OzVMX Forum
Clubroom => Tech Talk => Topic started by: 1983_Enduro_YAMI on June 15, 2016, 05:45:19 pm
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Suppose to have a good ride with the Big IT250K this arvo.....started the bike..here is the first problem, The bike was tuned by the professional mechanic couple of months ago..when i start the bike with choke...It's revving the hell out of it but as soon as i pull the choke off and warm it up, I have no trouble. Here is the second problem i just find out this afternoon....The bike turned itself off!!! I just put a new spark plug yesterday. It bogged down and die when i rev it (that's when the bike's warmed up) I have to push it all the way back from the paddock.
I have been doing all this work..replaced the crank seal, New boyesen reeds etc. I know it's a 30+ years old bike and it's hard to get it to behave but at least the bike shouldn't die on the paddock and playing up like this..It should run like what it's made for (not the top but like a motorbike)
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Disappointing.
Did you get it running again?
Sounds like carburetion.
I wonder if there is debris/water in there somewhere? Maybe something rubber from the choke (cold starter) falling apart?
Keep us informed re your progress.
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Nah i left it.
I don't really have any idea..Have to look in to it... :( :(
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Take it back to where the work was done?
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Choke issue sounds like an air leak around the enricher. check its tight and any boots or orings are in place.
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Choke issue sounds like an air leak around the enricher. check its tight and any boots or orings are in place.
Where about is the enricher in the carby??
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enricher=Choke.. could be an idea to follow lozza's suggestion i feel.
These carbies dont actually choke they open an enriching circuit hence the correct name should be enricher.
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You have an air leak ...possible manifold rubber or carb is totally rooted.
spark and petrol is what makes these old girls go and with out one the other wont work ..... do the process of elimination.
step by step checks .... not multiple
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Check your electric. Stator is tight& advance set correctly, check that rotor's woodruf key is not sheared of, make sure your kill switch is not stuck and works correctly, check all ignition connections&connectors,try another spark plug&make sure you have spark. See if the bike starts with choke off. It may take a few kicks. Old CZ had no choke and started.
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when you got it from the pro mechanic did you run the bike with the fuel tap off till it cut out coz no fuel left in the bowl?if not after 2 months the fuel turns to shite then white powder but blocks up jets but they normally fire up on the choke but die when the choke is switched off.try taking the over off on the bottom of the carb for a look/see
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when you got it from the pro mechanic did you run the bike with the fuel tap off till it cut out coz no fuel left in the bowl?if not after 2 months the fuel turns to shite then white powder but blocks up jets but they normally fire up on the choke but die when the choke is switched off.try taking the over off on the bottom of the carb for a look/see
The bike runs fine and crisp without choke. The problem is when i turn the choke on, It's revs the hell out of it. Like what the other people said up there..I properly have an air leak..Have to look into it with a can of WD40 and a spanner
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Check your electric. Stator is tight& advance set correctly, check that rotor's woodruf key is not sheared of, make sure your kill switch is not stuck and works correctly, check all ignition connections&connectors,try another spark plug&make sure you have spark. See if the bike starts with choke off. It may take a few kicks. Old CZ had no choke and started.
The timing was advanced by the mechanic last time..but not long after i replaced the old CDI with a new one. I didn't care about the timing after i replaced it. Maybe that's an issue too?? Yep, That's what i did the day before. New spark plug and runs like crisp and yesterday..same thing..It died.....
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You say 'i have been doing all this work' 'crank seals', was that done by the shop or by the owner. maybe the left crank seal has been misplaced or incorrectly fitted [which is unlikely & not easy to muck up--Soooo---, i'd guarantee the choke jet in the bowl is blocked therefor it just opens the air bleed--like opening the throttle a bit in effect.Jet's not easy to clean or even find for the unwary as is down a cavity that a long brass tube fits down. In the bottom of that hole is a minute jet. Get something about the size of wire brush wire or something straight & high tensile so it won't bend easy & give it a poke. then go the other way from the feed into below that jet using something bigger like a drill bit. With the wire, be sure it's gone through the jet to dislodge whatever's in there & maybe follow it up with a squirt of crc with nozzle right into the jet from the top--like down the cavity side. Sorry about the long winded essay but hope you get the idea. [hope i'm right too lol]. ps, doesn't take much to block that jet so unlikely to be related to the mechanics work but i now see you say the bike turned itself off & had to push it home--so maybe another problem or [has left crank seal come out--still very unlikely].
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You say 'i have been doing all this work' 'crank seals', was that done by the shop or by the owner. maybe the left crank seal has been misplaced or incorrectly fitted [which is unlikely & not easy to muck up--Soooo---, i'd guarantee the choke jet in the bowl is blocked therefor it just opens the air bleed--like opening the throttle a bit in effect.Jet's not easy to clean or even find for the unwary as is down a cavity that a long brass tube fits down. In the bottom of that hole is a minute jet. Get something about the size of wire brush wire or something straight & high tensile so it won't bend easy & give it a poke. then go the other way from the feed into below that jet using something bigger like a drill bit. With the wire, be sure it's gone through the jet to dislodge whatever's in there & maybe follow it up with a squirt of crc with nozzle right into the jet from the top--like down the cavity side. Sorry about the long winded essay but hope you get the idea. [hope i'm right too lol]. ps, doesn't take much to block that jet so unlikely to be related to the mechanics work but i now see you say the bike turned itself off & had to push it home--so maybe another problem or [has left crank seal come out--still very unlikely].
