Derbi Predator Stage II Upgrade

[Marko]

Hello All,

It's been some time since I've posted anything, but I am finally starting my Stage II upgrade for my 2002 Derbi Predator LC. Here is the rundown of parts that I will be upgrading to:

Dell'Orto 19mm Carb
Metrakit 70cc Cylinder/Head
Metrakit Ecologic Pipe
4.5gram roller weights
Air-box modifications

Progress so far:

Removed selective body pieces
Removed pipe
Disconnected all fluid lines and battery
Removed old head and cylinder

Wow, what a blast it is taking this thing part and seeing the guts of this bad boy! I must say that the frame on this Derbi is very impressive. It's nice to see good cross-bracing on the frame and a well thought out layout. What a joy!

The pipe removal was pretty easy, but I could not get over the sheer weight of this pig! That stock pipe must have weighed 30 lbs.! The Metrakit pipe will shave, at least, half this weight which is significant on a bike of this size.

I have attached some pics of the initial transformation. Next step is the new cylinder install, carb removal, carb install, pipe install, and roller intall. I should get back on this early next week. More pics to come!

Adios for now!

-Marko

[florida derbi rocket]

Marko...We don't get many LC Derbis on here..upload all your Scrap LC assembly Photos..Everyone wants to see them...(All "Head shots" ) John .

[marylandmark]

The pipe removal was pretty easy, but I could not get over the sheer weight of this pig! That stock pipe must have weighed 30 lbs.!

HAHHA- that thing is HUGE! I had mine removed before I ever picked my scoot up.

[Marko]

Marko...We don't get many LC Derbis on here..upload all your Scrap LC assembly Photos..Everyone wants to see them...(All "Head shots" ) John .


No problem. Here are some more pics. I'll take some more pics tonight (with a better camera this time). I should be finishing the new head install. If I'm lucky, I'll get to the carb upgrade.

[Marko]

HAHHA- that thing is HUGE! I had mine removed before I ever picked my scoot up.

Ya, I know. I've been following your posts pretty closely to help avoid any potential pitfalls during my upgrade. You've given some great information - thanks a bunch. Looks like you've got quite a beast!

I thought about the Stage III, but I knew that I was going to do the install myself and didn't like the idea of having to touch the drivetrain components. Engine headers, carbs, pipes, .... all pretty straightforward 2-stroke stuff a simpleton like me can do without screwin' it up too much. :)

-Marko

[Marko]

Hello All,

Well, I made some more progress last night. The new 70cc piston and complete head unit were installed without any major problems. It was a little tricky keeping the piston rings in place while compressing them to fit inside the head - definitely a 2 person job here. I was a bit surprised to see in the Metrakit documentation that the coolant thermal sensor removal is recommended (it doesn't fit, anyways). My bike is liquid-cooled, so I thought that this would be required, but the head thermostat is still utilized, so I guess this isn't a huge concern.

Anyway, I moved on to carb removal which led to some confusion and frustration regarding cable attachment. I'm definitely not a carb expert, so getting the linkages disassembled, automatic choke removed, and assembling the throttle and manual choke linkages into the new carb took some time. I finally had to call it quits (at about 12:30 am!) as I was about to chuck the carb out into the street trying to get the throttle cable linkage just right and still have some adjustability. I did calm down and decided to sleep on it. I should be able to modify the cable jacket to get the proper "throw" on the cable, but this will have to wait until Day 3.

I have attached some more pics (used the good camera this time!) from last night with more shots of the frame and head/cylinder. Day 3, unfortunately, won't happen for a couple of weeks as I will be travelling on business. So, don't expect any new posts until then. Bummer, too, as I am close enough to taste it - driving me nuts! I can't wait to drive this thing again as the weather is getting better. Oh well.

Enjoy the pics. I did reduce the size by 25% to eat up less room on the server, but if anyone is interested in the full pics (or more of them) just email me and I can send them to you.

-Marko

[Marko]

Hello All,

Last night was truly a momentous occasion. Monster Derbi Predator took it's first breath and fired up - it's alive ... ALIVE!!! Upon completion of the carburetor and pipe, I was able to start up this bad boy and hear it for the first time. Wow, what a rush! The combination of the new pipe and larger piston really creates a more "throaty" sound than what I had before. I can't wait to hear what it sounds like tearing down the road at 50+MPH!

