87’ should the throttle snap closed?

[saddlebum]

Hate when that happens. You can try cleaning the hole out with brake clean and air pressure. Drop a tiny amount of JB Weld aluminum epoxy into the hole. Coat  a slightly too long bolt with light grease or heavy oil and thread  bolt in until it just about bottoms out after the epoxy has cured back the bolt out. wait at least 24 hours before reassembling. 50/50 chance it will work but have had good luck with this when I came across similar situations were someone ran in too long a bolt (usually happens with plastic rad tanks or two piece aluminum valve covers).

Edited October 8, 2021 by saddlebum

[Pasta Burner]

All parts came in, boots, seals, diaphragm and sliders, and needle shims. Put it all back together (aside from fitting the throttle cable correct, but it works in the half ass position).  Correct C/E clips instead of alligator clips.  Fired her up and synced the carbs.  Carb sync took a little time because at first the carbtune wasn’t even registering and giving throttle stalled her out.  WOW! What an improvement to have everything acting and reacting like it should!  In the garage that is…hopefully the snow will be gone and roads clear on Friday to get out and do a road test.

Edited October 14, 2021 by Pasta Burner

[saddlebum]

11 hours ago, Pasta Burner said:

All parts came in, boots, seals, diaphragm and sliders, and needle shims. Put it all back together (aside from fitting the throttle cable correct, but it works in the half ass position).  Correct C/E clips instead of alligator clips.  Fired her up and synced the carbs.  Carb sync took a little time because at first the carbtune wasn’t even registering and giving throttle stalled her out.  WOW! What an improvement to have everything acting and reacting like it should!  In the garage that is…hopefully the snow will be gone and roads clear on Friday to get out and do a road test.

SNOWWWW Whats this talk about snow ? @Flyinfooljust what are you trying to pull

Edited October 14, 2021 by saddlebum

[Pasta Burner]

@saddlebum it only flurried so far, better than they predicted.  Picked up a new battery today, so still hope tomorrow to get on the road after a few weeks down.

[Pasta Burner]

Got out on the roads around town on a beautiful afternoon for a test ride.  She fired up and warmed up and idled beautifully!  Backed into the street and dropped into gear for a spin around the block and stall.  Stall.  Stall…maybe four times I stalled in place.  Twisting the throttle just bogged her down and any load out from the clutch stalled her out.  Of course there is a cop sitting in the church parking lot across the street watching my misfortune.  Finally decided to just ease into it and feather the clutch and throttle to hopefully get moving.  Down the road I went and she moved like a bat outta hell in upper RPM pulling all the way to redline.  First intersection pulling away she wanted to stall out but baby steps I feathered it on its way.  Straight to the gas station I went and filled up with 91 ethanol free.  Still bogging when twisting the throttle I decided maybe to adjust the cable in the parking lot.  No joy it was adjusted as well as it’s going to get.  So either back home or just keep testing.  Up and down the streets redlining as often as possible just riding like I stole it and really having fun.  Back on the neighborhood streets I did maybe two dozen stop and Starts.  Either one two or both things happened.  I just got used to it not revving up fast, it started revving faster or a combination of both.  Put all the plastic back on and praying tomorrow she runs just as well as when I pulled into the stable this afternoon.

[Flyinfool]

On 10/14/2021 at 8:58 AM, saddlebum said:

SNOWWWW Whats this talk about snow ? @Flyinfooljust what are you trying to pull

I like SNOW!!!!!

You know it is that time of the year where I have to dust off the snow machine and and start the fall tuneups and do a few calibration runs.

Since @cowpuc is not here I have to work at finding a new favorite target.  

@saddlebum sounds like a volunteer.......

It would make @Freebird happy that he will not get as much collateral damage from Pucs overshoot, which will ultimately let me spend more time out of the penalty box in the corner so I can play more.....

[Freebird]

I know it's coming and we need NO help.  

[Flyinfool]

Stalling off idle and still running "like a bat outta hell" at speed is often a sign of plugged idle circuits in one or more carbs. These engines run amazingly well on 3 cylinders. There are people that rode on 3 for years and never knew it till it got fixed.

Check to see if you have one or more cylinders not running at idle. From cold, start it up and monitor each exhaust pipe to see if they all heat up at the same rate.

I would start with a healthy dose of seafoam in the gas tank and let it idle for a good long time, then shut it down and let soak overnight and then rind it some more using the idle circuit as much as possible. Repeat, repeat repeat till it cleans up. If you are lucky this will often help clean things out.

These engines love ethanol free gas, BUT these engines do not really like high octane gas. You get noticeably more power with the lower octane. High octane will only make more power in an engine designed and set up to NEED the high octane. I understand that in today's world it is hard to find E free low octane. and in reality the E free will make more power while the 91 will reduce and it probably all equals out in the end. Ethanol can damage parts. High octane will never hurt anything but your wallet.

[Flyinfool]

33 minutes ago, Freebird said:

I know it's coming and we need NO help.  

You know what happens when someone rattles my cage and wakes me up.......

[Pasta Burner]

1 hour ago, Flyinfool said:

Stalling off idle and still running "like a bat outta hell" at speed is often a sign of plugged idle circuits in one or more carbs. These engines run amazingly well on 3 cylinders. There are people that rode on 3 for years and never knew it till it got fixed.

Check to see if you have one or more cylinders not running at idle. From cold, start it up and monitor each exhaust pipe to see if they all heat up at the same rate.

