Trying to fix an issue
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I never take it right the way out! Just force it back a half inch or so to give enough room to work. I jam a half inch drive extension bar in between the frame and the front of the airbox...
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@SpookDog I've never needed to move the airbox simply to get the carb in or out.
I mentioned removing the airbox completely (which requires removal of the rear shock) in order to make a proper job of sealing the carb-to-airbox rubber where it joins the airbox. As with any task where you have to clean something thoroughly before gluing it to seal it, it's best to remove it from the bike completely to give yourself room to work. This also allows you to stand the airbox on the workbench in such a way as for the glued joint to sit horizontally so the glue can set where you want it to rather than running off all over the place.
If you don't seal this joint with petrol-resistant glue (as Yamaha did during manufacture, albeit not very well) your engine will suck dirt as it is downstream of the air filter, I mentioned this in another thread:
https://dt125r.co.uk/topic/2917/refitting-carb-hacks/2?_=1656365602155
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@HOTSHOT-III
Sorry bud, was actually replying to stevie
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Fuel tap rebuilt + new fuel tap installed. We’ve definitely fixed that problem.
Air boot / box has been cleaned and seal-all’d and a brand new air filter installled
Put it all back together and fuel pisses out the overflow and leaks from the float bowl (i can only assume that’s my doing and I’d just forgotten to tighten up the screws adequately). Bike also won’t Rev out past 5k (rough guess as I don’t have a working Rev gauge)
Float heights been checked and it’s all in spec + float needle in perfect working order
So now what? I’m gonna get the carb back out again when I have a moment and have it fully rebuilt
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@Stevie-Wonder when the carb is next out, put your lips on the fuel inlet and blow, tilt the carb upside down and continue blowing. Confirm that the float needle shuts off the fuel.
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Also remove the brass cup that the needle valve sits in and check the o-ring condition. Make sure the neoprene rubber tip of the needle is in good shape and secure to the needle ‘body’. Also make sure the spring loaded dowel pin is moving freely...
It’s best checked with the carb off and blowing down the fuel pipe while manually closing the needle valve like Calum suggested. If it closes tight but still leaks out the bottom outlet pipe check the bowl drainage screw/stop-pin is in good order and closing without leakage...
Good luck bud. You’ll get there
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@Calum said in Trying to fix an issue:
@Stevie-Wonder when the carb is next out, put your lips on the fuel inlet and blow, tilt the carb upside down and continue blowing. Confirm that the float needle shuts off the fuel.
I’ll be doing this in 5 minutes now I’ve found some time. Must admit thought I’ve swallowed a pill and I’m giving my carb to Jim Bailey.
The pilot’s jet’s head is fucked as my precision screwdriver turned out to be between not precise enough.
The air screw has not been adjusted for as long as I’ve had the bike, I’ve just not needed too. Thanks to this and our british weather I’m pretty sure it’s seized.Long story short I’m taking the L. I still have to use the bike to get about and it’s not until I get my car/big bike license I don’t then have to rely on the bike. Which means every time I’m back at square one chasing mechanical dragons again I lose money and time I don’t necessarily have ultimately putting me further away from getting those licenses.
To be fair though, I’m not an engineer, I don’t have a ultra sonic cleaner so I think either way I’d still have needed to give it to someone else.
Thanks a lot though boys, safe to say I don’t roll my eyes at the thought of carbs anymore because of you lot
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I’ll reopen this thread again if ever the issue reoccurs and I can’t solve it, there’s a lot of useful info here.
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When my pilot jet got chewed up I used a small ‘sharp’ cross head screwdriver, I used a small hammer and tapped it into the jet using one edge of the cross to line up with the original slot. A few light but sharp taps worked a treat!...
Also a good soak of WD40 and later a water bath in a suitable bowl with a kettle of boiling water usually loosens up stubborn threads without damaging any o~rings, ect...Let us know what the man says the problem was!...
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The message I got from Jim prior to my carb being posted back to me
“Morning mate,
I got your carb sorted 1st job today
Your fuel leaking was the float valve quite worn so fitted a new Japanese one for you.
I managed to get the air screw out ok, first one this year they're usually well seized.
Had to drill the pilot jet out though, I fitted a decent used one in there now.
Your power jet was partially blocked, tiny black deposits came out of there so maybe from a rotted bit of hose at some point in its history,
And your emulsion tube was a bit grubby so cleaned that for you, I took a picture of that”My reply:
“ Wicked mate beyond happy, I’ve not had a spare jet to knock out the emulsion tube so even in the past when it’s been ultra sonic cleaned that’s remained in situ.The air screw I had suspicions that you’d be okay with, I’d messed about with it before but since my bikes been jetted perfect since the day I’ve got it I’ve had no reason to play with it. Anytime I’d loosened it off it’d come out it was just a bit of a tosser.
As for the float valve, do mean the little bit with the rubber tip? Because I’d had it out before checked the spring on it and rubber and all seemed okay (not that I’m arguing or saying you’re a lier, I’m just eager to hear what I missed so I can learn from my mistakes
)Sorry about the pilot jet too, if you could recommend a good screwdriver for pilot jets to avoid that rookie error I’d greatly appreciate it man
Also happy about the price, I thought it’d be more
, one last thing as well did you put in new gaskets etc?”
(Price was £70)Jim’s reply:
“ Hiya mate,
I use a mains tester screwdriver with the plastic sleeve cut off for the pilot jet it seems to fit perfectly.
The rubber on the float valve was quite worn you can see a line around it that's quite deep, I have changed that and the brass seat that it sits in.
Your carbs sat now below my Lc tank with petrol going into it so will leave all day to be sure.
