|
|
Post by mattb on May 19, 2008 9:46:24 GMT -5
Hey All. My bike had been running fine for a year; indeed it used to stall a bit at the lights last winter, but since summer even that problem had ceased, until a couple of weeks ago. Now, in the last week, the plug will foul up with soot almost immediately. It will constantly surge and is sluggish, the idle jumps untsably between 1000 and 2000rpm, it wants to stall constantly at the lights, and will begin to stall and misfire at stand-still even when I rev it, at which point it dies. It is also backfiring a little when I roll off the throttle. The weather has gotten colder - winter has arrived - and it does seem to have co-incided a little with that, though we're talking moderate Melbourne (Australia) cold. But other than this there has been no changes done to the bike. She is burning a bit of oil from time to time in smoke out the back on start up - could this via bad rings be fouling the plug? I figure oil-fouled is quite different to dry carbon fouled. I disagreeumption is that the bike is running rich (always has a little). I did the fuel/air screw up all the way in (this is right?). Still fouled up. It got a new air filter last week (after the onset but prior to this becoming really problematic in the last week). I'm guessing the general cause to suspect is rich fuel mixture? And that means perhaps not enough air somewhere. I run it on BP Ultimate, always have, and I take it off choke almost immediately and do not over-use the choke in starting. d**n, she had just got to teh point of being a fine starter and non-staller!  Matt |
|
|
|
Post by spindlehead on May 19, 2008 10:26:20 GMT -5
It does seem rich. Inside the carb, it's possible that the air jet is clogged.
|
|
|
|
Post by stevec5000 on May 19, 2008 10:27:45 GMT -5
Sounds like the needle valve is leaking or float sticking. Either way you need to clean the carb and check the float level.
|
|
|
|
Post by spindlehead on May 19, 2008 10:58:18 GMT -5
Good one Steve! I always forget about the floats and that tricky little valve.
|
|
|
|
Post by mattb on May 20, 2008 4:08:32 GMT -5
Time for the next frontier! I've put off the scary job of opening up the carbie (on my only transport), figuring that there's no need to fix - or stuff - what ain't broken. This old bike is teaching me a lot! The SR500: making mechanics out of riders for 30 years! (-or mechanics out of 30 year old riders!)  |
|
|
|
Post by StewRoss on May 22, 2008 4:44:20 GMT -5
Hi Matt, Check to see if you're fuel pump rod has become disconnected from the lever at the lower end...pin missing etc. SR |
|
|
|
Post by mattb on May 22, 2008 9:07:06 GMT -5
Stew, is that what here is referred to as the "accelerator pump linkage"? www.siue.edu/~rsutton/SR/mikuni.htmI think I found a likely-looking lad! I opened up the air filter box, and the air filter had come loose, leaving upwards of one centimetre's gap to let dirty air in! The inside of the box is always a little dusty anyway, despite my efforts, so I suspect that dirt has got into the carbi and blocked...the air jet (does that sound right?) or something like. My air filter is held in place by a bent piece of metal and garden hose that is pushed between the air filter and a piece of molded plastic; time to improve the system. I only changed the filter a couple of weeks ago, so it has happened since then and co-incides with the onset of the problem. I didn't have time to open and inspect the carbi, but I blew some Honda carb cleaner stuff (aerosole) into the float bowl vent and the air inlet, got it going - still wasn't easy! - and then started it again having put carb cleaning stuff into the petrol. I rode for five kms until it stalled, and wouldn't start till half an hour later. The bike is no longer surging, and the idle is no longer erratic, however it's lost a little zest in the acceleration, and tends to stall as I drop the revs coming to a stop; and it's harder to start when hot (first kick again when cold). Plug is still getting fouled, but not like before, and it still blows black smoke when I rev hard. I can't go any leaner on the fuel/air mix screw - should I try to file off the limiter, and how do I do that? I think the thing still needs an inspection and cleaning asap. I might find a wise old man to help me do it though, I reckon I couldn't tell if parts were worn or not. Matt |
|
|
|
Post by malakiblunt on May 22, 2008 9:09:17 GMT -5
Hi Matt
your right to asume rich if the plug is just sooty itll look wet and balck if its oil.
this is realy simple but have you cheaked your air filter is not blocked, becuase it will cause the symptoms listed if it is.
|
|
|
|
Post by StewRoss on May 22, 2008 22:39:31 GMT -5
Hi Matt, Yes that's the linkage...check to see if the lower pin is in and the pump lever moves when the throttle is turned. SR |
|
|
|
Post by caferacercarl on May 23, 2008 4:30:17 GMT -5
Talk to andy at sumoto m/c in melb, he knows SR's and might be able to quickly sort out which thing is causing the grief, [as its hard online]
|
|
|
|
Post by davedunsboro on May 25, 2008 4:34:06 GMT -5
Hey don't do what I did a couple of weeks ago ,I overhauled my stock carbie & put it into my new project .Couldn't quite get it to run right so I went back to the stock airbox/filter tried a different pipe & muffler , it still ran very rich & uneconomical & fouled up the plug every time .So whilst I was in the Yammy shop getting some bits I got a stock jet to try .Funny that when I took off the float bowl , there was no jet as it was at the bottom of the bowl(I can hear you laughing Carl!) I mustn't have nipped it up as it ran like crap as soon as I put the carbie in ! Now it runs great cheers Dave.
|
|
|
|
Post by fenz on May 25, 2008 16:24:42 GMT -5
Hey Dave your not on your own there,i did exactly the same thing on one of my dirt bikes but the main jet didnt come off until i was out in the middle of the bush with no tools.
Slow trip home when you could only run on the pilot jet...........
|
|
|
|
Post by davedunsboro on May 26, 2008 8:52:29 GMT -5
Aaron theres more to the story , I was heading down Caves road on full throttle to see what it would do & all of a sudden it got more power & sounded really good so I took it for about 20ks .I pulled up at my neighbours to show him my new toy & when we looked at my new muffler its guts had come out & there was about a foot of pipe sticking out of it ! Back to the drawing board for fine tuning & more mods . I did get a good laugh out of it though & I recon I've got the best test track , hills ,twistys ,sweep bends ,straights & a great downhill You know its right or wrong & mobile phones are handy for a quick rescue/recovery mission cheers Dave.
|
|
|
|
Post by caferacercarl on Jun 9, 2008 0:27:48 GMT -5
Thats what I love about SR's, we've all done the same things just at different times, we were trying to set off to the first SR club rally and my bike had spat the muffler off 4 times!!, Deus will have exhausts in stock soon designed by me on the Dyno and made by Hi tech, very good aussie pipes, fire them off an email asking how long till they hit the online store, tell them I sent you, cheers,Carl.
|
|
|
|
Post by wotavidone on Jun 15, 2008 7:34:36 GMT -5
Tell us more Carl.
Single wall bigbore header pipe? Reverse cone muffler? packed/repackable? Nice and light? for 400's or 500's (I'm assuming there must be some difference)?
Quiet enough to keep the Constabulary away? Will I need to sell one of the children to raise enough bucks?
Can't wait for more details.
Mick
|
|
