Carb tuning guide for most used Walbro carbs.
Very good common knowledge with pictorials and lots of hints.


http://tech.flygsw.org/walbro_tuneup.htm

Great site, and post.

I remember seeing it before, but this time I printed it off, I am sure it will get used...

what's wrong with the Walbro carb manuals?????

No pretty pictures??



AV8TOR

Better yet...what is wrong with us reading any manual we want???????????????????????????????

I never got any carb manuals with my weedeaters and chainsaws Besides.. manuals are so formal ! hahaha

I just wish I had a good enough memory to read it once and never have to again !

Good question. oh wait... "I read it on the internet, it must be true...."

Beware the governor on some Walbro carbs. I am posting this to hopefully save someone the grief I had trying to tune a Ryobi 31cc.
There are a few vague references to this, but none very detailed that I found. It seems Ryobi and maybe others need to limit the wide open rpm on their engine, due to most likely aweak con rod. Walbro solved this for them by inventing a little check ball spring combo that opens and enrichens (a lot) the high end mixture, causing the engine to 4 cycle and bog down to limit the rpm. It works by a combination of hich venturi vacuum and the fact the little ball resonates at the desired rpm acusing it to open. Several models of Walbro carbs have these, but are usually screwed in from the outside and more obvious. Mine, a Walbro WT-152 has it as an integral part of the main jet and I thought it was the high speed check valve which is used to prevent over rich on decel, boy was I wrong! I practally wore the screws out taking this thing apart ant putting back together. Tried different pop off pressure, fulcrum height, blah blah to no avail, it always went rich and 4 cycled at anything over about 6500 rpm.

You can plug it which I did, or if it is on a string trimmer just be aware you will NOT be able to tune for 2cycle operation at WOT and low/no load. This may be ok to save grenading it from someone running it wide open with no load.

Here is a picture of the governor, with the little ball visible in the middle.

And I thought I knew something about carbs and engines

Ryobi used electronic rpm limiting in their ignition HT coil. Check the patent pending numbers of the parts to see the schematics involved.

You won't find walbro tuning in your sex manual.The factory manual is the best source of information and its free.