What could be the cause of backfire of a Honda Rebel 250cc 1984?

Question

I have an 1984 Honda Rebel 250cc that I am using as my starter bike. I rode it all this past season with minor problems i.e. bike not starting, cutting off with choke fully released. But I have since figured out how to get it going, I have to let it warm up for 5 minutes before riding with the choke on and then release it slowly as my ride progresses, but the problem I am having now is with it backfiring. I have it stored in a garage (not heated) and have been starting it every week to make sure the battery does not die (I do not have a battery tender attached), and letting it run for 15 minutes, right when I turn it off it makes a really loud back firing noise. Today I added fuel stablizer, and want to know if this will fix the problem or is there something else I can do. I plan on having a tune up completed before the next season starts, but thats not for months, in the mean time any suggestions would be greatly appreciated. Thanks

I will try the sealing suggestion. But with the carb suggestion, besides having the carb taken apart and soaked for cleaning do you know of an additive I can put in with the gas to "clean" the carbs that will hold it over until Spring? Thanks

Answer 1

sounds like you have an air leak in the manifold,not unusual on a bike of this age ..easy test is spray manifolds with engine running it will run better for a moment as liquid seals leak.common for them to leak between head and rubber.or to be cracked.

Answer 2

This Site Might Help You.

RE:
What could be the cause of backfire of a Honda Rebel 250cc 1984?
I have an 1984 Honda Rebel 250cc that I am using as my starter bike. I rode it all this past season with minor problems i.e. bike not starting, cutting off with choke fully released. But I have since figured out how to get it going, I have to let it warm up for 5 minutes before riding with the...

Answer 3

Sounds like what you have is a *muffler explosion*, usually due to rich mixture not burning in combustion chamber but rather in exhaust, exploding. A true backfire is lean mixture where the fuel mixture explodes before going into the combustion chamber. Muffler explosion, when riding and backing off the throttle, is usually and over rich mixture and timing issue.

What you are doing is running the engine for 15 minutes with a rich mixture and the bang comes at the end of running the engine means you have a rich mixture and it is loaded in the muffler. It would probably do this normally when you ride it but then you have heated up the entire exhaust system, thus, no problem.

I would have the carbs cleaned and adjusted. I also would not continue to 'high-idle' the engine weekly to keep the battery up. Remove the battery, clean the top, especially around the terminals and store it on a piece of dry wood in a warm place.

I had an '85 Rebel and many other bikes as well.

Answer 4

your carborator is probabally having chunks in it, and the engine is trying to burn it but doesnt completely so it shoots out of the exaust pipe, so if you want to stop it clean the carb

Answer 5

you carb most probely has to much fuel inside so it is trying to get rid of it before it turns to jelly

Answer 6

Sound like dirty carbs to me, but could be several things.