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Dynoed the ltz490

14K views 40 replies 15 participants last post by  kfxguy 
#1 ·
Well I finally decided to dyno the kfx400. Pretty decent numbers out of a completely rideable, tame combo. Made 59.08hp and 38tq

Head: self ported with stock size valves
Cams: web cams custom grinds I specced out
Valve springs: r/d springs
Carb: 43mm fcr
Compression: 12.5
Fuel: pump 93 octane
Dyna ignition with my own custom map
1 3/4" to 1 7/8 stepped drag pipe built by me
Yoshi exhaust was tested also, made a tad ove 57hp with the yoshi
Fuel customs Yfz intake
Gearing: stock
Tires: 20" dyno tires
+5mm stroke and +6mm bore
450r lockout clutch, stock doings and Barnett cf clutch (clutch was found to be slipping, so I changed springs afterward to 400ex hd springs)

Was dynoed in fifth gear, I found out afterward that 4th is my 1:1 gear and 5th is an overdrive. Not sure if that makes a difference.

Graph:


Video. You can count the shifts to fifth gear

http://i218.photobucket.com/albums/...E6-AA63-FE67C951FDDB-408-0000002AB7743959.mp4

Just figured some of you gear heads would be impressed with the little ole '400! Lol
 
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#3 ·
Well I never had a 450 but I was seriously considering turning this quad at one point. I almost started buying the stuff to do it but decided its wouldn't be too trail friendly with a turbo hanging off of it! Lol. I ride this thing everywhere with my kids. My 13 year old rides it often too. You'd never know the engine makes the power it does just by riding it around, it has big cams but is still really torquey and smooth.

I took the head off the other day to open it a bit more. From the dyno graphs it looks like it isn't breathing too well. I think the intake port is too small and to get it any amount bigger I have to cut off the beginning of it and well another one on. I made the part already and it's getting welded on today. Bigger carb is ordered too. Then back to the dyno again. Goal, 65hp
 
#6 ·
#8 ·
Thanks. Big 48mm lectron is going on it and the intake port was welded up yesterday...... Hopefully I should see a nice power increase.
 
#12 ·
Thanks man! I noticed you have alot of r&d in your bike as well. I checked out your page. Nice write up! The clutch was slipping because 1) I have the 03 style clutch and it has one less fiber than the new style 2) had stock springs in it with less preload. The 450r lockout I used sits up higher than the spring retainer therefore not putting as much tension on the pressure plate. I've since added 400ex had springs and a little more weight to the lockout fingers.

I make my own lockout clutch covers too.



Made this cover too and extended my brake pedal outward



Cutting down the bosses on a 450r lockout to make the springs fit over them


Here's my drag pipe I built







I cannot take credit for the exceptional welding on the pipe. My uncle welded it. The end piece is a barker megaphone. The header flanges and stuff I made also. It's a 1 3/4" to 1 7/8" step. Picked up 2rwhp throughout the whole rpm range.
 
#13 ·
I can't wait either. I'm hoping I finish the head this week but I have alot of work to do. When I'm done I have to re powder coat it too. Good thing is I don't have to farm that out. Ill post my new results when I get it done.

I bought a high velocity insert just incase the 48 doesn't act right.
 
#16 ·
Thanks buddy!
 
#17 · (Edited)




My little port job. Basically cut the mouth off, made a billet one and welded it on......



Ring I made out of a solid piece of billet like its leaning on



 
#19 · (Edited)
The torque lines are not overlayed in the correct spot
 
#23 ·
Thanks guys, I've put alot of time in effort into this thing. I guess I like a challenge is why I build this instead of a better platform.

I'm going to try my best to have it back running tonight. The port work turned out excellent, I can't wait to see if this thing has more top end pull. It felt really good before but let me tell you what I'm going after. I don't want a long Swingarm and tires that hook up so hard that I can't keep the front down. I want something that comes out the hole pretty decent but rolls out on topend. If I get taken off the line I want the power to run them back down. I had a daily driven street car I built that was based on this philosophy. It won lots of races. Lost less than half a dozen. It would trap 125mph in the 1/4 but only turn 11.40-11.50 passes. If I raced the average mid 11 second car.....I ate their lunch. This was back in 99-2000 with a sleeper 92 camaro. Kinda after the sand thing with my bike. Not many people build these things. So it's not expected to have 60hp.
 
#24 ·
It's back together. Forgot to get an oil filter so I couldn't crank it. Bummer.
 
#27 ·
^^^thanks!

I got it running this evening. I was a bit discouraged at first because it felt lazy and didn't wanna idle under 1800 without dying. It usually idles nicely around 1200-1300. I measured the exhaust temp and it was under 400 near the head so I thought it was running rich. Well that would be impossible since I just slowed the velocity down a bit and the engine is not sucking as hard on the carb so it was too lean. I had a 45 pilot in it and went up to a 48. It idled much better. I felt like it was still a tad lean so I wanted to go to a 50 but only had a 52. Too rich now. Now I'm on the hunt for a 50. The cycle shop in my town never has 50's in stock so I may have to order one. No ride impression yet tho. I did take it down the street and manners were still excellent. Seemed like it still had good bottom end. I stabbed it in second from a low roll and it instantly hit the limiter. In the back of my mind I keep thinking about that 4th gear low roll I tried and it felt lazy. I guess I can't go by that because my main jet remained the same and I know it has to be too lean. Heck on the dyno my afr was in the 13. Range before opening the head up. It revved up kinda lazy too. I went up from a 170mj to a 178mj and it felt much more responsive when revving it. Guess I need to get it tuned in correctly before stressing over it.
 
#28 ·
Just found out I haven't been getting full throttle since I put the fcr carb on. Not like the amount it wasn't lifting is gonna make much if a difference.....everything counts. I had to grind the linkage inside the thumber to let it pull farther. Do you think a 450r thumber would have more pull? It's fixed for now, but when I get the lectron I'm going to need more throw.
 
#30 ·
Thanks! You used to be a member on suzukicentral didn't you? Think I recognize the name
 
#32 ·
Took it out yesterday and did a little tuning and decided to see what it would pull top end mph wise. I was disappointed with the results until I figured out my trailtech was off. According to a gear calculator it topped over 89.6mph. I easily hit the limiter in 5th. This is not accounting for tire expansion at that speed. I had the limiter set at 11,000rpm, 14t front, 40t rear (stock gearing) and 20" stock 450r rear tires. I figured this on 10,750rpm because when I dynoed it, it pulled to the limiter which was set at 10,500 but showed 10,250 in the dyno. That's why I subtracted 250rpm. I tried to recalibrate my trailtech vapor but it won't go into setting mode.
 
#34 ·
Very strong. Stronger than it was and the carb is not right yet. I can run it through the gears very quickly but if I try to go from a 30-40mph roll in 5th gear it stutters really bad. I think I had it too fat, but I'd rather be safe than sorry. I'm planning a dyno trip within the next week or so. Ill get it dialed in to see the before and after of the port work then ill throw this on there.....








It came in today. I'm in the process of modifying my stock thumber to open it all the way and I'm about 95-97% there....I'm just having a hard time getting it all the way open. I was reading a few days ago some other quads thumber had a longer pull than most. I can't remember what it was. A warrior maybe?
 
#40 ·
Very impressive!
 
#41 ·
Thanks man! I try!
 
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