TBS

What are your symptoms when the TBS is out of sync?

DISCLAIMER: As mentioned before, I'm no real wrench (I am a tool, but that tool is not a wrench.) But I'm feeling helpful today, so here goes.

Rough idle.

Poor throttle response.

Clicky here for a good tutorial on the process of TBS.

GunMD

Thanks.

I'm dealing with a rough running engine after the TPS recall was completed. In attempting to track down the cause I'm curious as to whether the TBS has any effect???

Here's the original thread

My idle is GREAT! However, any RPM beyond idle is rough, almost missing rough. As such I'm thinking it may need the "unofficial TBS". Currently, the dealer has the Feej and is also unsure as to the problem.

It's a long shot, I know, but could my situation be caused by the TB's being out of sync?

SPORT said:

GunMD
Thanks.

I'm dealing with a rough running engine after the TPS recall was completed. In attempting to track down the cause I'm curious as to whether the TBS has any effect???

Here's the original thread

My idle is GREAT! However, any RPM beyond idle is rough, almost missing rough. As such I'm thinking it may need the "unofficial TBS". Currently, the dealer has the Feej and is also unsure as to the problem.

It's a long shot, I know, but could my situation be caused by the TB's being out of sync?

Click to expand...

Sport,

So I don't have to go reading through your earlier threads, how many miles on your 05?

Reason I ask, my 04 was suffering essentially the same symptoms as yours, but mine were caused by a fuel pump gummed up with rust. Not saying your tank is full of rust, but improper fuel delivery on my bike mirrored your description to a "T".

While the bike's in the shop, with the tank up and everything accessible, ask how much to do a Fuel Pressure test and a Fuel Pressure Regulator test. If your pump isn't putting out enough pressure, or your FPR is over dumping fuel pressure back to your tank, your bike's going lean and will run pretty much the way you're describing.

Still shot-gunning here.

If your bike had carbs, I'd say to clean the pilot jets and drive happy.

RadioHowie said:

Reason I ask, my 04 was suffering essentially the same symptoms as yours, but mine were caused by a fuel pump gummed up with rust. Not saying your tank is full of rust, but improper fuel delivery on my bike mirrored your description to a "T".

Click to expand...

Hmm?

I have 14,900 miles. The bike has ALWAYS been garaged kept. Though it seems unlikely, I'll look into it. Moreover, I would think that IF it were the fuel pump or just gummed up, I would not have such good acceleration (0-120MPH is still very strong!)

Thanks for the suggestion, and I'll keep you posted on my findings

Sport,

One thing you may want to do is shine a flashlight in your fuel tank just before you gas up. If you look at the fuel pump pictures RadioHowie posted, he shows a lot of rust flakes surrounding the intake. With an empty tank you will be able to see the condition of your tank. Any sediment in the bottom should be visible with a light shined on it.

Brodie

Just did a quick TBS using my home made TBS tool. It seems that TB's which are out of sync can also affect performance. My engine idles MUCH better and does not buck nearly as much while riding now. I do have an issue of sync while up in RPM's, but that ought to be cured when I complete the un-authorized TB Sync. some time in the next couple of weeks. I noticed that #2 TB dropped considerably while at 3,500 RPM.

Thanks again for your insights.

Sport

SPORT said:

Just did a quick TBS using my home made TBS tool. It seems that TB's which are out of sync can also affect performance. My engine idles MUCH better and does not buck nearly as much while riding now. I do have an issue of sync while up in RPM's, but that ought to be cured when I complete the un-authorized TB Sync. some time in the next couple of weeks. I noticed that #2 TB dropped considerably while at 3,500 RPM.
Thanks again for your insights.

Sport

Click to expand...

There was another thread earlier from a fellow in Anchorage, AK that had a low value on his #3 (name = Chief?). Never heard if he fixed it. We offered suggestions to look for vacuum leaks, or a stuck cold-start valve on the bottom of the TB. Low vacuum can be mainly caused by air leaks, but low volumetric efficiency in that particular cylinder from ring or valve leaks can contribute some as well, but not as much.

The idle TBS will balance at idle an a bit above. Before I'd do the throttle shaft screw adjustments at higher RPMS I'd want to make sure everything was good and tight (vacuum hoses, caps, TB clamps) on all the TB's, especially #2. A compression reading on all four with a warm engine would be a way of identifying any potential valve or ring issues. The do the full synch if you have the patience.

