bertieboy Posted January 11, 2015 Share Posted January 11, 2015 Hi Guys,I purchased this Motorhispania RX50 for my son a few months back as a none runner. The lad who owned it had left it standing in his garden not running for many months. I got it home and replaced the spark plug, fitted a new exhaust system and managed to get it running again. I put it in for an MOT which it passed with a few minor repairs done, but it has always spluttered when it reachs about 35mph and it only revs upto 6500/7000rmp no where near the red?If i leave it in the garage for a few days it will not start (it is electric start only) unless i remove the sparkplug dry it off and drop a bit of fuel direct into the hole. Once started it will start on and off all day and the next day, unless i don't use it for a couple of days. The choke cable has always come out of the lever bracket and i have to push it back it, but seems to work. The air filter looks old and ill fitting and the last owner had drilled holes through the air filter box, then covered them up again with tape??I have not drained the old fuel.Not cleaned the carb.Not de-restricted the new exhaust.The idle screw and mixture screw have been adjusted, i don't know if they are set right or wrong?Out of the information given above, what would be causing the bike not to want to start?And why would it not rev up fully and struggle when there is plenty of twist to go on the throttle grip?Could the choke be sticking on slighty causing fuel to flood the bike if left unused for a couple of days, and could that also cause the bike to struggle at higher speed?If the fuel is dirty or water has got in, or the air filter knackered cause any of these issues?I don't know a great deal at all about engines and what things are called, and where they go what they do, so i may need to ask more seemingly simple questons.Thanks in advance! Quote Link to comment Share on other sites More sharing options...
Adam Posted January 11, 2015 Share Posted January 11, 2015 Well you need 3 main things to start the bike, a spark, fuel, and air. I'd start by changing the fuel, although it doesn't sound fuel related but it could be contaminated, secondly a new air filter will allow the bike to breathe more freely. Check the Haynes for the carb screw settings and put it all back to standard and work from there. If the bike has a fuel tap make sure it's turned to OFF when the bike is left over night etc this will stop any fuel dribbling into the carb. Quote Link to comment Share on other sites More sharing options...
eastanglianbiker Posted January 11, 2015 Share Posted January 11, 2015 is it only in top gear it peaks out early on the rev counter if so thats possibly because the bike has reached its restricted speed limit if the revs are being held back in other gears as well then it is likely to be a fuel mixture problem and you need to see what colour the plug is when engine hot so run it round the block fast as safely possible hit kill switch pull plug out to check colour to light and its running lean to dark and its running rich Quote Link to comment Share on other sites More sharing options...
bertieboy Posted January 11, 2015 Author Share Posted January 11, 2015 Thanks for the answers Adam,The bike hasn't got a fuel tap, but i'm thinking that if the choke is slightly stuck on because the cable is loose in the lever bracket on the handle bars, would this mean that it would be letting a small amount of fuel to continue through to the carb when standing. This causing it to be flooded when left idle and unused for a couple of days?Also if the choke is slighty stuck on, would this cause the bike to struggle/stutter when it reachs a certain speed?I will replace the air filter, and drain the tank, but do i need to clean the tank and if so, how do i do this please? Quote Link to comment Share on other sites More sharing options...
bertieboy Posted January 11, 2015 Author Share Posted January 11, 2015 Thanks, eastanglianbiker:The bike won't rev high when in nuetral and seems to start to stuggle when in 5th/6th at about 35mph?I put a brand new standard reccomended plug in it and it comes out looking quite dark i would say. Quote Link to comment Share on other sites More sharing options...
eastanglianbiker Posted January 11, 2015 Share Posted January 11, 2015 this could be a good reference guide for the plug colour http://www.advrider.com/forums/showthre ... 8&page=186 if it is to dark then its running rich and needs more air in which case the mixture screw would need undoing a tiny amount no more then 1/4 turn each time and checking then how bike will rev Quote Link to comment Share on other sites More sharing options...
Stu Posted January 11, 2015 Share Posted January 11, 2015 or there is this one steve viewtopic.php?f=27&t=7955 Quote Link to comment Share on other sites More sharing options...
eastanglianbiker Posted January 11, 2015 Share Posted January 11, 2015 oops i never look in the guides guess i should really Quote Link to comment Share on other sites More sharing options...
Stu Posted January 11, 2015 Share Posted January 11, 2015 it is buried a bit though Quote Link to comment Share on other sites More sharing options...
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