it when trying to start it. anyone wanna take a wild guess on what the electical do-hicky on the carb is? One of the wires is broken off so gotta be replacing it, would help the search to know what to look for.



Again I`m no expert but shouldn`t there be a clip? These fookin teens... probly costs five cents to get one...



a propable cause for the wandering idle and why it`s having a hard time coming off the revs. The PO had overtightened the jubilee clip enough to dig into the carb boot and cutting through.



Oh dear... any guesses? Water pump shaft seals maybe? Just condensation from standing outside for a long time? Something worse? There wasn`t any oil in the coolant to be seen.



There was some sludgy muck in the magnet that might have contained some amounts of small metal shavings like metal filing dust but nothing bigger. A word of advice for the PO, teflon tape is NOT the correct way to try and seal an oil sump plug... I`ve never seen a crush washer that`s practically fused itself into the bolt. I had to tap it with a hammer and a flathead screwdriver to pry it off the bolt.

And that boys and girls ends the first day of the teardown. Nothing surprising really but it`s gonna be challenging to keep the costs at minimum as so many essential parts have to be changed.
 

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Discussion Starter · #4 ·
arent mopeds 49cc? dont lie to us
Depends of the make and model (bore and stroke), they`re usually 49cc-ish from the factory to allow for a piston swap and overbore when it wears out, although all current mopeds seem to have nicasil or some other hard chrome cylinders that can`t be bored.
 

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Discussion Starter · #5 ·
Just took a shower and started to think could it be that the PO had just connected the two spillage tubes to each other? Cause if the coolant catch can is connected directly into the airbox, if it boils it`s gonna snort up any overflow into the engine?! That doesn`t seem like a factory fit to me... Gotta get me one of those "how to fix yer shit" books...
 

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Discussion Starter · #6 ·
Did a little research: the electric thingumabob at the side of the carb is a heating element! Never seen one before...



Spoils of the first shopping spree today. Splurged a little into a quick lock fairing screw kit to have the same fasteners everywhere. Not bad IMO to pay 24eur for the kit

Top end seal kit, new carb boot, battery, fork oil, some detergents to clean the engine and a big exhaust clamp as I need the U-bolt from it. All together around 104eur.



For reasons unknown to me, there are two anchor bolts in the roof of the garage, so figured why not make good use of them.


I dug an old square pipe from the corner and made some cuts and drilled a few holes...



Welded the U bolt into the pipe...





...and bolted the pipe onto the roof. Every now and then it's a good thing to own a chain winch :D

I've never taken a front shock apart, does anyone have any link to share or could do a quick writeup on the topic, do I need any special tools, what is the correct order of things to do, do I have to/can I release the pre-tension of the spring so it won't smash myself on the face etc...
 

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V four honda whore
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Forks are quite easy. From my own experience, loose the bolts on forks while they are on bike. Therefor you wont have to use vice. But in idea, drain the oil, take them apart, clean the shit out of them (i used lots of paper towels) some thin and hard piece of stick helps if you stuck too much towels in fork and need to get them out. Oh also, i used electrical insulation tape wrapped around pipes to get new seals in lowers.
 

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Hey Mattson, since those seem to be a typical damper rod fork:

1- drain 'em then break ALL the bolts loose while still clamped in the trees.
2- with fork caps still on, loosen and removed the screw on the bottom of the slider, hidden up inside the recess for the axle. That bolt is what locks the damper rod in the slider
3- now pop your fork caps off

-The caps will come off under tension, but not more than you can easily overcome by hand. Don't let it go flying across the shop, but it shouldn't be too bad,really.
- If the damper bold don't wanna come out and the whole works is just spinning, pop the cap off, remove the spring and shove a broom handle (or other non-marring thingy) down inside to lock the damper rod from spinning.

BTW, sub'd. :) That is a cool looking little dude.
 

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Discussion Starter · #9 ·
...ssooo when I open the top nut the slider won`t try to skewer me? or shoot anything out? Meaning I`d reckon the spring inside the tube is under some kind of pretension is it not?

Oh; and forgot to mention, since the clutch isn`t releasing properly I`m going to open the clutch cover (you saw what kind of sludge came out so I reckon it`d be a good idea to check and clean the stack). This means I`ll be tearing apart the water pump anyway so again did a little research, the two shaft seals would have cost around 16eur at Motonet where I got the other parts, but instead I ordered a full water pump rebuild kit with seals, gaskets, shaft and a new impeller through ebay for 25.

EDIT: oh, shiny beat me to it while writing. Cool guys, thanks for the info!
 

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V four honda whore
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If i can press them in by hand, i doubt it will do any damage
 

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Discussion Starter · #11 ·
Yea specially since this is just an itty bitty moped not a hulking 1400cc beast that weighs three times what I do.

