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Hi Guys,
I recently purchased an 06 KLX 250S wit less than 2k miles, but after getting into it a little I question that number. For some reason the stock carb had been removed. The existing one ran ok, but it had a poor throttle response, and no choke. The previous owner used a turkey baster to squirt a little fuel in the carb before starting. I'm not gonna do that forever. I decided to replace the carb with the correct model..
My desire for stock parts was halted by a pretty hefty price ($400+) for a new CVK34 carb. I found what appears to be a very close copy on eBay, and it was so cheap I decided to try it. I installed the carb, pulled out the choke, and the bike fired up straight away. It idles great. It responds to the throttle great, and it starts great. It actually worked so good out of the box it made me a little nervous.
While running the engine to complete a cooling system flush and refill I noticed the header pipe glowing red. I've never noticed it before, but I have also never looked to see.
My question is this - Do any of you have any experience with these inexpensive "CVK" carbs from, I guess, China, and do you have any recommendations? Like I say, everything seems to be working great, but that red pipe bothers me just a little.
Thanks for your input.
When it gets hot enough, stuff will start melting.
Some engines will run with red hot exhausts if your running flat out for extended high speed periods, this probably isn't your case.
Your engine is running extremely lean, the carb needs to be jetted. Most riders here don't use those carbs, so you should either take it to a shop with a 'carb' man, or get the correct carb soon.
When it gets hot enough, stuff will start melting.
Some engines will run with red hot exhausts if your running flat out for extended high speed periods, this probably isn't your case.
Your engine is running extremely lean, the carb needs to be jetted. Most riders here don't use those carbs, so you should either take it to a shop with a 'carb' man, or get the correct carb soon.
Out of curiosity, what are the concerns with those carbs, other than the jetting?
When a bike sits and idles a single wall exhaust will heat up to the point where it will glow red and even orange (very noticeable at night/in dark). If you ever saw a bike with the head pipes blued, and who hasn't, that is due to the pipes getting hot enough to blue the chrome. That exhaust moving through is around 1300-1500 degrees.
Excessively lean mix is a danger to an engine, but don't think that it is causing the glow of the exhaust. A perfectly tuned engine will have the head pipe glow if there's no cooling air moving over it.
I posted this before, Ryan Villepoto on his KX at the starting gates before a moto. If anyone has a bike that is tuned properly, that would be a factory pro's bike.
So don't get too shook up if you know the carb is jetted fairly well, but your pipe still glows red or orange. Simply start riding and get some air flow over it and it will quit glowing. I had my SR500 pipe glowing bright red when warming it up for a cold ride home one February. It wasn't glowing within a couple hundred yards down the road.
OP, did you open the carb before installation to see what jet numbers, needle profile, and float level this carb came with as delivered? Was the carb sold and described for the KLX250 in particular or as just something to replace a CVK34? Maybe others have purchased this particular, generic, CVK34 clone...if it is a true clone...but I've never heard of this replacement. However, if it works, it works, I guess, but I don't think I'd even run the engine without knowing what jetting is in there. Are you hearing any detonation/pinging under load when running the bike? You do realize without knowledge of the jetting that you could damage the engine, right? I'm wondering if the jets and needle have numbers that correspond to Keihin components so that you know what you're dealing with.
On the red header pipe, I'm also guessing that your air injection system is still hooked up? This added air into the exhaust will also cause a secondary burn in the exhaust which can aggravate the heat in the exhaust. Many maybe most of us disconnect that system to alleviate aftermarket jetting and/or carbs. I don't know...I find it hard to give advice on a carb like this with so many unknowns. Again, maybe someone else has plowed this ground with this particular carb.
Go up to the top of the forum, in the first section there is a listing for "MANUALS", don't know how that could be any simpler.
For you carb, we don't even know what you got, my crystal ball broke about 5 years ago.
Go up to the top of the forum, in the first section there is a listing for "MANUALS", don't know how that could be any simpler.
For you carb, we don't even know what you got, my crystal ball broke about 5 years ago.
I used to play music for a living. When you are in that world you always cross paths with people who know more than you. You also always cross paths with people who know more than you, and cant understand why you don't just know more than you do, and do their best to make playing music a competition, which totally takes the fun out of it. It is those people that make learning seem like climbing a mountain while wearing a blindfold. Then there are people that know more than you do, and realize that they also had to learn what they know, and are willing to share their knowledge, and resources, in a way that is helpful, and not condescending. Thank you for being a part of the first group, because you help make the second look so much better. If smartass remarks and insults are all you have to offer, please refrain from "helping" me. It is a waste of both our times.
2006 KLX 250S New Carb Install
