Derbi senda running issues; loss of power at high revs

[HD]

Hey.

I have a 2006 Derbi Senda 50. Havent bought it that long ago. Im sure it isnt running properly. It doesnt take any choke whatsoever to start it and yes, maybe thats a good thing but just wondering if that has anything to do with it. It seems almost automatic cos for the first 30 seconds it revs normal then after it ticks over 2 stroke style if you give it a few revs. When riding it it seems that if you rev it hard it almost loses power at high revs. So I change gear earlier and yes, less wear and tear on the engine but I seem to be going up hills at like 20 screaming it in 2nd cos if I go to third, it bogs. Any ideas what this could be? It hasnt got a rev counter so I cant tell if when it is 'losing power' it is actuall at like 10k but sounds fairly low. The guy did say that he had fitted a jet size 1 bigger to it if that means anything?

Thankyou very much people. Any replies will be greatlu appreciated
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Rusty '02 Vito Camper + CBR600F3

[wr125x2011]

Only half read your post, more then likely you have a flat spot.

Clean the carb?
Is it derestricted?
Restricting cone at the engine end of the exhaust.
Could be running rich, if so, need to make it run abit more lean, an K&N air filter, and then jetted accordingly, with a deristricted exhaust etc should have you running faster and smoother.

[warped one]

I'd lean for either you've:

Picked some crap up of the bottom of the tank,
Seized it,
Or...

The plain and simple fact it is a Senda and will spend more life in the garage than out of it, because one slight knock on the left side and it takes the oil pump off and will keep seizing pistons until you realise.
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amnesia - Never in the history of usernames has one been more accurate. Warped indeed. You sir are a fecking oddball.

[HD]

Yep, its deristricted. I will clean the carb. Also, I dont know how to fanny around with jets so not too kjeen on fitting a K&N...
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Rusty '02 Vito Camper + CBR600F3

[Paulington]

The jet could be causing all of this.

Fit a standard jet and that will most likely solve the issue.

Think horses, not zebras. .
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"Four wheels move the body, two wheels move the soul."
Current Vehicles: '89 Kawasaki KDX200, '99 Yamaha XV535, '00 Honda ST1100 Pan-European, '08 Suzuki GSX-R1000, '08 Mitsubishi Lancer GS4 2.0 TDCi, '15 BMW 1 Series 116d Sport Turbo.
CBT: 27/08/08. Theory: 04/09/09. Module 1: 16/09/09. Module 2: 01/10/09.

[HD]

What you mean horses not zebras?

And how do I go about that then? Dont know where I should buy it, where abouts on the carb to fit it etc.
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Rusty '02 Vito Camper + CBR600F3

[wr125x2011]

Your bike; https://www.adrenalin-pedstop.co.uk/cp-SENDA_DRD_50-4973.aspx

The Carb jets https://www.adrenalin-pedstop.co.uk/PI-SENDA_DRD_50_CARBS__REEDS-5088.aspx

[HD]

Okay. Thanks mate. I take it I will have to get a whole pack but what one? And what size do I fit? And how Gonna have a word with my dad tomorrow, see what he thinks.

You defo think it is this though?


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Rusty '02 Vito Camper + CBR600F3

[woll]

IF my senda is anything to go by, sell it quick. Then run away and never look back.
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Current Bike- Suzuki DRZ400 SM K6
Previous bikes - Derbi Senda Xtreme50r, Honda CBR 125, Kawasaki ZZR 250, Yamaha DT125R, Suzuki Bandit 600, Gas gas ec 250, Honda CBR600FW
Damaged spleen, damaged kindey, 2 popped lungs, 2 broken ribs, broken face, broken wrist and 5 back fractures... remember kids walls hurt

[Carvel]

Is everything standard on the bike, exhaust air filter etc?
Also what mileage is on the bike?
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2002 Aprilia RSV1000R, Cbr600Fs, Mk1 B12, Vfr400 NC30...

Matt B: I can deal with crushed nuts to beat Ollie.