I use royal mail
No gaskets needed but did replace the power jet pipe as that was a bit stiff.”Long story short apparently my float valve was the problem. Admittedly I feel like a bit of a tool for not just replacing it for the sake of it to rule that issue out but we live and we learn.
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£70 sounds like a fair price, especially if parts have been replaced with Japanese. I’ve seen the ‘cheap’ fleabay valves and the build quality is ‘not good’...
It would of been causing running problems for sure. Interesting about the power valve, never thought of clearing it through...
If the screwdriver isn’t the exact, tight fit, to the jet slots width (also diameter of jet helps!), it just lets the end-edges of the screwdriver bite into and ‘shiver off’ bits of brass. I’ll try and find the exact size flathead size...
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@Stevie-Wonder good price that, myself and a few others advised you of the float valve a while back. And yes he's right about the screwdriver, that's what I use just have to cut the red plastic sleeve off with a Stanley knife. There's a special pilot jet screwdriver available but it's £30.
https://www.ebay.co.uk/itm/374176786046?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=4ytB3dNFSrS&sssrc=2349624&ssuid=7ztfcrwyt6w&var=&widget_ver=artemis&media=COPY -
Draper do a flathead screwdriver that is perfect. The markings on it are: DRAPER 75mm x 5mm
PAT 24584The tip is 5mm wide X 1mm thick. It is also the ‘go to guy’ for airscrew as well as bowl drainage
Yep! The electrical screwdriver is a proper fit. There are three main sizes, I don’t know which of the three it is. Middle or biggest. Probably middle...
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£70 for new jap valve, air screw to free’d up and the pilot jet drilled out with a replacement jet. Definitely not to shabby.
@markus-w i know mate, I know.
I could’ve swapped it out after inspecting it just to rule it out the question but I didn’t. It’s a lesson learnt.
Not feeling to hard about it though as either way I’d have had to give someone my carb to drill the pilot jet outAlso the pair of you are angels. I’ll be buying one of those immediately to avoid this happening again
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Good news!
No fuel leaks, bike feels a bit more powerful too however I fear that she still won’t Rev out and through band.
I rode the bike last night after letting it warm up whilst I worked on the fazer and she revved out further then before
but felt hesitant. Not the sort of little hesitation an oil injected two stroke has when going through the band the first or second time either.Last time I had this problem the powervalve was the issue (plastic pulley was on the incorrect angle of the diamond, causing the pulley to look like it’s correct whilst making your valve offset and out of alignment with your exhaust port…)
To deal with this I’m bring a 5mm Allen key so I can loosen the bolts and spin the pulley cover to check the valve is fully rotating. I’ll also disconnect the powervalve and set it as ”pinned” so we no if the problem ensues it rules anything powervalve related.
So on this grim cloudy yet still warm Sunday, I’m gonna get Stella the DT out and brush off the cobwebs.
Given the air box etc has been cleaned with new filter and mesh it’s fair to say we can rule anything to do with that being a problem.
The carbs just been sorted out, idle screw is now responsive again and an air screw that moves freely.
could the air screw being in the wrong position cause this?Whilst the carb was out I took the Liberty of removing the Reed cage to inspect the reeds etc, they’re all spotless and OEM. I couldn’t see anything wrong with them.
My pipes getting a little bit rusty at the neck but still has no holes in it so I can rule that out
So I guess all that leaves us with is electrics? Which funnily enough all work
Fingers crossed that when I take her out she’s a happy girl and I get to enjoy the feeling of going through powerband.
Let’s just say it’s been a while since I last had my fix. -
@Stevie-Wonder Glad your carb rebuild went well.
If you want to pin your PV for test purposes, cut down the shank end of an old 4mm drill bit to about 35mm; this obviously locks the pulley in the open position but can't go anywhere when you put the pulley cover back on.
I keep one of these with the tools I carry on the bike as "get you home" in the event of a PV cable breaking. Just remind yourself to remove it before reconnecting the cables/servo as I think the servo would be powerful enough to wreck its own internal gear train if you switched on the ignition with the PV locked in place like this.
Also have you ever replaced the HT lead? I had a high rpm misfire on my 1990 and it turned out to be this; took about an hour to change so the bike wasn't at operating temperature by the time I put it back together and tested it, but it was STILL noticeably faster/more responsive than before I changed it (I nearly flipped it pulling out of my driveway
).On the stock coil you can cut off the very top of the plastic case (i.e above where the actual lead fits into it), get the old lead out (it's glued in), then clean up the output and solder on the new lead for a really good connection.
Looks a bit messy as you have to tape it up afterwards and seal with silicone but in practice, usually a better option than a LBS replacement coil as these often have the wrong primary and secondary resistances for specific bikes (and BTW it's also worth measuring these).
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@HOTSHOT-III
Good idea that bud, I think I used a twig once when I was riding in a ForrestNot sure if you knew this though but one of the ignition cycles when you turn on/off the bike leave the PV in the open position instead of closed, once it’s like this all you’ve got to do is unplug the servo via the 4-pin plug by your radiator and you're set
As for the HT lead, nah I haven’t. I have been looking for an excuse to buy a nice new red “race” ngk one for a while though….
What’s on there is an old NGK one or OEM original to the bike
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The power valve is open at default any was. It’s only when you start the bike that it ‘closes’...
You could pull the plug before starting the engine...You do have the power valve set at open/flush when the engine is off don’t you?...
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@SpookDog said in Trying to fix an issue:
The power valve is open at default any was. It’s only when you start the bike that it ‘closes’...
You could pull the plug before starting the engine...You do have the power valve set at open/flush when the engine is off don’t you?...
Yep, admittedly I haven’t checked but I doubt it’s just magically jumped out of place since I last set it
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How long have you been having this problem? Hasn’t been since you last set up the power valve has it
