derbi senda 50 rebuild

[con]

hi, going to rebuild my derbi senda, putting a 74cc kit on, how long should i run it in for? and what jet shall i use? bike is all standard at the min no race pipe or bigger carb, thanks alot
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con

[Lynxx]

not sure on jets mate as i never done a senda. But my mechanic told me run in is 300 miles if i remember right.

All breaking in, is heat tempering the rings, piston and cylinder. As long as your engine is running cool you can thrash it. what you dont want is heat though, if it gets hot all your new parts will be wore out very fast, make sure you have plenty of 2 stroke in your mix. only problem with lots of 2 stroke is the bike runs hotter slightly and spark plug will start to foul and low rpms.
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Current: 1992 Suzuki GSF400V - 1984 Honda MTX200 (SOLD) - 1975 Honda Xl350 (SOLD) - 1993 Honda CB250 (SOLD)

[con]

thanks alot mate, its still on the auto-lube at the min and not pre mix, should i change to pre mix or not maybe?
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con

[Lynxx]

you can add a little bit of oil into the tank if you wanted too, somthing like 200:1 mix.. and keep the auto lube going.

When you install your kit make sure you put lots of 2 stroke on the piston rings and cylinder walls. And make sure you have the right sized jets or jets too big.. If the mix is too leane it will burn your engine up, if its too rich it wont hurt it too badly.
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Current: 1992 Suzuki GSF400V - 1984 Honda MTX200 (SOLD) - 1975 Honda Xl350 (SOLD) - 1993 Honda CB250 (SOLD)

[Lynxx]

i just heard that, i always kept low revs until at least 100 miles but its kinda hard to do on a 50cc or 70cc. and after 300miles will hold it wide open. depends how long you want your engine to last though, when we raced flat track, you only broke the engine in for 50 miles and held it wide open around a track for an hour. if it blew up u just pulled the spare bike out the trailer.

just keep under 5000rpm unless shifting gears, and after 100 miles you can do 6000rpm then after 200 do 7000rpm cruising rpm. after 300 go all the way with it. Or somthing along those lines, just dont give it hell until its at least in the engine for 50-100 miles, dont hold it wide open either that never does much good to a fresh engine. And keep it well oiled wouldnt hurt to put a colder spark plug, say your running a Br8es, put a Br9es in.. if your running a Bpr5es, put a Bpr6es in... cant seem to find the spark plug for a senda so i dont know what to tell you. when you go to the shop ask for a colder spark plug then stock.
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Current: 1992 Suzuki GSF400V - 1984 Honda MTX200 (SOLD) - 1975 Honda Xl350 (SOLD) - 1993 Honda CB250 (SOLD)

[HD]

[Lynxx]

k put a B9es in then

EDIT: it will foul alot more often but engine runs cooler. I always run a cooler plug unless i have a bad engine seal. when engine seals are good the plug will last months and keep the engine running cooler. If seals are bad it will leak oil into the engine and foul the plug out, alternativly on a 4 stroke if you have bad rings or valve seals it will foul alot more often.

Also you could use a Br9es, the R in the code means electrode i think. doesnt make much difference if you use Br9es or B9es.
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Current: 1992 Suzuki GSF400V - 1984 Honda MTX200 (SOLD) - 1975 Honda Xl350 (SOLD) - 1993 Honda CB250 (SOLD)

[Lynxx]

[bikersupermot...]

hey chr15 ... hope u dont mind me asking you ... ( you seem to be very knowledgeable on the subject and know what your talking about - instead of those that think they do ... or "their m8 told them - so it must be true" kinda thing lol )

iv got a gilera gsm50 - it keeps fouling up the plug - its running a ngk br10eg plug ...

plug keeps fouling up, the bike revs up to 8k rpm but struggles to get up to 10k rpm even in neutral - an thats pinning it ... and at 10k its not revving clean - smokey/spluttery etc and under load it will only juts get to 8k.

what plug wud u recommend i change to?

cheers,

jay
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[Damon]

[bikersupermot...]

hey damon ...

i only just recently bought it. tbh its running like a pig really an dunno why.

with just me on it it struggles to build up revs an eventually on the flat with throttle pinned it ll get up to 8k rpm ... (but red line is at 10k) i change up an again it takes ages to get to 8k ...

an top speed is about 35mph. ... it ll go faster an rev up to 10k going downhill and also if i keep it in neutral an pin the throttle open an just hold it there, the revs go up to 8k, it splutters a bit/lot, then gets up to about 10.5k an wont rev any harder.

iv seen other guys with these bikes an pin the throttle the rev counter flies round an off the scale - so defo sumthin up with mine.

i thought maybe it gummed up a bit, so sat on it throttle pinned for a good 15 mins ... it smoked loads, got up to 10.5k rpm, an it did run bit better after than ... an loadsa crap came out the exhaust ...

have just bought a new br10eg plug for it an it arrived today so ill put that in tonight an see how / if its any better.

an ill take the air filter out as well - do u know about this automatic choke thing? - iv never heard of it on a 50cc supermoto kinda bike - only ever seen manual chokes. - wots the correct starting technique for it? - i just turned the fuel on, dont touch the gas an just kick it over - but having to bump start it recently but now it just wont start at all even with 5mins of walking it around in 2nd gear. grrrrrr - so fkn frustrated with it that im gonna rev the fkn tits off it when it does eventually start lol.

will let u know how i get on. cheers for gettin back,

jay
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