In order for the engine to idle, it needs a certain amount of fuel and air. So yes, there should be a gap between the bottom of the chamber and the bottom of the slide if that’s what you mean. As for the hoses on each side of the carb, these are the overflow hoses. In the even of a crash or you drop your bike or something, they’re supposed to drain the fuel out of the bowl instead of let fuel into the cylinder and ‘flooding’ the engine. Well, the fuel inlet is also on the side, however that is below the two symmetrical overflow hoses. (The inlet is shown at 3:20 for reference)
What sound does the throttle make again? 😂 thanks for the explanation mate, very well done! I have got myself a ttr250 that was running but wasn't reving out (had no power). Do you think it's something to do with the diaphragm area of the carb? Ran fine at idle, but as soon as I used the throttle, just got bogged down, no power.
Hahaha yeah sound was a little bit unco there hey 😆 All good mate, cheers! This was actually made for a school assignment, so I never expected it to go further than that and actually help people! As for the problem your having, I think it would depend on when in the rpm the bike would start to bog... the diaphragm area of the carb, or accelerator pump, is used to help the bike build rev's quicker by squirting extra fuel into the intake when the throttle is twisted quickly. At least thats my understanding of it. I actually had a similar problem to what yours sounds like that happened to me literally just yesterday; I came came down from a wheelie and as soon as the front wheel came back down the bike sounded as if it was running out of fuel, however this wasn't the case as it still had 3/4 of a tank left. The bike would idle fine but any revs and it would bog exactly like if it was being starved of fuel. I actually have a video of how it was running and can post it if this is a help. however, after playing with the throttle and trying to give the bike a few short sharp blips, the bike returned to running normally and revving out again. I think what happened is a small piece of garbage got stuck in the main jet, blocking fuel from getting through. This explains why it wasn't revving out as the main jet provides fuel to the upper 3/4 of the rev range, while the pilot jet is used for idling. Giving the throttle a few short sharp blips would have tried to force fuel through the main jet (and the accelerator pump however I don't think this is enough fuel to keep the bike running by itself) and eventually doing this must have cleared the jet. I would say your main jet might be blocked, so I would be checking that first I think. keen to hear how you go.
@joel.newell thanks for taking the time to answer my question mate! I just got a carby rebuild kit in the mail, new gaskets, seals and some replacement jets. So will put that through the old carby and see if that fixes it. Thanks again 👍
I’ve been fiddling with this myself recently actually, the workshop manual states the pilot screw (assuming this is the air fuel mixture screw) should be 1-1/2 turns out. I think from memory I have mine set just under 2 turns out, as this is where the bike seems to be happiest running, although the difference I’ve found is barely noticeable.
I have to clean my carb once a year after winter it's a pain. Usually a plugged jet. The screw in the bottom of the bowl is steel and with all the ethanol in our fuel in Canada it tends to rust when it sits
Anytime mate! Ahhh that’s a pain hey. Yeah I’m gonna be honest I’m not confident on the science behind how different climates affect carby’s and the difference in fuels we have between Australia and Canada etc etc.. however I just had the thought, would this be something that a inline fuel filter could help prevent? Or does it block just because the fuel gums up over winter? Also maybe it could be possible to look at getting a stainless steel screw from a hardware store of sorts and modifying it to fit?? Might be an idea, might not be. just thinkin out loud. 😁
Hey man, ive just bought a brand new carb for my ttr 250 and i know the adjustment settings for the air fuel screw, ( 2 turns out ) but there is another screw on the back side of the carb that i dont know the correctly adjust. Is it possible you can send me some pointers?
Yeah sure! Just to clarify- do you mean the idle adjust screw? From memory this is the only other adjustment screw on the outside of the carb and is located next to the choke… I’ll have to double check on that though. Is the new carb you bought a genuine replacement or a aftermarket one?
@@joel.newell the new carb is a genuine yamaha ttr250 carb, i can even show the model number. But the screw im speaking of is on the backside of the carb and is almost in the center of the backside, but not quite.
