Rough running low down and high idle when warm - Page 2

FrankenDesmo · 12-03-2020, 09:40 PM

Nope, had to google it!

I'll chalk it up to motoring cultural differences between here and the colonies

FrankenDesmo · 13-03-2020, 10:43 PM

Minor progress - front cyl carb is mostly stripped bar the butterfly (not quite sure how to tackle that yet) and the idle screw (only screws out to a point). Emulsion tube appears to be round (as opposed to oval) which is almost disappointing. Haven't seen any obvious sign of blockage or residue anywhere yet. Still, I do have another whole carb to strip, and that's the one that appears to be running lean (although the front cyl seemed to be the one doing all the hesitating, if exhaust pulses from the can were anything to go by).

I think I am going to go with buying an ultrasonic cleaner rather than sending them off, seems like it'll be fairly cost effective given I've got at least 3 other carbs to do for another bike.

Can't seem to find any markings on the main jet so far (assuming the push-in jet is the main and the screw is just a retainer, although it looks like a jet too), and have pulled out 3 other tiny jets. Absolutely no idea what they are for, nor the small spring-loaded diaphragm on the side under the plastic cover.

Off on holiday on Sunday so wont be making much more progress, but I'll come back ready to tackle the clean & rebuild as well as checking the valve adjustments.

utopia · 13-03-2020, 11:00 PM

Don't take this as a definite but, from my fairly recent work on the carb from my honda dominator, which is a similar diaphragm carb, I think the small, spring-loaded diaphragm on the side is a "coast enrichener", whose purpose is to reduce any tendency to pop and bang on the overrun.

And while I'm posting .. are you aware of Allen's Performance as a source of carburettor spares ?
I've had decent service from them, as have other forum members.
They seem to keep a good stock of jets and other carb consumables.

FrankenDesmo · 13-03-2020, 11:06 PM

Aye, I have seen reference to them, but thanks for the reminder. Unsure if anything needs to be replaced as yet, but I'll see when I get the other carb open, and work out what jets I've got vs what I probably need to baseline it.

FrankenDesmo · 15-03-2020, 07:45 PM

Bah.

Stripping down the other carb tonight (French ski resorts all closed so no going away for me), and I got to the point of getting this wee jet out of the top, had the screwdriver set in there nice and square, taking care and all, and as soon as I turn it CRACK

I'm guessing I'll need to get this to a specialist of some kind for extraction, or will any old engineering shop do? Also can anyone tell me the name of that jet...

the lodger · 15-03-2020, 07:49 PM

Try forcing in an allen key and using that to undo it

FrankenDesmo · 15-03-2020, 08:00 PM

1.5mm fits in but can't seem to force it to get any purchase. 2mm is too big. Cheers for the suggestion though, and I'll take any others!

Mr Gazza · 15-03-2020, 08:47 PM

That's unlucky! and a very bad start.
It's exactly why I would always try everything in the book before doing a carb strip as it nearly always opens an unknown can of worms, but hey ho, you had no choice really.

I would try an easi-out on that sometimes called a stud extractor. You might have to drill the hole out a bit bigger perhaps to get one in, but they do go down to some very small sizes.
Get the carb body held carefully in a vice or get some thick gloves and then pour boiling water on the body when you're ready to apply the easi-out. You could also soak the body in penetrating fluid while the tools are coming in the post or whatever.

Good luck, you will start to move forwards with this soon I hope.

FrankenDesmo · 15-03-2020, 09:40 PM

The other carb come apart fine, but this one decided to be problematic - and it's for the top cylinder, which was running lean, so that's probably a sign...

Unfortunately I'm not really kitted up for drilling something out - no drill, no vice (yet). Easi-outs can cause their own problems, too, though I don't see any other option here. I think I'll probably get a pro to look at this.

Thing is, I don't even think I needed to remove that as it is an air jet and unlucky to be replaced - and I'm having a very hard time trying to find it online, definitely doesn't seem to be a part that anyone ever removes. Too overzealous with the disassembly!

In saying that, it's only the slot for the screwdriver that is damaged, so I could just leave it. Of course, I can guarantee it'll cause problems if I do that. Do it properly. Just gotta track down a replacement somehow. I know it's called an air jet/nozzle (based off a parts diagram I managed to find in German which listed it as "Luftdüse"), but when I search all I can find is reference to the air jet in the intake bell mouth.

Luddite · 15-03-2020, 10:19 PM

Is this any help? It's for a Yamaha TDM850 but I think the carbs are Mikuni BDST the same as yours.

https://www.partzilla.com/catalog/ya...50d/carburetor

FrankenDesmo · 15-03-2020, 10:25 PM

Yes, perfect - I totally forgot about the TDM having the same carbs.

