KX Riders
Maintenance & Technical => KX500 Original => Topic started by: c-152 on September 03, 2007, 11:39:46 PM
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Okay, I have had my k5 for over 2 yrs now and love the thing. I run in tight trail and areas were we are making new trails threw nasty stuff all the time (all with landowners permision). The low end power alows me to slog threw anything. The poblem I am having is running out of fuel very quickly. Most of my buddies run 125s or 250s and seem to run all day on one tank, were as I keep having to make everyone turn around about an hour and a half in to go back for fuel. It seems like the thing runs about 2hrs on one tank. In fact, had I not broke my bars on a hill climb during my last harescramble, I would have not had enough fuel with me to finish and I took 4 gallons. This does not seem right to me as I dont remember this being as much of an issue last year. I do not want to put a big tank on it unless I absolutelly have to. My question is, does this sound about right for fuel use to you guys or should I be looking for a leak? I haven't noticed anything.
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My '04 K5 sucks the fuel. I think it has something to do with the twisty thing of the right side handle bar. My bike has low hours but I have been buying parts just to keep in stock. I want to be ready when I need them. I got a new piston and man I did not realize just how big they are until I had it in my hand. My lean on the fuel issue is this... Twice the displacement of the 250 but about the same weight. I would guess the K5 would use 1/4 to 1/3 more fuel. Could it be your racing ahead and idling waiting for the pack to catch up? Most of my riding buds have quads and that's what I do run ahead and wait. I did buy a IMS tank, I think it adds 1.2 gal. of extra fuel. I'm going to make the bike street legal and need the extra fuel. Not to ride on the street all the time. I want it legal for the dual sport rides I go on. We have to ride on the State Highway between trail heads. It can be 5 to 20 miles of Highway sometimes. The last 2 years I have stayed between legal bikes and hope for the best. No tickets so far. As you get older you will get tired before you get low on fuel. Getting hurt real bad back in Dec. of '04 took allot of stamina from my body plus the muscle lost to atrophy, not being able to do anything for 8 months. I think the fuel issue is part of owning a KX500, we'll just have to deal with it. I'll let you know how the bigger tank feels when it's full.
Danger4u2
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if you are pushing your kx5 very hard at all then 2 hours on a stock sized tank of fuel is about right. i recently rode a couple days in sand and could only ride a hard 1 1/2 - 2 hours and had to return to base for fuel and that was with rest breaks figured in. I rode my k5 with a ktm 550 , and a cr250. one ride we(the two big bore bikes) had to sacrifice fuel to the cr250 after he ran out so he could make it back to base. thank god for the empty h2o bottle in my pack. i've never tried the desert tanks but i think they would feel odd with that extra weight up that high :|, but if you need the extra fuel what other choice do you have. i've seriously considered buying a desert tank. if i keep riding in the dunes i may have to. MADDOGGY :-P :-D
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Thanks guys, I new this would be an issue and I think I am just now getting to realize it because I am more comfortable on the bike know, riding a lot more (thus riding better) and using the go stick more liberally. I think I might have to invest in a long range tank but really don?t want to if I don?t have to because I am weight conscious (about the bike not me) and really to want a bulky tank. Danger I would love to hear your opinion on how you like the larger tank.
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i put on a clarke 3.9 gal desert tank and love it. i had an ims b4, but after 5 years, it started to get surface cracks on the side. i'm 300lbs, so i can still man-handle the beast even with the extra weight. i added an acerbis 1.3 gal aux tank to the forks, and took it off after one ride.the weight on the front end made me work too hard, but just a desert tank wasn't a problem. i can probably get 70 miles out of a tank(and that's riding pretty hard). if you stick with a stock tank, short rides are something you'll just have to deal with.
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You would be suprised, if you have your jetting spot on, you will easily double your fuel. My KX500 on a stock tank would outlast my KX250 anyday by far. Both were spot on jetting.
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THanks for the tips guys, I think my jetting is pretty good based on my plug and how it runs but I will keep an eye on it.
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I agree with Gowen,
My 500 can outlast any stock-tanked 250 MXer. Jetting is the key. It is also possible that a good portion of your gas is dripping out the carb overflow while your ride. I had that problem so now I run my float level slightly low. At slow speed in trails your bike bounces and angles, all of which cause the float bowl to overfill and then spill out the overflow. Cam.
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I will try the float bowl thing - thanks for the tip. I can se what you mean about bouncing aroun on a rock hill off the gas might cause fuel to leak. If course I also have the issue of my bike laying upsidedown on a hill that 125 frequently go up that also causes gas to leak however I think the fix to that problem will be a little harder 8-)
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Back in 89, Team Green fitted 89 KDX 200 fuel tanks to their 89 ISDE KX 250s. They were able to use the KDX rad shrouds and it looked factory installed. The tank holds about 3 gallons and isnt as bulbouse as the Clarke or IMS tanks. Since the 88-89 KX 250s shared the same basic frame and body work as the 88-04 500, I would think that it may work on the 500 also. Im just not sure of any clearance issues between the pipe and the cylinder. The KDX tanks that could possibly be used would be the 89-94 models. The first water cooled KDXs. I would get about 50 miles out of my 88 K5 with the stock tank. Just enough to make the gas stops at the enduros.