Yeah no I have no doubt it’s a genuine one if you say so I was just curious. Unfortunately I have not yet had a chance to go and look at my bike for myself, but I am planning to tomorrow morning. I haven’t forgotten just haven’t had the time yet. However looking through the video to try and find where you mean in the mean time, I’m gonna be honest and say I’m still struggling to find where exactly you mean. When you say the backside of the carb, are you referring to the side that faces toward the kickstart side of the bike? Or the side where the air box bolts on? The larger of the two Philips head bolts on the kickstart side of the carb (closer to the middle and slightly toward the engine side (under thumb at 3:05 in vid)) I am pretty sure was done up tight and I didn’t bother trying to fiddle with it as I didn’t know it was a adjustment screw… I think. My memory is struggling haha I will go and have a look in the morning just figured I’d let you know I haven’t forgotten. :)
@@joel.newell WOW man your pretty cool! Yeah its that big fat philips screw thats on the kickstarter side. I removed the old carby and checked to see that it was all the way screwed in on that one, so i figured it prolly didnt need adjusted. So i installed the new carb, now i just gotta change the oil and fingers crossed 🤞 i hope she purrs. Thanks for the help man this last comment you wrote gives me a lil bit more confidence that its prolly fine and that the screw doesnt need adjusted. Cheers mate!
@@neilatchley3675 haha I try my best 😅 Yeah I meant to reply back again and completely forgot sorry! basically I went to undo that screw and it was done up really really tight so I didn’t wanna try anymore in fear I’d strip the thing or break it or something. Yeah sweet as I reckon she’ll be right. Ttr’s are pretty bullet proof and don’t take much to run. Haha all good mate! Happy to help! Let us know how it all goes haha I’m keen to hear about it!
Thank you for the video, good reference!
The diaphram thing is called an acceleration pump
Haha yes it is indeed! Thank you mate! Only learnt that after I posted the video lol
@@joel.newell any idea how many turns out the fuel air mix nob should be out ?
Just replied to your other comment :)
Should there be a gap in your slide or should it close all the way and what are the other hoses,one on each side of the carb
In order for the engine to idle, it needs a certain amount of fuel and air. So yes, there should be a gap between the bottom of the chamber and the bottom of the slide if that’s what you mean. As for the hoses on each side of the carb, these are the overflow hoses. In the even of a crash or you drop your bike or something, they’re supposed to drain the fuel out of the bowl instead of let fuel into the cylinder and ‘flooding’ the engine. Well, the fuel inlet is also on the side, however that is below the two symmetrical overflow hoses. (The inlet is shown at 3:20 for reference)
What sound does the throttle make again? 😂 thanks for the explanation mate, very well done! I have got myself a ttr250 that was running but wasn't reving out (had no power). Do you think it's something to do with the diaphragm area of the carb? Ran fine at idle, but as soon as I used the throttle, just got bogged down, no power.
Hahaha yeah sound was a little bit unco there hey 😆
All good mate, cheers! This was actually made for a school assignment, so I never expected it to go further than that and actually help people!
As for the problem your having, I think it would depend on when in the rpm the bike would start to bog... the diaphragm area of the carb, or accelerator pump, is used to help the bike build rev's quicker by squirting extra fuel into the intake when the throttle is twisted quickly. At least thats my understanding of it. I actually had a similar problem to what yours sounds like that happened to me literally just yesterday; I came came down from a wheelie and as soon as the front wheel came back down the bike sounded as if it was running out of fuel, however this wasn't the case as it still had 3/4 of a tank left. The bike would idle fine but any revs and it would bog exactly like if it was being starved of fuel. I actually have a video of how it was running and can post it if this is a help. however, after playing with the throttle and trying to give the bike a few short sharp blips, the bike returned to running normally and revving out again. I think what happened is a small piece of garbage got stuck in the main jet, blocking fuel from getting through. This explains why it wasn't revving out as the main jet provides fuel to the upper 3/4 of the rev range, while the pilot jet is used for idling. Giving the throttle a few short sharp blips would have tried to force fuel through the main jet (and the accelerator pump however I don't think this is enough fuel to keep the bike running by itself) and eventually doing this must have cleared the jet. I would say your main jet might be blocked, so I would be checking that first I think. keen to hear how you go.
