The Walbro WG8 Carburetor
If you want to save hours searching for info on the Internet and, much worse, not learn the hard way, check the sites and info below. There are many pilots who have become experts on how Walbro carburetors work, especially the WG8, and I have posted their important work here. The Walbro is a simple device but it is not tolerant of rough handling or abuse. This page is specifically for the WG8 but most of it applies to other models, as well. Remember: The WG8 has no way to easily modify the high speed mixture because the Miniplane version has no high speed needle adjustment. If you need to do this, see my tech note below. Do not consider making changes to the high speed mixture unless you install a CHT (cylinder head temperature) gauge. Failure to have a CHT will likely result in burning up your engine. The "spark plug color" method is imprecise and time consuming and I do not recommend using it. It is for general use ONLY and is useless for any accurate jet calibrations. If you have any questions or comments let us know. -- Had Robinson
If you do not want to do the repairs yourself but have a professional do it, you may send it to us. Please contact us for details.
Adjusting the Idle and Low Speed System - Had Robinson
Flooded Engine - by Had Robinson
How to Modify Jet Sizes - by Had Robinson (These notes show you how to modify the existing jet on your carburetor without making permanent changes.)
Metering Lever Problems - from Walbro (What happens if you accidently -- and easily -- bend the metering lever.)
Reading Spark Plugs - If you insist on doing this, here is the best way to do it. However, if your motor is running very rich, this is an inexpensive and easy way to tell. Most pilots should NOT change their spark plug from the manufacturer's specification unless they are skilled. Remember: The gap must be correct for the plug to do its job. If your Top 80 sputters at full throttle and lacks power, it is likely a spark plug with too great gap.
Stalling under Sudden Throttle Increase - Had Robinson
WG8 Parts Diagram Note: The WG8 model used by Miniplane has a FIXED main jet instead of an adjustable "power needle" jet -- part#40. This fixed jet is only available from Miniplane. If you need specific parts, like the tune-up kit, for your WG8, contact us with the number of the part you need.
Walbro Service Manual - from Walbro
This site was last updated 10/31/13