More power from Honda Nifty Fifty?

[Rabbi]

I own a Honday Nifty Fifty, its my jew mobile... I'm trying to save money on petrol.

The one I have is GUTLESS though... a friend of mine has a Suzuki(?) Jog scooter and his one pulls wheelies when you take off on full throttle. My one cant even get to 50 km/h on the flat.

I took a look at his and he doesnt run an air-filter so we put a filter on his and it ran like mud... BINGO "why dont I just remove the air filter on my scooter?".

I tried removing the filter tonight and it died every time I gave it full throttle... what could be causing that?
Too lean?
Too rich?
The scooter has a filter box with a panel filter... similar to a car. All I did was remove the filter box's lid and pulled out the filter (foam).

I tried messing with the carb settings but nothing made it good at full throttle... though turning it ALL the way in the clockwise direction helped a bit.

Do I need:
A longer intake tube length?
More/Less fuel?
Different timing?

Any help on getting this scooter to run quicker would be greatly appreciated!!

Chur,
Alex

[Mr. Peanut]

I think you'll find your friend has a slightly different transmission system to yours. Sure your transmission belt isn't stretched?

Good info here.

http://www.scootertherapy.com/runslowpage.html

and here

http://www.taffspeed.co.uk/page9.html

Could be any number of reasons your scooter is slower, I say live with it and leave it be....

[Rabbi]

Cheers for the tips man... I've read a little bit but not much.

By the sound of it I wasn't really doing much by playing with the mixture screws as they are both idle related... dammit!

I'll unbolt the manifold tomoro and remove the restrictor washer... then my next port of call is the CDI... I dont know what it is yet but apparently it restricts the engine to only 7000RPM?

I'll see if there's a way to raise it to 8000RPM or something? MUAAHAHAHAHA

Does anyone know how hard it is to modify the transmission to make the gearing taller? I'd like to do 60km/h on the flats instead of 40km/h

[Shadows]

I tried removing the filter tonight and it died every time I gave it full throttle... what could be causing that?
Too lean?
Too rich?
The scooter has a filter box with a panel filter... similar to a car. All I did was remove the filter box's lid and pulled out the filter (foam).

I tried messing with the carb settings but nothing made it good at full throttle... though turning it ALL the way in the clockwise direction helped a bit.

Do I need:
A longer intake tube length?
More/Less fuel?
Different timing?

Sounds like removing the filter has leaned the mixture out too much.
The screw that you were playing around with will only affect the idle mixture, so will not solve your problem.
If you are intent on increasing air supply to the carb, then you will also need to replace (or have enlarged) the main jet in the carburetor to let more fuel through.
After that you may or may not need to open up the exhaust a bit.

HOWEVER....

I wouldn't recommend running with no air filter. The scoot was designed to run with one so there must be something wrong if you need to remove it to make the engine run better.
Try replacing the filter element if it is dirty (or cleaning it), and make sure that the air box lid is sealed properly. It might already be running too lean if the airbox is been letting in too much air around the edges. This can affect top speed. Use duct tape or PVC tape to do this if you have to.
There may also be a breather pipe between the air box and the crank. Make sure that is connected properly at both ends and isn't blocked.
Also check the rubber tube between the airbox and the carb, make sure that has no holes in it and that it is connected properly at both ends.
Another possibility could be that your petrol tap is partially blocked, you might need to whip it out and give it a blow job!

[Rabbi]

Yeah looks like I will have to look further into doing the airfilter properly... I'll eventually get a pod filter I think. Depending on whether or not I need to connect a billion vacuum tubes..?

My biggest questions right now are:
1) does anyone know how to modify a CDI? (And where do I actually locate the CDI on my scooter?)
2) is it possible to adjust my main jet to give more/less fuel? or is it fixed in one position?

[diesel pig]

Did you put the lid back on? Taking out the filter and the airbox lid mite make it breath to well and run way lean.

1. Cdi are sealed units you would have to a different one to make it rev higher

2. A main jet is a small brass screw with a hole drilled in the center of it for the fuel to pass through. If you have access to very small drill bits you could drill it out to let it pass more fuel through it.

[Rabbi]

yeah i did... with the lid on and filter still out it made it much better. still no real gain over having the filter in though.

It's freezing tonight so that would just make it leaner... I need to figure out how to get the carb to give more fuel. Might need to take it into a shop?