@joel.newell thanks for taking the time to answer my question mate! I just got a carby rebuild kit in the mail, new gaskets, seals and some replacement jets. So will put that through the old carby and see if that fixes it. Thanks again 👍
Any idea where the air mixer is supposed to sit. Like how many turns out?
I’ve been fiddling with this myself recently actually, the workshop manual states the pilot screw (assuming this is the air fuel mixture screw) should be 1-1/2 turns out. I think from memory I have mine set just under 2 turns out, as this is where the bike seems to be happiest running, although the difference I’ve found is barely noticeable.
Good to know thanks Mr
I have to clean my carb once a year after winter it's a pain. Usually a plugged jet. The screw in the bottom of the bowl is steel and with all the ethanol in our fuel in Canada it tends to rust when it sits
Anytime mate! Ahhh that’s a pain hey. Yeah I’m gonna be honest I’m not confident on the science behind how different climates affect carby’s and the difference in fuels we have between Australia and Canada etc etc.. however I just had the thought, would this be something that a inline fuel filter could help prevent? Or does it block just because the fuel gums up over winter? Also maybe it could be possible to look at getting a stainless steel screw from a hardware store of sorts and modifying it to fit?? Might be an idea, might not be. just thinkin out loud. 😁
@joel.newell oh for sure it's the ethanol is the problem but I think a brass or stainless screw would help for sure too
Hey mate where are you located
South east Queensland
Hey man, ive just bought a brand new carb for my ttr 250 and i know the adjustment settings for the air fuel screw, ( 2 turns out ) but there is another screw on the back side of the carb that i dont know the correctly adjust. Is it possible you can send me some pointers?
Yeah sure! Just to clarify- do you mean the idle adjust screw? From memory this is the only other adjustment screw on the outside of the carb and is located next to the choke… I’ll have to double check on that though. Is the new carb you bought a genuine replacement or a aftermarket one?
@@joel.newell the new carb is a genuine yamaha ttr250 carb, i can even show the model number. But the screw im speaking of is on the backside of the carb and is almost in the center of the backside, but not quite.
Yeah no I have no doubt it’s a genuine one if you say so I was just curious.
Unfortunately I have not yet had a chance to go and look at my bike for myself, but I am planning to tomorrow morning. I haven’t forgotten just haven’t had the time yet.
However looking through the video to try and find where you mean in the mean time, I’m gonna be honest and say I’m still struggling to find where exactly you mean. When you say the backside of the carb, are you referring to the side that faces toward the kickstart side of the bike? Or the side where the air box bolts on?
The larger of the two Philips head bolts on the kickstart side of the carb (closer to the middle and slightly toward the engine side (under thumb at 3:05 in vid)) I am pretty sure was done up tight and I didn’t bother trying to fiddle with it as I didn’t know it was a adjustment screw… I think. My memory is struggling haha I will go and have a look in the morning just figured I’d let you know I haven’t forgotten. :)
@@joel.newell WOW man your pretty cool! Yeah its that big fat philips screw thats on the kickstarter side. I removed the old carby and checked to see that it was all the way screwed in on that one, so i figured it prolly didnt need adjusted. So i installed the new carb, now i just gotta change the oil and fingers crossed 🤞 i hope she purrs. Thanks for the help man this last comment you wrote gives me a lil bit more confidence that its prolly fine and that the screw doesnt need adjusted. Cheers mate!
@@neilatchley3675 haha I try my best 😅
Yeah I meant to reply back again and completely forgot sorry! basically I went to undo that screw and it was done up really really tight so I didn’t wanna try anymore in fear I’d strip the thing or break it or something. Yeah sweet as I reckon she’ll be right. Ttr’s are pretty bullet proof and don’t take much to run. Haha all good mate! Happy to help! Let us know how it all goes haha I’m keen to hear about it!