i just bought a racing carb from zoombicycles, i havent had time to mount it yet but ill let ya know
RAW 80cc 2 stroke performance upgrades
- Thread starter moosinatrix
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My front mount worked loose causing the extreme vibration and caused my chain to break from working to loose. I fixed that problem with a lagrer bolt that I drilled sideways and placed a cotter pin to keep it together. Also I installed a shock bushing as a mount. The viabration is all but solved now (see pic). I still need to fix my 36 tooth mounting system The 3-piece washers they sent me are thin and week zink anti-metal. I can't get the sproket straight. To much run-out. The washers just bend. I am in the process of making new ones out of hard steel. I'm using the steel from an old lawnmower blade. This should work fine with new hardened bolts and locknuts. I did a test run with the 36 and I am pleased with the power band and all, but I just want the run-out issue solved before I can trust it for more than a test run. I also had my chambered exhaust on, but the viabration prooved to be to much for it. The mounts broke. With no front mount, and the engine just flopping around, its no wonder. Now with the viabration issue solved, I can put it back on. However, I need to fabricate a heavy duty mounting system for it as well. Better safe than sorry. I am very interested in the results of the race carb??
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If that cotter pin is to keep the nut tight, you might want to consider a castle nut instead. They are made to work with cotter pins. I personally would have used a nylock but the cotter pin and castle nut is more secure.My front mount worked loose causing the extreme vibration and caused my chain to break from working to loose. I fixed that problem with a lagrer bolt that I drilled sideways and placed a cotter pin to keep it together. Also I installed a shock bushing as a mount. The viabration is all but solved now (see pic). I still need to fix my 36 tooth mounting system The 3-piece washers they sent me are thin and week zink anti-metal. I can't get the sproket straight. To much run-out. The washers just bend. I am in the process of making new ones out of hard steel. I'm using the steel from an old lawnmower blade. This should work fine with new hardened bolts and locknuts. I did a test run with the 36 and I am pleased with the power band and all, but I just want the run-out issue solved before I can trust it for more than a test run. I also had my chambered exhaust on, but the viabration prooved to be to much for it. The mounts broke. With no front mount, and the engine just flopping around, its no wonder. Now with the viabration issue solved, I can put it back on. However, I need to fabricate a heavy duty mounting system for it as well. Better safe than sorry. I am very interested in the results of the race carb??
Later I will go to a castle or a nylon. Thanks for the great ideas. This is what I have to work with at this time. I will just need to check it once in a while. At least it won't fall off.
Here we go again with the theoretical armchair racing... "a 20T rear sprocket @ such n such RPM should make my bike go 60 MPH.... yadda yadda..."
The higher the gear, the more torque the engine needs to get back up to those RPMs... these engines just don't have any torque!!! this has all been argued here before.
& when clocking for top speed, DOWN HILL DOESN'T COUNT!
The day when someone ACTUALLY BUILDS a bike that can go 50MPH on flat ground; bring it out & prove it! stop talking about it, because so-far no one has been able to prove it yet!
I don't want to discurage anyone from tinkering & trying... but so-far, the "best of the best" MB builders haven't been able to do it!
I'm pretty sure i'm 40mph
my engine from Bicycle Engine Kits - Rock Solid Engines
SBP Tuned pipe
SBP shift kit
'racing carby'
still breaking in and it's been pretty good so far.
Plenty of us have built bikes that can do over 40 MPH... Welcome to the club.I'm pretty sure i'm 40mph
my engine from Bicycle Engine Kits - Rock Solid Engines
SBP Tuned pipe
SBP shift kit
'racing carby'
still breaking in and it's been pretty good so far.
(Most of us have done it with stock engines & modified stock parts...)
I'll add this to my statement... It does take a smaller rear sprocket to get there!
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yah, i plan on getting a road racing rear cassette on the back wheel so i can get high top end speed without redlining the engine, also don't want to use any gears above 6th as i'm paranoid about the chains clipping eachotherPlenty of us have built bikes that can do over 40 MPH... Welcome to the club.
(Most of us have done it with stock engines & modified stock parts...)
I'll add this to my statement... It does take a smaller rear sprocket to get there!
Are we still doing this?
This is the endless/pointless thread- thread.
Adding gear will not infinitely (or even close) increase top speed.
At some point (around 36-40T) the engine JUST WON'T PULL THE GEAR ANY MORE without mods, and most of the mods I read about are for top end power, which in this case is a lost point.
This is the endless/pointless thread- thread.
Adding gear will not infinitely (or even close) increase top speed.
At some point (around 36-40T) the engine JUST WON'T PULL THE GEAR ANY MORE without mods, and most of the mods I read about are for top end power, which in this case is a lost point.
You need
a.) More torque, and not just a little.
b.) Less weight, once again, a considerable amount.
c.) Less/no wind resistance. (let me know if you can magicly adjust the numbers associated with drag coefficients).
a.) More torque, and not just a little.
b.) Less weight, once again, a considerable amount.
c.) Less/no wind resistance. (let me know if you can magicly adjust the numbers associated with drag coefficients).
the smaller cassette is so that i don't need to use 6, 7 and 8th gears on my bike as with the shift kit i'm paranoid that the chains are too close and will catch at high speeds.
a) agreed, the SBP tuned exhaust would help a little here
b) i weigh 150pounds and my bike without motor is a feather
c) yes, so making less perpendicular surface area to the direction of travel is best and well about the only thing we can do besides changing our tyres.
c2) there's a M7 bike path that goes for 20+miles here in sydney, it was especially built for cyclists and runs alongside one of our new motorways, so there are points where there are sound/crosswind barriers up and makes for a nice stretch with little to no wind, perfect place to test
There is only so much we can do because the jules needed to move a mass of X weight up to Y velocity. So besides tuned pipes (forced induction), changing fuels and ignition timing and compression, also a little port timing, the only other way is to increase capacity or go with electronic direct injection...
i think just a simple spring and stop setup would work the spring on the primary carb would give just enough to open secondary seems simple in my head cool thread though 
!!
!!
I think this thread (& the other "how fast?" thread) have gotten so long that no one even reads all the pages before posting anymore...
nope, won't work on these without lots of $$$i think just a simple spring and stop setup would work the spring on the primary carb would give just enough to open secondary seems simple in my head cool thread though
agreed.I think this thread (& the other "how fast?" thread) have gotten so long that no one even reads all the pages before posting anymore...
and some people need to realise gearing is only here because of the limitations within the engines themselves, limited to a rev range, and even smaller than that a powerband for each appropriate gear.
Also there is a big difference in between power and torque and many people don't even know that there is a difference yet alone how much of a difference there is.
^^^ probably doesn't make much sense at the moment as i'm fast asleep still
Alrighty folks....I'm shutting the lid on this long dead thread. If you want to post about miraculous speed secrets and going 35 mph, there is another thread here-
http://motorbicycling.com/f13/40mph-speed-secrets-revealed-11141-10.html
http://motorbicycling.com/f13/40mph-speed-secrets-revealed-11141-10.html
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