KX Riders

Maintenance & Technical => KX500 Aluminum Frame Conversion (AFC) => Topic started by: robicon on March 27, 2016, 07:54:07 AM

Title: engine weights?
Post by: robicon on March 27, 2016, 07:54:07 AM

Hi I am new to the AF world. does any one know the weight difference between a 4t 450 and the kx500 engine? what have you do to your suspension for the difference?
Thanks

Title: Re: engine weights?
Post by: sandblaster on March 27, 2016, 08:16:15 AM

KX250 54.2LB WITH SPARK PLUG, KICK LEVER, REED, AND BOOT, NO CARB, NO OIL

KX500 62 LB WITH OIL, KICKER, AND SPARK PLUG, NO CARBURETOR.

KX250F 53LB NO CARB - INCLUDES OIL, PLUG, AND KICKER

Perhaps someone else will join in with the 450...

Title: Re: engine weights?
Post by: FL_Sharpshooter on March 27, 2016, 11:07:41 AM

Quote from: robicon on March 27, 2016, 07:54:07 AM

Hi I am new to the AF world. does any one know the weight difference between a 4t 450 and the kx500 engine? what have you do to your suspension for the difference?
Thanks

I weighed both my 500 engine and 450 engine when I was doing my 500AF swap. My 2000 KX500 engine weighed about 64 pounds (with trans oil), the 2009 KX450F engine weighed about 67 pounds (with trans/motor oil).

Title: Re: engine weights?
Post by: robicon on March 28, 2016, 07:14:21 AM

Cool thanks for the info my bike was done when I bought but I needed to replace the engine. seemed heavy that is why I was thinking about my spring rates.

Title: Re: engine weights?
Post by: bandit88 on May 17, 2016, 05:25:52 AM

Quote from: FL_Sharpshooter on March 27, 2016, 11:07:41 AM

Quote from: robicon on March 27, 2016, 07:54:07 AM

Hi I am new to the AF world. does any one know the weight difference between a 4t 450 and the kx500 engine? what have you do to your suspension for the difference?
Thanks

I weighed both my 500 engine and 450 engine when I was doing my 500AF swap. My 2000 KX500 engine weighed about 64 pounds (with trans oil), the 2009 KX450F engine weighed about 67 pounds (with trans/motor oil).

Im surprised there inst more of a difference in weight.

Title: Re: engine weights?
Post by: sandblaster on May 17, 2016, 08:49:18 AM

If they decided to build the KX500 motor again and did the same R&D they did on the 450, I'm certain the KX500 engine would come in a few lbs lighter then it currently is.

But of course that will never happen...  :|

Title: Re: engine weights?
Post by: Denver5hundo on July 08, 2016, 04:49:17 AM

I had slightly different weights when I weighed my motors...


2010 KX450F DRY, no throttle body or kick start - 68.5#s

1991 KX500 DRY, no carb, or kick start - 60.2#s

As far as suspensions goes...

I am 200#s...

Stock KX450F suspension (with the 450 motor) I should bump up both front a rear one size.
KX500 AF with same stock suspension is just about perfect for me. They say it's a hair on the soft side, so I use heavy weight fork oil and play with my settings (they're on the stiffer end of the spectrum).

Title: Re: engine weights?
Post by: KXDINO on July 09, 2016, 09:52:08 AM

First thing you do is after you swap engines is do your sag , get that in the ball park and your on your way if it still not what you want then tackle the valving , a few pounds on a engine not going to change it much , when i put the k5 in 01 250 frame i went up rate on the back spring the hardest thing was getting the bladder forks working right , still the 4 bangers have come a long way imagine how heavy a xr ,klx dr tt , big bore would weigh any one got one lying around for comparison sakes.