A forum for owners of Yamaha TTR250 trail and enduro bikes!

For my '93 OE?

numero uno - 4RR-14341-00-00 NOZZLE MAIN

numero due - 4GY-14341-20-00 NOZZLE, MAIN JET

Anyone knows diferences ? or should I just buy the cheapest?

Whoops - sorry about that - more speed less haste! I have deleted my post to save any confusion. Well spotted Brindabella 

I looked back at the Russian fiche for a 1996 TTR and it's also got the 4RR number - see http://www.megazip.ru/ru/bike/yamaha/view/1086/15363/191813#g191820

I have a couple of carbs in pieces so will get the nozzles out and see if I can spot the difference(s).

Interestingly, the "nozzle sets" (which include the needle) have the same part number from '96 through to '06. 

Brian

..but looking at the US parts list, it seems that between 1999 and 2006, the only change was in 2000, and that consisted of a different emulsion tube plus a different jet shroud, which persisted to at least 2006.

Throughout that period, the slide, diaphragm, etc stayed constant, as did the pilot jet (#50) and the main jet (#137).
So in the US, the new emulsion tube did NOT require a new main jet.

In the Russian 1996 list, it seems that it is pretty much the same as US 1999, BUT they have the main jet as #147 (same as later European and Australian models). BTW, that list has a mistake in the main jet part number (14239 instead of 14329). The implication is that not only can the "new" emulsion tube work with the "old" main jet, but conversely the "old" emulsion tube can work with the "new" main jet! Who is to say which is the best though?

Interestingly (and relevant to the emulsion tube question) there is a post in  http://www.ttr250.com/carb_fix.htm  (with pictures) which details how putting the old parts in a newer carb on a standard bike gave an improvement!

To me, a question is, why did the US models run a #137 (for ALL US TTR variants in all years 1999-2006) when it seems that in other parts of the world (except older UK models??) a larger #147 main jet is standard? Maybe the US were more serious about emissions or noise or exhaust sparks and/or actually had a REAL restrictor in the system, even though those models were apparently not registerable for road use.

So jetting is a big puzzle.

Maybe those funny US TTR models are the source of the (mistaken??) belief that the TTR has to be jetted up and have its header, airbox and muffler modified to achieve "real" performance (and noise and placebo effect!). People even seem to believe that the throttle stop adjusting screw is some kind of evil attempt by Yamaha to limit the performance of their motorcycle. And attempts by owners to replace the jets with ones from different manufacturers (eg mikuni, with different numbering scheme) has probably lead to even more internet driven confusion. Plus so many old bikes have gummed up carb jets that ANY jet change would be for the better (although proper cleaning may be cheaper and more effective).

Having said that, I guess there must be some optimum tuning setup, but it is a balance of peak power versus part throttle power versus low rpm power versus noise versus fuel economy as affected by riding style and terrain and altitude and temperature. So I reckon we will never have agreement on what is best Anyone got any good dyno charts?

Thank you for doing the proper research Brindabella!

I thought I had found "The Answer" to the 147 v 137 jetting conundrum so jumped to a conclusion much too quickly 

So, as you say, the 147/137 jetting difference (which on the face of it is a big one!) explanation has still eluded us.

I have a feeling that, if the US models had a different restrictor to the rest of the world, we would have heard about that by now and it would be figuring large on a Thumper Talk thread under "free mods" and cutting CDi wires etc 

Anyone else know any more about this?

Brian

Although the article is written ref a 2-smoke KDX200, there is some useful info here to explain how carbs work.

I copied the following from it and would acknowledge Canadain Dave's work on it.

The Parts- No jet acts independently of the others but rather they work together to deliver gasoline to the engine. They do however target specific throttle openings and have the most effect is that area. See below.

I thought I would add my findings to this thread...

The late blue model carburetors use the V95G0 main jet nozzle which is longer than the early pre-1999 models which use a V05 nozzle. This explains why there is two slightly different float height settings.

The petrol baffle is the same in both carbs.

I am going to fit an 0-ring (for the first time) to the older V05 main jet nozzle and see how it goes.

The older fuel nozzle is on the left side of the pic below (with the O-ring fitted).

I will upload my finding after a test ride.

Jarrah

I confess that I have no recollection of ever seeing an O ring on the nozzle and I have stripped many TTR carbs - where they there and I just didn't notice or do they disintegrate over time?

Must have a look at my "new" carb to check for O ringiness 

Brian

I was just stripping out a carb for cleaning and was surprised to find the emulsion tube was bent - how could that have happened 

I was looking through my carb spares and came across an old (slightly corroded - weird - how does petrol do that to brass?) tube and saw that it was shorter then remembered this thread! See pic above. The V95G0 is on the left and the V05 on the right.

I guess we are no further forward in explaining the differences in the carbs. Not sure about using that old nozzle so had better buy a new one I guess 

Brian

petenz wrote:

---

Diddn't diffrent years have diffrent length main jets ?
put a short main jet in the long one / long main jet in the short one
they may end up the same length...

---

 The main jet is still the same size and thread pitch, but the nozzle is different. This is why there is two different float heights between Open Enduro models v's 1999 blue models.

IMO- the shorter VO5 Open endure nozzle giving more throttle response and better on rough, rugged sections as there is less fuel slosh.

yamaha42 wrote:

---

If you install the shorter OE nozzle will you have to change the float height?