[HD]

Oh. Was it bad and yes everything. Mileage is 8800 ish I think. Not 100% though. Would a video of what I mean be good?
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Rusty '02 Vito Camper + CBR600F3

[wr125x2011]

Could be worth taking a look/replace the piston & rings if you or your Dad are mechanically minded.

[HD]

Yeah. He definately is. We are going to do that then gaskets. Drain oil and refill. Spark plug. And he thinks the clutch may be slipping and causing this. New air and oil filters and a look at the carb. Gonna have a proper look next weekend. Thanks
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Rusty '02 Vito Camper + CBR600F3

[wr125x2011]

Sounds good, let us know how you get on.

[HD]

Will do! And thanks for the advice
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Rusty '02 Vito Camper + CBR600F3

[HD]

Hey again. Just stripped the bike down (well mostly). Havent taken the head off yet but will have a look tomorrow. I noticed a few things in the process, however.

The exhaust is in one big pipe, then the silencer, not like motocross bikes where its front and rear. In the silencer, there are supposed to be 3 bolts, there was 2. These were, however done up so tight I have bent a T-wrench. At the front, the bit where you screw the exhaust on (separate mount thingy) was not screwed on properly. It was tight but wasnt square. There was also no air filter. The exhaust (at the front) is shaped like a 250 2 stroke.

Would the exhaust issues affect running and the air filter? We are gonna do a top end rebuild anyway. Does anyone have an idea of the intervals? I think my mileage is in km but my speedo is in mph :/ It is at 8840ish.

I am also gonna whack a video on youtube that I recorded last night. You can hardly see anything cos it is pitch black though haha.

Thanks for any help
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Rusty '02 Vito Camper + CBR600F3

[wr125x2011]

From what i can unnderstand whilst being pretty toked, are you talking about the front of the exhaist pipe, which goes into the cylinder head, make sure the bolts are done up tight, so no fumes can come out from the join, there *may* also be a restricting cone inside the front end (engine side) of the exhaust pipe?

On my old Gilera rcr 50, which is the same as your senda, i replaced the piston and rings every 5k miles.

You really dont wanna be running your bike with no air filter.

If you wanna be fussy, you can rebuild at more frequent intervals, having no air filter will deffonetly effect the bike, wack one in.

so basically;

Would the exhaust issues affect running and the air filter?

yes.

[HD]

Thanks And yes, it was done up tight but not square to the cylinder head, so loss of pressure? (power)

There is no restrictor as as far as I can tell the washer has been removed and the rest taken off with a dremel. (I watched this in a video and it looks the same).

As for the air filter, I should be getting one tomorrow.

If my mileage is in kilometres, the bike has done around 5500 (yn). I think it is because it does go up very quickly if it is miles. Just a trip to the shops can add a few units on the clock.

Thanks for your help anyway
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Rusty '02 Vito Camper + CBR600F3

[HD]

Heres the video: https://www.youtube.com/watch?v=H6oceKmlI08

It took so long to upload cos my computer is shite haha.

Anyway, The way I am revving in the video is where I change gear every time, if I go any higher, it loses power. Read the description aswell.


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Rusty '02 Vito Camper + CBR600F3

[HD]

Today we took the whole cylinder off. The spark plug was very sooty as was the top of the piston and the gap was quite big on the spark plug. The piston had a few 'scrapes' on 3 sides and the barrel had much of the same in a few places. You could feel it at one point with a bare finger. Also the thing that the piston sits on, think its called a push rod, has no movement up or down but a bit from side to side 3-5mm. Would you say there needs to be a new bottom end bearing?

Also, do you think it would be alright to take it somewhere so they can re-bore it or better to just buy a new cylinder kit?


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Rusty '02 Vito Camper + CBR600F3

[HD]

Today we took the whole cylinder off. The spark plug was very sooty as was the top of the piston and the gap was quite big on the spark plug. The piston had a few 'scrapes' on 3 sides and the barrel had much of the same in a few places. You could feel it at one point with a bare finger. Also the thing that the piston sits on, think its called a push rod, has no movement up or down but a bit from side to side 3-5mm. Would you say there needs to be a new bottom end bearing?

