Found 2 sets of numbers on my new to me homelite saw xl12. numbers are T8300267 and E0131.can you tell me about these?

Standard plug gap for a chainsaw 0.5mm

that must be a old one my books dont go back that far , if the case was lt /gold id say 80's if case was orange then it early 90s

Here are free UT10490 Parts Diagrams you can print:

https://www.jackssmallengines.com/jacks-parts-lookup/manufacturer/green-machine/homelite/chain-saws/xl12-chain-saw-ut-10490

Found a website with all the equivilant homelite XL12 illustrated parts lists. You may need to look down the list to find the exact match.

Homelite XL12 parts manuals

There seems to be 1 to many numbers in the model # UT104654 is it possible that it reads UT10465A.
If so here is a link to the parts diagram for a Homelite XL12 UT10465A ,
http://www.jackssmallengines.com/help.cfm#/Homelite/XL12_Chain_Saw_UT-10456-A/Engine_Internals/1010129/0609011010046

Yes you do! The ratio is 50:1 fuel to oil. Be sure to use a modern synthetic saw oil available at home centers, hardware stores, and saw dealers. Be sure to use fresh fuel and mix the two in it's own container. Be sure to shake the container thoroughly each time just before refueling to prevent oil starvation in the engine. Don't make up more than one gallon at a time unless sawing is your business. Hope this helps!

32:1 (1 gallon of premium fuel to 4 ounces of quality 2-cycle oil) according to this
http://www.acresinternet.com/cscc.nsf/ed1d619968136da688256af40002b8f7/a17d735d551f0f1e88256b78005f6a7b?OpenDocument

It will operate better on 50:1 (1 gallon of premium fuel to 2.6 ounces of quality 2-cycle oil) once adjusted. HTH
Lou

The procedure is logic and common sense buoyed up with as much information as you can obtain.

This is a typical fuel system and a tip or two:
http://www.fixya.com/support/r3706813-2_cycle_fuel_system_repair

The IPL (exploded parts list) for your saw is the only detail for fuel line routing and it is sketchy at best; components are listed but may be on different illustrations. (About 30 XL-12s; I defer to you)
Homelite/Ryobi.com (authorized parts supplier)
https://www.gardnerinc.com/recons/disclaimer-lg.php - Agree; Choose “Product Line”; “Select OEM” & “Select Catalog” both to “Homelite Consumer Products”. A drop down list appears; self explanatory from here.
The numbers Homelite & Ryobi use do not match the numbers everyone posts. A careful inspection of your saw should find something that matches. Good Luck. HTH
Lou

The preset is to turn them all the way in (Don't tighten them hard or you will damage the needle) and then back each out 1 1/2 turns. This will get you started. You can then run it at full throttle and turn the high speed jet in untill you hear a change in the RPM. Then turn it out untill you hear the same. Find the happy medium.