Carb Tuning guide (setting up a Dynojet or Factory Pro kit)

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fabiostar
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Re: Carb Tuning guide (setting up a Dynojet or Factory Pro k

Post by fabiostar » Sat Dec 24, 2016 10:03 pm

and old thread but what a great read :thumbup:
the older i get,the faster i was :lol:

bfarthing83
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Re: Carb Tuning guide (setting up a Dynojet or Factory Pro kit)

Post by bfarthing83 » Wed Mar 28, 2018 3:12 pm

VTRDark wrote:I thought it was about time this thread was awakened and built upon. :biggrin Thanks for your kind words Roger that is actually quite something to hear that from you. It's only from bits I have had to learn for myself from research and put together.
one question - what is the base settings for the mixture screws ?
Good question as in the workshop manual it says it should be Front 3 Rear 2 3/4 turns out with 45 pilots, but this is for Canada/California. Note these are approximate settings and every bike will be slightly different.

The base setting will be determined by the size of the pilot jet and the majority of carbs I have seen over here have 48's in them. I know Honda soon updated to 48's and it was only the real early ones I think that came with 45's as stock.

VTR V models......45
VTR W,X and Y....48

With a 48 pilots because this is larger and allowing more fuel flow, then the fuel screw wont need as many turns to to get an even air/fuel ratio and smooth running and would be more like Front 2.5 Rear 2 1/4 turns out

The base setting would just be a starting point as every bike will be different due to many factors including engine wear (valve lash, carbon deposits, etc.) Altitude, temperature, humidity and each engine will need to be dialled in/adjusted accordingly for accuracy.

STOCK SETTINGS
(as received from Honda)
Stock From Honda: Stock Filter/ Stock Exhaust / Stock Advancer
-Mains Jet Front 175 Rear 178
-Pilot Jet Front 45 Rear 45
-Fuel Screw (Turns Out) Front 3.0 Rear 2. 3/4
-Stock needles

With 48 Pilot jets
-Fuel Screw (Turns Out) Front 2.5 Rear 2. 1/4

For more info here's a nice write up on air/fuel ratios explained.
http://www.bristoldyno.com/tech/airfuel.htm

(:-})
I apologise if this is a stupid question but how would you know what pilot jets are on an s reg 1000f?
Cheers Ben


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popkat
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Re: Carb Tuning guide (setting up a Dynojet or Factory Pro kit)

Post by popkat » Wed Mar 28, 2018 5:46 pm

bfarthing83 wrote:
Wed Mar 28, 2018 3:12 pm
VTRDark wrote:I thought it was about time this thread was awakened and built upon. :biggrin Thanks for your kind words Roger that is actually quite something to hear that from you. It's only from bits I have had to learn for myself from research and put together.
one question - what is the base settings for the mixture screws ?
Good question as in the workshop manual it says it should be Front 3 Rear 2 3/4 turns out with 45 pilots, but this is for Canada/California. Note these are approximate settings and every bike will be slightly different.

The base setting will be determined by the size of the pilot jet and the majority of carbs I have seen over here have 48's in them. I know Honda soon updated to 48's and it was only the real early ones I think that came with 45's as stock.

VTR V models......45
VTR W,X and Y....48

With a 48 pilots because this is larger and allowing more fuel flow, then the fuel screw wont need as many turns to to get an even air/fuel ratio and smooth running and would be more like Front 2.5 Rear 2 1/4 turns out

The base setting would just be a starting point as every bike will be different due to many factors including engine wear (valve lash, carbon deposits, etc.) Altitude, temperature, humidity and each engine will need to be dialled in/adjusted accordingly for accuracy.

STOCK SETTINGS
(as received from Honda)
Stock From Honda: Stock Filter/ Stock Exhaust / Stock Advancer
-Mains Jet Front 175 Rear 178
-Pilot Jet Front 45 Rear 45
-Fuel Screw (Turns Out) Front 3.0 Rear 2. 3/4
-Stock needles

With 48 Pilot jets
-Fuel Screw (Turns Out) Front 2.5 Rear 2. 1/4

For more info here's a nice write up on air/fuel ratios explained.
http://www.bristoldyno.com/tech/airfuel.htm

(:-})
I apologise if this is a stupid question but how would you know what pilot jets are on an s reg 1000f?
Cheers Ben


Sent from my iPhone using Tapatalk
S registration was September 1998 to end of Feb 1999 so yours is most probably a 98 model which would make it a 'W' but it could also be an 'X' (1999 model). Both these models should mean you have 48 pilots.