I also changed out the weights on the variable drive unit to ease up the drive engagement. Upon doing so, I must have turned the cylinder over a few too many times, because I flooded the thing! Oh well. I decided to fire it up another day and finish putting the body work back at a later date (it was 1 AM by this point!).

What's left? Well, I need to charge up the battery to ensure a good start next time. Once fired up again, I will proceed with body panels, choke mounting, and a test drive. From that point, it's going to be fuel/air mixture adjustments until it performs correctly. The remaining assembly should be wrapped up in one more night, hopefully. I can't wait to drive this thing again!

I have attached more pics of the assembly process.

[florida derbi rocket]

Nice Job marko.. I wouldnt be in such a hurry to put body panels on..I would make sure you are scootin' first. I wish I had a buck for every time ive taken the side panels off, and put them back on!! :rolleyes: John

[marylandmark]

50+MPH?

You will be getting a LOT more out of that monster than that bro!!

[rydah]

does your bike have the piaggio motor in it?

[Marko]

Hey John,

Good advice. I'll keep this in mind. Outside of difficult access to the carb, are there other reasons for leaving the side panels off right now?

- Marko

[Marko]

50+MPH?

You will be getting a LOT more out of that monster than that bro!!

I hope so! More importantly, I want to get to 50 faster. I'll do my best to get some accurate MPH figures for everyone once I find a stable setup.

[Marko]

does your bike have the piaggio motor in it?

You know, I'm not entirely sure. According to the mechanic's manual, they refer to the Predator LC as a WVTA model. I'm thinking that it is not a Piaggio motor.

Does anyone have any idea what WVTA stands for?

-Marko

[florida derbi rocket]

Hey John,

Good advice. I'll keep this in mind. Outside of difficult access to the carb, are there other reasons for leaving the side panels off right now?

- Marko
Actually Marko...I was doing a lot of wiring...my rear fender is shaved off..and I have good access to my carb..You are right.....It looks like you have a Derbi motor...not a Piaggio...but..do you have an external water pump? I didn't see it in the photos of your motor. John

[Marko]

Actually Marko...I was doing a lot of wiring...my rear fender is shaved off..and I have good access to my carb..You are right.....It looks like you have a Derbi motor...not a Piaggio...but..do you have an external water pump? I didn't see it in the photos of your motor. John

Hey John,

Fortunately, my fairings allow for enough clearance to access the new carb.

Yes, I do have a water/coolant system which should include a pump to allow flow through the radiator and back to the motor. Attached is a best pic I have of this setup. The coolant reservoir is the one with the blue cap. Sorry I don't have a more detailed picture for you.

[Marko]

Hello All,

Well, I'm finally done with the project - yee haw! This thing is much quicker - way more mid-range. I'm still tweaking the A/F mixture setting to optimize top end, but I've hit 50-55MPH no problem (and getting there much faster!). My main issue right now is getting enough air for this bad boy. I've moded the airbox quite a bit, but I think I may have to resort to drilling it out. I took off the airbox/filter (I know, I know, not a good thing to do) for a temporary check on performance without any air restrictions - holy moly! This thing took off like a monster! It was WAY too loud - especially at 10pm. Neighbors are loving me now!

Anyway, I'll keep working on the tuning, but it's a blast riding my baby again. Here are some final shots of humpty-dumpty all put back together again.

[florida derbi rocket]

Marko..here is where I drilled out mine..I had to cover the holes till I got the jets for the bigger carb (which was about 10 minutes ago!) so I may be messing with this the next few days. Yes there is a lot of reed/carb noise...but not that noticable until you are standing in front of the airbox. I Only drilled 2 - 3/4" holes..I don't know if you would need more. Hey...Check my garage..I finally got the Camera back! o_o John

[vr6101]

o_o forget about the airbox get a k&n filter remove the aibox and get a 95 mainjet put on your carb big difference i got a 04 gp1 with a 21mm dellorto carb malossi mhr rep 70cc kit and a leo vice rr pipe right now my top speed is 60mph on flat ground with a handheld gps tomorrow i am getting a malossi multivar variator it should take of a little faster and go a little faster will let you know as soon as i get it on i will post some pics of my project as soon as i get a chance

[speedy_scooter]

some people just dont like the loud intake sound when you put an aftermarket filter on. yes they perform better by letting the carb breathe better than stock but they do make it louder. i know that if you run a stock filter and a 70cc you will run a bit slower but be much quieter and will really only hear exhaust sounds.

