The Really, Definitely Completely Un-Authorized TBS

[Queensland Ken]

So, can anyone confirm whether this procedure needs to be modified for the 2013 model ( it's Gen 4 in the UK but maybe Gen 3 in the US - whatever, it's the 2013 - 2015 model)

In the service manual, it suggests that if you cannot get the sync within the 1cm you have to clean the throttle bodies, then gives you the procedure.

The sync on my project FJR changed quite considerably after I cleaned the bodies.

 

[Constant Mesh]

I'm of the opinion it's counterproductive to adjust the throttle valves. If they were perfectly clean (no crud buildup on the edges) and the throttle bodies were nice and clean inside an adjustment might offer an improvement.

But once crud begins to appear it has to affect the air flow for the small valve openings which are available for no-load conditions.

The valves are barely open for no-load conditions. Even at a 65 mph load on level ground the throttle valves are not open very much.

When there is a crud buildup in the air stream the adjustments will be affected by the crud variation from cylinder to cylinder. That effect will be most prominent for small valve openings. Once the valves are opened a lot more the crud's effect on air flow will be negligible.

My experience with these adjustments has been unsatisfactory. I wished I had never touched them.

After an adjustment I think I see improvement but very quickly I realize I was seeing a mirage.

Regrettably the FJR engine is a bit rough just above 4K rpm. You can't adjust it out. It's a feature of the engine.

The designers have acknowledged this by changing the gearing (slowing the engine) on the '06 and now again in 2016.

 

[Fred W]

You are the only person who has reported a bad experience. I made mention of the cruddy buildup being a possible issue earlier in the thread. But I am still of the opinion that adjusting the throttle plates on 1st and 2nd Gen bikes is a highly productive way to reduce engine vibrations, even if they are somewhat dirty.

The sooty buildup is going to be relatively even on all 4 throttle plates. If that were not the case then this procedure would not work at all, and my experience is that it does significantly reduce the vibration, especially at or around 4k rpm and above. The soot is going to have the biggest effect on the air flow when the throttle is mostly closed. Every time that I have done the procedure I have always checked to be sure the vacuum stays mostly constant in all 4 cylinders as the throttles are opened, and that has always been the case, even when my throttle plates were quite dirty.

Once you have eliminated the bypass air from the 4 air screws, you will have to open the throttle more than normal just to maintain something close to idle speed.

On 1st Gens you can try to do that by cranking down on the idle speed adjuster, but the 2nd Gens have another 4 port bypass valve for adjusting the idle speed, so you need to find another way to slightly open the throttle and hold it steady at a reasonably low rpm.

I haven't done this procedure on any 2nd Gens lately , but I would think a good way to go about it on one would be to disconnect the 4 vacuum tubes that go from the idle adjuster to the 4 throttle bodies and plug those port on the TBs and also close down all 4 air screws. Make all you throttle linkage adjustments in that state (with the throttle held slightly open), and then re-install the idle adjuster tubes and open the 4 air screws 1 turn each, and re-adjust the air screws to compensate for any unevenness of the idle adjuster.

 

[jammess]

All this is very interesting but you don't suppose those 4 throttle bodies are matched on a flow bench in which case maybe one should leave the throttle valve linkages alone especially if Yamaha says so? If these TBs are matched on a flow bench they were clean at the time so all one should have to do is squirt some cat converter friendly carb cleaner in the TBs to restore to original matched condition. Just maybe this is all you really have to do or should do for that matter. The air bypass screws on a TB are really just fine adjustments while the TB valve adjustments are the course adjustments that are typically set at the factory on a flow bench to create a matched set and are not adjusted in the field.

 

[Fred W]

Then don't do it. For those of us that have made the adjustment and improved the way the bike runs, I guess it doesn't much matter how the throttles were originally set.

 

[jammess]

Hi FNG, that's good advice. Maybe just run a bottle of Techron thru it and call it good.

For me this is my first multi-cylinder machine after many years on beemers beginning with a new '77 R75. Plan to fetch my nearly new 2010 FJR next weekend so for me going from a flat twin to a multi I doubt if I would notice vibration anyway. Maybe in a few months in which case I'll maybe give your sync method a try but for now there is much I'm going to have to get used to. I'm really looking forward to getting aquatinted with this fine motorcycle.

