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rotang
14th December 2004, 19:34
Whenever i ride i always get thick black oil dripping from the bottom of the muffler on to the swingarm its also hard to start when hot and will only start with wide open throttle i run a 40-1 mix. Has anyone any ideas what might be the problem??

FzerozeroT
14th December 2004, 20:03
low flowing air filter? high float level? definitely sounds like it's rich, pull the spark plug out and tell the masses what it looks like (black, brown, white, deposits?)

Motu
14th December 2004, 20:15
Ah,two stroke puss...it oozes from wounds in the exhaust and builds up a thick crusty scab at the barrel port.At least it did in my day running 20:1 on engine oil.A modern 2 stroke oil at 40 or 50:1 should leave almost no deposits.I'd say you were running rich - hard starting hot and full throttle to clear - definate symtoms.Check your float level and needle valve seat.

ajturbo
14th December 2004, 20:29
sell it ...worry all gone!
buy a 4 stroke.... :moon:

ajturbo
14th December 2004, 20:29
would any one else like me to fix their bike problems???

Wellyman
14th December 2004, 20:34
check your exhaust bracket where the pipe joins onto the silencer that bracket may be broken and need replacing or just tightening. good luck.

Kickaha
14th December 2004, 21:41
what kind of riding do you do with it?

F5 Dave
15th December 2004, 08:32
It IS too rich so the petrol/oil mix that doesn’t burn exits the cylinder. In that mixture the petrol disappears leaving burnt coloured oil reside. If the combustion was complete it would burn most of the oil no matter what ratio you run.

Oil ratio is not your problem & anyone who says so needs a slap in the face with a wet kipper.

Your task is to find out where it is rich, pilot, main or all of the above.
Guess one is the pilot.

Read a jetting article (search net, there's heaps about) & fiddle some brass.

rotang
18th December 2004, 18:55
low flowing air filter? high float level? definitely sounds like it's rich, pull the spark plug out and tell the masses what it looks like (black, brown, white, deposits?)
yeah its black. how do you correctly set the float level? how can u find out what jet size is has, & what size should it have??

pete376403
18th December 2004, 23:52
Are you racing this bike (MX) or trailriding? Factory jetting would be for WOT racing, and probably on the rich side. Trail riding an RM - most of the time it would be on the pilot jet, or closed throttle.

FzerozeroT
19th December 2004, 07:37
more experienced people correct me if I'm wrong:

lean your bike over to about 45 degrees, if petrol starts leaking out your carb then float could be too high, if not try lowering your main jet and tighten pilot jet.

Clean outside of carb WELL, clean workbench etc, ANY shit gets inside your carb you're wasting your time.

(after turning off fuel) unwind the lid at the top and pull out the plunger (spring and metal thing) the pointy needle bit at the bottom is your main jet, unbolt air filter and carb from engine and remove, drain fuel out of carb by rolling it around in the air to different angles into an old ice cream container(i'm assuming you've never worked on a carb before, gas can get stuck in all kinds of places)

If float level was too high then undo the screws on the bottom and slowly lower the bottom off with the carb upright as if it was on the bike, the float will be hanging down, put the bowl (the bit you took off) down and GENTLY push the float up, you'll see a small thing getting pushed up into a hole (no nasty comments please) by a tab on the float, if the tab looks bent (even a tiny amount) so when the float is at it's highest point it is not level then you need to bend that tab (DON'T BREAK IT!) so that the float looks level. put the bowl back on and tighten screws like a car tyre, crossing over and gradually tighten (not too tight).

If you did adjust the float level, put carb back on bike NOW

look in the inside end of the carb closest to the engine and you will see a little goldy needle sticking up (pilot jet), this is for the low revs fuelling if it is too far open (down) then theres too much gas at low revs, find the screw below the jet and wind it in until it seats - counting turns - (gently of course) then wind it back out 3 turns (guesstimate), probably a little rich but better than too lean, if you wound it out less than you wound it in then chances are this was the problem and reassemble your carb NOW

the fidgetiest is the main jet the one thats attatched to the throttle cable with the spring you need to pull out the throttle cable then spring and get the plate then the needle out, on the needle there will be five notches, center is standard, if the circlip is in the lower notches the bike will be richer, if it is higher the bike will be leaner. generally the higher in altitude you are the leaner you want your mixture, you should place the circlip up one notch from wherever it is, if it is right at the bottom put it in the middle. now try and put the springs and cables and needles back the same way as it came apart.

when you are putting the plunger (top part) back in the carb it has a groove down one side, it stops it from turning, the flat side of the plunger goes at the back of the carb, if it won't seat still the needle could be not going down it's hole so don't force, jiggle with slight pressure.

clean the plug with some fine sandpaper and wash with petrol (maybe some of the stuff you poured out of the carb)

idle for 10 mins and check plug, if it is light brown/very powdery (too lean) unwind pilot 1/4 turn, medium/dark brown all good, if it is black/greasy twist in your pilot 1/4 turn. clean plug and repeat until good.

take it for a ride and if plug fouls now lower main jet one notch.



you are now the carb mastah, show your friends and impress the chicks.

P.S. in case you weren't paying attention, the plug is your guide to tuning, ideally you want a brown that isn't powdery

FzerozeroT
19th December 2004, 07:44
p.p.s. first make sure you have the standard plug and a clean air filter

all else fails take it to a motorbike mechanic and spend $60 and save 2 hours of your life

rotang
20th December 2004, 16:53
Cheers guys looks like il be ripping the carb appart this weekend!

FzerozeroT
20th December 2004, 21:53
some of that stuff could differ on your carb, i was actually thinking afterwrds you could have a flatslide carb, in which case none of it will apply :D