Honda PX with mods but poor top speed

Vicent Fabra Edo /

Hi everybody!

Im Vinny from Spain.

I've an Honda PX 50 from 1984. Its basicaly same engine as a camino but with different transmission.

Stock runs about 40-45 kmh flat , downhilll and uphill haha

Now i just installed a few ungrades:

65cc (46mm) Metrakit cylinder

Carbon reeds. (0.35)

Hand made welded intake with an 29mm diamenter intake

Amal 18mm as a carb with hiflow filter (85 main jet)

Turbokit exhaust (specific for the caminos , PA's and PX's

Specific Polini Vario with a total wight masses of 48g (Stock is about 80gr)

Rear clutch spring from Malossi (YELLOW ONE)

New sparkplug BR7 (indicated for the MK cycilnder)

With all these mods runs about 53kmh flat and 65kmh in a long downhill. Its seems to me poor top speed... What do you thing?

I try with less and more weighted roller weights but any improvement on top speed so i think actuall weight is fine.

I've the malossi gears 13/35 at home for mounting.

Any suggestions? I read some Camino's with similar preps that runs over 70kmh.

Honda PX.jpg

Re: Honda PX with mods but poor top speed

Beach Club Nick /

Awesome bike! We never got those in the USA but I'd love to have one. My roommate has a Hobbit with a metrakit, Mikuni VM20, and Crank's pipe that does between 85-95 kmh. My bet is on the variator tuning being off. Do you know if you're reaching full variation? If it's not the variator it's probably the pipe, Biturbo's aren't the highest performance pipes out there.

Re: Honda PX with mods but poor top speed

Brandon Weiss (Detective brandon to you) /

A minty PX is one of my dream bikes.

It could be anything, you need to verify that your timing is set properly, that you have no vacuum leaks, and that your jetting is in the ballpark. After that, then look into transmission tuning and other variables, or else you'd be putting the cart before the horse.

Re: Honda PX with mods but poor top speed

Beach Club Nick /

> Brandon Weiss (Detective brandon to you) Wrote:

> -------------------------------------------------------

> A minty PX is one of my dream bikes.

>

> It could be anything, you need to verify that your timing is set

> properly, that you have no vacuum leaks, and that your jetting is in the

> ballpark. After that, then look into transmission tuning and other

> variables, or else you'd be putting the cart before the horse.

Yeah I kinda assumed that these were already checked with my response, but these could definitely be hamstringing your performance

Re: Honda PX with mods but poor top speed

Nice bike. You might want to look into some nu50 Urban Express build threads here, exact same motor minus the pedals and a different carb/airbox, closer than comparing to camino/hobbits.

Some people here have laced a 16 inch rim onto the rear hub, or get the biggest 14 inch tire you can find.

Re: Honda PX with mods but poor top speed

what belt are you using? a worn out stock one will limit your top speed.

also, what variator are you using, got a link for it?

Re: Honda PX with mods but poor top speed

Vicent Fabra Edo /

I wear stock belt but with only about 2000km old. Vario is an specific one of Polini that i buy from an old stock of a shop.

What total weight for the vario will be okey? Im in 48g now.

Re: Honda PX with mods but poor top speed

Vicent Fabra Edo /

I just take a look at the timing and isn't son impressive. Is like 110/160. I opened a bit the transfers and polish the exhaust port. No leaks in exhaust or any other places. The carburations with the main jet of 85 is great.

Im in doubt about the weights for the vario , and if wear stock clutch spring or yellow one from malossi.

Re: Honda PX with mods but poor top speed

Downhill Harvey (OFMC) /

The px has a CDI. No timing adjustment.

If you're ever going to ditch the pedal parts, I'd buy them. My dream is an NU50 with pedals.

Re: Honda PX with mods but poor top speed

Vicent Fabra Edo /

And there are any "Performance CDI" for this bike or an better one?

Anyway I think its possiblo to set and configure the spark timming

Re: Honda PX with mods but poor top speed

> Vicent Fabra Edo Wrote:

> -------------------------------------------------------

> Anyway I think its possiblo to set and configure the spark timming

yes, it is, you just time it without the woodruff key. you'll need a timing light and a timing micrometer

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