My 100cc motorized bicycle is backfiring...dont know how to fix?
- Thread starter Twrb79
- Start date
Before anyone answers this, lets not go into 10 million threads of problems like "Joel" did with his problematic, always altered, and modded, and totally screwed up bike and motor with his own "self-inflicted wounds" as regards his bike build.
Below is a link to some unorthodox modifications that Twrb79 has already done to his motor so anyone who can help him will already know whats done so your not guessing at a million different scenario's and possible solutions without having all the facts known thus far.
It appears, judging by a previous thread from the OP that he is not talking about a regular 100cc CG here, but a 100cc bottom end with an 80cc jug and a different head entirely...Good luck guys, Im out of this one...lol...I'm not knowledgable enough with modified 2 strokes to know the downsides of this build configuration...DAMIEN
Engine
Is it possible to run an engine that has a 100cc bottom and an 80cc top with a CDHpower high compression head?
motoredbikes.com
If anyone remembers "Joel", this is what we all went through back then...At least ten pages worth of multiple problems that for the most part were self-inflicted...lol.
Karl Snarl
Well-Known Member
Backfire usually indicates a lean condition. But idk. I have no clue what your sporting or what's been done. Fill us in please.
What do u mean by lean condition?
Karl Snarl
Well-Known Member
When the stoichiometric mixture is below around 13-14:1, I'm guessing you will be around 9:1 or so if it is back firing. Bring up the A/F ratio, as well as check for air leaks.
Ty Karl snarl. I didn't go ahead with the 80cc/100cc configuration. Right now it's 100 percent 100cc. I've checked for air leaks and that's all good but I have a gallon gas tank and my bike was not running for about a month.ive been doing a 40:1 oil gas mixture. I'm thinking I should drain my gas tank and make a fresh gallon.... what do u think?
Karl Snarl
Well-Known Member
Sound like a good idea. Check for any kinks in the hose and for damage while you are there. Pop the plug and have a look at it too while it's draining.
Oh an check the jet for any clogging, clean out the fuel bowl too.
Chainlube
Well-Known Member
While you're doing all that, pop of the mag side cover and look for any metal shavings, could be a sign the timing is out. My spitty back fires when the timing is out.