.
http://www.bidefordmotorcycles.co.uk
2014 CRMC Post classic Superbike champion.
2014 CRMC Post classic senior production champion. On a Suzuki Katana 1100
My bikes, Firestorm, Yamaha MT10SP, 2 x Honda RC24 road and race, Popup Katana and a some XJ600's

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VTRDark
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Re: Carb Tuning guide (setting up a Dynojet or Factory Pro kit)

Post by VTRDark » Wed Mar 28, 2018 7:29 pm

A can of worms this one...pilot jet size and fuel screw settings. The majority of UK models will be a 48 pilot as standard. This does not mean it is right for your bike. That depends on what else you have going on. Standard needles and / or mains or not, any other modifications, how much wear and tear etc. Stick 48's in and go from there. If it's too lean and your at the max adjustment on the fine tuning fuel mixture screws then go to 50s, if it's too rich and your at max adjustment on the fuel mixture screws then drop down to 45s. No two bikes will be spot on exactly the same.
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fabiostar
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Re: Carb Tuning guide (setting up a Dynojet or Factory Pro kit)

Post by fabiostar » Sun Apr 01, 2018 7:47 pm

i went to 48s on the blue one and could not get it to run low down which kinda surprised me , so as carl said they are all different, back to 45s and smooth as butter. mains wise from memory iv 185f and 180r.

go figure these old beasts.
the older i get,the faster i was :lol:

davebrannigan
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Re: Carb Tuning guide (setting up a Dynojet or Factory Pro kit)

Post by davebrannigan » Thu Jun 27, 2019 4:22 pm

Hi Folks, anyone following my story on the welcome board titled "New to Forum" will know that I'm trying to resurrect a gift of a VTR and get it on the road. All MOT'd now and stopper mod done with new CCT's fitted. All gone well other than a hesitation at light throttle openings which is really annoying. Id go as far as to say awful.

Long story short I've checked and cleaned all jets. It's running 48s on the pilots. 175 and 178 respectively on the mains. Standard exhausts, airbox and filter.

I fabricated a tool to adjust the pilot screws and have just followed the guide on this thread on adjustment. With an 1800 rpm idle set I started adjusting the front carb. I ended up screwing it all the way in and no change in speed or sound noted at all. Left that as it was and moved to the rear. Sure enough that went all the way in with no change to running speed of exhaust note either. Neither one seemed to do anything.


What's a guy to do in this situation? I'm all ears.

Cheers

Dave

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sirch345
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Re: Carb Tuning guide (setting up a Dynojet or Factory Pro kit)

Post by sirch345 » Thu Jun 27, 2019 7:23 pm

davebrannigan wrote:
Thu Jun 27, 2019 4:22 pm
Hi Folks, anyone following my story on the welcome board titled "New to Forum" will know that I'm trying to resurrect a gift of a VTR and get it on the road. All MOT'd now and stopper mod done with new CCT's fitted. All gone well other than a hesitation at light throttle openings which is really annoying. Id go as far as to say awful.

Long story short I've checked and cleaned all jets. It's running 48s on the pilots. 175 and 178 respectively on the mains. Standard exhausts, airbox and filter.

I fabricated a tool to adjust the pilot screws and have just followed the guide on this thread on adjustment. With an 1800 rpm idle set I started adjusting the front carb. I ended up screwing it all the way in and no change in speed or sound noted at all. Left that as it was and moved to the rear. Sure enough that went all the way in with no change to running speed of exhaust note either. Neither one seemed to do anything.


What's a guy to do in this situation? I'm all ears.

Cheers

Dave
IIRC you've set your idle rpm's too high.
Try it again with idle set at 1100/1200rpm's.

Chris.
A closed mouth gathers no foot. :thumbup:

davebrannigan
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Re: Carb Tuning guide (setting up a Dynojet or Factory Pro kit)

Post by davebrannigan » Thu Jun 27, 2019 7:35 pm

OK Ill try Chris though the guide definitely stated 1800. What I would say is that after doing this I set it to about 1000 and it still idled perfectly where, if the jets were closed off Id expect it to stall. I haven't driven it yet like this. Hoping for some guidance first.


