KX65 plug reading after full engine rebuild - with pics

[Mike-Evans]

Whats your thoughts on the plug colour. Just run a full engine rebuild in, 2 heat cycles on the stand (5mins idle then cool completely), 15 mins half throttle then warm up and into bands gently.... 125ml putoline to 5 lites fuel (40:1). Standard jetting.

Thinking of dropping the needle 1 position and maybe 1 richer in the main?

Also, should I run the 32:1 ratio per the service manual?

[Foxx4Beaver]

it's hard to give an accurate answer with a pic, as the lighting/image is never the same, as it is actually having it in hand to see it for ourselves....but, judging by the pics, I'd say you're correct in going a little richer, as that plug does look a bit light/lean.

[Mike-Evans]

It is very close to a light tan, but too be safe I will richen her up.

Question is, what circuit do I make richer? Needle or main?

[Foxx4Beaver]

you might be alright just richening up the needle position one notch, unless it's ridden wide open the majority of the time, then you'll wanna go up one on the main too...you'll have to do a few plug chops/readings to determine what's best, because you might be able to get away with just richening up one circuit.

[Mike-Evans]

Took  the lad out tonight, went 1 richer on the main ( now 200 ), this is the plug colour.





Why would the jetting now require adjustment after a rebuild? The bike picks up perfect from the throttle just being cracked open and crusing in third, then opening it up.....

On the way back to the van, the bike was hot after 30 mins riding, there was a lean bog straight off idle, got the fastest idle rpm about 1 1/2 turns put on the air screw. Lean bog was not there when we starting riding tonight??

[bandit88]

On the way back to the van, the bike was hot after 30 mins riding, there was a lean bog straight off idle, got the fastest idle rpm about 1 1/2 turns put on the air screw. Lean bog was not there when we starting riding tonight??

I would check for a air leak.  Maybe something loosened up?  Also, I had the mixture screw back out on me while riding.  Check that too.

[Foxx4Beaver]

Why would the jetting now require adjustment after a rebuild? The bike picks up perfect from the throttle just being cracked open and crusing in third, then opening it up.....

On the way back to the van, the bike was hot after 30 mins riding, there was a lean bog straight off idle, got the fastest idle rpm about 1 1/2 turns put on the air screw. Lean bog was not there when we starting riding tonight??

because you now have a "tight" fresh motor....it's not unusual at all to have to re-jet after a rebuild, in fact, it's always a "good thing" to check your jetting after a rebuild....that way you don't take the risk of blowing a new motor, and all the money/time you put into it.

that plug looks much "safer" now.

you may need to try going up one size on your pilot jet, to get rid of that "lean bog off idle" you mentioned.

[Mike-Evans]

Cheers guys, ill raise the needle 1 position next time out.

Im extremely paranoid now with making sure the top and bottom end is in good condition and not having one or both of them fail on us again.

What checks/maintenance should I perform, and how often?

[Foxx4Beaver]

keep the filter clean...

change the gearbox/tranny oil often...

use good full synthetic 2 stroke oil in the pre-mix....and stick with the 40:1 ratio you're running it at, otherwise, every time you change the pre-mix ratio, you really need/should re-jet it to the different ratio....so just stick with 40:1...

grease the suspension and linkage as needed, usually 3-4 times a year for the average weekend warrior rider will be good....

try not to use soaps/degreasers when washing it....soaps/degreasers do find their way into suspension bearings and break down the grease...

[Mike-Evans]

Thanks mate.

What about top end inspection/ring-piston replacement?

Also what about bottom end inspection/replacement?

[Foxx4Beaver]

a simple compression test will tell you how the top-end is doing....but it never hurts to pull off the cylinder a couple/few times a year, just to verify the cylinder walls are good, and there's no cracks in any intake/exhaust bridges...if the 65 even has bridges.

you can check the crank tolerances when the cylinder's off easy enough...just be sure to get a service manual, so you know what the tolerances are.

as for the tranny, just keep that oil clean, change it often, and it should last you a couple seasons easy, providing you replaced all the bearings and seals, with this fresh rebuild you said you just did.

[Mike-Evans]

I'll have to get a compression gauge.

The only thing I didnt replace is kick start bearing, gear drim bearing and water pump bearing, they were in good condition. Everything else was replaced.

My manual says to replace the piston and rings on 12.5 hours, that seems short as we've done 1.40 hours now since rebuild

[Foxx4Beaver]

My manual says to replace the piston and rings on 12.5 hours, that seems short as we've done 1.40 hours now since rebuild

that's probably under full race conditions....if you're just a weekend play rider, you should be able to get much more than that out of the top end.

[bens87braap]

Jordan has clicked over 35 hours trouble free

[Mike-Evans]

Being paranoid since the rebuild and after every ride Ive removed the front pipe to look up into the cylinder.

Theres some rub marks in the back wall, no depth at all to them - is this normal?

There cross hatch is still strong around the cylinder.

Just hit 5 hours ride time on the rebuild.