This can't be right, What am I missing?

[QuicktimeRacing]

I have a 99 400EX which has an HMF muffler, 14 tooth sprocket, Aluminum airbox with K&N air cleaner, and 21x11x10 Sand Gecko paddle tires. I took the bike to Buttercup a few weeks ago and noticed that it was absoluetly pathetic when racing up Comp hill. Basically whatever gear I went through the whoops in is what I would be lucky to be in at the top of the hill. Most of the time I could keep it in third all the way up the hill but sometimes I would have to downshift in to second. I tried starting out in second through the whoops and even went through them in third gear pinned but it just seems as if my bike lacks the power to get the wheel speed up. What am I missing here? I am not sure what the jetting is set at but was told that it was already set and I shouldn't have to mess with it. On flats the bike has tons of bottom end and keeping the front end on the ground is a chore in itself. Is this just a four stroke thing that I should get used to or is there an obvious problem here? Let me know what you guys think I should do to better the performance... Thanks, Trent
http://g.myspace.com/00052/32/50/52510523_m.jpg

[Thump_It]

2nd gear is the hill climbing gear on a 400EX. For a faster revving engine and more all around power I would get a 416 kit. They are fairly cheap and very reliable. I would also think about throwing in a Hot Cams Stage II cam. You could purchase all this stuff for under $500 total. Good Luck.

[QuicktimeRacing]

In all honesty, are the four strokes not great hill climbers? I wasn't sure if maybe there is something wrong with my bike or what. I can smoke by buddies banshee out of the hole at any given time but obviously once he hits his top end he is gone. It's tons of fun to play with the bottom end torque but I don't want to keep getting smoked up the hills everytime I go the dunes. Any pointers on combinations or riding style to add to this? All help will be greatly appreciated... -Trent
http://g.myspace.com/00052/32/50/52510523_m.jpg

[TheFontMaster]

The combination or sand, and going uphill robs you of lots of power. There is more resistance in sand, and you will be slower in sand than in hard pack, or pavement. If I remember corectly from what I've read comp hill is pritty big, and your trying to hit it on a nearly stock 400ex. Bottom line, it doesn't have the power.

Thump_it sugested a cam and a 416 kit, I second that.

[Chef]

Welcome to the world of 400ex...

Actually, in all honesty, get rid of those friggin Geckos and get some 20x10x10 8 paddle Haulers, and you will have alot better luck.

[stevo3176]

Paddles rob my 400 of power. Mine was a dog when I had them on. Geckos are heavy to begin with plus yours are too large I believe.

[QuicktimeRacing]

Are you thinking it's the size of the tires or the paddle design that's hurting me? What paddle tires do you guys recommend? Will I really tell that big a difference if I swap them? As for the big bore kits, is the 416 the size to get? I thought there were bigger kits for the 400, whats the downfalls to the different kits?
http://g.myspace.com/00052/32/50/52510523_m.jpg

[Chef]

Originally posted by QuicktimeRacing
*Are you thinking it's the size of the tires or the paddle design that's hurting me?

* As for the big bore kits, is the 416 the size to get? I thought there were bigger kits for the 400, whats the downfalls to the different kits?


Both.

If done right, there aren't really any downfalls. After time, with the big motors, they stretch the cases because of the extra horsepower and you WILL have a large engine failure. However, it takes a long, long time, and it may never happen to you. Mine broke, but it was also a 465 for 4 years.

[QuicktimeRacing]

Am I missing any obvious things? What jets should I have in the carb? I noticed that it is idling rather high and it is adjusted as far down as it will go on the cable. I guess that to be a sign of running rich. What about sprocket sizes, would I be happier stepping down another size? I am not afraid to start doing motor work but would like to fix the simple problems first before I go back to Glamis Presidents day. I appreciate all the input guys, the more the better... -Trent
http://g.myspace.com/00052/32/50/52510523_m.jpg

[wilkin250r]

Sand will rob you of power, no doubt about that, especially trying to go uphill. Thump_It mentioned that second gear is the hill-climbing gear on a 400EX. I don't personally know what Comp Hill looks like, but I would think that a 14t front sprocket would allow you to do better than 2nd gear. I know I can climb Sand Mountain in Nevada in second gear (on a stock 400EX) with a 15t front, I could easily do it in 3rd gear with a 14t front sprocket.

[crandles]

High idle is usually not a sign of running rich. Sounds to me like you might be a little lean and its robbing you of top end power.

[QuicktimeRacing]

I will check the plug for color and let you know what I find. I replaced it right before I went so it should be fairly easy to read.

In addition to my original question:

1. What paddle tires does everyone recommend for
my application.

2. What jetting should my bike have?

3. Sprocket size, keep it or change it?

http://g.myspace.com/00052/32/50/52510523_m.jpg

[QuicktimeRacing]

Alright, I think that since everyone keeps telling me the tire size is hurting me I'm going to change my sprockets to compensate. I realize the Geckos are heavy so I will change them when money permits. For now, I think a sprocket changeout should get me better off. I'll let you guys know any mods I make and let you know how they work. Thanks for the help guys, Trent

http://g.myspace.com/00052/32/50/52510523_m.jpg