US D shape pilot tool loan ?
- Thread starter STWendigo
- Start date
Ok…. I will do my best to keep this to a readers digest version.
I have succeeded, though few things are a simple as they may seem with carbs
At one point I had all of the pilot screws at 1 7/8 turns out 3 plugs that matched each other though darker than I prefer and one plug that was not bright white like brand new but no more than dairy heavy cream
I messed around with several turn adjustments and landed on 1 3/4 for the three dark ones, that went toward what I was after but not all the way( I figured at this point I was fighting against the 128 mains and stopped focusing on those altogether
Now I had the creamy one to sort and I wanted to make the biggest shift I could so I moved it to 3 full turns out
Result… creamy all around but now with tiny peach freckles around the top ring of porcelain on one side. So it had gotten a minor amount more fuel in the cylinder
Some of you know right now why that was but it took me a couple hours for me to confirm and deal with it
First was check the exhaust pulses coming from each muffler end. Yep right side weaker and cooler than the left
Surmised that the float valve needle is hung up in near fully closed position
Opened the bowl drain screw for opposite carb and measured the out flow. Opened the drain on culprit carb and got a few drops
Took the fuel supply off the right front carb and poured the best fuel cleaner I know of ( sharperTEK ) in till I could see it coming up thd elbow ( didn’t take much ) left it over night then blew lung power air into the elbow and heard air coming out the bowl vent
Suspected the needle had fallen to the fill position. Applied fuel till it came up the elbow. Drained the bowl and the out flow was the same as the other carb tested presumed that the float and needle had raised and closed off the inflow
Reset the wide open pilot screw to 1 3/4 out and fried it up nice and clean. Check the exhaust, pulses even in pressure and temperature
Ran it till the fan came on then pulled the plug for previously goofy cylinder and it looks the same as the others
Tomorrow I’ll ride it and see if fuel continues to successfully feed the carb
Either way I’ll know what if anything will need to be done
Thanks
steve
I have succeeded, though few things are a simple as they may seem with carbs
At one point I had all of the pilot screws at 1 7/8 turns out 3 plugs that matched each other though darker than I prefer and one plug that was not bright white like brand new but no more than dairy heavy cream
I messed around with several turn adjustments and landed on 1 3/4 for the three dark ones, that went toward what I was after but not all the way( I figured at this point I was fighting against the 128 mains and stopped focusing on those altogether
Now I had the creamy one to sort and I wanted to make the biggest shift I could so I moved it to 3 full turns out
Result… creamy all around but now with tiny peach freckles around the top ring of porcelain on one side. So it had gotten a minor amount more fuel in the cylinder
Some of you know right now why that was but it took me a couple hours for me to confirm and deal with it
First was check the exhaust pulses coming from each muffler end. Yep right side weaker and cooler than the left
Surmised that the float valve needle is hung up in near fully closed position
Opened the bowl drain screw for opposite carb and measured the out flow. Opened the drain on culprit carb and got a few drops
Took the fuel supply off the right front carb and poured the best fuel cleaner I know of ( sharperTEK ) in till I could see it coming up thd elbow ( didn’t take much ) left it over night then blew lung power air into the elbow and heard air coming out the bowl vent
Suspected the needle had fallen to the fill position. Applied fuel till it came up the elbow. Drained the bowl and the out flow was the same as the other carb tested presumed that the float and needle had raised and closed off the inflow
Reset the wide open pilot screw to 1 3/4 out and fried it up nice and clean. Check the exhaust, pulses even in pressure and temperature
Ran it till the fan came on then pulled the plug for previously goofy cylinder and it looks the same as the others
Tomorrow I’ll ride it and see if fuel continues to successfully feed the carb
Either way I’ll know what if anything will need to be done
Thanks
steve
Nope not getting consistent fuel flow into the carb
I can bump the needle valve open and get the bowl full and start it, in the time it takes to turn on the fan the pilot circuit will color the plug to an acceptable degree but once I ride it it seems clear that the needle valve is open just enough to keep fuel going thru the pilot circuit and nothing more
When I get back the plug is cream colored and no more
Unless the secondary windings in the coil are failing and unburned fuel is simply washing the plug clean ?