Looks like it is part #32 - pilot air jet. That's getting me somewhere! Thank you Luddite!

FrankenDesmo · 16-03-2020, 07:17 PM

Bugger - the yamaha jet appears to be a #1.4, and the jet that I successfully pulled out of the horizontal cyl carb appears to be a #1.3 - which is proving impossible to find online in the UK. I've emailed Allens and Factory Pro to see if they can supply them (if Factory Pro can I'll probably get his Config 30 jet kit and needle jets - maybe the long-boy idle mixture screws too).

Edit: Naturally as soon as I post this I stumble into the actual shop part of the Allens website, and find it listed as a BS30/97 jet

the lodger · 16-03-2020, 07:32 PM

If your carb is a Mikuni, give Steve Doran at Motocarb a call. If he doesn't have what you need he might be able to suggest an alternative. He can also remove that jet if you can't

http://www.motocarb.com/

the lodger · 16-03-2020, 07:40 PM

Perhaps I should have said that you would need to file a spike on the end of the allen key that is just too big, then hammer it in. It will knacker the jet but then so will any easyout ( which never work for me )

FrankenDesmo · 16-03-2020, 07:46 PM

Quote:

Originally Posted by the lodger

If your carb is a Mikuni, give Steve Moran at Motocarb a call. If he doesn't have what you need he might be able to suggest an alternative. He can also remove that jet if you can't

http://www.motocarb.com/

Cheers, good to have another source on hand. Doesn't stock the 1.3 size according to the site, and the pricing is about the same as Allens so I'll put an order in with them.

Quote:

Originally Posted by the lodger

Perhaps I should have said that you would need to file a spike on the end of the allen key that is just too big, then hammer it in. It will knacker the jet but then so will any easyout ( which never work for me )

Ah yeah. I'd need to get myself a file (no problem), but also a vice I think - not quite there yet! Need a decent workbench to bolt it to first

I'm going to take the carb to a place round the corner from work - even if I did have the setup with ez-outs etc, I wouldn't trust myself not to cock it up and knacker the tube the jet sits in as well (or the thread at least).

If I get stuck I'll see if Motocarb can help out.

15-03-2020, 07:49 PM	#21
the lodger Registered User Join Date: Oct 2019 Location: Chorley Bike: M900 Posts: 160	Try forcing in an allen key and using that to undo it __________________ Contents may settle !

15-03-2020, 08:47 PM	#23
Mr Gazza Lord of the Rings Join Date: May 2013 Location: Norwich Bike: M900sie Posts: 5,963	That's unlucky! and a very bad start. It's exactly why I would always try everything in the book before doing a carb strip as it nearly always opens an unknown can of worms, but hey ho, you had no choice really. I would try an easi-out on that sometimes called a stud extractor. You might have to drill the hole out a bit bigger perhaps to get one in, but they do go down to some very small sizes. Get the carb body held carefully in a vice or get some thick gloves and then pour boiling water on the body when you're ready to apply the easi-out. You could also soak the body in penetrating fluid while the tools are coming in the post or whatever. Good luck, you will start to move forwards with this soon I hope. __________________

16-03-2020, 07:17 PM	#27
FrankenDesmo Member Join Date: Sep 2019 Location: Glasgow Bike: M900 Posts: 108	Bugger - the yamaha jet appears to be a #1.4, and the jet that I successfully pulled out of the horizontal cyl carb appears to be a #1.3 - which is proving impossible to find online in the UK. I've emailed Allens and Factory Pro to see if they can supply them (if Factory Pro can I'll probably get his Config 30 jet kit and needle jets - maybe the long-boy idle mixture screws too). Edit: Naturally as soon as I post this I stumble into the actual shop part of the Allens website, and find it listed as a BS30/97 jet Last edited by FrankenDesmo; 16-03-2020 at 07:29 PM..

16-03-2020, 07:32 PM	#28
the lodger Registered User Join Date: Oct 2019 Location: Chorley Bike: M900 Posts: 160	If your carb is a Mikuni, give Steve Doran at Motocarb a call. If he doesn't have what you need he might be able to suggest an alternative. He can also remove that jet if you can't http://www.motocarb.com/ __________________ Contents may settle ! Last edited by the lodger; 16-03-2020 at 08:56 PM..

16-03-2020, 07:40 PM	#29
the lodger Registered User Join Date: Oct 2019 Location: Chorley Bike: M900 Posts: 160	Perhaps I should have said that you would need to file a spike on the end of the allen key that is just too big, then hammer it in. It will knacker the jet but then so will any easyout ( which never work for me ) __________________ Contents may settle !

