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Subject: "HP4 flywheel" Archived thread - Read only
 
 
Conferences > International Scooterist BBS > Topic #41589
Reading Topic #41589

LeoPX200E
Member since Sep-14-05
12 posts
Sep-14-05, 08:22 AM (EDT)
 
"HP4 flywheel"
 
   hello,
I got a second hand HP4 flywheel for my px200.
the seller said it was from a 125px.
It fits ok other than the fact the fanwheel diameter is frighteningly smaller than that of the original flywheel, and also the timing is out of phase - some scary backfires from my JL exhaust.

1. is it possible that this will fit my px200E?

2. how many degrees should i retard/forward my stator?

I can post a picture as well, later.


 

 
djriel
Member since Aug-30-05
131 posts
Sep-14-05, 08:35 AM (EDT)
 
1. "RE: HP4 flywheel"
In response to message #0
 
   There are two notches for the woodruff to fit into: use the one that matches the magnet on the hp4 to the magnet on the old flywheel...the backfire is probably from using the wrong notch.


http://www.steelcityscooters.com
http://www.steelcitysoul.org


 
Greyhound
unregistered user
Sep-14-05, 08:38 AM (EDT)
 
2. "RE: HP4 flywheel"
In response to message #0
 
   >hello,
>I got a second hand HP4 flywheel for my px200.
>the seller said it was from a 125px.
>It fits ok other than the fact the fanwheel diameter is
>frighteningly smaller than that of the original flywheel,
>and also the timing is out of phase - some scary backfires
>from my JL exhaust.
>
>1. is it possible that this will fit my px200E?
>
>2. how many degrees should i retard/forward my stator?
>
>I can post a picture as well, later.

You can't just slap a flywheel on and expect it to work. You can do some serious damage if your not careful. My HP4 has two keyways - you need to establish the correct keyway for your bike and then correctly set the proper timing.

I don't have my notes with me - but what head do you have on the bike - stock? or a kit?

The keyway info may be on the SIP site or the Worb5 site. Good luck.

J.D.

VCOA Pres.
http://vespaclubusa.org

Sputnik!SC Pres.
http://www.sputnikokc.com


 
LeoPX200E
Member since Sep-14-05
12 posts
Sep-14-05, 09:02 AM (EDT)
 
3. "RE: HP4 flywheel"
In response to message #2
 
   hey, thanks.

I tried both keyways, actually, but indeed heard that some timing change is required.

I run a stock setup at the moment, with the JL pipe and a bigger needle.

does anyone know if this flwheel, which was off a 125px is good for my 200px?


 
djriel
Member since Aug-30-05
131 posts
Sep-14-05, 09:07 AM (EDT)
 
4. "RE: HP4 flywheel"
In response to message #3
 
   Well I run a hp4 on a ported malossi setup with a jl - i set the timing to the malossi - i didnt change it when i added the jl and hp4

maybe it needs changed for a stock but I don't know.

It wouldnt make sense that the timing would have to be changed for the flywheel, because the magnet is in the same place as a stock flywheel...


http://www.steelcityscooters.com
http://www.steelcitysoul.org


 
phonIEracer
unregistered user
Sep-14-05, 10:01 AM (EDT)
 
5. "RE: HP4 flywheel"
In response to message #4
 
   the hp4 keyways are generally for a p200 or small frame. the one on the right is for a p. don't know if a 150 will work on the 200 though. be careful also with the fan, they can be brittle and the screws can also back out and cause some real fun!!


 
Red_6
Member since Sep-22-02
748 posts
Sep-14-05, 12:27 PM (EDT)
 
6. "RE: HP4 flywheel"
In response to message #3
 
   The HP4 is a pretty seriously lightened flywheel.

I have noticed that very few 200+ motors run well with it on. I have on on my 177 and it absolutely makes the bike. I put it on our 210 and it was interesting but not as beneficial as on the 177.

I feel like the PK and the P150 euro flywheels are a more functional option for lighter flywheels when comming from a US market p200.

Some work well, but are ususally at a pretty high state of tune. Downsides are that it wont idle the same and your hole shot is greatly compremised. Upsides are that it will excellerate much harder much sooner in the powerband.

In my experience, this is not helpfull in a vespa platform as the front already comes up pretty easily in low RPM's and peak power is more usefull between mid and high rps where you are moving allong pretty well.

As for timing, asside from the 2 slots thing; each flywheel is subject to the manufacture's tollerences for spec. some are dead on, some are off, best thing to do is to check it with a timing light, a TDC device and a degree wheel before running it for much. Usually better to error on the side of retarded than hole the piston.

Fire It Up!
Scotty


 
Stanley
unregistered user
Sep-14-05, 05:38 PM (EDT)
 
7. "RE: HP4 flywheel"
In response to message #6
 
   I am running one on my PX, it's off at the momemnt as I'm getting a starter ringer gear adaptor made for it. The idea being to add a little weight and re gain the electric start.

The HP4 weighs 1.08 kg.

I found it great. Acceleration is greatly increased, it won't really add to the top speed, just get you there quicker.

The downside is that the scoot won't idle quite so well. I found that just knocking the idle up very slightly helped. It also takes some getting used to taking off in first. Over cook the throttle and you are away very fast, great on the straight but be careful if taking off and turning at teh same time, drag the back brake! Under cook it and it is easy to stall. Just takes some getting used to.

Here's a photo showing the two keyways. Mine is marked for the PX.


 
kyle01
unregistered user
Sep-14-05, 06:15 PM (EDT)
 
8. "RE: HP4 flywheel"
In response to message #6
 
   i like to run hotrod scooter al's lightened flywheel on my polini 210 rally... it's between hp4 and stock- but makes a pretty noticeable difference... motor is more revvy and responsive. a bit easier on yr
flywheel side bearing too.