[florida derbi rocket]

I have a Performance filter..and plan to use it...but I really don't like the "Plastic" sound Ive heard other modded scooters make..(Carb/Reed noise)...it really does add some kind of sound that takes away from the exhaust note.....I like that Crackle when I let off the throttle.. (sorry...sound engineer Here)... ;) John

[marylandmark]

I run my filter right off the carb and it is LOUD. I love it!

[Marko]

Hey All,

Well, I've been running my new ride and have had some issues getting past 45mph. I've opened up the intake to the airbox to get more airflow to the carb and have tweaked the a/f needle to the point of frustration, but I just can't seem to get anything past 60% throttle without getting a random skipping of power. I'm not sure if I'm getting enough fuel, air, or spark at this point. I have also taken the airbox cover off completely with very little change in performance, so I think I'm getting enough air. Also, the a/f mixture seems to only affect the low to mid-band power curve. Does not seem to be affecting the high rpm very much which makes sense as the main jet should start taking over at this point. Any suggestions or advice?

The good news is that I'm getting great acceleration up to 45, but I'm hitting a wall and know that this thing can do better - definitely something wrong with my setup.

Thanks,

Mark

[florida derbi rocket]

Hey Marko. I seemed to get a little more top end when I Adjusted my throttle cable . I twisted it almost all the way in at the grip. I got more play from it and it stays tight. Just a side note , I really like how I have my Throttle twisted forward. (so WOT is at 3 0r 9 O'clock Depending on how you look at it.) It keeps me from Re-positioning my hand. Try it. :race: John

[Marko]

Hey Marko. I seemed to get a little more top end when I Adjusted my throttle cable . I twisted it almost all the way in at the grip. I got more play from it and it stays tight. Just a side note , I really like how I have my Throttle twisted forward. (so WOT is at 3 0r 9 O'clock Depending on how you look at it.) It keeps me from Re-positioning my hand. Try it. :race: John

Hey John,

I think my linkages are correct - I definitely spent some time on this part! I've got a couple of things to try in the meantime. I taped the air intake port and, as expected, it bogged down quite a bit and dropped performance. But, once I got up to speed the motor is still skipping and dropping. I think I may have a fuel delivery issue or not enough spark. I'm still using the stock fuel lines and plug. Any help here would be great.

Thanks,

Marko

[florida derbi rocket]

well..I'm not that far yet..still don't have my 70cc on yet..They sent me the wrong jets for my carb.. _o Now I'm not sure I understand the taping of the inlet.(the snorkel??)....my airbox is drilled out..but with my stock carb...I gotta tape over the holes or I will bog so bad..I can barely go 2 mph..and the motor will almost die.(too lean)...the other thing that has happened is when I take off my fuel line,and re-connect it...it takes a while for the fuel to fill the line...I know this from running a clear fuel line..it will fill up about 1/2 to 3/4... till I hammer on the bottom of my tank to get the valve to dump more down. then after riding for 20 min or so...it will finally fill up.?? (Not strong enough Vacuum??)...If I didnt hammer on the tank..the line will go dry and It will die. if I had a black rubber fuel line...I never would have noticed this. Is your vacuum line totally tight?... sorry if my posts are confusing...My mind works faster than I can type...(I'm trying to help anyway ) John

[florida derbi rocket]

oh...yea you should be using a "9" plug..BR9ES I think you need the longer plug for LC..The BR9HS is for AC. NGK...I don't know the other brand #s John

[Marko]

well..I'm not that far yet..still don't have my 70cc on yet..They sent me the wrong jets for my carb.. _o Now I'm not sure I understand the taping of the inlet.(the snorkel??)....my airbox is drilled out..but with my stock carb...I gotta tape over the holes or I will bog so bad..I can barely go 2 mph..and the motor will almost die.(too lean)...the other thing that has happened is when I take off my fuel line,and re-connect it...it takes a while for the fuel to fill the line...I know this from running a clear fuel line..it will fill up about 1/2 to 3/4... till I hammer on the bottom of my tank to get the valve to dump more down. then after riding for 20 min or so...it will finally fill up.?? (Not strong enough Vacuum??)...If I didnt hammer on the tank..the line will go dry and It will die. if I had a black rubber fuel line...I never would have noticed this. Is your vacuum line totally tight?... sorry if my posts are confusing...My mind works faster than I can type...(I'm trying to help anyway ) John

Hey John,

I appreciate the feedback. I'm not sure if the fuel line is the issue, but I will attempt to remove the fuel line from the carb to check for proper drainage to see if it's clogged or not. I do feel that I'm getting enough vacuum because my mid-range is consistent without any dropping - regardless of how much I drive it. I basically have to keep it at 60% (or lower) throttle and I have no issues.