Just came back from the garage, the quick lock fairing bolts were a FUBAR buy, can`t use em on this one. Oh well, off to the "random bike shit" box then.

There doesn`t seem to be any drain screws in the front shocks so I assume I`m supposed to drain the old fluid out via the rod bolts at the bottom. Seems to be the only place where it can be done apart from taking them to bits and just pouring the old stuff out. Don`t know yet when I got time to continue but it`s not going anywhere so I just gotta see when I can pop in the next time.
 

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Subbed! This is gonna be an awesome little toy!
 

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Discussion Starter · #14 ·
Hopefully what it's gonna be is an awesome little profit towards my next project ;) It is registered but the previous owner have returned the plates which suits me fine cause that way I didn't have to make an insurance for it at all. Don't really got any burning desires to ride it. Gotta keep a close eye on the costs to keep myself on the plus, there's so many things broken that it is gonna be a bit of a challenge but even if I break even in the end I don't really care as the bike's main goal right now is basically to keep me sane through the winter ;) tinker therapy as I tend to say...
 
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Discussion Starter · #16 ·
http://mobcross.free.fr/text/Notice%20derby.pdf

DERBI SENDA 50CC SERVICE MANUAL DOWNLOAD

Just gonna drop this here for safekeeping, and tag it for anyone else looking for one. I asked about the shocks through another (Finnish) forum and one chap chimed in that happens to be a former service tech at a dealership so he threw that link at me. Also confirmed what you guys said about not even bothering to try to open the bottom bolts of the shocks by hand it's just gonna spin endlessly. I do have a compressor and a bolt gun so gonna try to gently shoot them off. Will probly go till weekend until I can make it to the garage again but that leaves me good time to peruse the service manual and study what's what.
 

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Discussion Starter · #17 · (Edited)


Decided to try out the new ultrasonic cleaner I bought the other day so dug out the carb and started taking it apart.



The heating element has a piece missing from it, wild guess someone had tried to overtighten it. Haven`t been able to find a new one so it`s probly an OEM only part. Might leave it out as it only activates below +5c anyway.



A common problem with these things is that the main jet is too small causing it to be hard to start and lacking a bit of power so many rejet these. The only problem is that the OEM jet is around 60-65 and the new recommended size is a 70. Watcha reckon is an 80 too big?



Right, off to the bath then. I`ve heard pretty mixed things about these washers (was on sale in a local Lidl for 30eur) some say they`re useless crap and others that they work perfect for cleaning little stuff like carb innerds. Much to my surprise it seems to do a pretty decent job, the second I turned it on a cloud of crap flew out of practically every part and the little bits are dancing all around the vat.



The carb itself took a few rounds to get every little cranny a bath but eventually got that fairly clean too. Some stubborn crap was left on the outer surface but I`d think the passageways should be cleaned, at least the oxidation that was on some of the jets just flew off of them so hoping for a similar result in the pipelines.



One thoroughly cleaned carb ready to be reassebled.



When I get my creative juices flowing and get into the build zone I often forget to take pics so sorry not much to show. Basically the magneto cover is a gonner, the exhaust has been sitting on it so the plastic has melted, it`s missing a bit from the back and overall just look really tatty with the brushed black finish so I started thinking that would be a good place to try and add a little bling to the bike. To my bewilderment I found out that the cover is in fact plastic so that on one hand made it easy to work, and on the other made me change my plans a bit. Another thing that ended up helping me and made the process quite a lot easier was when I drilled the center open and found out that there is actually quite a lot of room between the flywheel and the cover contrary to what I`ve been accustomed to, which is such a tight fit the nut sometimes touches the cover if it`s not properly tightened.



Now bear in mind this is NOT the finished product, just a quickly cobbled together proof of concept. That cover will be scrapped and a new one will be bought that will be modified to a similar finish. Only a lot more finished :D















There will be most probably green lights in there as blue is a strict no-no color in any civilian vehicle here. This model doesn`t have a starter motor so I can use the bendix wheel cover mounts to bolt a small piece of aluminum angle stock under the flywheel and drill four holes for superbright LED:s which happen to work straight on 12v if connected in series so should be a doddle to fit.

Watcha think? Pretty teen IMO :D The cover is warped and beaten so it looks a bit strange and off-round, I`ll probly drill the actual hole with an 80mm hole saw instead of the 102mm and enlarge if necessary.
 
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V four honda whore
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I heard astory that in 60's or 70's people who wanted to get out of closed put blue loghts at their houses. Maybe thats the reason.for no-no on blue
 

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Discussion Starter · #19 ·
Yea, that must be it :D
 
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