 
Johnny Diablo
Member since Sep-1-05
1179 posts
Sep-14-05, 10:39 PM (EDT)
 
9. "RE: HP4 flywheel"
In response to message #8
 
   how does this HP4 compare with the old pinasco flywheels? I used to run the piss out of the pinasco flywheels until the rivits come loose....then souce a new pickup and flywheel.

I still have a pinasco welded flywheel waiting here for my next scoot but I have learned to hate them for trashing stators

Widebody Modding Forum:

http://diablossc.com/Forum/default.asp


 
Stanley
unregistered user
Sep-15-05, 04:46 AM (EDT)
 
10. "RE: HP4 flywheel"
In response to message #9
 
   Johnny they don't compare. The Pinasco was shit.

The HP4 is very well built see photo!

It is all securely kept together as you can see.

Here are a few stats for you:

(courtesy of my local green grocer's electronic scales!)

PE/PX pre disc model flywheel : 2.9 kg

PX Disc model: 2.2 kg

HP4 : 1.08 kg (plus electric start, coming soon, approx 1.4 - 1.5kg)

Kyle, as for you saying the the flywheel bearing will wear out quicker with the HP4, nothing could be further from the truth mate!

There is less stress on this goofy bearing, the less the flywheel weighs!!!


 
LeoPX200E
Member since Sep-14-05
12 posts
Sep-15-05, 07:31 AM (EDT)
 
11. "RE: HP4 flywheel"
In response to message #6
 
   thank you all.

scotty, what do you mean when saying:

"your hole shot is greatly compromised"

>> so I understand the HP4 flywheel comes only in one dimension that fits all engine sizes but works better for the 125-150 series ?

according to the reviews, even if i manage to fit it on, I might get dissapointed with the overall performance, as I am preety satisfied with the acceleration as it is, and also like the benefits of traction and engine braking that a heavier flywheel offers.

I think I will try to get a 2.2kg flywheel from the late disc models, and sell the HP4 one.


 
Johnny Diablo
Member since Sep-1-05
1179 posts
Sep-15-05, 12:39 PM (EDT)
 
12. "RE: HP4 flywheel"
In response to message #11
 
   >like the benefits of traction and engine braking that a
>heavier flywheel offers.
>
>I think I will try to get a 2.2kg flywheel from the late
>disc models, and sell the HP4 one.

As a rule (that I break rarely from time to time) engine braking is a no no on something that you put oil in the gas.

I ran a late model px flywheel after my pinasco blew up my motor. It was a bit lighter than a p200 flywheel and could never much tell the diffrence between the two. This was on a full mod malossi210, reed, 30mm carb and pipe combo.


Widebody Modding Forum:

http://diablossc.com/Forum/default.asp


 
Dr Sparks
unregistered user
Sep-15-05, 01:46 PM (EDT)
 
13. "RE: HP4 flywheel"
In response to message #12
 
   Engine brqaking on a two stroke?

If you say so, can't be arsed arging with idiots anymore. Feel free to hurl more abuse, I'm getting used to it. But try and back your arguments up with more than a bland statement... such as 'there is no difference in a 2-stroke piston under engine braking stresses and a four stroke one.' Do the math, its basic physics. In fact its probably less due to four strokes generally have a heavier piston, giving greater twisting action on the crank, therefore putting greater strain on the engine components.

The HP4 is a nice idea for a sprinter. For a road going bike (ie one thats used for distance work) its not a hugely good idea. One of the aadvantages of having a heavier flywheel is that the momentum of a heavier flywheel keeps the revs from falling as quickly when you encounter a hill.

So it depends what you want to use the scooter for. Great fun around town and on the track, an absolute pain on the road... get used to the third gear shuffle.
Yes, I've run one (not a HP4 I hasten to add, but a one off on a Lammy, but the principles are the same, this one came in around 1.3kg lighter by the time we'd finished with it). The bloody thjing stayed on for one rally before I swapped it with a mate for a stock one.


 
Stanley
unregistered user
Sep-15-05, 06:04 PM (EDT)
 
14. "RE: HP4 flywheel"
In response to message #13
 
   Would have to agree Dr Sparks, I can't be arsed discussing 'engine braking' with people here who seem to have invented the phrase!

Suffice to say, there is nothing wrong with engine braking. It does not do the scooter any harm and is a useful move in certain circumstances. (especially if your cruciform is of the flat variety! )

As for the difference between an older 2.9 kg and a newer 2.2 kg flywheel, yes there is! I have swopped from one to the other in the same day and yes there is a small difference, one that you would notice!


 
smallframeasshole
unregistered user
Sep-16-05, 00:58 AM (EDT)
 
15. "RE: HP4 flywheel"
In response to message #14
 
   NO MAGIC HERE. the hp4 is a stock piaggio flywheel. for a smallframe ,the second keyway for the px is cut later and broached, and there is no difference between any px flywheel a far as timing slots go.


 
smallframeasshole
unregistered user
Sep-16-05, 01:02 AM (EDT)
 
16. "RE: HP4 flywheel"
In response to message #15
 
   PS nothing is perfect SET YOUR TIMING WITH THE PROPER TOOLS!!!


 
LeoPX200E
Member since Sep-14-05
12 posts
Sep-18-05, 03:00 AM (EDT)
 
17. "RE: HP4 flywheel"
In response to message #16
 
   thanks for all your comments,
they are much appreciated. actually i do have the proper tools to set the timing, so i'll give it a go.

BTW, I drive in town every day, lots of traffic and traffic lights and I use engine-breaking or whatever you call it as much as I use reverse steering...


 

 

 


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