Other 07 TTR 125L won't run/idle without choke

H

Heath

I have an 07 TTR 125L I bought from a friend for my wife. The bike had not been rode for a while. Bike originally would kick start fine within 1 or 2 kicks, idle like a champ, but any throttle would kill it immediately. Took the carb apart, was extremely gunked up and choke line was stuck inside the carb (stuck choke out). Bought a new carb and replaced the old one. Now the bike won't start or idle unless the choke is fully pulled. Changed air filter, and spark plug. Carb is seated in intake/exhaust ports with no leaks or suction issues. Bought a jet kit and put in 110 main and 22 pilot jet. Needle is set 2nd slot from pointed/bottom end. Found new carb didn't have a spring on the coasting enricher so put old carb spring in there. Throttle cable has been checked and is functioning properly. I'm new to dirt bike maintenance but everything I've read it'd seem to be the pilot jet not giving enough fuel. Stock pilot is 17.5 so the 22 jet i have in should be plenty. With the choke fully pulled it'll kickstart first kick and idle fine. Soon as I push the choke in even just a little bit it starts to die. I've messed with the fuel mixture screw, no change. I've adjusted to high idle and pushing the choke in still causes it to wanna die immediately. I left the choke fully pulled and rode around a bit. Bottom end is sluggish, requires high rpms. Top end is decent, a little sputtering/backfiring in 5th gear with throttle wide open. I'm at a complete loss as to what the problem is any input would be much appreciated. Would it be okay to just leave the choke pulled and ride it around like that if that's what it comes down to?

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Trfsrfr

Trfsrfr

I've had a couple of them now and have never had any luck with them. They are not built to very tight tolerances and you never really know what you're getting. Their QC sucks, and that jet thats supposed to be .050 just might be .060. Not having a spring on the coasting enrichener is a good example of this.
If it were mine, I would do everything I could to try and utilize the OE carburetor. If that isn't possible and the chinese carb must be used, I would spend some time tuning and paying particular attention to the spark plug as it's probably gonna be your best indicator as to what that carb is doing.
Maybe some of the other guys here have had better luck than I have and can offer some better advice, but I would run the OE if I could. In fact, I would buy a used OE carb off eBay before I would run a new chinese carb.
 
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Trfsrfr

Trfsrfr

I did some digging.
It seems there are many people who have issues with the stock carb, and some have successfully used another carb off a different make/model;
https://thumpertalk.com/forums/topic/457877-stuck-choke-cable-ttr125/
https://thumpertalk.com/forums/topic/191437-well-i-fixed-my-sticking-choke-lever-today/
https://thumpertalk.com/forums/topic/913427-best-replacement-carburator-for-ttr125/
And some more possibly helpful info;
http://www.socalxrs.com/Tech/Yamaha TT-R125x Visual Jetting and Airbox Modifications Guide.pdf

Heath:
With the choke fully pulled it'll kickstart first kick and idle fine. Soon as I push the choke in even just a little bit it starts to die.
Click to expand...
It looks like your choke adds fuel. So when you push the choke in you're removing fuel.
What does the plug look/smell like? From what you're describing it should be dry.
I would also get a look at that float height like @PALMER84ONE suggested. It could be set too low which would give a lean condition.
 
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H

Heath

Tinkered around with it some more today. Pulled fuel tank off and cleaned the petcock. Blew all the gunk off the screens (not incredibly dirty). Drained the fuel tank and blew compressed air throughout. Fuel is running through the lines just fine. Took carb off and checked everything. Blew air through pilot with jet in and out. Air seemed to be moving through ok. My service manual only has the measurements for checking the fuel level instead of measuring float height. I attempted to measure the fuel level with the tools i had. Fuel level was about flush with the height of the bowl. I adjusted the float to be a little richer anyway. Put pilot air screw in tight too just to try and make it richer there as well. Put everything back together. Kicked it with no choke and after a few kicks it maintained a very slow/weak idle for maybe 10 seconds and died. Adjusted idle screw to increase idle speed and tried again. Wouldn't start unless choke was pulled. Messed around with trying to get it to idle without choke by adjusting idle and pilot screw, still no luck. Sprayed some seafoam around rubber boots on both sides of carb and airbox. No leaking or sucking there. After all that pulled the plug and it was dry, some white discoloration on the tip.

Last idea I have is adjusting float height to be about as rich as it can possibly get. Just to rule out the float as being the issue. Like someone brought up the new carb i bought for it was a cheapo from Amazon (Wilk was the name of carb). Maybe it's just garbage and it doesn't matter what size pilot jet I put in it's just never gonna allow enough fuel into the mix to idle without the choke. It's for the wife to ride and we haven't even gone riding yet. So idk if she'll even enjoy riding and the bike will get rode often or if she won't like it and it'll just end up sitting in the garage most of the time. So I'd rather not put a whole lot of money into it. Would it be okay to ride if i just lock the choke to full out or do i risk doing serious damage to the bike? I wouldn't think so but I'm new to all this. If someone thinks a quality replacement carb will get it runnin right I'll give it a shot. Does it have to be the same exact carb or do they have different aftermarket carbs i could try out? From what i saw online there's all kinds of carbs but in essence they're just replica styles of the stock carb.

Thanks again for all the input.

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H

Heath

Trfsrfr:
I did some digging.
It seems there are many people who have issues with the stock carb, and some have successfully used another carb off a different make/model;
https://thumpertalk.com/forums/topic/457877-stuck-choke-cable-ttr125/
https://thumpertalk.com/forums/topic/191437-well-i-fixed-my-sticking-choke-lever-today/
https://thumpertalk.com/forums/topic/913427-best-replacement-carburator-for-ttr125/
And some more possibly helpful info;
http://www.socalxrs.com/Tech/Yamaha TT-R125x Visual Jetting and Airbox Modifications Guide.pdf


It looks like your choke adds fuel. So when you push the choke in you're removing fuel.
What does the plug look/smell like? From what you're describing it should be dry.
I would also get a look at that float height like @PALMER84ONE suggested. It could be set too low which would give a lean condition.
Click to expand...
Doh! I read the linked threads u gave after i typed up my new response. I can afford to try one of the other carbs suggested and will probably do that. I've read forum after forum and feel I've tried everything there is and the issue is exactly the same so rippin the carb completely out and putting a larger one in sounds like the best option to me.

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H

Heath

Trfsrfr:
It's a Yamaha, so it's worth something, and gives you options.

I found a 2007 ttr125 carb with a manual choke for $30 + shipping. Not sure if its junk like they say, but it's super simple and certainly better than a chinese copy;
https://www.ebay.com/itm/2007-Yamah...ash=item1c968b8e96:g:FcoAAOSwl-FXMzJW&vxp=mtr
Click to expand...
Did some more reading and just ordered a Mikuni VM24. Those are supposed to be great and fix all the issues I've been having. It ran me 110 bucks but it should be a genuine, not a clone which people had issues with when it came to quality and jet threading. If it gets it runnin right I'll be happy. I'll post an update when I get it installed.

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SRAD97750

SRAD97750

Moderator
Staff member
Idle screw should bump the slide about the height of a dime from closed.
FUEL screw should be at 2 turns from lightly seated.
Being that it runs on the choke proves, without a doubt, the pilot circuit is incorrect. It could be internally blocked, but that is extremely unlikely.
I have never once been disappointed by a Chinese carburetor. Never. Put north of 10 on different small displacement quads and bikes.
I do have a bucket of OEM Japanese carburetors that I would melt down if aluminum scrap was worth more.
-BIG DAN:thumb:
 
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