backfiring after teardown

mitchberry

Registered
the subject is vague i know.

Basically, i tore the fairings, header, exhaust, the octopus thing on the front of the block for emissions, the radiator, oil cooler off of the bike in order to start fitting things for a turbo application.

I got an RCC plenum, had a header custom made, and bought 99% of the other things i need to put a turbo kit together.

The bike had been apart for 4 weeks give or take. Since im still missing a few parts here and there and do not have the ability to tune the bike for the turbo, and since i really wanted to ride this weekend, i put it back together as stock.

Last night i rode it without the air box on it just to make sure it ran ok and to get some of the cobwebs out of it (literally and figuratively).

When i slow using the engine, the engine backfires around 2500 RPM. this was never the case before. It would also die on me at idle, or when holding the clutch in coming to a stop or a slow down (like in a steep corner that i didn't want to fly around ..e.g. entering a service road from another road.

I figured it was because the sensors were not hooked up for the air box. Today, i plugged the air box sensors and put the stock air box back on the bike, and i took it for a short test drive.

it has about 5x more power than it did running no air box and feels about like it should, but it still back fires around the same rpm, but not nearly as often.

fearing permanent damage to my bike, i brought it back home and parked it again.

I did not have back firing issues before i took the bike apart.

I didn't do ANYTHING to the head, or ANYTHING internally to the motor.

why would it be backfiring now?

obviously, backfiring usually has to do with timing, or valves. but it worked fine before i took the cooling system, header, and oil cooler off of the bike, so why would it be backfiring now?

One thing worth noting is that i DID take the "octopus emissions thing" off of the front of the block, and i did not hook up the brass whatcha-ma-call-it to the bottom of the air box. I realized it after i put it all back together, and there is 1 hose that went to the far right side of the air box that once unplugged, fell out of the bike, and i dont know where the opposite end of it is supposed to plug up.

could those 3 things be causing my issue?

I didn't put the "octopus thing" back on the front because i have read several places that if you have aftermarket exhaust, having that thing on the front CAUSES it to back fire and to run rough, and i bought block off plates to cover the inlets on the block. IF i put my full exhaust back on, i have tsukigi's.. so either way, it's not stock.

For the last 500 or 600 miles, i had run the bike without pipes on it at all. I took them off at the Y pipe, and it ran fine.. no issues. (this was before the "turbo build")... i tried different variations of having the extensions that go to the cans on and off the bike to see how it ran, and it ran better if i took the pipes off of the Y pipe, though its loud as all holy hell. (i don't mind though).. NORMALLY, this could cause backfiring issues, but, i know that it didn't back fire before i took the bike apart.

so................... thoughts?

I want my damn bike to run right.

Since i'm putting it back to pretty much exactly what it was BEFORE the turbo build, it SHOULD run exactly like it did before i took all the crap off of it.

let me know what you guys think.

thx

p.s. it NEVER ran with the turbo on it... i fired it up for 2 seconds one time to make sure it still ran, but never beyond that, and the battery has been unplugged and replugged at least twice since then. I don't know if the computer "learns" on it's own, but , it never knew the turbo was there, and i've started it half a dozen times since i put it back together... and another 20 if you consider the bike dying being a re-start. so it shouldn't have tuned itself for air fuel ratio and all the crap ecu's do.. nd if it did, it should have figured itself out again by now.
 
crap... worth mention also, while the airbox was off, i DID change the sparkplugs (few weeks ago)... that's another change i made.. im 99.9% sure they are the correct ones for the bike given i sell bike parts for a living, but i did not gap them. not sure if that would matter, help, or hurt the situation.
 
wow.... i thought you guys were supposed to know everything..

i thought it was just a holiday lull.

anyway, i plugged the rest of the stuff back to the airbox and it runs great now.. that's all it was i guess... thanks for the advice. :thumbsup:
 
Sounds like maybe 2 plug wires are reversed!
 
Back
Top