stihl 026 runs crappy & only at high rpm

joemag

my 026 will start relatively easy (2 or 3 pulls), but it run rough & only in the start position or higher throttle. it sprays fuel from the carb. intake (the higher the rpm, the heavier the spray). i have replaced the intake needle assembly, diaphram and all gaskets in the carb. someone mentioned the cylinder being scored, but the cylinder has an ashy color(not shinny), but does not appear to be scuffed or scored. could anyone help me?

Bruce Hopf

I started a Thread Trouble Shooting for Carburetors, that I Copied out of my Carburetor Book, for Stihl Power Products. See if that will help you. Bruce.

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joemag

thanks for the reply. the only thing in that thread i havent already checked or replaced is the plastic vane in the jet. i'm not that familiar with these type carbs. do you by any chance have a diagram of the carb, or maybe a flow chart you could email me a copy of? all help is greatly appriciated. thanks.

newguy18

Hole in the fuel line?When you rebuilt the carb,was there any gasket residue left?If so then the new gasket didn't seal.

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old schooler

joemag

i've checked the fuel lines during the reassembly of the carb. it does'nt seem to have a fuel delivery problem. it sprays out the carb throut at half thottle. i cleaned all the carb surfaces with a soft stainless steel brush, that i use on all carbs i redo. i do alot of lawn mower & auto carbs, but not many 2 strokes. i've read something about a valve in the main jet on some of these carbs that can be damaged by blowing air thru it, any ideas?

newguy18

Where on the carb is it spraying from?Oh and a wire brush for cleaning carb surfacesIt can score the surfaces deep enough to where the gasket won't seal and cause an air leak,i recomend a single edge razor blade in a scraper,this is coming from someone who has rebuilt probabley 2,000 carbs on everything from boats to saws.Heres a pic of what i recomend,

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old schooler

joemag

its spraying from the intake port(venturi), the spray is light at half throttle, but gets progressively worse as thottle is opened. its pretty heavy at w.o.t. i did use the scrapers when i first started with carbs, but they tend to damage the cast ridges that are there to provide pinch lines and better seal. then i found these brushes that have very thin & soft stainlesssteel brissles, they don't damage the aluminium but are very good at removing gasket residue, but not corrosion, still have to scrape that. anyway thanx for the tip and advise, all help is grately appriciated.

newguy18

Heres a pdf,if its spraying out of the venturi then it must be getting too much fuel and on the compression stroke the engine is pushing excess fuel out of the cylinder,your carb needs retuned.Oh,i've never had trouble with a scraper,but being some what open minded,i'd like to see a pic of these brushes.
http://bricomeca.free.fr/Stihl/stihl%20026%20IPL.pdf

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old schooler

joemag

i think the pdf you sent may have solved my problem. i read somewhere about a valve in the main jet, but did'nt know antthing about it. the parts list says it is a valve jet so it must be. i read that it was sensitive to air pressure, and since i did blow thru it during cleanup, i think i damaged it. so i got a new one on order. all i have to do is figure out how to get the old one out. any advice? as for the brush, i'll get you a pic asap, don't have digital camera, may take a couple days. i get them at the local hardware store(its a real oldtime store, not a home improvement or do it yourself center) and you can get them in brass or stainless which i prefer due to corrosion resistance. thank you very much for the help.