Emilio's79620 Posted September 26, 2015 Report Share Posted September 26, 2015 I'd like to know how to raise the top speed on my l20b stock hitachi it barely wants to get 50 and I need to be able to get it onto the freeway any suggestions thank you guys you have been most helpful so far Quote Link to comment
datzenmike Posted September 26, 2015 Report Share Posted September 26, 2015 Change the fuel filter, do it now. Only $4... if not it, probably time for a new one and only $4. Set the valve lash and timing. Does it idle OK? If still 50MPH top speed perhaps the secondary jet in the carb is dirty plugged. Maybe secondary is stuck. When warmed up take top off air filter is choke open or closed? Quote Link to comment
distributorguy Posted September 26, 2015 Report Share Posted September 26, 2015 That defines a severe state of being out of tune. Do you have a manual for your truck? Follow the tune-up guide. Valve lash, then engine timing (distributor) then fuel mixture. Of course make sure you're not starving it of fuel with a plugged filter. Could be a bad pump, clogged carb, sunk float, lots of fuel related issues. But its just as likely a seized advance mechanism in the distributor, valve lash WAY out of adjustment, etc... Quote Link to comment
Emilio's79620 Posted September 26, 2015 Author Report Share Posted September 26, 2015 Thank you guys I will buy a fuel filter as soon as I'm off work and also dizzyguy I love that 620.. But last night after I posted this I drove my shortbed again and it got to 50 better and faster than it normally would but it still struggles to get to 60 but I will definitely do as you guys said thank you again guys.mike always a pleasure hearing from you king rat Quote Link to comment
Emilio's79620 Posted September 26, 2015 Author Report Share Posted September 26, 2015 Forgot to add... It idles fine just has a bit trouble getting to 60 Quote Link to comment
datzenmike Posted September 26, 2015 Report Share Posted September 26, 2015 Fuel filter is never a bad thing to try, simple, easy cheap and no harm done if it does not work. A part plugged filter will allow enough gas through to run the engine at idle, low speed and moderate speeds but during high demand like climbing a hill or out on the highway it can be a speed limiting factor. Usually a filter problem reduces vehicle speed and performance gradually as it plugs up further. If this does not help we move onto other things more involved than $4. Quote Link to comment
banzai510(hainz) Posted September 28, 2015 Report Share Posted September 28, 2015 Carb choke plate could be stuck on causeing no high speed flow. if electric choke then wire could be off ,mean choke is always ON Quote Link to comment
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