TheBoltons Posted August 8, 2012 Posted August 8, 2012 So... After having stripped EVERYTHING, and I mean EVERYTHING from the bike, cleaned it all, checked all engine specs, altered valve clearance height, installed new gaskets, cleaned cylinder head, piston, installed new rings, refitted electrics, cleaned air filter, went over the whole bloody bike cleaning every terminal and square mm of the damn thing, remounted engine, filled with silkolene, fitted new jet on the carb, and started it up... I was pleasantly surprised that it started well, without choke or throttle, but didnt idle for long. As I expected as the fluids need to circulate etc. So eventually it ticked over nicely, and I adjusted the fuel mixture and it still ticked over nicely... Until The bike went bloody beserk, revved itself up to full whack and didnt stop, so I hit the killswitch. And it happened two or three more times. When I got it idling again, I tried kicking it into first and every time I tried it just died. Am depressed now and in need if help!!!
Moderator Cynic Posted August 8, 2012 Moderator Posted August 8, 2012 Sounds like it was running out of fuel, is the fuel supply to the carb ok, no kinks or such?
TheBoltons Posted August 8, 2012 Author Posted August 8, 2012 Nope. New fuel line. **headdesk** I have just had a thought though, maybe I should open up the carb and check the slide is the right way round. Fairly sure it is, but doesnt hurt to check. It just really pissed me off because I had less problems before I did any work. *sigh*
TheBoltons Posted August 8, 2012 Author Posted August 8, 2012 Checked carb, all seems fine. Thought maybe the barrel might be catching on the air screw... Not the case.
Moderator DirtyDT Posted August 8, 2012 Moderator Posted August 8, 2012 ...................I have just had a thought though, maybe I should open up the carb and check the slide is the right way round................... Easily done. I did it the other day! It must be fuel. It can't burn anything else. Are all the jets sitting right and any rubber grommets in the carb OK?
TheBoltons Posted August 8, 2012 Author Posted August 8, 2012 As far as I can tell... I did reset everything to factory spec. Giving it another go now before I lose light.
TheBoltons Posted August 8, 2012 Author Posted August 8, 2012 And throttle now kills the engine... Fandabbydozy
Moderator Cynic Posted August 9, 2012 Moderator Posted August 9, 2012 Still sounds like a fuel issue to me. Fuel flow or crap floating about in the chamber.
TheBoltons Posted August 9, 2012 Author Posted August 9, 2012 Cynic you are nearly right and you are right. It is a fuel issue - nothing to do with the carb. Managed to isolate it to the tank and fuel tap. The main line was blocked. Only reason I realised was because I switched it to reserve instead if off to drain the carb and then we had fuel!! Soooo, it is now functioning perfectly, and starts with no choke or throttle and I went up and down the road fine. But... Still have this issue where it picks up revs with no throttle movement at all, no choke, and it revs up to top whack and stays there. (if I let it. Which I dont) Sometimes a twist on the throttle causes it to come down when I release, sometimes not. It is happening less frequent, and after it does I can then no longer kick into gear without it cutting out. Really dont want to ride it if out of nowhere it will accelerate with no signs of stopping!
Moderator drewpy Posted August 9, 2012 Moderator Posted August 9, 2012 yep, bit of shite in the fuel bowl or above the float valve.
TheBoltons Posted August 9, 2012 Author Posted August 9, 2012 Checked the carb eleventeen times... Float working fine, needle working fine, no overflow, air filter clean, the only "if" in the carb is the main jet. The nozzle is clean as a whistle, as is the jet screw, but there is a possibility that the hole in the main jet screw is smaller than standard. Being that I had no screw to start with (only the remains of one) I had nothing to compare it with. My local yamaha dealer had no specific parts in for the carb, so I gave him the specs instead of part number and he found one to match. Thinking about buying a whole new carb instead, but would rather avoid that if possible. And then it still dies completely if I try and put it in gear. Putting it away for tonight and hoping I can fix it tomorrow. All help has been and will be appreciated! Thanks!
Thunderchild Posted August 10, 2012 Posted August 10, 2012 Does it have a TPS (Throttle Position Sensor), on the carb? I have one on my XVS 125. If it's faulty, it could be causing the engine idle speed to increase. You could check it (if it has one), by following the manual or this video shows you a generic carb test.
dt502001 Posted August 11, 2012 Posted August 11, 2012 OK I said I wouldn't help you but after 3 day's of watching you need it. Try running the bike with a jerry jug of gas hung to act like a gas tank... after making sure ther is nothing in the carb bowl and if all goes well then. GREAT go to step 1 ......if not have a spray jug of water and start spraying around the vaccumme leak areas. (carb joint rubber top of carb ect) 1) clean the tank with acid and re seal it or put in a filter( crap is getting in to the carb even micro shitt can do this stuff your talikng about) 2) re clean the carb and check the seals( now as we never got thoes little bikes here not sure if it has a diapharam (cv) type carb or a accelerator pump type) either the diaphram on the top of slide has a micro hole in it or the accelerator pump seal is NFG. Both can cause the sudden WFO ( wide F open) problems. And air is 70-78% nitro and it can burn given the smallest agent for combustion to check the dia remove it and put a small amout of gas on 1 side and if any wet spot show up on the other side its NFG. Thunderchild the TPS is only used for the computer to caculate the ing map and has nothing to do with fuel deilvery on a carb bike only fuel injected bikes.... But a great vid yo found for testing tps.. Though he forgot to show if you sweep ( move it up and down) the throttle you will see a diff in the ohms reading
TheBoltons Posted August 11, 2012 Author Posted August 11, 2012 Thanks dt. My old man told me to do something similar but with wd40 instead of water. He reckons its a definite air leak (he was a mechanic for years before his accident) so will be doing that over the weekend. Also replacing the couple of gaskets that I didnt first time round and using gasket sealant this time as I didnt before. Havent been able to keep the bike at a decent enough temp long enough for gaskets to make properly. Few screws are also questionable so replacing them and will whack em in with an impact driver. I do have an inline filter, but will be flushing the tank too. Thanks again all.
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