Derbi GP1 LC 50cc cutting out By frolicndetour (Read 4,465 times)

[frolicndetour]

Hi all--

About a month ago I bought my first scooter. It's a 2003 Derbi GP1 Predator liquid cooled. Previous owner bought it in 2006 and only put approximately 580km on it. He's getting up there in age (68) and doesn't trust his balance anymore, so that's why he sold it. Important to note, it sat in his garage for years with all fluids present.

I don't know much about scooters. I drove them for a pizza delivery job I had once. I test drove it and it zipped up and down the block. I paid and went my way.

Primary problem

My biggest problem right now is that it often cuts out. Sometimes I can make three in-town round trips in a day and have no problems. More recently, however, I get 1/4 mile down the street to my first stop sign and wait for traffic. When I get the right of way to go.. I twist to open the throttle and it cuts out. A few weeks ago it would do this but it would start back up. Lately, it doesn't give me that choice. I have to walk the bike home.

One coworker said it was cold natured because we have been having some cold mornings here in Delaware. I tried to let it idle for a bit and that seemed to help for a short period of time. It doesn't help anymore. The same coworker suggested the carburetor is most likely gummed up from ethanol gas sitting in there. However, another friend suggested I test the petcock first prior to taking on a big job like the carburetor (because I am inexperienced, and I could potentially mess it up).

Also, I rode around the other day and the scooter stayed running for a long time but it started to overheat. I suspect that the coolant is old and sludgy.

Secondary problem

Secondary and not as important, my turn signal won't turn off once activated. I can turn it left, and right to activate the signal. However, the off button in the middle doesn't turn it off. I called a scooter shop and he quickly said it was the flasher. I better explained that it will activate, just wont turn off, and he was baffled.

Plan of action

I plan to try to test the petcock by pulling off the vacuum line and gas line to try to simulate vacuum to see if gas runs. If it doesn't, I need to learn to disassemble/clean my petcock. If it operates correctly, I'm under the impression I should next move on the carburetor as suspected to be gummed up. If it comes to that, I am concerned I wont know how to reassemble it. Also, there is a hose clamp on the intake manifold that doesn't have a screw (it's just a metal ring with a crimp) that I don't know how to remove.

Additionally, I am going to tackle the recommended maintenance that the booklet suggests for amount of time (because it was sitting). I am trying to figure out how to drop the coolant but can't find a plug or a hose to remove.

Any advice and insight would be helpful. I realize my story is all over the place, but I am new to this and eager to learn!

[Guitarman]

First things first. Take it apart and do a complete PDI on it That's likely to solve many of your problems. During the PDI, check and set the valves correctly. And while you're at it, clean the fuel tank, fuel lines, and carb. Might as well replace the filters while you're at it, oil and gas... Flush and fill the coolant system also.

I bet after doing this, you will have eliminated 98% of any issues you now have and will be cruising for many miles.

You can look in the library here for PDI's but I'd strongly recommend this one;
Big Guy's PDI

The reason you should do all of this is because the problems that most often crop up on these bikes is something that would have never happened if a proper PDI had been done.  Save yourself tons of frustration and broken knuckles by getting it done right up front.
Really... This is your first best defense against the very problems you've described.

WARNING!
READ THE ENTIRE pdi BEFORE YOU BEGIN ON YOUR BIKE.
There are lots of little gotchas hidden in there that you will avoid simply by reading it first.

The only thing he doesn't cover is changing your brake fluid.  Check any number of YouTube videos to learn how to do that.  When I first got my scoot, the fluid in the brake lines was chunky.  Yeah, I said "chunky".  It looked like a handful of sand was tossed in with the fluid.  Drain and replace with REAL Dot3 or Dot4 Brake fluid.

[Guitarman]

One last thing... Are you Kevin Spacey or just impersonating him?

[Bashan]

Usual suspects

Set your valves and get that off the table in addition to Andy's advice.

The turn signal switch is bad. Try squirting a little WD40 into it and then push it a few times. WD40 won't hurt the connection and it might free things up.

[frolicndetour]

Oct 10, 2014 20:52:46 GMT -6 Guitarman said:

One last thing... Are you Kevin Spacey or just impersonating him?

I'll read the PDI tomorrow. That'll give me a starting point to try to troubleshoot.

And I am not Kevin Spacey, but I did enjoy him in House of Cards!

Thank you.

[frolicndetour]

Oct 10, 2014 21:15:57 GMT -6 Bashan said:

Usual suspects

Set your valves and get that off the table in addition to Andy's advice.

The turn signal switch is bad. Try squirting a little WD40 into it and then push it a few times. WD40 won't hurt the connection and it might free things up.

I will definitely start down the road of Andy's advice. I have heard tell of valve adjustment. I've been getting mixed information as to whether it HAS valves. I forgot to mention it is a 2 stroke. Does it still have valves?

I'll try squirting the WD40 in there after I'm done working with it on other stuff. It bugs me to no end when it keeps flashing.

Thank you.

[Guitarman]

Never saw House of Cards. I'm not a big TV fan. Most of it is mind numbing trash not fit to reside on a sheet of yellow press.

Watch this:


Stroke or Cycle... Same thing.  And they do both have valves.

[cyborg]

that engine is a 2 stroke ,,,no cams and poppet valves,,,it has instead reed valves right behind the carb in a block,,,pull the carb and check them,,,they look like two rectangular leaves that touch on one end like a triangle,,,sometimes they split or a chunk cracks off the tip then the bike runs like poo,,,,also since it's a 2 stroke you have been putting 2 stroke oil in it correct?,,,it has oil injection that "mixes" the oil in the fuel stream,,,there is no oil in the crankcase like a traditional 4 stroke engine the oil is in the fuel,,,without it you will seize the engine

[Bashan]

I'm sorry, I do that every time, two strokes do not have valves to gap, they have reed valves. I always think in terms of four strokes since that is what I cut my chops on. Ignore what I said and heed the other guys' advice. Two strokes are actually a great motor and produce more power than a 4T. But due to pollution laws their time is probably limited in the USA.

[frolicndetour]

Bashan-- I understand, I forgot to mention it was a 2 stroke. No worries.

Cyborg -- I have driven it 100km since purchase and have added ZERO oil. I look in there and can see oil in the reserve from the cap under my seat. It looks fairly full. Is there a certain way I should check it aside from peeping into that hole?

Same for the coolant. I look in that hole and it looks full. But the coolant looks like it has rust specks in it.

[cyborg]

thats only 80 miles or so ,,,,i would top it up,,,and as far as checking it see if there is either a sight window or a clear line on the side of the reservoir,,,,i still would pull the carb and reeds to see if you have a cracked or chipped (flaked reed),,this will cause a big over rich condition and when the engine warms up ,,,too much fuel and stall

[frolicndetour]

Okay very good. I plan on finishing up schoolwork and taking this all on soon (pulling all the body parts and going to work).

Here is a diagram of my carb from a parts website. I can't find the reeds. Any advice?




Source: www.derbimotorcyclespares.co.uk/genuineparts/9187/017/derbi%20gp1%2050%20-%20upto%202005/carburetor?uID=0

[Bashan]

That's because they are between the carb and case:

[Bashan]

A reed valve looks like this:

[Alleyoop]

His 2 stroke does not have a REED VALVE it has your basic 2 stroke carb which usually have a AIR RATIO screw on the AIR FILTER side of the carb like this.

The 2 strokes that usa reed valve have a FLANGE that bolts up to the intake manifold and the Reed Valve goes in there.
Alleyoop