Also, do you think it would be alright to take it somewhere so they can re-bore it or better to just buy a new cylinder kit?



Ps, you can see in the pic the progress we have made. Forgot to take pics of the actual piston/cylinder and my dad has got it now so oh well. And the rag is sort of covering the hole from top-bottom side so you can only just see the 'push rod' I was on about.
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Rusty '02 Vito Camper + CBR600F3

[wr125x2011]

As you said the spark plug was sooty, that pretty much means the bikes running an excessively rich air-fuel mixture.
This could be the reason why the bike was bogging down at high revs.

You could take it somewhere so they can re-bore it, could be worth getting a quote first though, as may work out cheaper to buy a new cylinder kit? Could be worth checking that out

Also could be worth cleaning the carb and jets whilst you're at it.

[HD]

Didnt want to update at different intervals partly because I was getting so many parts and I have had exams lately etc.

The bike is now finished

So, from where I left off. We got the cylinder rebored and an oversized piston with rings. While putting that together we were holding the piston in line with a paintbrush. Dad went a bit overboard and yes, it snapped and went in the crank; catastrophe!

So we put it all back together and were just gonna strip the flywheel off and get to it that way.

Meanwhile all of the carb was off and fitted new jets, needle and stuff. New airfilter was on and had ordered a new exhaust. The one that was on there was rusted in the front end! So thought best to order a decent one if I am ordering one at all. Went with a Metrakit.

Got all of the carb back together ready to put on. While all of the reeds were off and that I could see the crank. So I gently pulled down the kickstart and what do you know? The paintbrush came around. After much swearing, tinkering, pulling, pushing we finally got it out. We were losing light so we called it a day!

Got the carb back on with all of the reeds and airfilter together. Started it and was fine; lovely. Noticed that the clutch was a bit 'iffy'. When you pushed it in gear with the clutch held it wouldn't roll. But when the bike was running with the clutch in in gear, it would. So we decided to strip down the clutch. Turned out the plates were all worn so we replaced them. Bought a new cable and bunged it all together. It wouldn't work. We put it together just as we took it off. And the cable was too short.

We then ended up taking it off, putting it back together VERY carefully. Same.

Finally yesterday we got a bit of relief. I bought a new clutch lever (the one that sits on the spline) as the one was there before was a bit knackered after all of the fiddling. Turns out we had put it back together wrong but hard to know as the manual is shit. Turned out the actual front plate where you put the springs through and screw down (Dont know what it is called) had to sit beside a notch where the Derbi logo met it, how odd. Dad working his magic again Also, we have put the original cable back on.

That was yesterday. The next lot is all in the wrong order but you get the general gist of it.

Put the exhaust on and it wont fit snug because it hits the frame where it bends keft but it is fairly tight and isn't blowing so thats good.

Chain and sprockets changed.

New front disc as the one that was on the was warped. Dad stripped the callipers and completely sorted both of them (nearly seized apparently). Fitted with new fluid and new pads. Sprayed the callipers as they went that funny colour brakes and engines do when they are never washed. He also sprayed the inside of the discs so they look new.

New spark plug (iridium) so that should make it better. Dad repaired the thermostat as we weren't even sure it would work as the wiring was rediculous and had almost split.

Now all thats left to do is put the new headlight on, bars with grips and levers, touch up some of the plastics, fix the indicators (relay? look at other thread) and make the electrics a bit tidier as they are really messy.

If you've read all of this well done. Thanks for your help needsy.

Very happy guy now

My bike runs well but I dont know if it was just cold or the jetting isnt right but it sounded cold when I was riding it. Not far as the engine has only got about 4-500ml oil in when it needs 600ml. Only rode it about 200m but I thought it would be warm although it was bloody cold.

Running it in is going to be a nightmare. Was trying to ride it slowly yesterday. It was crackling (like 2-strokes to when cold, hard to describe the sound/feeling) then it would just jump into the powerband, obviously I changed gear then as I dont want to damage this long and hurrendous (but fun) project. It never even had a powerband before... The power was shit but very constant, no jump in power.

As a side note, does anyone know where I can get throttle and clutch cables as I have tried two sets now but neither fit; both too short!