Thanks Mate, It was good. I'll give this a try. is it the little jet beside to the main jet??
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grab yourself a parts list diagram.
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grab yourself a parts list diagram.
Lucky my dad bought one of these old edition 80's CLYMER IT manual. Got everything i need. Even the improvement of the performance that the new edition didn't say.
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then study it from cover to cover MANY TIMES especially the fuel section then youll know about the starting circuit of a mikuni carb and where it is ;)
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The bike runs fine and crisp without choke. The problem is when i turn the choke on, It's revs the hell out of it. Like what the other people said up there..I properly have an air leak..Have to look into it with a can of WD40 and a spanner
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am i missing something,or is everyone else?? ;), :P
wouldn't you just not use the choke ???
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Get something about the size of wire brush wire or something straight & high tensile so it won't bend easy & give it a poke. then go the other way from the feed into below that jet using something bigger like a drill bit. With the wire, be sure it's gone through the jet to dislodge whatever's in there & maybe follow it up with a squirt of crc with nozzle right into the jet from the top--like down the cavity side.
Oxy/Acet tip cleaners are good for this, lots of sizes, stronger than your average wire and 'barbed' for cleaning shit out of holes
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The bike runs fine and crisp without choke. The problem is when i turn the choke on, It's revs the hell out of it. Like what the other people said up there..I properly have an air leak..Have to look into it with a can of WD40 and a spanner
am i missing something,or is everyone else?? ;), :P
wouldn't you just not use the choke ???
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How am i going to start a cold engine without choke?? -_-
If something is not right. I will look into it an fix it. Even though it's a 30+ years old bike. It's still a motorbike and it should run like a bike
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You say 'i have been doing all this work' 'crank seals', was that done by the shop or by the owner. maybe the left crank seal has been misplaced or incorrectly fitted [which is unlikely & not easy to muck up--Soooo---, i'd guarantee the choke jet in the bowl is blocked therefor it just opens the air bleed--like opening the throttle a bit in effect.Jet's not easy to clean or even find for the unwary as is down a cavity that a long brass tube fits down. In the bottom of that hole is a minute jet. Get something about the size of wire brush wire or something straight & high tensile so it won't bend easy & give it a poke. then go the other way from the feed into below that jet using something bigger like a drill bit. With the wire, be sure it's gone through the jet to dislodge whatever's in there & maybe follow it up with a squirt of crc with nozzle right into the jet from the top--like down the cavity side. Sorry about the long winded essay but hope you get the idea. [hope i'm right too lol]. ps, doesn't take much to block that jet so unlikely to be related to the mechanics work but i now see you say the bike turned itself off & had to push it home--so maybe another problem or [has left crank seal come out--still very unlikely].
Thanks Mate, It was good. I'll give this a try. is it the little jet beside to the main jet??
Hi, 'no'--the little jet is the pilot jet [well think that's what you mean] no, the choke jet is 'not' removable & is down the bottom of a hole [thinking--] on the forward side of the bowl-inside the bowl. Have look inside the carb with the bowl off & you'll see a small tube extending down. Follow where that goes when you put the bowl on & it's down a the bottom of that hole. Good luck--mind you if that's not blocked then i'm out of ideas tonight.
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You say 'i have been doing all this work' 'crank seals', was that done by the shop or by the owner. maybe the left crank seal has been misplaced or incorrectly fitted [which is unlikely & not easy to muck up--Soooo---, i'd guarantee the choke jet in the bowl is blocked therefor it just opens the air bleed--like opening the throttle a bit in effect.Jet's not easy to clean or even find for the unwary as is down a cavity that a long brass tube fits down. In the bottom of that hole is a minute jet. Get something about the size of wire brush wire or something straight & high tensile so it won't bend easy & give it a poke. then go the other way from the feed into below that jet using something bigger like a drill bit. With the wire, be sure it's gone through the jet to dislodge whatever's in there & maybe follow it up with a squirt of crc with nozzle right into the jet from the top--like down the cavity side. Sorry about the long winded essay but hope you get the idea. [hope i'm right too lol]. ps, doesn't take much to block that jet so unlikely to be related to the mechanics work but i now see you say the bike turned itself off & had to push it home--so maybe another problem or [has left crank seal come out--still very unlikely].
Thanks Mate, It was good. I'll give this a try. is it the little jet beside to the main jet??
Hi, 'no'--the little jet is the pilot jet [well think that's what you mean] no, the choke jet is 'not' removable & is down the bottom of a hole [thinking--] on the forward side of the bowl-inside the bowl. Have look inside the carb with the bowl off & you'll see a small tube extending down. Follow where that goes when you put the bowl on & it's down a the bottom of that hole. Good luck--mind you if that's not blocked then i'm out of ideas tonight.
Yep, I know where it is now. I find it straight away (got the carby next to the computer with me :P )