[Shadows]

Yeah looks like I will have to look further into doing the airfilter properly... I'll eventually get a pod filter I think. Depending on whether or not I need to connect a billion vacuum tubes..?

My biggest questions right now are:
1) does anyone know how to modify a CDI? (And where do I actually locate the CDI on my scooter?)
2) is it possible to adjust my main jet to give more/less fuel? or is it fixed in one position?

Your CDI will probably be found at the non business end of your sparkplug lead. I wouldn't piss about with it if I were you.


You can't adjust jets but they can be modified by drilling or you can usually just buy them in the next size up. Don't try drilling it yourself though, take it to a bike shop or something. You need special jet drills which are extremely small.

One thing I forgot to mention was that maybe your problem is simply the result of a dirty jet. I have no idea what carburetor those things use but normally carbs have a float bowl on the bottom of them which can be removed with the carb body still in place. There will be a plastic float in there, make sure it is moves up and drops down freely. You should be able to see a couple of brass coloured screws above the float. These will be the jets (picture attached). Hopefully you can whip them out without removing the carb and give them a clean up in some petrol or carb cleaner, carefully sticking a single wire from a wire brush through the holes to clean them out. Don't spray carb cleaner willy nilly through your carb, it will ruin rubber parts. Throw the jets back in and see if it has made any difference.

[Shadows]

I need to figure out how to get the carb to give more fuel.

Bigger jets, or drilled out ones, will deliver the extra fuel.

Try the other things first. You may not need more fuel after all (and using more fuel will make it less of a jewmobile anyway).

[NSR-Dan]

ois it a 2 stroke or 4??

[NSR-Dan]

if its a 2 stroke i might be able to hlep you tune the thing up a bit, with some parts from the nsr50, might be able to fit some parts to the nifty, then you can leave your mate in the dust. but yeah it could be the gearbox slowing it down if its an auto

[texmo]

A 1980 honda nifty fity, its old so will have done a few kms and carbon coming out the exhaust will have blocked it up take the exhuast of the bike and clean it out with a LOT of degreaser or a propane tourch thinggy.

Scootling on grt north road next the the intersection of ponsonby and k'rd have a whole lot of scooter modding stuff in stock so maby pay them a visit if you wanna change your variator and or rollers.

[Rabbi]

diesel pig and Shadmeister,
thanks for tips regarding the carby... so basically what you're saying is I should first pull the carby apart and give it a good clean?
Thin wire for jets, carb cleaner for general grime and maybe a blast of compressed air yeah?
Then if it doesn't make it rich enough at full throttle with the filter removed I'll drill it out (in future I want to put a pod filter on but for now testing can be done filterless I'm thinking).
We have a lot of high end machinery and plenty of mechanical engineers at work so i'm sure i can get one of them to drill out the jets if need be... in exchange for a doz

DSR-Dan,
what do you recommend about changing the gearing to be a bit taller?
would simply replacing the old worn out belts (does it even use belts??) give me more top end?
i dont want to spend a lot of money at all... but if you have something you think would make this badboy go a lot better for a reasonable price let me know!!

Texmo,
Yeah I did several hours of reading last night about exhaust cleaning and carbon buildup... then slept in this morning cos i was so tired.
Basically what I got out of all the reading is that my best bet is to get some Caustic Soda... plug the end of the exhaust with a potato or something and fill it with Caustic Soda. Leave it for 5 hours or so and then rinse it out with a hose... leave to dry over night and then repeat the same thing the next day. Then run some vinegar through it to neutralise the Caustic Soda (very alkaline).


So plan now is:

Remove exhaust (I tried tonight and couldnt get the last nut off F&^%!!)
Drill out restrictor
Flush with Caustic Soda

Remove carb from scooter? Or just the jets? How do I get the jets without removing the carb?

[Shadows]

Remove carb from scooter? Or just the jets? How do I get the jets without removing the carb?

You might be able to get at them after removing the float bowl on the bottom of the carb. If not then you'll have to pull the whole thing out.

[Rabbi]

My carb looks like the one in the picture attached... that one is from a Honda Spree but mine definately looks similar.

The 2 screws up the top are for idle control... and apparently the lowest one is used to drain old fuel out of the carb.

Where is the float bowl on the carb pictured... how would you go about removing it?

Thanks a sheet load for all the help everyone!