Backfire?

[Brad_9876]

I've got a 05 450r with a uni filter, no airbox lid, hrc kit, and lte dual exhaust. I put the exhaust on and took it to the local honda dealership and had them jet it. I got it back and when I rev it up or am riding in the high rpms and let off, it backfires like hell. Could this just be wrong jetting? What do you guys think.

[Scro]

Do you know what size jets they used? It sounds like it's lean. You may want to check for any exhaust leaks at the head or sections where the pipe fits together. I wouldn't put it past the dealership, if they didn't replace the exhaust gasket or put clamps on any of the pipe fittings.:rolleyes:

[HoleshotR15]

sell the dual pipes and buy a dasa?

[Scro]

Originally posted by HoleshotR15
sell the dual pipes and buy a dasa?

And then it will backfire just as much as the setup he has.:ermm:

[Brad_9876]

I'm keepin the duals, I love them. Nothing looks cooler than duals, especially on a quad. Sounds awesome too, until it sounds like your being shot at... I'll pull it off and check the gasket.

[chevys&honda$]

dont all bikes pop a little when you go fast and then let off?? all my bikes did that with an aftermarket pipe and they were jetted right also. sounds normal to me. even my 2008 chev silverado pops when i go fast and then let off, thats with daul flowmasters of course.






07 trx450r

07 ltz400

86 lt250r

05 raptor 350 SOLD

76 chev nova SS 350 4speed

08 chev silverado

[Scro]

Originally posted by chevys&honda$
dont all bikes pop a little when you go fast and then let off?? all my bikes did that with an aftermarket pipe and they were jetted right also. sounds normal to me. even my 2008 chev silverado pops when i go fast and then let off, thats with daul flowmasters of course.


No it's not normal. If it's jetted right, it won't do it at all.

[chevys&honda$]

I dont know if its a back fire?? or if its just like a compression pop?:ermm: ? every bike i have been around does it, i not saying all the time, but like going down hill in a low gear, you gun it and let off and it pops, and also my buddys stock 700r does some times but i think there is somthing wrong with his cuz it does it kinda loud.

[chevys&honda$]

I found this on the net just googled, backfiring through exhaust

Idle Mixture - Can be Adjusted to eliminate backfiring
No this is NOT the same thing as the IDLE. The Idle Screw just limits the minimum throttle when you take your hand off the throttle. The Idle Mix Screws, actually controls the Gas/Air Mixture at Idle.
Most riders find that enriching the idle mixture by backing off the screws by 1/8 to 1/2 a turn will eliminate the popping. Enrichen as little as necessary, work in small increments, and test the results before backing out the screws another 1/8 turn.

[Brad_9876]

Thanks for all of the help guys. I pulled the header off and sure enough, no gasket. Ordered a new one and put it all back together and now there is no backfire at all. It does kinda fall on its face if i gun it from low rpms. It has the HRC kit and i know that favors the mid a little more, but how much bottom end is lost? Maybe a jetting issue?

[d3ktrix]

Originally posted by chevys&honda$
sounds like a leak jet issue

He has an 05, don't think there is a changeable leak jet in that carb.

The dealer might of put a massive pilot in it to try and stop the popping on decel, not realizing they forgot the header gasket.
This would cause the poor throttle response.
Just a guess though.

The 05 HRC cam is more of a top end cam.
Its low end is pretty lame IMO, but it shouldn't fall flat on its face.

[Brad_9876]

any recommendations on a pilot jet size or needle settings? kinda new to jetting it myself, don't know where to start.

[d3ktrix]

Whats in there now?
And what exactly is it doing? More details.

I've never jetted an atv with dual pipes before, so I would have to go by how you say its running and go from there.

[j-dawgs 450r]

Originally posted by Brad_9876
any recommendations on a pilot jet size or needle settings? kinda new to jetting it myself, don't know where to start.

recommendations? sell them and get a Dasa pipe, run a 180 main jet, 50 pilot and 2.5 turns on the A/f screw assuming ur anywhere from 0-500 feet in elevation

why in the hell would a single cylinder bike need dual pipes? it's not a V twin harley with 1400CC. have you not seen that the DASA makes the best power out of all the pipes and always comes out on top? if you're after performance, ditch the duals, they're not doing anything for ur bike except look kinda cool.

if you dont give a **** about performance keep the duals and quit whining your bottom end is gone :macho

900$ for a exhaust? ****, you coulda got a used DASA and a head porting from RAGE and got 8-10 hp :blah: :blah:

[exrider12]

not to steal the thread but what jetting should i be running.

Curtis sparks full

uni filter

no air box lid

hrc needle and 55 leak jet.

What should i start the needle at and what main and pilot

1000-1500 ft

in the summer so 60-90 degrees

[d3ktrix]

Originally posted by exrider12
not to steal the thread but what jetting should i be running.

Curtis sparks full

uni filter

no air box lid

hrc needle and 55 leak jet.

What should i start the needle at and what main and pilot

1000-1500 ft

in the summer so 60-90 degrees

Same as the HRC jetting.
165MJ
45 pilot
55 leak
HRC needle middle clip
Adjust a/f screw accordingly

Tune from there based off how it runs, prolly not perfect.