Trying to fix an issue
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@Stevie-Wonder the air screw only affects the pilot circuit so not that. You screw it out to allow more air. Check the float needle seat that it's seating correctly and the rubber isn't perished or missing because that would cause fuel to leak out of the overflow. Notice the little rubber tip.
https://www.ebay.co.uk/itm/194220758338?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=dpDE_KyJTQ-&sssrc=2349624&ssuid=7ztfcrwyt6w&var=&widget_ver=artemis&media=COPY -
@Stevie-Wonder
Can only be the float needle valve. Probably the oring on the brass insert that the needle sits in. Unless you've fucked with the float hight?
SpookDog -
@biohazard13 That O-ring often gets overlooked, good shout
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C Calum moved this topic from General Discussion on
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Gonna take the carb off and apart this afternoon, thanks for the help.
Always put off working on carbs but I’m slowly learning and getting more comfortable working on them. Turns out they’re not as bad after all if you just get stuck in.
I’ve never checked or adjusted float heights before, so I’m just checking the Haynes manual now
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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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@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.
Always Originate, Never Pirate!
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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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