Hi all my new project

[Greg58]

From what I’ve learned by trial and error is a longer head pipe before the expansion chamber helps low end torque. On the pipe I built that ran the best a 16” head pipe seems to perform best. The chamber I now have on my black bike is a fatty type that I welded a stock muffler on as a silencer, I could not stand the noise with out it.

 

[Pedalrat]

From what I’ve learned by trial and error is a longer head pipe before the expansion chamber helps low end torque. On the pipe I built that ran the best a 16” head pipe seems to perform best. The chamber I now have on my black bike is a fatty type that I welded a stock muffler on as a silencer, I could not stand the noise with out it.

Going for this exhaust. What do you think feed wanted plz

 

[Pedalrat]

Engine is a 70cc I think with 125cc carbi.im only getting 30km per hour speed is that about right?
Plus I'm 85kg

 

[Larry Trotter]

30 kph is terrible. 30 mph would be a little slow but respectable.

 

[Pedalrat]

30 kph is terrible. 30 mph would be a little slow but respectable.

Ok thanks for that Larry got some issues then need to fix will see if new exhaust helps .
My motor is still wearing in (new)

 

[Greg58]

I get 31-32 mph with both 48cc engines, my 66cc has been 40 mph.

 

[Greg58]

I haven't used that type of pipe, it has a small chamber that would probably work better on a 48cc. A 125cc carb will be jetted too rich for a 66-69cc unmodified engine and may be too rich for a reed engine.

 

[Pedalrat]

I haven't used that type of pipe, it has a small chamber that would probably work better on a 48cc. A 125cc carb will be jetted too rich for a 66-69cc unmodified engine and may be too rich for a reed engine.

Engine is GB 70 and carb is
Specification

• Outer Diameter to Air Filter: 50mm
• Outer/inner Diameter to Intake: 35mm/21mm
• Main Jet(dmm): 105
• Pilot/Slow Jet(mm): 38
• Size of two spare jets: 115mm/39mm and 125mm/41mm
• 21mm fit on 50cc to 100cc engine​

 

[Larry Trotter]

30 mph is terrible. 30 mph would be a little slow but respectable.

 

[Larry Trotter]

Well I meant to say 30 kph is terrible. Haha

 

[Pedalrat]

Looking for a straight reed box as I have enough room to fit as my motor is level this box is to much angled

 

[Larry Trotter]

If it was my problem a hacksaw and a trip to a welding shop would be my solution.

 

[Pedalrat]

Tried this. turned reed box upside-down, put on longer rubber joiner, carbi now on other side. But Having trouble starting! Would this be because carbi is now lower than reed box?

 

[Larry Trotter]

View attachment 108627 View attachment 108628 View attachment 108629
Tried this. turned reed box upside-down, put on longer rubber joiner, carbi now on other side. But Having trouble starting! Would this be because carbi is now lower than reed box?

No

 

[Pedalrat]

Put on back light. can I run front and back lights wich are LEDs strait of magneto?

 

[Greg58]

There’s a magneto coil you can add that is 12v to run lights, I’ve seen them on eBay for about $30.

 

[Greg58]

Here’s one I found, I’m not recommending it but it is a example of what I’m talking about.

12V Generator coil for 50cc 60cc 66cc 80cc 2-stroke Engine Motorized Bicycle | eBay

Find many great new & used options and get the best deals for 12V Generator coil for 50cc 60cc 66cc 80cc 2-stroke Engine Motorized Bicycle at the best online prices at eBay! Free shipping for many products!

www.ebay.com

 

[Greg58]

Several members here have posted on this on the forum, you can search for threads and find a lot of info.

 

[Pedalrat]

My engine has a magneto was just wondering can I run LEDs lights straight from it or do I need extra items

 

[Greg58]

The magneto is a low output system, a light robs power from the ignition. The old style coil had a white wire that several members have tried to use to run lights, a lot of people use rechargeable batteries in led lights for better results.