choke idle problems?

[shrike]

Hello,
I think I got some idle problems.
To tell about the bike. It has 1600 km's on it, 2005 model but bought brand new 3 weeks ago. I did the valves at 1000 km and I also adjusted the TPS yesterday to be close to the 76% value.
Now it's been 2 days if I use the choke when starting it cold the engine dies like it gets too much gas and gets flooded. I have to give it gas only.  Before that,  If I put the choke on the RPMs would rise to 3000 but I wouldn't let it go that high, usually between 1500-2000 RPMS.  I did not touch the carbs yet, I know it's supposed to be running a bit lean and the colour of the plugs would prove it's a bit lean.

Now it's been a bit hotter and much more humid these days so I don't know...when it gets around and above 25 degrees celsius you are not supposed to use the choke? Is that a normal behaviour?
The idle is adjusted so it stays around 1400 rpm when hot but when cold it's around 1000-1100.

Also when cold and at idle I hear something that to me sounds like a knock from time to time and at the same time the rpm goes down for a fraction of a second. I got the feeling more and more that this knock is in fact a small backfire.  Before adjusting the valves the engine even died when slowing to a stop light, this happened 2 times but since the adjustment it seems to be ok. By the way the valves were pretty much all but two on the tight side.

The carbs were never synchronized after the valve adjustment because I am still waiting on the morgan carbtune I ordered.

Can the knock/backfire at idle be caused by the carbs not being synchronized? What about the choke behaviour?
I know some people might suggest a dirty carb for the idle but I am thinking it should be clean since the bike never had gas in those 2 -3 years it had been sitting on the dealer;s floor. The first time they put oil and gas was when I took delivery of it

[txbanditrydr]

With warmer weather you may find you need less choke... a lot less.  I typically will only use about 50% on a cold engine during most of the year.

The little hesitation you describe happens on my 2005 as well.... a little unnerving to hear but it goes away when things get fully warmed up.  I'm assuming you have good throttle response and the gas mileage has not changed.  Don't worry and just ride the snot out of it (IMHO)

[shrike]

Well I see you live in texas where your winter weather is probably as warm as our summer weather minus the humidity.  You say you use 50% choke.  I cannot use it at all and it's only 25 oustide, ok maybe maximum of 30 degrees celsius which should be around 90 Fahrenheit. If I do  the bike stalls. Can the TPS adjustment affect the choke? I would doubt it.

About the  hesitation now...it does go away when warm but I am wondering if it's a knock because not enough oil gets to the bearing or backfire because of the lean condition? I am inclined to say it's a backfire since the RPM go down a bit, if it was a knock because oil starvation I don;t think it would have an impact on engine speed.

Throttle response seems good but I sometimes feel the bike should be faster, at least it felt faster when I got it ( I had a KLR   ). It felt a bit slower after the valve adjustment but it';s either I got used to it or the acceleration was more linear after valve adjustment.
Gas mnileage is not that great at 36MPG but that might change since I had that result while breaking it in and varying the speed a lot with roll-on.

What mileage do you get? Is the bike stock or did you fiddle with the carbs and exhaust?

[txbanditrydr]

Stock carbs... stock exhaust... about 40-45 mpg depending on riding style... and that's after 48,000 miles.

Sorry I wasn't more help.

[shrike]

Thanks for answering. It does help to know at least what I should expect as gas consumption. Just a quick question. You did not do anything to the carbs? Not even turn the air fuel mixture screws out?
I don't want to molest my carbs either unless it will be way too lean when temps get in the 40s

[shrike]

cooler temps this morning, choke was working fine. It seems it either does not like humidity or temps above 25 celsius

[pmackie]

I don't want to molest my carbs either unless it will be way too lean when temps get in the 40s

Hey Shrike

Colder (more dense) air would tend to make the bike run lean. Hotter (less dense) air tends to need less fuel, so the bike will NOT get leaner as the temp goes up.

However, the bike IS jetted lean, and tends to run stronger once the jetting is sorted out, but it is NOT lean enough from the factory to cause any problems. If you derestrict the exhaust with an aftermarket pipe/slip-on muffler then you should plan to rejet.

[txbanditrydr]

You did not do anything to the carbs? Not even turn the air fuel mixture screws out?

Nada... nothing... never touched them nor have they been off the bike.  I put my money into the suspension rather than engine.  I figure when I do jet it'll be a constant PITA to keep running right.

[shrike]

Hey Shrike

Colder (more dense) air would tend to make the bike run lean. Hotter (less dense) air tends to need less fuel, so the bike will NOT get leaner as the temp goes up.

However, the bike IS jetted lean, and tends to run stronger once the jetting is sorted out, but it is NOT lean enough from the factory to cause any problems. If you derestrict the exhaust with an aftermarket pipe/slip-on muffler then you should plan to rejet.

I meant 40 degrees fahrenheit or 5-10 degrees celsius. I hope it won't get to 40 degrees Clesius over here. It's going to be hell.  I might rejet it only if it runs like crap in cold temperatures. I am not planning to change the pipe. I like the looks of that  pipe and the sound also. I am not too crazy about pipes with a smaller diameter that are noisier.

[shrike]

You did not do anything to the carbs? Not even turn the air fuel mixture screws out?

Nada... nothing... never touched them nor have they been off the bike.  I put my money into the suspension rather than engine.  I figure when I do jet it'll be a constant PITA to keep running right.

Right now I think in the same way as you after having played with the carb on my KLR. I found it did not run as well afterwards.  So like I said int he previous post I will only jet it if it really runs like crap in cold weather. It's good to know there are bikes out there with a higher average mile/year and that run well on stock carbs.

[pmackie]

Hey Shrike

Being your from Canada (like me) I was thinking deg C...oops!

Even if you don't change the pipe, you can wake the bike up a bit with some zero cost (other than labour) changes. Drill the pilot plugs and put the screws out 2-1/2 turns +/- and shim the needles 0.5 mm. I have some carb shims if you want to try.

Lots of guys here have done similar, and I don't think anybody says that the bike runs like crap. The only changes you would see are; faster warmup, little smoother off idle response and a quicker bike in the mid range 3-6000 rpm.

Let me know if you want some shims. Bazza sent me a bunch, but I only needed 4 for my 600S.

[shrike]

I know about that mod. But I tried it on my KLR and people were saying the bike will be better performing. Nothing happened besides the choke that wasn't working well anymore
I used stainless shims I found at work, I am sure they are the same for the Bandit too.
I am going to wait a bit before deciding I really want to go ahead with that mod. I will do it if  the bike will be too lean in the fall
I really appreciate the offer and the help though!
I know it's a very popular modification that does not cost money, just a bit of time.
I don't know...but I really like the look of the stock pipe, as well as the sound.  I would not change it either.

That on the other hand would be nice if I had 6000 dollars to spare :

http://www.mrturbo.com/charge2.html