12-03-2020, 09:40 PM	#16
FrankenDesmo Member Join Date: Sep 2019 Location: Glasgow Bike: M900 Posts: 108	Nope, had to google it! I'll chalk it up to motoring cultural differences between here and the colonies

13-03-2020, 10:43 PM	#17
FrankenDesmo Member Join Date: Sep 2019 Location: Glasgow Bike: M900 Posts: 108	Minor progress - front cyl carb is mostly stripped bar the butterfly (not quite sure how to tackle that yet) and the idle screw (only screws out to a point). Emulsion tube appears to be round (as opposed to oval) which is almost disappointing. Haven't seen any obvious sign of blockage or residue anywhere yet. Still, I do have another whole carb to strip, and that's the one that appears to be running lean (although the front cyl seemed to be the one doing all the hesitating, if exhaust pulses from the can were anything to go by). I think I am going to go with buying an ultrasonic cleaner rather than sending them off, seems like it'll be fairly cost effective given I've got at least 3 other carbs to do for another bike. Can't seem to find any markings on the main jet so far (assuming the push-in jet is the main and the screw is just a retainer, although it looks like a jet too), and have pulled out 3 other tiny jets. Absolutely no idea what they are for, nor the small spring-loaded diaphragm on the side under the plastic cover. Off on holiday on Sunday so wont be making much more progress, but I'll come back ready to tackle the clean & rebuild as well as checking the valve adjustments.

13-03-2020, 11:00 PM	#18
utopia No turn left unstoned Join Date: Jun 2010 Location: leicester Bike: M750 Posts: 4,559	Don't take this as a definite but, from my fairly recent work on the carb from my honda dominator, which is a similar diaphragm carb, I think the small, spring-loaded diaphragm on the side is a "coast enrichener", whose purpose is to reduce any tendency to pop and bang on the overrun. And while I'm posting .. are you aware of Allen's Performance as a source of carburettor spares ? I've had decent service from them, as have other forum members. They seem to keep a good stock of jets and other carb consumables.

13-03-2020, 11:06 PM	#19
FrankenDesmo Member Join Date: Sep 2019 Location: Glasgow Bike: M900 Posts: 108	Aye, I have seen reference to them, but thanks for the reminder. Unsure if anything needs to be replaced as yet, but I'll see when I get the other carb open, and work out what jets I've got vs what I probably need to baseline it.

15-03-2020, 07:45 PM	#20
FrankenDesmo Member Join Date: Sep 2019 Location: Glasgow Bike: M900 Posts: 108	Bah. Stripping down the other carb tonight (French ski resorts all closed so no going away for me), and I got to the point of getting this wee jet out of the top, had the screwdriver set in there nice and square, taking care and all, and as soon as I turn it CRACK I'm guessing I'll need to get this to a specialist of some kind for extraction, or will any old engineering shop do? Also can anyone tell me the name of that jet...

15-03-2020, 08:00 PM	#22
FrankenDesmo Member Join Date: Sep 2019 Location: Glasgow Bike: M900 Posts: 108	1.5mm fits in but can't seem to force it to get any purchase. 2mm is too big. Cheers for the suggestion though, and I'll take any others!

15-03-2020, 09:40 PM	#24
FrankenDesmo Member Join Date: Sep 2019 Location: Glasgow Bike: M900 Posts: 108	The other carb come apart fine, but this one decided to be problematic - and it's for the top cylinder, which was running lean, so that's probably a sign... Unfortunately I'm not really kitted up for drilling something out - no drill, no vice (yet). Easi-outs can cause their own problems, too, though I don't see any other option here. I think I'll probably get a pro to look at this. Thing is, I don't even think I needed to remove that as it is an air jet and unlucky to be replaced - and I'm having a very hard time trying to find it online, definitely doesn't seem to be a part that anyone ever removes. Too overzealous with the disassembly! In saying that, it's only the slot for the screwdriver that is damaged, so I could just leave it. Of course, I can guarantee it'll cause problems if I do that. Do it properly. Just gotta track down a replacement somehow. I know it's called an air jet/nozzle (based off a parts diagram I managed to find in German which listed it as "Luftdüse"), but when I search all I can find is reference to the air jet in the intake bell mouth.

15-03-2020, 10:19 PM	#25
Luddite Registered User Join Date: Aug 2011 Location: Southampton Bike: M1100evo Posts: 2,465	Is this any help? It's for a Yamaha TDM850 but I think the carbs are Mikuni BDST the same as yours. https://www.partzilla.com/catalog/ya...50d/carburetor

15-03-2020, 10:25 PM	#26
FrankenDesmo Member Join Date: Sep 2019 Location: Glasgow Bike: M900 Posts: 108	Yes, perfect - I totally forgot about the TDM having the same carbs. Looks like it is part #32 - pilot air jet. That's getting me somewhere! Thank you Luddite!