Cheers

Dave

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VTRDark
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Re: Carb Tuning guide (setting up a Dynojet or Factory Pro kit)

Post by VTRDark » Thu Jun 27, 2019 8:00 pm

That suggests your too rich and the pilot is letting too much fuel through so you could either drop down a pilot jet size to lean it out which then allows some adjustment to fine tune and richen it up on the fuel screws or it maybe okay on the pilot size and too rich at the needle or worn needles and / or needle jets which is letting too much fuel into the pilot circuit and flooding it. Are you on the standard needles? There's also the float valves that can let too much fuel through if worn and these are replaceable. Needle jets are generally a non replacement part and suggest the carbs maybe worn so it might be better to find some good used carbs to replace the ones you have if the needle jet (hole where needle goes through) is badly oval and has lost it's roundness. What you have to remember is that you can't change or adjust one part without it affecting another and all circuits have to work in conjunction with each other and find that yin yang balancing point or happy medium. Even the mains have a very slight affect on the pilot circuit and the pilot circuit is very sensitive to the smallest of changes.

Also 1800 rpm makes it harder to do the mixture and hear any drop as well as gets the engine very hot very quick making it harder to get in and adjust things without burning yourself. The lower you can get the bike to idle without cutting out the better and easier to hear the drop where the engine is on the point of cutting out. I generally start highish at around 1200 rpm then work my way down low and keep tweaking the mixture until I can get the bike to idle around 500 rpm without cutting out. The lower the idle the more noticeable changes get but harder to keep running without stalling if not accurate, hence starting a little higher and working down. Once finished I then set my idle back up at 1000 rpm which is my preference. The workshop manuals recommend 1200 rpm for idle speed. But if other area of the carbs are not right then you wont be able to get the pilot circuit set because of the trickle down effect. This is why the first post in this thread (FP Instructions) starts with the mains and works it's way down. Saying that you can start at the bottom and work your way up but its harder and not as accurate. Plus I think we prefer to work on the bottom end as this is more noticeable and areas of the carb we use more frequently on the road.

A side affect of getting the bike to idle at 500 rpm means that when your sitting idling at regular idle speed and the bike has the odd splutter like they do from time to time, especially if in lots of heavy stop start traffic, and then the idle drops for a moment and rises back up the bike wont stall on you when it drops. VTR's do this from time to time as they get chocked up on themselves a bit like carb cough. It's often said to raise the idle speed for this issue but this just masks over the problem. These bikes are not huge fans of traffic and want to go. You should also consider checking and setting the TPS when doing the mixture. The combination of the two helps with getting a more accurate steady idle with less flutter and helps eliminate that sputter in traffic I was talking about. And don't forget your carb balance too especially if making major carb changes like needle heights, jet changes and TPS adjustment.

There is one other scenario where you can replace the front emulsion tube with the same as the rear. Quoted from Factory Pro's site: For persistent over richness at cruise, you can use another rear emulsion tube to lean out the front cylinder. The higher holes delay the onset of fuel delivery. Diagnosed by the need to have the front fuel screw almost closed for best idle - That's a superb test for pilot jet size.
http://www.factorypro.com/Prod_Pages/prodh77.html

Or you could take the HRC approach and follow 8541Hawks take on it https://www.vtr1000.org/phpBB3/viewtopi ... 31&t=28922

They are both methods of resolving persistent over richness but in practise I have found it's usually down to other areas of the carb at fault so check that first. If this has been ruled out then seek alternative methods including the possibility of replacing the carbs.

Hope that helps and makes some kind of sense :thumbup:

Oh...one more thing check you choke is operating properly and not sticking open. And BE CAREFUL with the plastic nuts on the carb end if you decide to undo them. They crack and spilt easily if heavy handed. And I'll have a Welsh Cake please :D
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davebrannigan
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Re: Carb Tuning guide (setting up a Dynojet or Factory Pro kit)

Post by davebrannigan » Thu Jun 27, 2019 9:53 pm

Great info to follow up on.
I’ll digest better tomorrow and decide where to go next.

I’ve changed the choke nuts to ally. They were both varnished in and solid until I freed them up. I believe they’re closing ok.

I’ll start by trying a lower idle though as I said I ended up back to 1000 rpm with the pilots fully closed and it idled well. Maybe I need to ride it now and see what it’s like?

The bike has only done 18000 miles so I doubt wear is a player here, but I’ll not rule anything out. I inherited a gunson co monitor with the bike. I Appreciate it’s not state of the art kit but could I use that in any way to guide me? What would I be looking for.

I’m all ears!