because of family needs I’m done with it for the season. I’ll take care of it next spring, put the 125 mains back in and tune to max efficiency and mpgs
Thanks for watching, I’ll be popping in and out thru the winter
steve
I can bump the needle valve open and get the bowl full and start it, in the time it takes to turn on the fan the pilot circuit will color the plug to an acceptable degree but once I ride it it seems clear that the needle valve is open just enough to keep fuel going thru the pilot circuit and nothing more
When I get back the plug is cream colored and no more
Unless the secondary windings in the coil are failing and unburned fuel is simply washing the plug clean ?
because of family needs I’m done with it for the season. I’ll take care of it next spring, put the 125 mains back in and tune to max efficiency and mpgs
Thanks for watching, I’ll be popping in and out thru the winter
steve
Well since I brought up the possibility of coil collapse yesterday I have found that the st has pack style coils
One coil with two output towers. That one coil fires both cylinders on the right side so it’s clearly firing the right rear cylinder full time so it would seem it’s firing the front full time as well
I put a new plug in the front cylinder and verified spark at idle and up to 3k before the last ride
I will pull and test the wire and plug boot to eliminate questions there
When I start on the float and rejet I’ll start another thread
One coil with two output towers. That one coil fires both cylinders on the right side so it’s clearly firing the right rear cylinder full time so it would seem it’s firing the front full time as well
I put a new plug in the front cylinder and verified spark at idle and up to 3k before the last ride
I will pull and test the wire and plug boot to eliminate questions there
When I start on the float and rejet I’ll start another thread
hmm...
as a baseline, the two EC spec ST1100 I run (and every other I'd ever worked at):
valve clearances properly set, #128 & #40 (OEM here), idle @2+1/8~2+1/4 turns (as in manual), OEM air filter, open (unrestricted**) carb boots
choke on, crank with no throttle, engine fires and ramps to >2000rpm, on which I move the choke lever so it settles ~1500rpm...
by the time I've put on my gloves the idle raises to ~1800 again, so choke off and go...
never managed to get cream/beige plugs on an engine with carburetors, they're always graphite gray*...
(* unless there is an aftermarket air filter in play -> crappy idle, plugs turn white with flakes on, with me pale over running too lean...)
(** P/N 16211MT3000 are fully open, P/N 16211MY3610 have a cast restriction, narrowing the diameter (German market, keeping it <98HP))
as a baseline, the two EC spec ST1100 I run (and every other I'd ever worked at):
valve clearances properly set, #128 & #40 (OEM here), idle @2+1/8~2+1/4 turns (as in manual), OEM air filter, open (unrestricted**) carb boots
choke on, crank with no throttle, engine fires and ramps to >2000rpm, on which I move the choke lever so it settles ~1500rpm...
by the time I've put on my gloves the idle raises to ~1800 again, so choke off and go...
never managed to get cream/beige plugs on an engine with carburetors, they're always graphite gray*...
(* unless there is an aftermarket air filter in play -> crappy idle, plugs turn white with flakes on, with me pale over running too lean...)
(** P/N 16211MT3000 are fully open, P/N 16211MY3610 have a cast restriction, narrowing the diameter (German market, keeping it <98HP))
ST1100Y
Thanks so much for the reference input.
Is either of your bikes abs/tcs ?
Interestingly when I was trying to get the primary color to deepen on the problem cylinder plug and pushing the pilot adjustments all over the place 2.25 was the average across the board where all the cylinders peaked vacuum
My local weather during prime riding season is 90F and above with oceanic humidity
That kind of intake charge does not leave much room to pick up and fully atomize fuel making it easy to be rich to the point of simply wasting fuel
On any set tune my bikes burn cleaner in the fall with cooler and drier air
I’ve had many bikes with every various engine layout and carb placements and in my experience the ST is simply the worst to be able to readily make adjustments but from input it seems that if you get it dialed in you can have many thousand trouble free miles
Thanks again
steve
Wouldn't make a difference... identical engine...
