backfire/missing when cold

[seestheday]

Update: I put in the NGK Iridium plugs and it rides like a new machine.

I can't believe the difference they made.  No backfiring at all, the engine sounds much smoother and my exhaust seems cleaner (had some black soot coming from it previously and have recently realized that it was unburnt fuel - probably fixed by the better plugs).

I'm still going to pick up a new air filter today to replace the oily one and am looking forward to seeing how that affects performance.

Thanks for all the help guys.

[Half-Caf]

A Harley rider was just telling me how iridium plugs are a bunch of BS.
I told him I begged to differ -they work wonders in out 750's

[sgtslag]

They made such an improvement in my 750, I put them into my Voyager...  No difference was detectable.  However, that does not take away from their performance.  All that indicates is that my Voyager's ignition system is much more robust (higher voltage, higher current output from the coils) than what my 750 has.  Also, the Iridium plugs will last 50,000+ miles (100,000 miles in cars, typically).  I don't regret putting them into my Voyager, at all.  We ride it, two-up, hundreds of miles from home, just the two of us -- no other riders with us.  I feel more confident with them in the Voyager, as a result of what I experienced with my 750.  I'm a true believer.  On the Voyager Forum, many of those riders eschew the value of Iridium plugs, even though the improvements are not detectable by the seat-of-the-pants dyno.


I'm tempted to put them into my '75 Ford F100 truck, next, but that requires 8 plugs, not four...  Don't want to put a whole lot of $$ into the Blue Bomber.  
Cheers!

[seestheday]

Put in the new air filter and it feels even smoother.  Although now I am noticing a slight stutter around 4300 rpm.  I am hoping that it'll go away after I clean my carbs this winter.  

It was probably there the whole time, I just wasn't able to notice until now.

[Half-Caf]

I have a little pop around the 4500 mark as well. From what I've heard this is common with our bikes.
Found this here on the forum:
http://honda-cb750-s.456789.n3.nabble.com/special-thanks-td3244278.html#a3257614

Anyone else confirm this?

[shinyribs]

Halfcaf,that stumble i was referring to there is an off-idle stumble.My bike has the round top carbs that has no accelerator pump.If you gag it real hard when its idling it wont rev.Sorry for the confusion.

[seestheday]

Ya, that isn't my issue. I'm finding a continuous slight jerkiness around 4500 that isn't there above or below.

Sent from my BlackBerry device on the Rogers Wireless Network

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From: "shinyribs [via Honda CB750'S]" <[hidden email]>

Date: Tue, 11 Oct 2011 20:55:58 -0700 (PDT)

To: seestheday<[hidden email]>

Subject: Re: backfire/missing when cold

Halfcaf,that stumble i was referring to there is an off-idle stumble.My bike has the round top carbs that has no accelerator pump.If you gag it real hard when its idling it wont rev.Sorry for the confusion.

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[Half-Caf]

shinyribs wrote

Halfcaf,that stumble i was referring to there is an off-idle stumble.

Ahh, my bad

shinyribs wrote

If you gag it real hard when its idling it wont rev.Sorry for the confusion.

So, basically no crazy burnouts or insane revving?

Still interested in this phantom 4500 issue then.
Seestheday: I m waiting for a new rotor and r/r to come in and then I will be syncing the carbs. I will let you know if this helps...

[shinyribs]

Once it gets off idle it will zing right up there.

[free2ride]

seestheday wrote

Ya, that isn't my issue.  I'm finding a continuous slight jerkiness around 4500 that isn't there above or below.

I have a bit of a problem like that in 1st and 2nd. I just try to morot a bit faster to avoid it

[TOOLS1]

Sounds like the needle jet is dirty. Try running "seafoam" through it.
TOOLS

[seestheday]

Thanks,

I ran some fuel system cleaner (said it was specifically for carb'd engines) through a little while ago, but I'll try seaform on my next gas tank.  I looked for it originally but couldn't find it, and have since discovered that it is in the marine section of my general parts store (Canadian tire) for some reason.

[sgtslag]

SeaFoam had its origins with outboard motors, so it makes sense that it be in with that product area.

I use SeaFoam to winterize my bikes every year.  Fill the gas tank to the brim, follow directions and add the correct amount of SeaFoam to the gas to stabilize it for the Winter, run it a few minutes to circulate it into the carbs, then turn it off for the long sleep.  In the Spring, I start them up, and ride as much as possible, to get the old gas burned up, and fresh gas to replace it.  Works fantastic.  Be sure to top off the tank, though, as air space will allow water to condense, which leads to rust.  The SeaFoam, by the way, will help to absorb any water in the gasoline.  Cheers!

[shinyribs]

Good tip Sarge!Thanlks

[seestheday]

Are you not supposed to add it to the mostly empty tank, and then fill it?

Sent from my BlackBerry device on the Rogers Wireless Network

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From: "sgtslag [via Honda CB750'S]" <[hidden email]>

Date: Thu, 13 Oct 2011 14:39:21 -0700 (PDT)

To: seestheday<[hidden email]>

Subject: Re: backfire/missing when cold

SeaFoam had its origins with outboard motors, so it makes sense that it be in with that product area.

I use SeaFoam to winterize my bikes every year.  Fill the gas tank to the brim, follow directions and add the correct amount of SeaFoam to the gas to stabilize it for the Winter, run it a few minutes to circulate it into the carbs, then turn it off for the long sleep.  In the Spring, I start them up, and ride as much as possible, to get the old gas burned up, and fresh gas to replace it.  Works fantastic.  Be sure to top off the tank, though, as air space will allow water to condense, which leads to rust.  The SeaFoam, by the way, will help to absorb any water in the gasoline.  Cheers!

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[TOOLS1]

It really does not matter. The vibrations, and jostling from riding will shake it up pretty good.
TOOLS

[Larry spillman]

If you shut off bike and dont shut fuel off 1 and 2 carbs can spill over into intake.Then when you use choke in morning and bike is still leaning on kickstand you get a very rich condition this is hard to locate with 4 into 1 exhaust but very obvious with 4 in to 2, If I have cold start issues like wont start I use starting fluid and it saves my battery everytime.Try shutting fuel off then run some out of carbs then shut motor off,when you start bike sit on it and keep it level so left side dosent load up.

[cdaiscool]

My bike doesn't do any of this, and I'm in Michigan (actually north of Canada!) and ride often. In fact, leaving within 10 minutes for a little ride.

YMMV.