Dave

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VTRDark
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Re: Carb Tuning guide (setting up a Dynojet or Factory Pro kit)

Post by VTRDark » Fri Jun 28, 2019 6:29 am

Gunson is a blast from the past. IIRC the co meter is the probe to shove up the exhaust similar to what they use on a dyno. I don't know you might be able to use it but there are two exhausts that mix together. Colourtune would be more useful but you wouldn't be able to get easy access into the cylinder and be able to adjust the mixture screws at the same time.
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8541Hawk
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Re: Carb Tuning guide (setting up a Dynojet or Factory Pro kit)

Post by 8541Hawk » Fri Jun 28, 2019 3:41 pm

VTRDark wrote:
Fri Jun 28, 2019 6:29 am
Gunson is a blast from the past. IIRC the co meter is the probe to shove up the exhaust similar to what they use on a dyno. I don't know you might be able to use it but there are two exhausts that mix together. Colourtune would be more useful but you wouldn't be able to get easy access into the cylinder and be able to adjust the mixture screws at the same time.
If you were going to try it out, use the left hand pipe. At low RPM (especially if you haven't "modified" the stock pipe) most of the exhaust flow is routed through the left side.....that's why it gets noticeably hotter than the right side if you idle for long periods of time or run at just low RPMs :thumbup:
They call me "Mr. Flat Earther"

davebrannigan
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Re: Carb Tuning guide (setting up a Dynojet or Factory Pro kit)

Post by davebrannigan » Tue Jul 02, 2019 8:47 pm

The plot thickens.

I’ve put my original choke cabl e back on. Though it doesn’t stay out through warm up It was a variable. I liked the theory that it wasn’t seating. So that done and set the tos to 500 ohm at the same time. Test ride. No better. If anything worse.

Put my gunson kit in the pipe (albeit the right side as I’d not read the last post until afterwards. Read about 3.5%. Not sure what it should be?

Tried changing pilot screws which seemed to make little difference to rpm or co reading. After a bit of head scratching and dismay the bike started spitting evert 5 seconds or so. Winding the screws either way made no difference. I decided to loosen the TPS screws and wind it back toward its original position. It stopped spitting. I’m not sure exactly what it’s set at now but it’s more than 500 ohm!

I tried pulling the choke a touch to see what effect it had on the co but with the slightest movement she stalled. This was repeatable. Are the bikes normally a bi t tolerant to a little choke when they’re hot?

If that be the case I’m wondering if 45 jets may be the way to go? I really wish I’m had some history on this bike to know what started the mess I’m left with. It’s now doing my head in. Does anyone have a set of 45’s I can try/buy?

Is there anyone in the SE wales area who’s good with these things coz I’m running out of ideas and patience.

Cheers,

Dave

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Re: Carb Tuning guide (setting up a Dynojet or Factory Pro kit)

Post by davebrannigan » Wed Jul 24, 2019 12:04 pm

OK so I eventually got time to get back to the bike and invested in a set of 45 jets Fitted them, reset the TPS to 500 ohms. Set the needles to around 1.5 turns out each and went for a ride.

It does seem a little better at very low revs and throttle settings but is possibly worse around 3000 rpm with slightly more open throttle. Lots of this is subjective of course.

I tried winding the screws all the way in and at least this time she started sneezing occasionally where before it had no effect. I've wound them back out a turn and that's how it stands. I don't know if I'm just being too fussy having come from a blade with efi?

One other thing, is the coolant through the carb body intended to prevent icing or to improve warm up time? When I remove the carbs I get a little fluid from these connections but not as much as I did the first time I removed them so I wonder if I'm getting proper flow through them and whether icing may be part of my problem?

Anyone close to SE wales fancy taking a look at this with me? It's going to be winter before I get this sorted otherwise...

Cheers

Dave

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8541Hawk
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Re: Carb Tuning guide (setting up a Dynojet or Factory Pro kit)

Post by 8541Hawk » Wed Jul 24, 2019 1:49 pm

davebrannigan wrote:
Wed Jul 24, 2019 12:04 pm
One other thing, is the coolant through the carb body intended to prevent icing or to improve warm up time? When I remove the carbs I get a little fluid from these connections but not as much as I did the first time I removed them so I wonder if I'm getting proper flow through them and whether icing may be part of my problem?
The whole "icing" thing has made me wonder for a while....personally I'm in the, they are there to help warm up" camp.

My reasoning for this is that the coolant only flows through the lines while the thermostat is closed.
The thermostat has 2 disks hooked together on it instead of the more normal 1 disk.

When one is closed the other end is open. This allows the coolant to flow through the carb lines while the while the thermostat is in the "closed" position.
When in the "open" position the carb lines now are blocked off (why it doesn't make sense,to me, that they are there for "icing" as why would you want them to shut off?)

This is also why it is completely normal for there to be different amounts of fluid in the lines when they are removed. If the bike was run and shut off before the thermostat has opened, the lines can be full and pour everywhere. If given a chance to fully warm up, the lines can be almost empty as the system pulls the fluid out of the lines. :beer:
They call me "Mr. Flat Earther"

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