need help on HIGH END TUNING

[808allday]

Right now my set up is

47mm af27 bore
2ab mini stroke crank
Pg long
Lighten mag
6.5 and 7 gram weights
Zx trans
Malossi fly clutch
Red malossi clutch spring
1000 rpm center spring
28 keihin carb
Jets is 138 and 55
7 to 1 gears

Bottom end is good but when it reaches the high end doesnt really pull any more what changes can i do to get more high end thanks in advance for the help

[Peteyparado]

What type of pipe u running ?

[kuromi]

Have you done any porting on your barrel?

[808allday]

What is dat barrel

[motormike]

What is that ?... barrel

cylinder

[808allday]

No ports been done to the cylinder

[MrJumps]

What pipe? Maybe a smaller carb? Lighter rollers?

[808allday]

What pipe? Maybe a smaller carb? Lighter rollers?

Pg long

[Wheelman-111]

Greetings:

At 76ccs, you still need some RPM to make good horsepower. Those rollers sound really heavy fir that spring. Consider a thicker Contra or drop to 30 or 33 grams total load to keep the revs up at higher speeds. I respectfully disagree that you can't make that happen with a PG Long, but tuning and gearing has to synchronize with the pipe's sweet spot. I agree that 28 is a lot of carb for that displacement. Although it is apparently a very popular carb in Hawai'i, I have found it makes it tough to tune. Consider a 24 for your setup.

[808allday]

Your right, the pg can get you there, but your not going to be anywhere near a scorp/arrow/sparrow. Not by a longshot. i think the trans sounds good, except I'd go stiffer on the contra I bet that pulley is opening up before he even takes off.


do you know what your rpm's are at, at top speed? this would help see whats going on.

No i dont know what my rpms are at top end i dont have a rpm tach should i go 1500 rpm on my center spring?

[808allday]

Pg long is a dud. It dies off at 9200 rpm, thats a fact. nobody can really say you will have a screamer in the top end, because we don't know the bore type. it could be a really nice taiwan kit, or an ebay special china kit that makes no power. its not ALL about CC, its about design.

Im guessing your issues are here

1: pg long
2: average bore design
3: bore not adjusted for proper port settings/compression


If you just stacked some base gaskets to make up for the mini, you messed up all your port timing, and you could also possibly be running too tight squish/compression, this will eventually burn a hole in your piston. You can't just slap in a mini without adjusting the ports.

My intake manifold port is matched up to my bore

[Wheelman-111]

Greetings:

Before you make any other changes, consider a TinyTach or similar and a CHT gauge to know where you are for tuning. I got my Vapor gauge from Graphite9, and was kicking myself for not doing it sooner. It even retains the top temperature and RPM for that last ride so you can see where you peak. If it's a Tai cylinder and ministroke crank, lean up the jets to shoot for 370F. and no more. If that's too much money, there are more-affordable CHT alternatives, or even buy a used one from someone here.

[1man8scoots]

How many base gaskets did you use.

[808allday]

you cant tune a bike correctly, without a tach and a temp gauge. If your not using a temp gauge, then you need to be doing plug chops. If you want to put effort into your bike and get it to run better, stop and get a tach, and temp gauge, otherwise your just going to be fighting it the entire way. its less than $100 for both gauges, or like wheel said find something used. There isn't really much anyone can do to help until you get the proper instrumentation

Ok just bought a temp gauge and rpm tach. How would i use these to gauges to tune my bike sorry for all the questions still new to wrenching mopeds

[808allday]

How many base gaskets did you use.

2 aluminum base gaskets