jrsunt Posted February 4, 2016 Report Share Posted February 4, 2016 sounds like it could be valve clearances. They do get hard to start when hot if the clearances are tight. Quote Link to comment Share on other sites More sharing options...
jonnyc21 Posted February 4, 2016 Report Share Posted February 4, 2016 I was just wondering about valve clearances... worth a check for sure. Quote Link to comment Share on other sites More sharing options...
menglovekai Posted February 5, 2016 Author Report Share Posted February 5, 2016 (edited) www.youtube.com/watch?v=euFH-kP4y1o Me stating the bike when cold . 11 degreeC in the moring . Just one kick . Can you compare the Idle speed of my bike compare to other 4rt ? Is it high enough? I check and adjust valve clearance as manual . Intake 0.12mm. Exhaust 0.3mm. I will adjust it to Intake 0.15 mm. Exhaust 0.35 mm. Is it possible that when you ride long enough that the engine temperature gets higher until the point where standard valve clearance can not deal with the part's expansion ? Or may be i have to check the valve clearance when the engine is hot. Edited February 5, 2016 by menglovekai Quote Link to comment Share on other sites More sharing options...
jonnyc21 Posted February 5, 2016 Report Share Posted February 5, 2016 I wil double check my manual but every bike I have ever had was checked cold. Also you want the valves as in the middle of the range as you can get. I have had a bike where the close side of the range and high heat did make starting a bit hard and when I put it right in the middle it fixed that. Let us know how it goes. Quote Link to comment Share on other sites More sharing options...
cmxi Posted February 5, 2016 Report Share Posted February 5, 2016 www.youtube.com/watch?v=euFH-kP4y1o Me stating the bike when cold . 11 degreeC in the moring . Just one kick . Can you compare the Idle speed of my bike compare to other 4rt ? Is it high enough? I check and adjust valve clearance as manual . Intake 0.12mm. Exhaust 0.3mm. I will adjust it to Intake 0.15 mm. Exhaust 0.35 mm. Is it possible that when you ride long enough that the engine temperature gets higher until the point where standard valve clearance can not deal with the part's expansion ? Or may be i have to check the valve clearance when the engine is hot. Your idle speed is higher than mine -05. Quote Link to comment Share on other sites More sharing options...
jonnyc21 Posted February 10, 2016 Report Share Posted February 10, 2016 Great news! Quote Link to comment Share on other sites More sharing options...
menglovekai Posted February 16, 2016 Author Report Share Posted February 16, 2016 After 5 day of test . Easier Hotstart but i still encounter the problem.so I check the plug, The plug is "dry carbon foul" . Then i took the air filter out , it looks good but once i squeezed ,it was full of blue grease .Oh god . It was just a nasty clog air filter. 1 Quote Link to comment Share on other sites More sharing options...
menglovekai Posted July 23, 2016 Author Report Share Posted July 23, 2016 Update on my Hot Start problem . If the weather is extremely hot 35+ degreeC and continuous ride about 30 min. There was a lot of vent out the breather hose and The fuel was boiling in the gas tank .I assume there is a fuel boiling in the injector rail too. So when i start , the Fuel mixture is too lean .(Spark plug never gets wet)I google a lot and find some word "Hydro lock" .solution 1. If the weather is extremely hot and sunny always park your bike under the shade , ride for a short period of the time. ( Under cloudy weather with 25 degreeC there will be no problem at all)2. If the bike can't start , open the gas cap to confirm there is a boiling inside. park the bike in the shade and wait 10 minutes . Quote Link to comment Share on other sites More sharing options...
guys Posted July 23, 2016 Report Share Posted July 23, 2016 Update on my Hot Start problem . If the weather is extremely hot 35+ degreeC and continuous ride about 30 min. There was a lot of vent out the breather hose and The fuel was boiling in the gas tank . I assume there is a fuel boiling in the injector rail too. So when i start , the Fuel mixture is too lean .(Spark plug never gets wet) I google a lot and find some word "Hydro lock" . solution 1. If the weather is extremely hot and sunny always park your bike under the shade , ride for a short period of the time. ( Under cloudy weather with 25 degreeC there will be no problem at all) 2. If the bike can't start , open the gas cap to confirm there is a boiling inside. park the bike in the shade and wait 10 minutes . Or add cooler fuel if possible... Quote Link to comment Share on other sites More sharing options...
jimmyl Posted July 23, 2016 Report Share Posted July 23, 2016 The boiling point of a liquid changes with pressure. Lower pressure lower boiling point and vice versa. As the fuel down stream of the pump is at higher pressure would be surprised if it would boils ??? 1 Quote Link to comment Share on other sites More sharing options...
richierich Posted July 23, 2016 Report Share Posted July 23, 2016 Hi I always come acroos "new" 4RT riders at trials struggling to restart hot engines; I have found the most effective way is to find top dead centre (TDC) before attempting to restart from hot. Takes a little practice to find TDC but, from experience, I can confirm that a hot 4RT can be kicked over continuously and will struggle to start but if you locate TDC and give a gentle kick, it starts first and every time. Also, my inlet valves closed up a little recently and made the hot start problem more difficult; I adjusted the inlets to the higher gap in the manual and now is back to normal operation. Setting the idle screw to close to 1900 rpm as possible also helps and be sure to make sure, as someone else said, that there is a little free play in the throttle cable; if the throttle cable is too tight, it will open the throttle valve a little and screws up the throttle body sensor settings making starting very difficult. Quote Link to comment Share on other sites More sharing options...
menglovekai Posted August 12, 2016 Author Report Share Posted August 12, 2016 Eventually, I found the problem .The Fuel filter was clogged by rust . After flush and clean the filter , Now the bike can hot start everytime no matter how hot the weather is. The root cause may be the crack fuel cap ,So the water can get in when washing the bike and after parking for almost 2 years.the rust buildup. Thankyou everyone. 2 Quote Link to comment Share on other sites More sharing options...
guys Posted August 17, 2016 Report Share Posted August 17, 2016 I've heard from this rust problem before, but didn't thought of it to link it to hot start problems. To avoid that problem, I had an aluminium tank bottom on my 2008 4RT (also saves a bit of weight). I also use Shell V-Power for that reason: less ethanol in the fuel = less water in fuel = less rust and other water related problems in fuel system. Honda finally addressed this problem with a plastic fuel tank bottom. Quote Link to comment Share on other sites More sharing options...
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