On a new top end and bottom end rebuild, after 500 miles of driving, how dark should the oil be?

I just changed the oil at the 500 mile mark after rebuilding the bottom end and replacing the top end and. The oil that I drained was pretty dark and what appeared to be dirty. I swapped out the oil filter with a new filter as well. Went with the OEM.

Less than 100 miles later, my oil is dark brown/black again. Is this pretty normal?

 

Assume you're speaking about your bike? Oil threads are dangerous territory, but I'll bite. I wouldn't lose too much sleep over a "darker" oil color, unless the viscosity has also seemingly changed. Is it thicker/thinner? Are there obvious (visible) metallic particles in it? A darker color means it's doing it's job, actually. I would encourage a complete heat cycle; i.e. don't just start your bike and go 5 miles and shut off, because the moisture and nasties don't have a chance to completely "burn off." That's as bad as not running it at all. On the other hand, if you're getting the engine so hot that it's frying the oil (hard stops, starts, high revs, abusing it) that's not good either. A medium "molasses" COLOR (not thickness) is not a huge deal.
OK; stand back..........

 

it's kind of clear/brown after my first ride after an oil change....100 miles...it looks like dark maple syrup....just long as it doesn't look milky..i think you are fine....

 

My dad taught me not to put much stock in color... rub some between your fingers. That will tell you what's going on! Feel for grit, and slippery-ness (if that's a word). Should feel similar to the new oil you're going to put in. If there's excessive grit or particles, check your oil filter.

 

it's not milky, I think everything is okay. I'll keep an eye out of for the viscosity. It appears to have normal viscosity when the engine is cold. Runnier when hot.

 

thin tube siphon/syringe or just a thin tube (suck with mouth to get the flow going) is good to have in your toolbox...i use it to take a little out to check the oil....and, i occasionally put little too much and need to take a little back out......just need to insert tube and tilt the bike to the right....might be good to have another person, but i can manage holding the klx250 on my hip while i keep my hands free to siphon...

 

It is normal for motorcycle oil to look dirty. The additive package in the oil turns it that color after its been heat cycled a few times. Also, anything that has a wet clutch like our bikes do, will have minute particles of clutch in the oil, which will darken the color as well.
I'd be willing to bet someone could ride one of these bikes (not me LOL) 10,000 miles without changing the oil and nothing would happen, IF the person kept the oil level full.
On a side note, I know that a late 90's toyota landcruiser will go 47,000 miles before it burns all the oil and blows the engine. I am a auto technician and I was in my 3rd 4th year as a tech. This person bought the landcruiser new and just put gas in for 47,000 miles. They tow'd the thing away so no idea whatever came of that lesson. Automotive Darwin award winner LMAO

 

riding at 7,200 rpm to 8,200 rpm range, mostly highway speeds...my klx250 gets near the minimum mark....have to add or oil change after 3,000 miles on mine....

 

Funny story there. Had a fried who's older brother had a little '80s Chev pickup. Drove it for 150K from brand new and only added oil when it got low. No oil or filter change. That says something!

And my cousin's husband had an old ford pickup that leaked like a sieve. He just added the used semi truck oil from the Chevron he worked at. For about 5 years that I knew of before he sold it.

 

I saw a guy bring a jeep grand cherokee in our shop that while he was a way for business alot he thought his wife had been changing the oil....she wasnt.... It had just shy of 40K miles on it.. first oil change.... lol...crazy.