Every morning I start the bike, it starts fine with just choke open. Then after warm up, I'd pull the throttle a bit to rev it mildly and the engine stalls. The engine stays running after few tries. After that, the bike runs beautifully. No problem at all. What could be wrong? Fuel pump? Throttle? Carb? I have no idea... Second thing, once in a while riding the bike around, I hear sounds like... "bong!" "pop!" etc, around the muffler. It's nothing irritating, but it sounds weird to me. All the bikes I've known didn't have that.(friends bikes) Is that what a working EXUP's supposed to sound like? Thanks for listening. <!-- s:alien: --><img src="{SMILIES_PATH}/th_Alien_Abduction.gif" alt=":alien:" title="Alien" /><!-- s:alien: -->
Hi Polyfzrrr, The bike will die in the morning because the oil is not up to working temperature and therefore the bike has to work harder. Also if you rev the bike with the choke on there may be to much fuel trying to combust and the engine dies. Not sure about that popping noise from the exhaust, it is not the exup valve working as it should. Does it happen under hard throttle or mild throttle. Check the condition of your exup cables and adjust them if they need it. Also the popping noise can be associated to the air box not being attached to the carbies correctly and bumpy roads can dislodge the box and create such a noise.
Mine was a bit tempramental when cold. At first start I had to hold the revs at about 3000 for about 5-10 seconds to get a bit of warmth in the chambers otherwise it would stall and be a real pain to get going again. The ""bong!" "pop!" etc, around the muffler" could be the exup rattling or sticking. Mine used to rattle a bit if the cables were too loose. - OR - Also mine had a squeaky rear suspension bush at the bottom of the shocker that had to be freed up and lubricated. Not too hard to get the rear shock out to do the job, just a matter of suspending the rear of the bike to get the weight off the suspension...
I was paying close attention to tacho and found out the sound is heard around 4500 rpm most of the time. I'll try to check the cables. I think my suspension is ok as I don't hear anything weird <!-- s --><img src="{SMILIES_PATH}/icon_smile.gif" alt="" title="Smile" /><!-- s --> Thanks for your input!
It could be the bushes on the exup ar worn and it is sticking or catching internally at a certain position. The rotation position of the exup valve is rpm related. The exup valve is a fairly simple arrangement.