---

As an experiment, take off the float bowl and put some plasticine or similar in the bottom. Replace the float and take it off again and see from the thickness of plasticine under the main jet how close it is to the recessed bottom of the float chamber.

My guess it is very close (it was on a later carb I tried earlier) which makes me wonder about float heights as surely the main jet must be about an inch below the top of the petrol in the float bowl whichever nozzle is used - or am I barking up the wrong tree 

Brian

TTRfan wrote:

---

yamaha42 wrote:

---

If you install the shorter OE nozzle will you have to change the float height?

---

As an experiment, take off the float bowl and put some plasticine or similar in the bottom. Replace the float and take it off again and see from the thickness of plasticine under the main jet how close it is to the recessed bottom of the float chamber.

My guess it is very close (it was on a later carb I tried earlier) which makes me wonder about float heights as surely the main jet must be about an inch below the top of the petrol in the float bowl whichever nozzle is used - or am I barking up the wrong tree 

Brian

---

 Measured the float bowls, result- both the same...

You are correct by saying that the 1999-2013 main nozzle sits very close to the bottom of the float bowl (in the recessed chamber).

Carb body to end of main jet= 40mm

Depth of float bowl= 43mm

This only leaves 3mm for fuel flow (if using aftermarket Sigma jets only 2mm [not sure about Mikuni jets]). This also verifies why my bike runs better with the shorter main nozzle as the main jet has more clearance. 

As to the difference between main nozzles, I have not measured yet but the earlier VO5 main nozzle is the shorter of the two.

I have not found a decent Open Enduro manual to check the spec, but I know the float heights are different. My assumption is that the Open Enduro models need a higher float level to accommodate the shorter main nozzle, but as I have said, I am unsure where to download the Open Enduro manual to verify this. 

Will do more investigation when I have time.

Enjoy!

Jarrah

Now just because you are running at full throttle on main jet..the pilot jet is still surplying fuel..
So if you have a lean pilot jet #48 you would need a richer main jet #147
if you have a rich pilot #52 you would need a lean main jet #137
but the combined fuel being surplyed from each combination is the same..
So why diffrent pilot jets... starting / idleing / slow running issues in diffrent climates ?

You could be right Pete but my guess is emission regs in different countries might also affect jetting and float levels.

What I only just noticed is that the fuel level is the same for both nozzles - so how does that relate to float height differences 

Even more baffled now coz its the fuel level that's important to the jet/nozzle height surely 

TTRfan wrote:

---

I was just stripping out a carb for cleaning and was surprised to find the emulsion tube was bent - how could that have happened 

I was looking through my carb spares and came across an old (slightly corroded - weird - how does petrol do that to brass?) tube and saw that it was shorter then remembered this thread! See pic above. The V95G0 is on the left and the V05 on the right.

I guess we are no further forward in explaining the differences in the carbs. Not sure about using that old nozzle so had better buy a new one I guess 

Brian

---

 Is the damage caused by cavitation perhaps?

Peter

yamaha42 wrote:

---

Sorry for asking but what's an emulsion tube? is it the part of the nozzle with the holes in it?

---

 It is the main nozzle, the main nozzle and emulsion tube is the same thing.

brindabella wrote:

---

 by the way I think I misrepresented Jarrah in my post above - actually he had discovered that the older shorter nozzle gave better performance for him, and the float level did not have to be adjusted. I have a hazy idea that Lin may have also discovered the same difference in a post somewhere in the history of this forum (but I didn't check).

---

 Correct! I didn't want to correct you as it may have confused things.

Well, I've had it apart and put the parts in. Runs much better but I'm pretty sure it was simply the float valve that was playing up. Couldn't see anything wrong with the other one but doing the fuel height was much easier. Hmmm. I shall take the advice to refrain from using carb cleaner more seriously. That's the only thing I can think of. I don't think the black bits of carbs like it.

I did put the fuel height at just over 10mm but I think I'll put it back to 8-9mm. Feels like it might be a bit lean now. While I was in there it was obvious that the 38mm float height has to be wrong. There isn't enough room and the float tang would be very bent.

By the way, here's a pic of the emulsion tubes.

Left to right is XT660, early spare, and the one from my blue '06.

I put an o-ring on the longer one when I refitted it with a 147 jet in it. I figured it can't do any harm.

That's an excellent work of reference Jarrah - very many thanks! 

Brian

I lost track a little on the this thread. Just checking, are you running the 4RR nozzle on your blue TTR carb with no problems Jarrah?

Brian

Perhaps we have a new fly in the ointment Jarrah 

The pic above is of a new 4RR nozzle. Note it has a V95 reference rather than V95G0. It also appears to be the same length as the V05 i.e. short - see pic below with the V05 on the right 

Brian

Never mind the year it was from, I found that out already-

Very interesting, it means there is now four different types of nozzles, one of which nobody has even seen so far (the 4GY-14341-20-00 ).

The plot thickens...

TTRfan wrote:

---

The V95 (4RR-14341-00) is 50mm which is the same as the earlier V05 nozzle compared to the later nozzle's 52.90mm (V95G0part # 4GY-14341-20)

So it would seem that the V95 would work perfectly well in the later blue TTR carbs?

Brian

 

---

 I cannot see a problem with it given that I am using the V05 in the later blue carb- Models: TTR250''M'', MC, N, NC, P, PC, R, RC, S, SC, T, TC, V, VC Years: 2000~2006 Color: Deep purplish blue solid e (0583); (plastic tank)
Carburetor: 5GF-14301-01-00

Jarrah