Bought the bike awhile back and it was missing wen I bought it but had been sitting up not used for about 2 years so I blamed a dirty carb or spark plug. I stripped the carb and found water in it so assumed I found the problem I also cleaned the air filter and put a new spark plug in and changed the gear oil but the bike has got worse to the extent it won't rev past half open all the time it behaves like it running on a fouled plug and won't rev out clean and bogs down. The bike has a new piston and rings which were done before I bought it and were just run in. Has anyone had this problem or shed any light on it? I was thinkin power valve problem or not set right with the cylinder bein off doin the piston but they seem closed wen the bikes not running. Or could it b a timing issue even tho it shouldn't have been touched with doin the top end? I've also checked the reeds and they seem good and its fresh fuel in the bike. Any help much appreciated.
problem 2002 ec300 wont rev out?
- Thread starter andy176
- Start date
Thanks for the reply I didn't try that I just checked if they were closed but at the minute I don't even know if it will rev high enough to open the power valves as even on the stand it will bog down wen I wack the throttle open it seems to have got worse but il give it a try cheers.
Yea its smokey but I did mix it pretty rich at 125ml to 5 litres and my even been abit extra it seem more like its that its to rich to rev but to much so that it can't be the heavy mix. Is there a filter in the fuel tap? Ive a in line filter on the fuel pipe to the carb and the fuel seems slow at filling it. Yea I checked the reeds and seem fine. By main seals do u mean crank? Wats the best way to test them? Thanks again for your help.
I took a look at the power valves today wen it idles the lever sits against the stop and it doesn't move til about 4k revs and wen I give it a quick rev they bounce open full and bounce back nearly like they are flapping about does that sound right as it doesnt seem right to me doesnt do it all the time tho. Also wen I rev the bike they either seem to b fully open or closed and they dont gradually open as the revs increase does that seem correct.? Thanks.
Jakobi
Super Moderator
It should sit against the stop at idle. Thats what the whole idea of adjusting the preload is about. In saying that it shouldn't stop the bike revving out. It will just make the bottom end soft.
I'd be looking at performing a leak down test to try and rule out any other issues.
I'd be looking at performing a leak down test to try and rule out any other issues.
Yea cheers again i ment it does sit against the stop at idle and then when I rev it it will open full and sometimes wen its open full it will go back a fraction and bounce back to full open like its flapping about. so should it be a case of them either being closed or fully open and no in between?
sorry wat do u mean by a leak test and how do u go about doin it and wat faults can it find?
sorry wat do u mean by a leak test and how do u go about doin it and wat faults can it find?
Jakobi
Super Moderator
A leak down tester plugs into the spark plug hole and you fill the engine with compressed air. Basically an engine in good condition should be sealed and hold pressure. If you have damaged rings, seals, etc it will be obvious by looking and listening where the air is escaping. Nice quick diagnostic.
I had an 01 300 that had great snap from idle to midrange, then went flat. After contacting the previous owner learned that he had jetted it that way on purpose, being an older guy who did all tight technical terrain and he didn't want it to rev too high or pull too hard on top end. A little re-jetting cleaned it up all through the rev range. I also found that due to the jetting he was using the PV cover was very carboned and fouled with oil, although it seemed to be working. I cleaned that up when I did the jetting, so that may have made a difference as well. A leakdown test is never a bad idea, but if there is no leakage the jetting is very easy to do, GGs carbs are very easy to get to. The 300 is a bit harder to get jetted perfectly than the 200 or 250, may take several tries to get it like you personally prefer it.
motopsycho87
New member
Check the head gaskets, they are only o-rings, and if it's been sitting a long time will dry out pretty easy.
socalscott
New member
Had this exact issue. Craziness b/c the final cause/fix was related to excess fuel, yet it seemed that beyond 1/2 throttle the fuel was not keeping up with the increase in air. Between fixing issues and others popping up, each one seemed like 'that's it!'. I was losing my mind.
Final fix was a newer carb body. The carbs float shifted sideways at lo-mid rpm vibration, allowing excess fuel to flow. A worn seat(hole) where the float pin resides.
Make sure the reed cage is not pitted and btw, std carbs need a mod to the pilot circuit(RB Designs). Consider replacing the carb with the soon to be available cast APT SmartCarb 38mm unit(no jetting required, self adjusts to altitude/temp, mpg+ and power increase).
Final fix was a newer carb body. The carbs float shifted sideways at lo-mid rpm vibration, allowing excess fuel to flow. A worn seat(hole) where the float pin resides.
Make sure the reed cage is not pitted and btw, std carbs need a mod to the pilot circuit(RB Designs). Consider replacing the carb with the soon to be available cast APT SmartCarb 38mm unit(no jetting required, self adjusts to altitude/temp, mpg+ and power increase).
motopsycho87
New member
Could you not replace the needle valve seat?
Bingo! Havnt been on in a while and only reading this now! I had replaced the ignition and no better took the cyclinder off and all was good including the powervalves so I replaced all with new gaskets. I checked the loom for bad connections and then opened the standard silencer and where the silencer bends the core had broke and partially closed the core and the exhaust packing was blocking the exit inside. I stuck a rm125 silencer on and it seems to rev out proper now but it wouldn't stay on so il have to butcher up somethin to check it better but it seems good! Il be looking for a full system for it as the messico header is in bad nick wat is the best system for them? Oh and thanks again for all your help folks.
I was fighting this same problem on my 2011 bike. The bike would not rev cleanly past 1/2 throttle.
I bought a box of NGK BR8ES plugs. I swapped plugs with the same ones (BR8ES) and the concern was not corrected. So I figured it was not the plug.
It never really clicked to me it started when I put the BR8ES plug in.
I finally dug around and found a new BR8EG plug, installed it and the concern was 100% corrected.
I bought a box of NGK BR8ES plugs. I swapped plugs with the same ones (BR8ES) and the concern was not corrected. So I figured it was not the plug.
It never really clicked to me it started when I put the BR8ES plug in.
I finally dug around and found a new BR8EG plug, installed it and the concern was 100% corrected.
bukwheat
New member
Glad thats all it was....I've seen that problem too many times and just about everybody skips checking the packing in the silencer. I guess why it sticks with me is because a good friend of mine missed a good desert race for the same reason.
