Trying to fix an issue
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@Stevie-Wonder same here, carbs used to frighten the life out of me, when I finally got the courage to open one up I realised they're really quite simple.
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Just found out that the emulsion tube sits under the main jet and comes out when you remove the retaining pin for the floats so I’m also gonna take that out make sure it’s not all gammy
@markus-w couldn't have said it better
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In the manual it says when measuring the float height “note that a fuel level is also given” what’s this mean? And what’s it for?
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Update:
Valve needle is clean and rubber conical tip is in place and perfect. Spring isn’t seized either
Spook, I also checked the O ring you was on about and it’s perfect
I also went to knock the emulsion tube out that’s under the main jet but I only have a hardened steel punches to use to tap it out which would make Swiss cheese of that brass. I also was also thinking I’d struggle to get it back in
The only thing I haven’t done is check the float height because being honest I’ve read the manual times but can’t make sense of how you do it
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@Stevie-Wonder just watch a YouTube video.
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@Stevie-Wonder said in Trying to fix an issue:
Update:
Valve needle is clean and rubber conical tip is in place and perfect. Spring isn’t seized either
Spook, I also checked the O ring you was on about and it’s perfect
I also went to knock the emulsion tube out that’s under the main jet but I only have a hardened steel punches to use to tap it out which would make Swiss cheese of that brass. I also was also thinking I’d struggle to get it back in
The only thing I haven’t done is check the float height because being honest I’ve read the manual times but can’t make sense of how you do it
The emulsion tube is an interferance fit in the carb body and is usually a bit tight to tap out, it's OK as long as you're gentle with it. If you have a main jet you don't need you can screw that back in without the brass washer and hit that instead to protect the tube. Also soak it in PlusGas etc overnight as it probably hasn't moved in a while and there might be some corrosion around it where it fits to the carb body (that space accumulates moisture which often results in rough mid-range running).
Float height is 15.5-16.5mm and is measured by placing a steel rule on the float bowl gasket face; the upper edge of the floats should be around 16mm from here. To do this accurately carefully tilt the carb from fully horizontal until the float just seats on the float vale spring.
It's well worth spending some time on this, I bought a completely stock '98 last year which ran atrociously, blubbering at part throttle then cutting out with the throttle fully open; turns out the previous owner had stuck a 270 main jet in it, realised it was running rich and set the float height too low to compensate! Can't tell you how pleased I was when I put it back to stock settings and it just behaved itself.
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Once you’ve removed the emulsion tube once, it’s a lot easier after. Mine had the outer caked in solidified ultra fine ‘sand’ the first time o removed it. I just tapped a sacrificial jet to loosen it...
You can use the overflow pipe/tube to measure the height of the petrol in the bowl. You just bend the pipe back upwards and keep it in place, open the drain screw on the bowl bottom and see where the fuel level stops. It should be pretty much inline with the bottom of the carb body...
PS carb has to be upright!...
The proper explanation and measurements are in the Haynes
if you can find them!!... -
Learned how to measure float height, it’s ridiculously simple.
Thanks for the help with that one.Good news as well, It turns out the float height is in spec too!
Ive found getting the whole air box out a bit of pain and don’t seem to be getting out as easily as mentioned.
Ive undone everything, took all the battery compartment etc out and see the coolant overflow feeds through part of the air box frame.I stopped here and scratched my head because by this point I was questioning if all the extra work is more hassle then how I was fitting the carb originally.
I also learned the DTR air filters can be slid in and out in place on their cage to be replaced very quickly.
You’ll laugh but you don’t know the amount of times I’ve put a new filter in not knowing that. Looking back makes me wonder how I did it
️I had also noticed as well when taking the filter out 2 things.
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Where there should’ve been foam, there wasn’t…
This must’ve perished years ago as by the looks of things someone’s seal-all’d or superglued some standard 5-6mm soft foam (like what you’ve have in a mousepad) to create a tight fit again and then cut out a square in the middle the same size as the air filter cage. -
The air filter was absolutely filthy, so much so that there’s an impression of the air duct on the filter that’s just thick with dirt and whatever else. I turned the filter inside out and give a blow through the part where the dirt was and there’s enough dirt there to act as a blockage/reduce flow so I believe that’s the cause of the bike not revving out + also how dirt is getting it’s way into my bike
From now on I’m taking @HOTSHOT-III advice and getting a few new air filters so that I can wash and replace them easily.
I’m also gonna get into a habit of checking my air filter after every blast I take off road. I’m often in fields or green lanes but to tell you the truth never bothered doing it, I never filters could get blocked up that bad.I’ll post pics soon but for whatever reason the imgur app crashes as soon as you open it so I can’t upload anything
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@Stevie-Wonder Glad you're moving forward with this, and yes the filter element always gets dirty just underneath the intake like that.
Forgot to mention I normally have to remove the shock to get the airbox out but if you've got this far it's not that difficult and a good time to give the top shock mount bolt a wallow in copper grease to ensure it will never seize, plus maybe an All Balls lower shock bearing whilst it's out as these always wear out faster than the rear suspension bearings which can be greased externally.
And perhaps add a grease nipple to the relay arm bearing if it doesn't already have one. The relay arm bolt always seizes so check out my M6 studding hack to get this out without surgery:
https://www.facebook.com/groups/244290520959009/permalink/244410394280355/
And speaking of surgery, that's what I've been up to for the past 6 months; probably why I forgot to tell you to remove the airbox...
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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...