I know on an oilhead it is a no no to tweek the TB stop screws but there are those of us that have done it. With only two TBs you sync just above idle by adjusting the throttle cables (one for each TB) which is kind of the same as adjusting each throttle plate on a multi. On the oilhead the throttle stop screws are the ones adjusted on the flow bench and are not to be touched or there goes the warrantee.

I use a sync tool called a Harmonizer which has only two ports but is just about as good a tool for carb or TB sync that i have seen. The guy that makes the Harmonizer is in the process of developing a 4 channel tool which would be great for one of these multis. Look on the advrider forum under venders to find the Harmonizer.

 

[Fred W]

Yeah, that'll fix 'er right up.

 

[kblackburn]

Fred W.

Many thanks for your post,

I have in the past had a vfr750 (v4) and the only way to balance those was as per throttle plates.

So now been the owner of a fjr1300 2002 gen1, which I balanced on the air screws, and thought that it was smooth as, but suffered from surging at constant speed, making what is a very good bike a bit of a handfull, adjusted the co via the dashboard, to smooth out the surge, to some extent.

So today I have fitted the g2 throttle tamer, and carried out the unauthorised tbs, what a bike, this is how they should leave the factory, 5th gear/ 1500 rpm, butter smooth in traffic and pulls without any hesitation or surging, brilliant, and fuel consumption of 51.14mpg.

kev

 

[mcatrophy]

... and fuel consumption of 51.14mpg.
kev

You should probably specify whether you are using UK or USA units since you are in the UK and most on this forum are Americans.
51.14 mpg (UK) = 42.58 mpg (US), which makes quite a difference to your bragging rights .

 

[kblackburn]

mcatrophy,

no braggin intended, so what does your bike return as fuel consumption ?, just so I have some figure to base mine against, to know wether it's any good.

 

[ionbeam]

'burn, it's apples to oranges between your '02 and mcatrophy's '14. The overall gear ratio has been changed and Yamaha has recalibrated the fuel injection mapping a number of times. Also, the '13 and up have coil over plug ignition and you have a dual coil, wasted spark system. With all the advancements many of the '13 and up FJRs get fuel economy (US measure) of >46 mpg.

Riding style and riding environment also play a big role in gas mileage. In the USA our fuel contains 10% ethanol in almost all locations which does nothing good for mileage. On my '04 riding alone I would get between 34 to 38 mpg. With pillion and less aggressive riding, even doubling the load on the bike we would get 40 - 42 mpg. There is one fellow I sometimes ride with solo and he goes 40 mph all the time, every place regardless of the speed limit and with the same '04 I have seen 48 mpg.

If your bike runs well and you are happy with it you only need to keep track of mileage for gauging gas stops and as an indicator that it might have a problem developing which needs looking into.

Increasing the CO causes your FJR to run a little richer which causes the engine to very slightly bog and this softens the abrupt fueling feel and improves lean surging at low, steady speeds. Putting a G2 on a standard concentric pulley makes you have to turn the throttle tube farther to get the engine to speed up which gives you the feel of better control at low throttle openings. This is not the intended purpose of the G2, the G2 was intended to cancel the effects of the non-concentric throttle pulley on the '06 engine.

 

[mcatrophy]

mcatrophy,
no braggin intended, so what does your bike return as fuel consumption ?, just so I have some figure to base mine against, to know whether it's any good.

Mpg quoting is dangerous territory from the forum admins, but if you want to see mine, I have full details of all three of my FJRs: 2006, 2010, 2014

 

[kblackburn]

mcatrophy,

That's some detail, all credit to you. I'll keep stum.

 

[Fred W]

I can't seem to get any more than abou 44 mpg on my 3rd Gen, and was a fairly consistent 40-42 mpg on my 1str Gen. Both in USA MPGs.

But you know, it really doesn't bother me in the least when I can whack the throttle open and pass 4 or 5 cars at a time on the 2 lane back roads...

 

[kblackburn]

So fuel consumption, seems to be about the same as Fredw,

I neglected to say that I had reverted back to stock co settings ( the settings that were on the bike, when I got it ) so I was pleasantly suprised to find the surging has been elimenated, by doing the tutbs, and the fitting of the g2 throttle tamer.