Same here, denser air leans the mixture, giving like 5HP extra when the temps drop below 15°C/60°F...
Interestingly will it run like crap with a less restrictive pattern air filter, as then the pressure differential is messed up...
Manual states to perform the 'idle drop method': slowly closing one idle screw till engine drops 50rpm, then slowly open to raise 50rpm, re-sync, same procedure on #2, #3 & #4...
Covers with my observation, never went over 2+1/4 turns for long (rather 2+1/8) as there is nothing to gain, only the exhaust starting to stink of raw fuel...
Plus it enriches anyway when riding into altitude up in the mountains...
Access & removal of carbs on a SOHC or even a CB600 Hornet isn't really easy either...
Careful cleaning of bowls, jets, float valves and sensible bench preset are the base... then a carb sync and the ST should fly...
Thanks for those confirmations
It has been said in this thread that the abs bikes have a less crisp cam profile making them somewhat less responsive to power tuning.
The ST is what it is and I can’t wait to do some cross continental riding on it
Flying is of course a subjective description though when the rpm’s and gearing is used to advantage it goes well. I have bikes that will bury the ST at all speeds and loads but they don’t have any of the ST’s finer points
Never came across such...
But you're invited to do some research: https://www.cmsnl.com/en-at/
Despite being a 'motorcycle' the ST is a different animal...
No sudden power at 6000, 9000 or 12000rpm...
there is torque, from 1200rpm onward, analogue, linear, reliable, in any gear, any riding situation, always...
And despite having only 5 gears it will still reach >230kph/145mph... with ease...
Due to recent experience this got me curious enough to investigate...
And indeed, not only the ABS, all US and CN spec ST1100's have -730 cams, whilst EC spec come up with a -000 end number.
(The versions shown green in enclosed document are the ones I currently have my hands on... sort of...)
I recently found out that an engine with the -730 cams but EC spec carbs (#40 & #128 jets) planted on, runs fine in mid- and top-range, but displays noticeable reluctance below 2000rpm (even slight ping and knock), whereas an EC spec engine with the -000 cams pulls smoothly from 1200rpm onward...
So my usual "... I'll cross that narrow roundabout in 2nd gear ..." suddenly turned out a bit odd...
Which concludes that the way of tuning a US/CN spec ST by simply replacing the #38 & #125 jets with #40 & #128, won't be the real deal, unless you also get a hold of a set EC spec cams to handle the increased mixture volume...
For me no big issue though, I have set of EC cams on the shelf to throw in, adjust the clearances and go ride!
I'll have to dig further into the carb part lists to see if there more discrepancies, like slides, needles, etc... but different P/N's don't necessarily indicate different parts, often just a different vendor/MFG (like -MT3- vs -MAJ- middle groups)...
Thanks for confirming that info and from my experience I agree with you that in my case, a US market abs/ tcs bike with …730 cams, will likely do better with the 125 main.
I will submit though that my particular bike as configured,128-40, has no lack of thrust from 1200. In fact it lights like afterburners right there and pulls strong to about 7k where I’ve been told most 1100’s begin tapering off a bit.
In my book if one where using more than 7k anywhere other than top gear on this bike a fella must be in some form of desperation and even then what’s the point you aren’t going to cross 150 anyway.
For me, that sort of velocity on this bike would be reserved for a lark along a 4 lane decided interstate 100 miles from the nearest city.
Once again thanks for coming back to this thread. This is useful information for others as well I suspect
steve
I will submit though that my particular bike as configured,128-40, has no lack of thrust from 1200. In fact it lights like afterburners right there and pulls strong to about 7k where I’ve been told most 1100’s begin tapering off a bit.
In my book if one where using more than 7k anywhere other than top gear on this bike a fella must be in some form of desperation and even then what’s the point you aren’t going to cross 150 anyway.
For me, that sort of velocity on this bike would be reserved for a lark along a 4 lane decided interstate 100 miles from the nearest city.
Once again thanks for coming back to this thread. This is useful information for others as well I suspect
steve
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There was a lot of good information here should carburetor repair be needed 