Carbs adjusted, can I get your thoughts please?

Macflurry · 06-07-2018, 10:11 PM

Hi guys,

Rebuilt a set of carbs for the first time a few weeks ago, managed to adjust them to what I thought looked and sounded good but as I had never done it before then my opinion isn't the most reliable!!

Had an issue where the bike got starved of fuel due to crap in the tank but it ran like a dog after more fuel was put through again.

So I've stripped the carbs again in case debris from the tank had got through, de-rusted the tank, replaced the fuel filter, put fresh fuel in and it still ran rough but better than before.

Spent yesterday evening trying to get it to sound right but no matter what I did it was still popping and sounding rough so I left it at 01:30 so I could go with fresh eyes today.

I put a sync tool on there today to see if that had gone out when I stripped them. I could hear a "coughing" noise when i had been adjusting the fuel which I thought had been from the mixture being out. But looking at the tool I could see and feel it was only on one side. Checked the plugs... one was fine the other had oil on it. Swapped them for a fresh set that i had to go on and instantly purred into life!! Simple things eh? Could have saved me hours of swearing and getting burnt trying to make adjustments last night!!

Anyway, it doesn't sound to bad as it is but I'd like an opinion from someone who has played with this a lot more than me... which is basically anyone. So before I starting dialling the screws back and going again from scratch, would you say this is fine where it is?

Sync tool plugged in and low revs:

https://youtu.be/LqJftfd6Crw

Sync tool plugged in and throughout the rev range.

https://youtu.be/wqR-yy5clz4

jerry · 08-07-2018, 10:02 AM

sounds fine to me air screws might crisp response up a bit if its lean or rich usually about 3.5 turns out is a good start point but its seems to sound good as it is

Jez900ie · 08-07-2018, 10:35 AM

It sounds quite good to my ear. Still if you watch you video closely, about 3/4 through the clock on the rightside in the clip shows different readings to the one on the left. First the needle trembles, then shows lower readings. Its not a big difference -t could even be the camera angle... I am certainly no mechanic!

Zimbo · 08-07-2018, 04:15 PM

Looks fairly good to me, I generally swap the hoses over between the two dials and re-test just to remove the possibility that the dials are reading differently as well!

Macflurry · 08-07-2018, 11:47 PM

Thanks guys. It's a nice bit of reassurance hearing it's not too bad. I was waiting for something obvious that I'd overlooked and not done.

This is my first bike since passing my test and as I took over someone elses project then I'm a bit paranoid that I missed something.

Took it out for the fist time tonight and it was great fun!! Thanks for the pointers, I'll definitely bear them in mind.

mick · 09-07-2018, 11:09 AM

Quote:

Originally Posted by Zimbo

Looks fairly good to me, I generally swap the hoses over between the two dials and re-test just to remove the possibility that the dials are reading differently as well!

Tip I saw the other day, use one gauge with a T piece in the hoses, then block one off at a time, haven't tried it but made sense.

Macflurry · 09-07-2018, 11:57 AM

Quote:

Originally Posted by mick

Tip I saw the other day, use one gauge with a T piece in the hoses, then block one off at a time, haven't tried it but made sense.

Ha, I actually ended up using t-pieces on this.

The gauges came with the brass pipes to fit that I read are supposed to stabilise the dials... which did nothing. So I added two little plastic t-pieces that had a thumb screw in the t and slowly adjusted them until they moved when you revv'd the bike but weren't going nuts any more and you could actually read them.

I read one guy saying that you just pinch the pipes to stabilise the readings but it's not really accurate if you pinch too hard at the wrong point plus you run out of hands to blip the throttle...

mick · 09-07-2018, 02:15 PM

The tip was to use one gauge connected to the inlets via a T piece, so that you know the gauge is the same for both inlets, just pinch one pipe at a time with pliers or mole grips.

06-07-2018, 10:11 PM	#1
Macflurry Registered User Join Date: Mar 2018 Location: Blakeney Bike: M900 Posts: 134	Carbs adjusted, can I get your thoughts please? Hi guys, Rebuilt a set of carbs for the first time a few weeks ago, managed to adjust them to what I thought looked and sounded good but as I had never done it before then my opinion isn't the most reliable!! Had an issue where the bike got starved of fuel due to crap in the tank but it ran like a dog after more fuel was put through again. So I've stripped the carbs again in case debris from the tank had got through, de-rusted the tank, replaced the fuel filter, put fresh fuel in and it still ran rough but better than before. Spent yesterday evening trying to get it to sound right but no matter what I did it was still popping and sounding rough so I left it at 01:30 so I could go with fresh eyes today. I put a sync tool on there today to see if that had gone out when I stripped them. I could hear a "coughing" noise when i had been adjusting the fuel which I thought had been from the mixture being out. But looking at the tool I could see and feel it was only on one side. Checked the plugs... one was fine the other had oil on it. Swapped them for a fresh set that i had to go on and instantly purred into life!! Simple things eh? Could have saved me hours of swearing and getting burnt trying to make adjustments last night!! Anyway, it doesn't sound to bad as it is but I'd like an opinion from someone who has played with this a lot more than me... which is basically anyone. So before I starting dialling the screws back and going again from scratch, would you say this is fine where it is? Sync tool plugged in and low revs: https://youtu.be/LqJftfd6Crw Sync tool plugged in and throughout the rev range. https://youtu.be/wqR-yy5clz4

08-07-2018, 10:02 AM	#2
jerry Old Git Join Date: May 2006 Location: Cricklade Bike: Multiple Monsters Posts: 2,909	sounds fine to me air screws might crisp response up a bit if its lean or rich usually about 3.5 turns out is a good start point but its seems to sound good as it is __________________ MONSTERMAN

08-07-2018, 10:35 AM	#3
Jez900ie Pleasantly surprised! Join Date: Nov 2016 Location: Stoke on Trent Bike: M900ie Posts: 780	It sounds quite good to my ear. Still if you watch you video closely, about 3/4 through the clock on the rightside in the clip shows different readings to the one on the left. First the needle trembles, then shows lower readings. Its not a big difference -t could even be the camera angle... I am certainly no mechanic! __________________ Monsters don't hide under the bed, they sleep inside the shed Last edited by Jez900ie; 08-07-2018 at 10:44 AM..

09-07-2018, 02:15 PM	#8
mick Registered User Join Date: Jul 2003 Location: newport Bike: M900 Posts: 76	The tip was to use one gauge connected to the inlets via a T piece, so that you know the gauge is the same for both inlets, just pinch one pipe at a time with pliers or mole grips. __________________ m900 in coming Last edited by mick; 09-07-2018 at 02:19 PM..

08-07-2018, 04:15 PM	#4
Zimbo Too much time on my hands member Join Date: Apr 2003 Location: Stonehouse, Glos Bike: Multiple Monsters Posts: 2,085	Looks fairly good to me, I generally swap the hoses over between the two dials and re-test just to remove the possibility that the dials are reading differently as well!

08-07-2018, 11:47 PM	#5
Macflurry Registered User Join Date: Mar 2018 Location: Blakeney Bike: M900 Posts: 134	Thanks guys. It's a nice bit of reassurance hearing it's not too bad. I was waiting for something obvious that I'd overlooked and not done. This is my first bike since passing my test and as I took over someone elses project then I'm a bit paranoid that I missed something. Took it out for the fist time tonight and it was great fun!! Thanks for the pointers, I'll definitely bear them in mind.