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help with TTR bogging down to stall

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Hello everyone,

I realize there is a lot of people who have problems with bogging on TTRS and I've read quite a few dozen of posts already but i still cant seem to figure it out. I bought the bike a while back for the GF but never really noted if it did it until i have been riding it recently.

Basically what is happening is when you blip the throttle from idle it bogs and if you hold it the bike will just die out, it only does it when you open up the throttle to about 1/2 way. Now i would presume there should be some bogging but the bike should pick up not just die correct?

The bike is a 2003 TTR 125 and what i have done so far is clean the carb like 6 times.. thinking about buying carb dip and trying it one last time. I also have replaced the pilot jet from a #15 to #17.5 which made the bike impossible to keep running. Now i have the stock pilot jet back in and I've been trying to adjust/check the float level also by which i'm using a clear gas line hooked on drain hole then opening petcock and holding line up to carb to see where fuel level is, kind of like how they are doing in the manual but is it so hard to then adjust the float tab and keep resembling everything to see float level again.

Any ideas or help would be greatly appreciated.

Thanks

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how many turns out is your fuel screw? have you adjusted the fuels screw and idle speed? what elevation are you at?

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darn sorry i left that out... I'm currently 1 1/2 turns out on fuel screw. and i have a tach. that i put on it so try to keep the rpms in between 1300-1600 like the manual says, but it always fluctuates anyway. and i have adjusted the fuel screw many times and what is weird to me is when i turn it in to like a 1/2 turn in the bog seems to be not as bad but then when dropping down to idle it kind of pops and hangs so it sounds like its running lean so i turn it back and if i go above 2 turns out it seems to bog even more. I also check the plug often to make sure im not running lean and the insulator is usually black but not a real wet oily looking. I also just checked the plug because i am messing with it now and the insulator is black but like half the electrode tip is white?? and im at about *360ft* above sea level.

Edited by Banger92

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Sounds like your main jet is too large.

Try to lean it out by raising the jet needle clip position up....

485562_583864938313648_1874691700_n.jpg

If this helps but you reach the top setting and it still is ''bogging'', go smaller on main jet 1-3 sizes.

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Sounds like your main jet is too large.

Try to lean it out by raising the jet needle clip position up....

If this helps but you reach the top setting and it still is ''bogging'', go smaller on main jet 1-3 sizes.

that's kind of what i was thinking. check your needle and raise it one position. what size main jet do you have in there? i have the same bike for my son, and we actually had to go up a size on the main jet at close to sea level. i'm interested to see what you have in there.

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hmm see i thought the bog was from it being lean but like i said i did notice a little black on the plug.. i figured if it was a rich bog it would still be able to pick its self up and not just fall on its face. But i will check to see what size main jet that is installed i just figured it was stock but who knows and i will also try raising the needle and see what that does. It is currently in the stock position(middle) and there is only three clip positions because i remember i checked that out when i had the carb. apart.

Thank you for responces

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OK so i raised the clip position on the needle to lean out the needle circuit and that did in fact help with the top end bog completely!

although l am still having a problem with the idle. it will idle fine then almost die out then pick back up? i tried messing with the fuel screw and it seems to idle best when it is only screwed out a half turn? that seems wild.. do i really need to go a smaller size on the pilot jet? most people say they run lean and they need to increase pilot size. What also amazes me is that if i turn the fuel screw all the way in the bike doesn't die? i'm not sure where to go from here, but thank you all for your help.

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anyone? i pulled plug out yesterday and the thing is now running lean.. so obviously leaning out needle was not a good idea. unless it has somthing to do with air filter not having enough oil?

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to be honest with you....this just sounds like a plugged passage way in your carb. have you taken it completely apart and cleaned out all the passages? sometimes, varnish and dirt can get in to passages, other than just your main and pilot jets. most people just take out the pilot and main and spray them out.

i thought i was having jetting issues with my son's ttr, when i just needed to do a more thorough cleaning job on the carb. there are a few passages in the carb that need cleaning. it's a pain, but worth the time.

these bikes are very simple, so the things you are trying should work. i'm really confused here....

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ok thank you very much for the response.. i am pretty stumped myself here also. I have cleaned the carb multiple times and taken apart every part but maybe i still am missing something? i will go and purchase that carb dip stuff and let her soak overnight to get any hidden passages. i will post a reply to how it goes.

 

thanks for help.

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If it was sitting for a while the petcock might've gone bad. On a ttr 125 that was stored outside for a year I has similar problems even after cleaning the carb. I don't know why but it runs fine if I have the petcock on res instead of on. This also happened on an old ttr 90 and crf50 if mine.

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hmm that is actually an interesting idea.. i will definitely check that out. i know for sure that the petcock is releasing fuel, but maybe not an adequate flow? i did install a fuel filter could that have something to do with it? i'm pretty sure it was still doing this before i installed the filter though..

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OK i completely dissembled the whole carburetor for like the tenth time and everything was pretty much spot clean.(i wonder why) i also  set the needle position back to stock and then reassembled. I also cleaned and re-oiled the air filter because i'm thinking i did not put enough oil on it the first time, I didn't think it would be that serious of a situation but i guess it really is.. I then adjusted the air screw to 1 1/2 turns out and started up the bike. it ran weird for a little then settled down. i proceeded to turn the air screw out more to 2 turns to get a more steady idle and i found it. The bike throttle response is also alot better now, but it does seem to still bog a little bit when opening the throttle from idle to wide open. Does anyone know the correct idle rpm for this bike? the manual i think says 1600 min? but what is the maximum? or does it not matter.

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i can't remember what it is.  you can go to the yamaha austrailia website and download a free manual.  free is good.

 

i think your bike is possessed.  these carbs are a pain, and require some time to really clean up.  i hate them.

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oh thats nice to know but i actually already have a manual and it says 1300-1500 idle rpm. but it kind of sounds a little low to me and the bike doesnt really want to idle that low nicely so does that mean i still dont have the a/f mixture dialed in? and yeah i think the bike is possessed!

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to be honest with you....this just sounds like a plugged passage way in your carb. have you taken it completely apart and cleaned out all the passages? sometimes, varnish and dirt can get in to passages, other than just your main and pilot jets. most people just take out the pilot and main and spray them out.

i thought i was having jetting issues with my son's ttr, when i just needed to do a more thorough cleaning job on the carb. there are a few passages in the carb that need cleaning. it's a pain, but worth the time.

these bikes are very simple, so the things you are trying should work. i'm really confused here....

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Whoops! Meant to ad a comment to the quote added above....damn nook and fat fingers! I would completely disassemble and soak for a few hours minimum. Then blow out all passages with carb spray and compressed air. Any speck of crap can cause big problems and lead you down the wrong path thinking it is something different. Any foreign object in a passage can move around with different vacuum loads under different throttle positions. Thus causing different fuel deliveries, and drive you crazy in return! My son's TTR 125 I just re jetted to 110/17.5 and did the airbox mod(removing snorkel and backfire screen only) and left the clip at stock position. Before I received the jets I soaked, replaced needle and seat and moved clip to 1st position(rich) and did air box mod. After jets installed I moved needle back to stock middle position. Mixture screw at 2 turns out. Running pretty decent. Hope this helps! Good luck!

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the carb passages are sealed with what look like tiny ball bearings, and due to the miniscule diameter of them they may be grimed up too hard to clean out. my bike sat for 3 years before i got it and i had to re-bore the tunnels (i have a proper machine press so i could do it). It will cost barely anything to get them drilled out, dont do it unless you have a good sturdy press or you could make the problem worse

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