Gary in Fairbanks

Gary,

Thanks for the suggestion. I don't think it's in the cylinders, but I'll go ahead and do a compression check since I've got the tools. I've also sprayed all hoses & lines with water and carb cleaner at various RPM's and found no differences in RPM fluctuation. Since the TBS has never been done and I have 15,000 miles on her, I figure it's time. I also understand that butterfly valves shouldn't move as they are set at the factory, but...

Also, I did the TBS with a home made TB tool and can't varify it's accuracy; hence the reason for purchasing the Morgan Carb Tune.

I'll post up when I have new findings.

SPORT said:

Gary,
Thanks for the suggestion. I don't think it's in the cylinders, but I'll go ahead and do a compression check since I've got the tools. I've also sprayed all hoses & lines with water and carb cleaner at various RPM's and found no differences in RPM fluctuation. Since the TBS has never been done and I have 15,000 miles on her, I figure it's time. I also understand that butterfly valves shouldn't move as they are set at the factory, but...

Also, I did the TBS with a home made TB tool and can't varify it's accuracy; hence the reason for purchasing the Morgan Carb Tune.

I'll post up when I have new findings.

Click to expand...

Good deal, and I'm sure it'll help smooth things out. I bought a Morgan unit almost four years ago, and have really enjoyed using it on the bikes I've owned since. I've done the full synch (TB idle and shaft screws) on three FJR's and three cruisers, and find it can help smooth out the engine. On three of them I ran the plumbing hoses to a readily accessible location and installed the Morgan with duct tape to the bars. I then tested the settings under load on the road versus a static cruise RPM in the shop. While some have suggested that an unloaded TBS at cruise RPMS may be a waste of time, I found that while the actual vacuum values did change at 3500 RPM unloaded to loaded in 5th gear, the differences between cylinders didn't significantly change and stayed as set within 1 cmHg. Fun to watch while scooting about too!

It's critical to preset the idle air screws at the same 1/2-3/4 turn out for all (pick one), adjust the shaft screws as required to balance at cruise RPMS (#3 to 4, 1 to 2, then 1 and 2 to 3 and 4), and finally set the idle values to #3 as suggested by Yamaha. Turn the shaft screw initially about only 1/8 turn towards whichever throttle body has the lower manometer reading is what I recall (think that's right, but?). If for some reason one idle air screw bottoms out while adjusting (= vacuum too low on that TB at idle compared with others), then re-adjust the differential shaft screw affecting that TB to just slightly close the throttle plate and raise the vacuum to allow at least 1/4 turn out from bottom on the idle screw (= leave some adjustment on the idle air screw). Be sure you still have control over the idle speed with the side adjusting screw (= TB plates not fixed too far open at idle to allow 1K RPMs min.). If not, close the throttle plates some equally with the shaft screws (either left and right, or both) and start over checking the balance.

From my experience it takes no more than 1/4 turn of the three shaft screws to fine tune things, and the Factory painted marks can be of help in returning them to stock in case you have to start back to the beginning for some reason. A compromise of equal values at either cruise or idle may be required. Picking equal at cruise I've found is best for me. The Factory initially sets them up on a flow bench up assuming equal volumetric efficiency for all cylinders, which is often not the case after some running time. Adjust as required for equal flow and engine smoothness at desired RPM's.

Just in case, write everything down so you can backtrack if necessary and it'll go well. Have fun.

Gary in Fairbanks

Post #82 of this link lists the cure to my wowes.

Thanks for all the insights.

Brodie said:

Sport,
One thing you may want to do is shine a flashlight in your fuel tank just before you gas up. If you look at the fuel pump pictures RadioHowie posted, he shows a lot of rust flakes surrounding the intake. With an empty tank you will be able to see the condition of your tank. Any sediment in the bottom should be visible with a light shined on it.

Brodie

Click to expand...

I think a BBQ lighter work work the best Get the light closer to the bottom of the tank................ :blink:

mattster31 said:

Brodie said:

Sport,
One thing you may want to do is shine a flashlight in your fuel tank just before you gas up. If you look at the fuel pump pictures RadioHowie posted, he shows a lot of rust flakes surrounding the intake. With an empty tank you will be able to see the condition of your tank. Any sediment in the bottom should be visible with a light shined on it.

Brodie

Click to expand...

I think a BBQ lighter work work the best Get the light closer to the bottom of the tank................ :blink:

Click to expand...

It's ALL fun and games 'til someone loses an eye.

RadioHowie said:

It's ALL fun and games 'til someone loses an eye.

Click to expand...

Then it's hilarious!