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so are you guys telling me that my jetting is not "spot on" and that is why my k5 likes fuel. i am not sure that i buy that, cause my bike runs awesome and plugs look spankin" new after a few days of riding. maybe a catch box for overflow like DOORDIE has on his roadbike would let you know if your losing fuel out the overflows. :| :| MADDOGGY
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Back in 89, Team Green fitted 89 KDX 200 fuel tanks to their 89 ISDE KX 250s. They were able to use the KDX rad shrouds and it looked factory installed. The tank holds about 3 gallons and isnt as bulbouse as the Clarke or IMS tanks. Since the 88-89 KX 250s shared the same basic frame and body work as the 88-04 500, I would think that it may work on the 500 also. Im just not sure of any clearance issues between the pipe and the cylinder. The KDX tanks that could possibly be used would be the 89-94 models. The first water cooled KDXs. I would get about 50 miles out of my 88 K5 with the stock tank. Just enough to make the gas stops at the enduros.
interesting concept of using a different model's fuel tank on the K5. Has anybody any knowledge of this for the 1987 model K5? Of course, i inconveniently own the year of KX5 that the parts market has forgotten about. What other bikes had frame set-ups similar to the 87 KX5? And also had bigger fuel tanks. I will need about a 100 mile range to feel good.
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There is a guy that races enduros here on the east coast that likes to tinker with projects. Last year, he rode what I thought was a 88/89 KX250. When I talked to him about it I found out it was an 87 with a 88 subframe and plastics. So, if you could put the bodywork and subframe, probably the airbox too, on your 1 year 87, you could possibly do the 89-94 KDX tank conversion. I did a similar swap with my 02 YZ426, I put a subframe, airbox and body work on it from a 2004 WR450. It was almost a bolt on and looked like it came that way.
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Back in 89, Team Green fitted 89 KDX 200 fuel tanks to their 89 ISDE KX 250s. They were able to use the KDX rad shrouds and it looked factory installed. The tank holds about 3 gallons and isnt as bulbouse as the Clarke or IMS tanks. Since the 88-89 KX 250s shared the same basic frame and body work as the 88-04 500, I would think that it may work on the 500 also. Im just not sure of any clearance issues between the pipe and the cylinder. The KDX tanks that could possibly be used would be the 89-94 models. The first water cooled KDXs. I would get about 50 miles out of my 88 K5 with the stock tank. Just enough to make the gas stops at the enduros.
Thats a good point.
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something to think about, my 125's carb is only a few mm smaller then a stock k5...
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I'm not sure I agree that a k5 should have better gas mileage than a 250. I ride both and they are both jetted right. I often take turns with them and the 500 is always drinking faster. The 500's piston is basically twice the piston right? I would say that jetting and float adjustment will help out, but saying the 250 drinks more fuel would be like saying a big block chevy should have the same gas milage as a small block or even an in-line 6 cylinder. Maybe you guys are getting older and heading back to the truck sooner for breaktime. Maybe someone should put these theories to a test. Milage test on the same trail or track.
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I'm not sure I agree that a k5 should have better gas mileage than a 250. I ride both and they are both jetted right. I often take turns with them and the 500 is always drinking faster. The 500's piston is basically twice the piston right? I would say that jetting and float adjustment will help out, but saying the 250 drinks more fuel would be like saying a big block chevy should have the same gas milage as a small block or even an in-line 6 cylinder. Maybe you guys are getting older and heading back to the truck sooner for breaktime. Maybe someone should put these theories to a test. Milage test on the same trail or track.
i have a 454 in my 98 chev truck with 4.10 gearing, i get about 13 to 14 mpg. my father has a 2007 dodge 5.7l (350 ci) "hemi" (even though it is a wedge head...) geared 3.43 getting the same fuel milage. i can tow a 28' covered trailer filled with bikes and a 3500 lbs camper, weight totaling about 9000lbs. i get about 10 mpg wi this set up. my father tows a 3000lbs trailer and gets 7mpg. just something to think about.
a yz125 has a 38mm carb, a stock k5 has a 39mm carb. my 99 yz runs dry long before my k5, but also keep in mind the yz's tank is smaller.
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I bought A 2001 Kx500 last year. This is my first dirtbike. It is crazy fast which i new it would be. I am finally getting comfortable on it. Anyways, I have noticed that it does drink a lot of gas. I would have to agree with Hillcimb #42. That the piston is much larger so it will take more fuel to fill the cylinder than a 250.