Honda Dio zx50 fresh build, help.

[mantrans]

HI guys/gals, hoping to get some help and that this is the correct place to post.

I just put together my zx50/dio and I am having some issues, I have been working on performance stuff for years, mainly cars,atvs and dirtbikes but I am new to this
Mods: 72cc malossi sport big bore kit,pg longpipe v8 pipe whatever,19mm polini carb and polini filter
Variator with 7.5 rollers
Polini race clutch with reinforced spring and 3k rpm clutch springs
Naruku de restricted cdi
Fuel is premix vp 110 with klotz 30:1
90 main jet
160lbs 5'10"
everyting else was just oem replacement stuff like stator and such.

On to the issues: Takes off ok, starts to accelerate hard when I hit 30mph it hiccups just a bit, not a huge bog or decrease in speed just a small hit like it lost a tad bit of power. The bike then comes on strong all the way to 48-50mph, then it completely loses acceleration, I have a tach that only reads 9k so the whole time the needle will be pegged to its maximum reading but at the listed speed it will drop instantly to about 8,200 rpm and stay there constantly, I might go from 50 to 52 but thats it. Its not making any noise but is feels as its hitting an invisible rev limiter. Plug looks good, I have tried 90,100,102,110,118 main jets and played for hours on a empty road with the air fuel mixture screw. Crazy thing is that 1 or 2 times out 10 the bike will just rip from 0 to 60+ but most of the time it just does its little limiter thing where it wont allow the bike to build any more power. Thanks for all the help in advance!!!!

Also I have a one off spark plug in there, as the factory size plug does not fit ( too small diameter wise) so I got some el cheapo from a auto parts store for a lawn mower. What is a good plug and correct size? thanks.

[Wheelman-111]

Greetings:

There are substantial differences between a PG Long and a V8 exhaust. "Whatever" doesn't help. In general a Sport cylinder makes most of its torque at or below 9000. If you don't match that with a pipe that resonates well at this engine speed, you kind of kill the low end. The V8 should provide that match but the Long almost surely will not.

You didn't mention your center spring gauge, but in general 7.5 sounds a little heavy. I suspect if you keep your throttle open and the wind is astern, once in a while the engine dances close enough to its power band to zoom on up to the 60-ish speed you mention? But if you lose commitment and the cam on the rear pulley shifts, the engine doesn't have the power to overcome wind drag with the tall gears you must have to be hitting 60 once in a while. If you say it's hit 60 with stock gearing, you need a new speedometer.

Drop to all 7s in the variator and see if you like it better. Watch for the revs to run a little higher in the transition from take-off to top speed. Then drop another half-gram until it stops improving.

I don't know what a 1-off spark plug is. Evidently someone re-drilled a stripped plug hole and made threads for the next size up? Easier to replace a cylinder head than to guess what plug heat ranges are available in an oddball size. Factory should be B8HS from NGK with your setup. Other brands might be close, but for $4 why be guessing?

[mantrans]

Greetings:

There are substantial differences between a PG Long and a V8 exhaust. "Whatever" doesn't help. In general a Sport cylinder makes most of its torque at or below 9000. If you don't match that with a pipe that resonates well at this engine speed, you kind of kill the low end. The V8 should provide that match but the Long almost surely will not.

You didn't mention your center spring gauge, but in general 7.5 sounds a little heavy. I suspect if you keep your throttle open and the wind is astern, once in a while the engine dances close enough to its power band to zoom on up to the 60-ish speed you mention? But if you lose commitment and the cam on the rear pulley shifts, the engine doesn't have the power to overcome wind drag with the tall gears you must have to be hitting 60 once in a while. If you say it's hit 60 with stock gearing, you need a new speedometer.

Drop to all 7s in the variator and see if you like it better. Watch for the revs to run a little higher in the transition from take-off to top speed. Then drop another half-gram until it stops improving.

I don't know what a 1-off spark plug is. Evidently someone re-drilled a stripped plug hole and made threads for the next size up? Easier to replace a cylinder head than to guess what plug heat ranges are available in an oddball size. Factory should be B8HS from NGK with your setup. Other brands might be close, but for $4 why be guessing?

,
Thank you, sorry about the pipe, it says valour and virtue Varoom on it, got it off of scooter swap shop if that helps, does not have the expansion champer, silencer on it.
Speed was done next to my car 2014 chevy. Even if it was not really 60mph it still climbed straight to where it said "60" a few times now it slows down greatly around 40-45 then completly stuggles when it hits where it says 50mph. Highest gps reading was 57.14, tried the gps app in my car and it was 1.5mph off only.
Has stock dio gears in it ( I have taller gears from scooter swap shop) 8.7:1 I believe. Has malossi mulitvar with polini clutch that has the spring adjustment alan head screws for each spring, the springs are the yellow 3k rpm ones which according to polini it is the 72cc recommended ones, step down a spring and it is for 50cc with pipe/ carb/filter and vario mods, and a step up from where I am at is for stroker builds.
I was running the reinforced white spring and just swapped in the blue 15% spring.
ALL of these runs are on a dedicated mile long strip that has zero traffic, I have markings on the road for distance I measured with a measuring wheel, ALL runs are ran with the wind or if there is a cross wind, no test passes are against the wind. I record times and adjustments and not temp, wind speed and direction of wind, if I change something I make note of it so I can track progress.. Thanks for the help, I appreciate it.

[mantrans]

Went out a little while ago, rpms stayed a little under 9k, I would assume im not creating the rpms correct? I have aroller kit from 4.5 to 9 grams, I will step down to the 5.5-6 gram range like you mentioned.

[1man8scoots]

So is this a kymco zx50 or a honda dio zx?

[1man8scoots]

It actually has to be a kymco zx50 if you have a stock speedo reading 60. Kymco speedo isn't off by much. It's real nice. 60 is achievable with stock gears but unfortunately the gears you have won't work on your engine. Primary swaps only. Malossi or polini 16/32 gears which give you a 6.89:1.

[mantrans]

So is this a kymco zx50 or a honda dio zx?

zx50 although it shares a good portion of its parts with the dio, the whole engine/carb and pipe were made for a dio.

[Downsouthdio]

Still a big difference in the two.

[Downsouthdio]

Its a pg long