Help me solve a problem...Honda Lead (Aero) 80

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naturalsystem
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Help me solve a problem...Honda Lead (Aero) 80

Post by naturalsystem »

Hey there!

Over the last two months I've been restoring and riding my first scooter - a Honda Lead (Aero) 80. The NH80 to be specific.
A problem I was having originally was that the idle screw would do nothing....
I went through all the cleaning and tuning steps, but was convinced there was an air leak somewhere as no adjustment would change anything.

What I have installed / replaced so far is the following:

Polini CP 21mm Carb w/ choke cable & Polini filter
Throttle Cable
Naraku Intake manifold
*Removed oil pump line*... premix now (40:1)
18x14 16g rollers
Drivebelt
"Race" Exhaust... (didn't have branding on it, quality welds though)

Jetting as follows:
Main 104
Pilot 40
Needle 14/22

I should make it clear that after installing the new carb and intake, the idle is able to be adjusted!

My problem are the following:

1. hanging idle (potentially pilot jet / needle clip point?)
2. weak take off until 20km/h, gets into a "power band"... bogs again between 30-40km/h and then just rockets away past 40km/h*
*I'm now hitting 90km/h (GPS verified)... That's 55mp/h

I thought it could be my variator face as it was worn... but I don't think so (I also don't have another face to try).
I machined the grooves out very lightly but didn't remove them completely.

I know these problems are able to be solved... I'm just needing some direction.
No mechanic in my area (Australia) is actually willing to look at a modified scooter....
Any help would be greatly appreciated!
1986 Honda Lead 80 :lol:
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Re: Help me solve a problem...Honda Lead (Aero) 80

Post by Meatball »

The CP carbs like small jets. Sounds like your pilot is fat. Ive never messed with the NH80 to be honest.
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Re: Help me solve a problem...Honda Lead (Aero) 80

Post by eclark5483 »

On my CP carbs, I notice this happening if I have the air filter cap off. Needs a bit of back pressure. And like Meatball said, smaller pilot. On mine with the 48mm BBK (68cc), they are both happy with a #36. I'd imagine yours would probably want around a #38 or possibly even the #36 as well.
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Re: Help me solve a problem...Honda Lead (Aero) 80

Post by Meatball »

Now get one of these kits...bore/hone your cylinder to match and make it 90cc!....let er rip! :rock:

https://www.motosport.com/product?adpos ... ent=badger
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Re: Help me solve a problem...Honda Lead (Aero) 80

Post by naturalsystem »

eclark5483 wrote: Sat Aug 18, 2018 11:18 am On my CP carbs, I notice this happening if I have the air filter cap off. Needs a bit of back pressure. And like Meatball said, smaller pilot. On mine with the 48mm BBK (68cc), they are both happy with a #36. I'd imagine yours would probably want around a #38 or possibly even the #36 as well.
Forgive my ignorance, but where is the air filter cap located?
If you're talking about a stock airbox - that has been deleted and I have a Polini "pod" style filter on it https://scooterswapshop.com/products/po ... od-filters

I'll order a pilot jet kit this week!

I've attached a VERY (hahaha) rough graph of how I perceive the correlation between RPM and speed... hopefully that helps illustrate the point better!
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Speed-Graph2.jpg (19.71 KiB) Viewed 7601 times
1986 Honda Lead 80 :lol:
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Re: Help me solve a problem...Honda Lead (Aero) 80

Post by eclark5483 »

My bad, I was talking about this cover:
Image

It helps you gain back pressure. Since you switched from a stock carb to an aftermarket, you need to adjust the carb for the bike. I'm going on the assumption you are using it. If not, please put it back on and retest.

Since you no longer have the stock air box helping create the needed backpressure, you need to experiment a bit and find out what works with the CP carb. TBH, CP carbs weren't really meant for scooters, the stock jetting you get might be too much for the bike to initially handle on the pilot, and too weak on the main depending on the size you bought.

I honestly know nothing much at all about the NH80, but from my understanding of 2 stroke engines, I'd almost guess a 21mm is too big and a 19mm would be better. Don't by any means spend more money.. just saying.. from what info I have discovered on the engine. And experience adjusting the Polini CP carbs.

EDIT: P.S., how bout some pics of the bike. :thumbsup:
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Re: Help me solve a problem...Honda Lead (Aero) 80

Post by naturalsystem »

Ok, so I've put the cover back on and will go for a ride / report back!

From what I read on various places online and talking to Brandon at Scooter Swap Shop, people have run up to 24mm carbs on the NH80... so I figured 21mm would be ok.
I will definitely look into the pilot jet and try downsize it to a #36 and test.

Any further suggestions would be greatly appreciated!

This is all VERY new to me, but I'm so deep into it already I don't want to give up until the solution is found hahaha
Plus I love riding it!