I would start with a healthy dose of seafoam in the gas tank and let it idle for a good long time, then shut it down and let soak overnight and then rind it some more using the idle circuit as much as possible. Repeat, repeat repeat till it cleans up. If you are lucky this will often help clean things out.

These engines love ethanol free gas, BUT these engines do not really like high octane gas. You get noticeably more power with the lower octane. High octane will only make more power in an engine designed and set up to NEED the high octane. I understand that in today's world it is hard to find E free low octane. and in reality the E free will make more power while the 91 will reduce and it probably all equals out in the end. Ethanol can damage parts. High octane will never hurt anything but your wallet.

Forgive my ignorance but what’s the idle circuit and how would I intentionally use it?  I grew up in the fuel injected generation so I know little about carbs, it’s been fun learning though.

would a plugged circuit still allow me to sync the carbs?

I have a few options around for E Free gas I think ranging from 87-91.  I’m at higher altitude too so higher oct doesn’t do as much in that regard either. 

[luvmy40]

22 minutes ago, Pasta Burner said:

Forgive my ignorance but what’s the idle circuit and how would I intentionally use it?  I grew up in the fuel injected generation so I know little about carbs, it’s been fun learning though.

would a plugged circuit still allow me to sync the carbs?

I have a few options around for E Free gas I think ranging from 87-91.  I’m at higher altitude too so higher oct doesn’t do as much in that regard either. 

The idle circuit is the smallest jet that passes fuel when the throttle plate is closed. It is the jet that supplies the fuel to the mixture you are adjusting with the idle mixture screw. Having that mixture too lean could also cause a stumble off idle. The idle mixture needs to be rich enough to keep up with the sudden in rush of air when the throttle plate opens.

Edited October 16, 2021 by luvmy40

[luvmy40]

A simple test to see if your problem is idle circuit related would be to open the enricher circuit a bit and see if the throttle response off idle improves.

[luvmy40]

Yes, you would still be able to go through the synchronization procedure with one or more idle jets clogged. As long as the engine stays running at some idle adjacent RPM.

Edited October 16, 2021 by luvmy40

[saddlebum]

3 hours ago, Flyinfool said:

I like SNOW!!!!!

You know it is that time of the year where I have to dust off the snow machine and and start the fall tuneups and do a few calibration runs.

Since @cowpuc is not here I have to work at finding a new favorite target.  

@saddlebum sounds like a volunteer.......

It would make @Freebird happy that he will not get as much collateral damage from Pucs overshoot, which will ultimately let me spend more time out of the penalty box in the corner so I can play more.....

[Pasta Burner]

1 hour ago, luvmy40 said:

The idle circuit is the smallest jet that passes fuel when the throttle plate is closed. It is the jet that supplies the fuel to the mixture you are adjusting with the idle mixture screw. Having that mixture too lean could also cause a stumble off idle. The idle mixture needs to be rich enough to keep up with the sudden in rush of air when the throttle plate opens.

Where is this screw to adjust?  Do I adjust the  actual jet or is there another screw?  This is accessible when the air box is removed?

Edited October 16, 2021 by Pasta Burner

[Pasta Burner]

Video from gas station yesterday.  It’s not dropping rpm, just slow to pick up. 

[Marcarl]

Idle circuit adjustment screws are hidden behind a sealing plug.

[Pasta Burner]

30 minutes ago, Marcarl said:

Idle circuit adjustment screws are hidden behind a sealing plug.

Ahh. I didn’t know those were them.  Thanks.

Why did Yamaha make those inaccessible?  To make you go to the dealer?

[Pasta Burner]

Thank you all for being patient and helping me along with this.  Just put about 20 miles on running errands around town and not a single hiccup.  I measured the exhaust heads as it warmed up and all came up to temp evenly with the exception of #2 cyl topping out around 145F while the other three were consistently in the 180F ballpark.  
every light and start up she idled smooth at 1k.  
letting go of the throttle it snapped closed and cut power as expected.

I've gotta say it was well worth the investment in new parts, I haven’t had this much joy on the bike so far.  It was such a pleasure to ride, can’t wait for the next ride.

[Marcarl]

Too many people think that screws are there to be played with (any screw), and seeing as the idle circuit has very little to do with the running of the engine as long as things remain clean and un-obstructed, there should be very little reason to 'play' with them, but if you do, it could make it somewhat miserable for a nice idling power plant. Now if things get gummed up or dirty, then it's time to dig deeper, hence there is a screw and the cap can be removed. Note: if the carbs were cleaned and the screws were not removed and the circuit cleaned, then you just might be running into what you are presently experiencing.

[Marcarl]

Keep in mind: If it ain't broke, don't try fixing it.

And you have no idea how much we like helping those who need it. Some of us were born to be doctors, some politicians, some lawyers, some plumbers, some builders, some electricians, and some mechanics. If we all work together we can easily do what one alone would find difficult.

Oh yah, after we all built the house we also need somebody that can live in it.

[Pasta Burner]

1 hour ago, Marcarl said:

Keep in mind: If it ain't broke, don't try fixing it.

And you have no idea how much we like helping those who need it. Some of us were born to be doctors, some politicians, some lawyers, some plumbers, some builders, some electricians, and some mechanics. If we all work together we can easily do what one alone would find difficult.

Oh yah, after we all built the house we also need somebody that can live in it.

And all this time I thought the name of the game was if it ain’t broke fix it till it is 😜