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Author Topic: Back fireing  (Read 3336 times)

blue

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Back fireing
« on: March 31, 2016, 01:21:09 PM »
What all makes your 50 cc scoot back fire.its all stock only thing done to it is new gas lines.
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Stig / Major Tom

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Re: Back fireing
« Reply #1 on: March 31, 2016, 02:01:46 PM »
Quote from: blue on March 31, 2016, 01:21:09 PM
What all makes your 50 cc scoot back fire.its all stock only thing done to it is new gas lines.
Have you tried putting old lines back on and run it?
Any change in fuel line inside dimensions?
Stig
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Boston Strong
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blue

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Re: Back fireing
« Reply #2 on: March 31, 2016, 02:57:05 PM »
Quote from: Stig on March 31, 2016, 02:01:46 PM
Have you tried putting old lines back on and run it?
Any change in fuel line inside dimensions?
Stig

Ya the dimensions were bigger so I got some stock gas line and trying that. ill see how it gos if it ever stops raining.
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blue

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Re: Back fireing
« Reply #3 on: April 01, 2016, 01:44:33 PM »
stock gas lines back on Now its hard starting. maybe the choke is bad.............how often do they need replaced.
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blue

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Re: Back fireing
« Reply #4 on: April 01, 2016, 10:32:44 PM »
OMG... do I feel like a fool. All it was is the bad gas line was pluged up.Not letting the bad gas out. on the carb...the littlest things.
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blue

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Re: Back fireing
« Reply #5 on: May 10, 2016, 12:37:52 PM »
Scoot is still backfireing. I was told there is a bad gas valve the size of a needle next to the main valve that is stuck shut. Only way of fixing is to replace the top end. so far I put over 2000.00 miles on the scoot and it still gets up[ to speed the way it should I can do 45 easy.  I now have a nick name popy.O well  they can hear me comeing now................

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CROSSBOLT

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Re: Back fireing
« Reply #6 on: May 10, 2016, 04:18:29 PM »
"Bad gas valve next to the main valve..." and this is in the top end which needs to be replaced...? I am curious who told you this? The top end and the carburetor are two separate assemblies that do work together.

Karl
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Karl

Three motorcycles 1960-1977 (restored a 1955 BSA)
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blue

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Re: Back fireing
« Reply #7 on: May 10, 2016, 10:46:08 PM »
Quote from: CROSSBOLT on May 10, 2016, 04:18:29 PM
"Bad gas valve next to the main valve..." and this is in the top end which needs to be replaced...? I am curious who told you this? The top end and the carburetor are two separate assemblies that do work together.

Karl   One of the guys I ride with said that's the only thing it can be. sense its not the carb . the carb is new and so is the muffler and all the gas lines and I have no air leaks. the scoot drives and runs great better then it ever did after the new carb. So I just learn to live with the backfireing after I start to slow down.
   they could be wrong......
« Last Edit: May 10, 2016, 10:48:17 PM by blue »
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CROSSBOLT

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Re: Back fireing
« Reply #8 on: May 11, 2016, 03:21:11 AM »
The reason I ask the question is, the statement does not make sense. I may be too picky about words but its a big deal to replace the top end so one needs to know just why before one spends a lot of moolah throwing parts at a problem only to find the recommendation was just a guess. That is what dealer techs do because they don't know how the systems work. Some of the common causes of backfiring are: 1. Too lean of mixture; 2. Retarded timing; 3. Temperature of engine too high; 4. Valve timing incorrect. Lets explore these four and find the one or more that may be causing the problem. Is the bike stock or has it been modified? What were the mods if any? What is out of whack if stock? And so on..

Karl
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Karl

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Yager 200i
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pipster326

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Back fireing
« Reply #9 on: May 11, 2016, 08:22:02 AM »
Gentlemen, I need some advice. My DT 300i is a 2012, I got it in October '15. It has less than 1800 miles. I noticed these little cracks in the tire. I don't know how or where it sat before I bought it. Should I replace the tires? Or should I wait? You guys have helped me in the past, I trust your opinions! Thanks 

    - Rich


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« Last Edit: May 11, 2016, 08:23:33 AM by pipster326 »
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Chris0381

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Re: Back fireing
« Reply #10 on: May 11, 2016, 10:17:18 AM »
Quote from: Stig on March 31, 2016, 02:01:46 PM
Have you tried putting old lines back on and run it?
Any change in fuel line inside dimensions?
Stig

Isnt there a timing adjustment on the scooter near the stator some where. I always equated backfiring to a valve timing issue.
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CROSSBOLT

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Re: Back fireing
« Reply #11 on: May 11, 2016, 01:26:46 PM »
Hey, Pipster! You hijacked this thread! Those cracks indicate the tires are quite old and should be replaced. Personally, I don't like the Maxxis. I think they are a really cheaply made tire and could not wait to replace them on my DT.

Karl
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Karl

Three motorcycles 1960-1977 (restored a 1955 BSA)
Agility 50
Yager 200i
Downtown 300i
Navy tech, Ships Engineer, pilot and aircraft mechanic

wkreps

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Re: Back fireing
« Reply #12 on: May 11, 2016, 01:41:18 PM »
Quote from: blue on March 31, 2016, 01:21:09 PM
What all makes your 50 cc scoot back fire.its all stock only thing done to it is new gas lines.
Would a clogged muffler cause backfiring? Is it a 2 stroke?
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Wayne


blue

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Re: Back fireing
« Reply #13 on: May 11, 2016, 01:48:21 PM »
Quote from: CROSSBOLT on May 11, 2016, 03:21:11 AM
The reason I ask the question is, the statement does not make sense. I may be too picky about words but its a big deal to replace the top end so one needs to know just why before one spends a lot of moolah throwing parts at a problem only to find the recommendation was just a guess. That is what dealer techs do because they don't know how the systems work. Some of the common causes of backfiring are: 1. Too lean of mixture; 2. Retarded timing; 3. Temperature of engine too high; 4. Valve timing incorrect. Lets explore these four and find the one or more that may be causing the problem. Is the bike stock or has it been modified? What were the mods if any? What is out of whack if stock? And so on..

Karl
   The only mods is lighter rollers. and new stock carb new stock muffler.the timeing has been resit. maybe the lighter rollers threw the timeing off............
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pipster326

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Re: Back fireing
« Reply #14 on: May 12, 2016, 07:20:08 AM »
Sorry, I thought I posted on the other thread. I get up at 3am, I probably posted before my 2nd cup of coffee. Thanks for the input.

        -Rich


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