Here are a couple of images of it recently :)

Image

Image
1986 Honda Lead 80 :lol:
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Re: Help me solve a problem...Honda Lead (Aero) 80

Post by eclark5483 »

I love Autumn backgrounds when I see old Hondas. That's a very pretty bike in such awesome shape. Hope you get the tuning down on that beauty.
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Re: Help me solve a problem...Honda Lead (Aero) 80

Post by Meatball »

The graph leans towards your roller weights being too heavy. Once the RPM’s reach a certain point, inertia forces the rollers outward and makes the variator pulley open/close creating a “gear shift” if you will. The RPM threshold this happens is determined by weight of rollers. Heavier rollers will shift sooner while lighter weights require higher RPM’s to move.

An optimally tuned trans will shift once the motor has reached it’s peak horsepower. If rollers are too heavy, the trans shifts too early and will drastically drop RPM’s and lug causing slower acceleration....its like shifting your 5sp car at 2000 rpm’s as opposed to 3,500.

My recommendation: dont just buy ONE pilot jet..buy a kit in the range you think you need so you have more options than one. Also, buy a roller weight kit to tune your trans to shift at the optimal rpm.
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Re: Help me solve a problem...Honda Lead (Aero) 80

Post by Meatball »

Also, love “peace” mirror....but here in the US we would need it on the other side. :2thumbs:
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Re: Help me solve a problem...Honda Lead (Aero) 80

Post by naturalsystem »

Meatball wrote: Sun Aug 19, 2018 1:43 am The graph leans towards your roller weights being too heavy. Once the RPM’s reach a certain point, inertia forces the rollers outward and makes the variator pulley open/close creating a “gear shift” if you will. The RPM threshold this happens is determined by weight of rollers. Heavier rollers will shift sooner while lighter weights require higher RPM’s to move.

An optimally tuned trans will shift once the motor has reached it’s peak horsepower. If rollers are too heavy, the trans shifts too early and will drastically drop RPM’s and lug causing slower acceleration....its like shifting your 5sp car at 2000 rpm’s as opposed to 3,500.

My recommendation: dont just buy ONE pilot jet..buy a kit in the range you think you need so you have more options than one. Also, buy a roller weight kit to tune your trans to shift at the optimal rpm.

Ok now we're getting somewhere!
That makes sense to me, it feels transmission related but I didn't want to assume...
It does feel like it's shifting too early!

SO, I guess my next question would be - how light of a roller should I start at?
Currently they are 18x14 16g rollers.
There are kits with 3 of each weight available from 6g - 17g.
Or should I buy multiple sets of same weighted rollers?

Hopefully this + Pilot jet kit will solve my woes!
Meatball wrote: Sun Aug 19, 2018 1:49 am Also, love “peace” mirror....but here in the US we would need it on the other side. :2thumbs:
HA! It's not the greatest mirror, but it certainly attracts smiles :)
1986 Honda Lead 80 :lol:
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Re: Help me solve a problem...Honda Lead (Aero) 80

Post by eclark5483 »

How much weight to use. Now THAT will always be the million dollar question. I know Dr. Pulley makes a kit with different weights so that you can test. It really is trial and error when it comes to CVT tuning. Your tune might not be what another person needs. If you really wanna get to the bottom of it, get a kit, a note pad, a tach, and a GPS app and figure it all out. From the sounds of it, your rollers are maybe too heavy. But again, get a kit and test different weights. That thing shold rip when you get it right. Contra spring makes a difference too, if you wanna get into that. But then getting deep into it involves better parts then stock IMHO.
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Re: Help me solve a problem...Honda Lead (Aero) 80

Post by Meatball »

Every scoot is different and nobody can accurately tell you what jet, rollers, etc will work best. Here is some roller tuning info to chew on: rollers are rated by individual weight, in your case 16g. However, the TOTAL weight of all rollers together is the number you should ultimately be tuning with. If you have 6 rollers your total weight is 96g. You could try dropping 6g by using all 15g weights. If this drop is too much, you could use three 16g and three 15g to drop your total weight only 3g.

Just remember, when using different weight rollers they must be staggered when placed into the variator so not to cause an imbalance. Example: 16-15-16-15-16-15...get it?

This is why you buy a kit with various sizes. Try a weight combination, ride it, try another, ride it...etc. Dont forget to have fun while youre doing it!
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Re: Help me solve a problem...Honda Lead (Aero) 80

Post by naturalsystem »

I'm guessing the rider's weight would also contribute to the varying tuning factors!
So all the above in mind, I'm going to purchase the following:

#32-40 Pilot Jet kit
6g-17g Roller Tuning Kit

Once I've run some tests with the GPS and get some noticeable changes, I'll report back!
In the mean time, if anyone has any further suggestions - I'm all ears :)

Thanks for all your help so far!
1986 Honda Lead 80 :lol:
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Re: Help me solve a problem...Honda Lead (Aero) 80

Post by Meatball »

Its nearly impossible to jet a carb without a CHT.
I need to find some new haters...the ones I have are starting to like me.
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