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Rusty '02 Vito Camper + CBR600F3

[HD]

Thought I would update as if anyone is having problems similar and is just good for browsing.

Riding around at the end of January and noticed my headlight wasn't working. Thankfully it wasn't dark so I went where I was going and got home just as it went dusk.

Replaced the headlight bulb time after time ... after time and it kept blowing. Tried rewiring the whole headlight assembly and it worked a few times but when you flicked it to main beam it would blow some times. Others I could do high and low, then ride it for a little bit and then it would blow (10 seconds).

Asked around and went to a few bike shops and they said reg/rec. So we replaced that. Problem was still happening so went to get some more bulbs. On the way back, the bike just died. Doing 45 cruising and just died. Pushed it to my school about 200m away and gave it a mechanical check over and everything was sound. Turns out it wasn't sparking so we put on a new coil. Worked for about an hour then went again. FOR FUCK SAKE!!!

(I think) We re wired the headlight and coil and reg/rec and it worked, for about 30 mins.

So we decided it was time for the garage. In it went. A couple of days later we phone up and are told it is the loom. So phoning around and it is £75 for a loom. Go to order one with my chassis number and it is £100 as it is special edition. But it is practically the same but with a twin headlight. Although I was converting it to a single headlight anyway. Thought it would be best just to fork out the money and then it is sorted. So it took a week to be diagnosed. Then a week of them saying they were getting it and they didnt. So I ordered it and it took 2 weeks for the part to come. Then it took a further 2 weeks for them to fit it.

Eventually got it back. Rode it to my mates football match. Leaving there it wasn't starting properly. Then eventually got it to go. Kept it singing for about 4-5 miles even sat a traffic lights with it revving high. A few times it misfired a bit. Got to my mates girlfriends and stayed there for about an hour. Then got a call asking to go for a ride so I did. Took ages to get started from there but (for the 1 mileish journey) it ran the best it has ever. Revving cleanly through every gear, fast and responsive. Lovely! Then arrived at asda and turned my bike off, thought should I, shoudln't I? Eventually I did and convinced myself the bike was just being a bit funny and after the amazing performance on the way there I thought it would be fine. Not so.

After many kicking, bumping attempts. Different people trying, we just couldn't get it started. Ended up getting picked up at 10:30pm by my best mates dad who wasn't very happy to see me I picked the insurance with £100 less excess as my mate said his dad would pick me up, opposed to £100 more but free breakdown cover. So about 3 hours riding time in over a month.

Took it to the garage and after about 1-2 weeks they decided it was the magneto. Now I tried to source the part but couldn't. They told me loads of times that they found the part and it would be here in 2 weeks, the part didnt fit, we have found the right one, that didnt fit, one will be here in 3 days, none of them fitted...

They have now decided they have found the correct one and it should be here two weeks last Monday (a week ago). They said they had one that would fit but came with the flywheel and was £230 but have now found one that will fit and it is £75. So hopefully by the end of the week they should have it. Then the question is how long will they take to fit it?

I have not had it since the end of January and am gagging for a bike. When I do get it back I won't want to ride it in fear of it breaking down!

What else can actually go wrong though? Every electrical component has been replaced?!

To rub salt in the wound I took the (rusty after 2 months) exhaust off the bike and the exhaust bracket fell off the frame.

I did/do have a journey to Newquay planned next weekend but dunno if it is a bad idea? I will be riding at around 50 which is the speed limit for about 1/3 of the way. Another 1/3 is 70 and the rest is normal A/B roads. I will be riding with a 125 and 400 so do you think it is too much? One of the guys rode it numerous times on two different 50's and never had any problems but what if I break down? I wanted to leave about 2 weeks before riding outside of Plymouth, is this a bit overkill? My other option is sticking the bike in my mate's dads van and just riding it around Newquay and then putting it in again on the way home but this isn't confirmed. Is this more logical, it doesn't seem more fun?
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Rusty '02 Vito Camper + CBR600F3

[tvchimp]

Get some breakdown cover. Sorted
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Bike: Currently Bikeless... Gahh