1. Clats97

    Shaving head, intake, exhaust

    Ok so I've shaved the head a bit and ended up increasing compression. I read somewhere that you can shave some of the exhaust port to increase top end performance? Is this true? If so how do I go about this. I've already dremeled the intake manifold so it's the exact same size as the port. It...
  2. D

    Exhaust system for 4-stroke

    I have a huasheng 49cc 4-stroke engine on my bike and it has the standard exhaust that comes with it. I would like to "Upgrade" or change it out for another better looking and better performing exhaust system. I want it to go all the way back to the middle of the rear wheel and have a better...
  3. herbilious

    Bike accelerating without using throttle

    Hi, I've got a relatively new (3rd tank of break-in) 66c motor that has a weird issue. I just installed a new expansion chamber banana exhaust because I broke the stock one, and something I've noticed is that once I start the motor and let out the clutch, the bike accelerates relatively fast...
  4. S

    Does anyone have experience with a wingsmoto exhaust?

    Link to product: https://www.amazon.ca/dp/B07LB548TR/ref=cm_sw_r_cp_apa_i_Cnm6CbZFCX20R I won't mind bending the exhaust a bit. The darn thing is real cheap, but I'm still sceptical.
  5. B

    Exhaust repercussions if any

    I was wondering if i put my exhaust from my 2 stroke on my 4 stroke what could i expect. I appreciate any advice i can get
  6. R

    Custom Exhaust help 49cc

    I am designing a motor limo bicycle 49cc I was thinking adding 2 exhaust together first the expansion tube exhaust in the front then piped down to a poo poo long pipe muffler going down the side. Was wondering would doing that hurt any performance or anything
  7. lukecanna

    KX65 Expansion Chamber or similar?

    Hi Everyone, Wanting to buy a expansion chamber for my bike as im still using the stock one with no baffle and holes drilled in it. What are your recommendations? I saw a post where someone said they put a kx65 econ there bike but they didnt give any info, i can weld btw so that isnt a problem...
  8. O

    Exhaust extension

    Hi guys! First post, so hello! I'm new into this scene and I purchased my first 80cc kit a few weeks ago. Installed onto a newer trek mountain bike, but ran into some issues. Frame is wider than the standard frame, so I had to fabricate a custom mount for it. No big deal, its sturdy and not...
  9. D

    Finding a nice expansion chamber in Australia

    Hi, I'm looking for an expansion chamber for my 49cc china kit. At the moment I have the eBay banana pipe but I'm looking for something more for a decent price available in Australia. Side note, I have done a few things to my bike and am in the process of doing more. I have done the; Banana...
  10. greenjon

    4-stroke mufflers and spark arrestors

    I'd like to know your experiences with mufflers and spark arrestors on 4-stroke bike engines. I'm not sure a muffler is required in my area, but the spark arrestor definitely is (it's practically all USNF here). Spark arrestor part numbers for Honda GXH50: 18350-ZM7-801 PCA-1151
  11. CrazyDan

    7/8" flex pipe for 4 strokes

    I found a cheap source for 7/8" galvanized flex pipe for exhaust sold by the foot...
  12. Kelster66

    Expansion pipe silencer.

    So I'm trying to come up with a good silencer for my Boost expansion pipe from Gasbike but not having any luck at all. Any suggestions or ideas?
  13. Matt Barrack

    Engine Trouble Multiple engine problems.

    I have come across a few problems. The bike currently runs fine but there are a few things that worry me. 1. The engine is spewing oil. It is coming out of at least 2 places. The first one I noticed is out of the exhaust gasket. It drips a little. The second and probably more serious part is it...
  14. B

    Engine Trouble Mr Smith

    First all hello. I'm a brand new motorized bike ower. I have a two-stroke mounted to my Trek frame. I have been fixed everything I can on it and have now tackled performance. I bought it used so I don't have any history on the bike other than what I have learned that was wrong with it after I...
  15. Matt Barrack

    Exhaust More leaks...

    I got a leak from the exhaust. Oil is coming out of the seem on the bottom. Or the top of the part that comes off when you unbolt it.
  16. The-DMV

    Exhaust Is this pipe I made hindering performance?

    So, I have a Skyhawk 66cc engine, and I'm still messing around with the jetting and I'm having issues with the CNS carb, but I want to make sure that the exhaust isn't part of the problem? Does this look like a decent design? I had to weld it to fit the bike. That extension after the expansion...
  17. D


    Hi there. I'm mounting a grubee skyhawk 66cc gt5a on a early 60s schwinn jaguar. I lost my job and Im just a teenager so I really don't have that much cash to spend right now and I'd like to know what cheap performance modifications I can make to my bike to increase the acceleration and top...
  18. L

    Upgrades for 50$

    Hi im new to this forum i have 50$ to spend on upgrades i would like to improve performance and maybe looks right now the exhaust had the muffler part cut off so i would also like to reduce the noise a bit
  19. J

    In search of an exhaust! Any help?

    So it's finally come to the point where I need to focus on my exhaust system (the standard one right now) and am looking for a decent one for top to mid range power. I've heard great things about the Snake pipe and the Torquer II but the snake pipe isn't available anymore and the torq seems to...
  20. cmb271

    Running without back-pressure?

    Okay, I haven't posted much in a while because after loosing the key that holds a sprocket onto the 7G transmission of my 49cc 4 stroke and not having the means to replace the transmission I lost interest in investing time into my motorized bicycle. Now that my car is currently sitting in my...