You know, another thought crossed my mind today - could I have a restrictor plate in my MK pipe? I thought that someone posted a thread on this before. I'll have to check on this, but I'm really at a loss why nothing I've tried seems to give me the top end I should be getting.

marko

[Marko]

oh...yea you should be using a "9" plug..BR9ES I think you need the longer plug for LC..The BR9HS is for AC. NGK...I don't know the other brand #s John

Ya, I'm switching between Champion N2C and NGKB9ES plugs right now with no improvement in performance. I'm not familiar with the BR9ES or BR9HS plugs - are these similar?

-marko

[florida derbi rocket]

Ya, I'm switching between Champion N2C and NGKB9ES plugs right now with no improvement in performance. I'm not familiar with the BR9ES or BR9HS plugs - are these similar?

-marko
Yea they are the same except for the length of the threaded part. Your cylinder head needs a longer plug than The air-cooled. Sorry I don't know any Champion #s. Keep tweakin Bro...and don't break any OEM parts...We are in Parts limbo until ( or If ? ) Derbi comes out of hiding. I pray that Piaggio didn't buy Derbi to Squash the competition :eek: John

[01venice]

If you are only loosing power in the top end you need a larger main jet. Full throttle is where the main jet realy comes into play. I would recomend starting with only one size bigger at this point.

[marylandmark]

Champion RN2C and NGK BR9ES what I am running most of the time. I step up to the 10's every now and then but they were fouling too fast during break in..

[Marko]

If you are only loosing power in the top end you need a larger main jet. Full throttle is where the main jet realy comes into play. I would recomend starting with only one size bigger at this point.

Thanks for the info. Right now I'm running a 95 main jet. Do I really need to go any higher? I'm starting to wonder if I've got poor vacuum or low fuel flow from the tank?

[florida derbi rocket]

If I remember, Jered or Lennox recomended putting an extra tie wrap around the hose to make sure it's tight. My vacuum line was expanded where the fittings were...I just trimmed off a 1/4 inch and it was a lot tighter.

[Marko]

If I remember, Jered or Lennox recomended putting an extra tie wrap around the hose to make sure it's tight. My vacuum line was expanded where the fittings were...I just trimmed off a 1/4 inch and it was a lot tighter.

Thanks, John. I'll inspect the vacuum line and give the tie-wrap a shot.

[Marko]

Sorry I kind of disappeared for a while. I managed to cut a tendon in my finger w/ a powered miter box saw several weeks ago. I'm just now getting up to speed, literally. I have tried many things to solve this problem, but I think I'm at the point where I need to seek professional help (in more ways than one!). I called a few shops locally and have found some help. Hopefully, I can get it in next week for a look to see what's wrong.

Just to reiterate, my main issue right now is with fast throttle response. Whenever I really rip the throttle, my scoot seems to stall/skip a bit and doesn't respond very well. If I baby the throttle, I can get up to speed without any hick-ups.

I have also purchased a GPS receiver and have clocked my new top speed - 49~50mph. What's more important for me is the acceleration which is much improved despite the modest gain in top speed. I'm hoping to see gains in top speed with some tuning help as well. We'll see.

Adios!

Marko

[florida derbi rocket]

Lennox...You work on a Derbi..Any Ideas?

[Lennox]

you say you have a 95 main in there? Have you tried any others? What setup again?

[Lennox]

Dell'Orto 19mm Carb
Metrakit 70cc Cylinder/Head
Metrakit Ecologic Pipe
4.5gram roller weights
Air-box modifications


you said earlier that you tried it without the filter, have you tried covering some of the "drilled" holes?

[derbi123]

have brought a derbi predator 1998 50cc and are wondering how you derestrict it and were the restricter is also how it can be made to go faster without any new parts.



thanks sam

=]