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KTM 625 SMC: Is a carburator-engine bad or good thing?

auntiebling said:
i searched the net, couldn't find any similar experiences. which leads me to believe that CA gas has something to do with it. it'll also dry out into a fine tan powder, vanish would almost be better, which i've seen in a neglected bmw K bike gas tank as well as the FCR experience.

i know, i know, i need more evidence.

it happened to be on a ktm too, and the valves were way out of adjustment. that'll make a kick only bike hard to start lemme tell ya.... (but i digress)

digging into carbs isn't really my favorite thing to do, so i shut the gas off a block or two before i get home, it's kind of an unnecessary game i'll play.
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If you can kick start the bike, chances are the carb is fine. I've had my share of troubles with carbs, but very little issues on a big single. Most carb issues were on my old GSXR which would eat up emulsion tubes.

A new KTM that has been unmolested should be fine. If the airbox and exhaust have been gutted there may be some jetting issues so get someone who knows what a good running bike should feel like before you commit to buy it. I haven't get the foggiest idea what the jetting is on my KTM, but it runs and starts fine, so if it ain't broke, don't fix it.
Good luck!
 
my duke 2 with sudco jetted fcr starts cold with jus a twist of throttle. choke wasnt even hooked up.

from sea level to 7k ft no issues.
 
A clean, well-adjusted carb should start fine, and run at altitude well enough. Last week I took my carbed bike from sea level to 9000 ft and back in the space of 4 days, with constant altitude changes, and it started every morning and ran fine. I'd rejet if I moved to the mountains, but no need to bother for a quick trip. The plus on carbs is they're easy to work on (other than getting them on and off the bike), and they're usually more forgiving on gas quality; that's one reason the KLR650 is such a popular round the world adv bike, it'll eat anything.
 
I actually prefer a carb on many applications... especially thumpers. Cheaper to tune with a little knowledge. Easy to fix if there ever is a problem. Dont let the fact that a bike you want isnt injected sway you away from the purchase. Carbs can and do work VERY well. Use it as an opportunity to educate yourself about how they work.
 
My buell has 38k miles on it and I have never had a carb issue. Had to rejet after exhaust change, and I had the air needle fall out never to be seen again. The issue with fuel injection is it is complicated. My carbs got two electric inputs for the tps and autochoke, an injected bike must have like 10 electric parts along with the injectors. If anything fails you will be troubleshooting for awhile. The nice thing about injection is mapping and the tunability.
 
I love plugging in a laptop and tuning my effing ess. Carbz ain't all that hard, tho, just dirtier to monkey with. :D
 
Just to have my .02 out there (and others may disagree):

All my bikes are carb'd and yet I've had to learn the following lesson several times. Don't trust the PO to have any idea how carbs work. When you buy the bike, assuming it runs well enough, take it out and get to know it as-is. Then, go buy the stock needles and jets, set the idle screw back to factory spec and ride it again.

Every bike I buy I hear all about how the PO had this exhaust or that intake put in so they *had* to re-jet, and every bike I buy I end up fiddling with the carbs for months trying to dial them in until it occurs to me to just try the factory settings and, weird, the thing runs like a champ.

Now, there may well be many an expert out there who has dyno'd or view-sparked their carbs to aftermarket poetry, and if you feel like you've lost power after going stock, throw their jets etc back in and enjoy, but trust me its worth the $20 to experiment with a fresh start.

Plus you'll learn all about that magic little box early in your ownership, one less thing to fear having to crack open later
 
The stock tune on some of these bikes is an engine killer. I got my bike with 6k miles on it and it burned lots of oil. The blast had a nasty backfire when the throttle was cut. The backfire killed the original muffler. Stock tune is so lean it chews up the exhaust valve and piston. The piston crown was detonated and pitted. It's a fine balance and you need have a feel for it.
 
I appreciate everyone's input. So I got the bike. It has 4K miles on it. The first thing I did was (1) installed a new battery and (2) drained old fuel from the tank and a float chamber. However, the bike still would not start. I engaged the choke and still no luck. I decided to connect the bike's battery to my FJ Cruiser using jump cables and was able to start the bike without a problem. After that, through out the day, I had no problem starting the bike through out the day. The idle was fine as well.

Edit: when I try to start it, it is cranking, but will not start.

However, next day, I tried to start the bike againn. I had the same problem. The bike would not start. I have no idea what the problem is. Is this a battery problem, even though I purchased a brand new battery?

Any help would be much appreciated!
 
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Going to need more details and you will need to buy a volt meter, there is a really good sticky about troubleshooting batteries in the garage section.

When you say not starting, do you mean not cranking, or it cranks but won't start? Will it kick start?
 
bpw said:
When you say not starting, do you mean not cranking, or it cranks but won't start? Will it kick start?
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Thanks for bring this to my attention: when I try to start it, it is cranking, but will not start. I used the voltmeter and it showed 12.
 
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deadmazai said:
...Any help would be much appreciated!
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Clean the pilot jet and make sure the passageway is clear. Drop in a fresh plug. For a cold start pull the enrichner and don't add any throttle. Should bark right off. On a hot start, no enrichner and a small crack of throttle.
 
deadmazai said:
Thanks for bring this to my attention: when I try to start it, it is cranking, but will not start. I used the voltmeter and it showed 12.
Click to expand...

Just because it's cranking that doesn't mean the battery so good enough to start the bike. The fact that your bike started when jumped makes it look like a battery issue. You may have 12 volts, but need to get the numbers under load
 
russ69 said:
Clean the pilot jet and make sure the passageway is clear. Drop in a fresh plug. For a cold start pull the enrichner and don't add any throttle. Should bark right off. On a hot start, no enrichner and a small crack of throttle.
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Russ, what fresh plug are you referring to? Thanks.
 
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12.6 is a fully charged battery that has not been on a charger for a few hours, 12.4 is considered discharged.

I suspect a slightly clogged carb since it starts fine hot. The stronger cranking from the car battery may have been enough to start the bike even without perfect mixture, and if the bike had been cranked enough before connecting to the car it might have warmed up a little or flooded enough to richen the mixture.

Give the carb a good clean, it's a hassle but not that unpleasant if you take your time. Might also take some practice to figure out the proper start procedure for cold and hot starts. My xr600r was a one kick bike if you did everything right or a 20 kick bike if you didn't follow the starting procedure.

Charge the battery up on a charger or by riding around and see if it holds voltage, would also be worth checking that the charging system is working while you are at it. See the garage sticky on charging.
 
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