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carbs
Apr 4, 2009 20:06:13 GMT -5
Post by bikerz on Apr 4, 2009 20:06:13 GMT -5
Hi all, can anyone tell me the correct size mains for a '95 ntv 650. recently acquired bike, been standing needed the carbs cleaning and it had a 128 in the rear and a 135 in the front - surely this should be the other way round?
any ideas please, thanks
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carbs
Apr 6, 2009 2:53:40 GMT -5
Post by ilegalalien on Apr 6, 2009 2:53:40 GMT -5
the maual says P models front 132 rear 128 S & T models 125 on both all models i've looked at show larger jets in the front Hawk manual says 142 + 138
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carbs
May 4, 2009 7:08:59 GMT -5
Post by bikerz on May 4, 2009 7:08:59 GMT -5
hi ilegalalien thanks for the info. I went to order a 132 main jet at honda dealer who told me the front main jet takes 128, the rear 132. guy in workshop also said this.now am really confused.any chance you can send email me a scan? of manual page saying front jet bigger than rear? thanks
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carbs
May 4, 2009 7:35:41 GMT -5
Post by Glenn Rowell on May 4, 2009 7:35:41 GMT -5
Hi Bikerz, Checked in the NTV650 manual and what they have there is,
Front #140 Rear #135
This is for Caburetor model/Identification code VDG4A or VDGPA
If you would like a pdf version of the manual let me know. Just send me your email address.
Hope this helps.
Glenn
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carbs
May 6, 2009 2:43:56 GMT -5
Post by ilegalalien on May 6, 2009 2:43:56 GMT -5
it seems different manuals and bike shops have a selection of answers, every place i've sourced says the big jet are in the front (NOT sure why but it would be interesting to find out), i'm not so sure it matters as long as there is a 5 point difference and the air screws are changed to suit the jets, i suppose it's a fuel consumption/speed issue and depends on what your after, the NTV is a downtuned engine (this is why they last forever), am not too sure about my fast NTV but i think both jets are in the 140's with a 70mm silencer and this goes like the proverbial
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carbs
May 8, 2009 15:46:23 GMT -5
Post by honda on May 8, 2009 15:46:23 GMT -5
I have covered this before but cant remember the sizes. However, consult the Honda EPC it will give you the correct size for model. Look at the screen yourself, some of the parts people dont know their --- from a hole in the road let alone the front from the back cyl Bike shops deal in aftermarket parts. Its the same with brake pads. HONDA pads for the NTV are very thick and give a reasonable brake on the single caliper whilst the after market will recommend pads the correct shape but are noticably thinner. These thinner pads are for other twin disc models where "harder" pads are used. The use of these harder pads result in having to use excessive pressure on the lever. Its a compromise. The reason the jet sizes seem the wrong way around compared to other models is the exhaust restrictions imposed by both the shape of the exhaust port and not helped by any further by the tight bend in the downpipe. This compromises the combustion in the rear cylinder (just a little) resulting in the differant main jet size. Never the less the air fuel ratio is correct with the correct jets. There is a differant size used between the 600 and 650. Useing one size down on each carb will help fuel consumption slightly without compromising the engine. One size up will protect an engine in sustained extreme use and do the fuel consumption no good. Setting the air jet/screw has precious little bearing on the mixture much beyond closed throttle. This screw is for setting the idle mixture. On full throttle the mixture is controlled by the type of needle and main jet size. The theory of having the idle screw out by 1 & 1/2 turns is the place to start when setting them initially or after a carb rebuild. This setting usually lets the thing idle initially. It is not the definitive setting. The idle screws should be set where the engine idles the smoothest. Any other setting will make it harder on fuel (rich mixture) or sore on the valves (lean mixture) The carbs should of course be balanced useing a pair of vacumn gauges. All setting should take place with the air box and filter fitted. Hope ths helps a little Regards D
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carbs
May 9, 2009 9:11:56 GMT -5
Post by Jake on May 9, 2009 9:11:56 GMT -5
I have covered this before but cant remember the sizes. However, consult the Honda EPC it will give you the correct size for model. Look at the screen yourself, some of the parts people dont know their --- from a hole in the road let alone the front from the back cyl Regards D Nice to know you're still with us D.. Your input is always welcome, especially on technical areas.... Bikerz, I'd just add that in my experiance, David Silvers are pretty reliable for sourcing genuine Honda parts. If in doubt, just give them a ring..... They won't give you a parts number for example, but if you place an order with them, they will send you the correct item(s) for the year and model of bike and delivery is usually pretty quick...... www.davidsilverspares.co.uk/parts/
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carbs
May 9, 2009 12:32:43 GMT -5
Post by everydaybiker on May 9, 2009 12:32:43 GMT -5
While we're on the subject of carbs, my spare bike displays some strange characteristics which I think are down to carburation... I should state first of all that although it's a Revere it's got a later 650 engine and (I believe) 650 carbs though not the ones from the bike that donated the engine. Done before my ownership so I can't be certain what's there and I can't find where to identify the carbs (I have a spare set but I can't find an ID number on them either). Anyway, the symptoms are a bit odd and rather variable: - Bike runs pretty well in the midrange, but won't rev past 6k (starts to misfire) and is lumpy at tickover (stalls after a while).
- Tickover better when cold, though revs naturally at about 2k as if on choke when it's not.
- Recently started to go on to 1 cylinder at low revs pulling away when engine still cold, improves as engine warms up. Plugs and leads seem to be all good, and as there's 2 per cylinder anyway I doubt that's the problem.
It may well be that the carbs are out of sync, having come from a different engine, or even that they're 600 carbs, but any suggestions would be welcome. This bike is currently having to do 3000 a month commuting while my 650 is laid up having some much needed maintenance!
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carbs
May 10, 2009 9:47:15 GMT -5
Post by Jake on May 10, 2009 9:47:15 GMT -5
Hi Derek, Sounds similar to the problems Norman had: 'Hello, when bought my NTV it would not pull above 4000 revs, pistons in the carbs were sticking, this is what McF mentioned. Gave them a good polish until they moved freely and now it goes like the clappers. Red lines in every gear no probs. Make sure the diaphragms are properly seated, one of mine was out of place when I took the top off the carb. PLUGS, OIL AND FILTER, AIR FILTER SORT OUT SLIDES AND DIAPHRAMS AND NOW THE OLD BUGGER FLIES, WELL MAYBE FLIES IS NOT ACCURATE FOR A ntv BUT IT PULLS STRONGLY UP OVER A 100. good luck Norman.'growell.proboards.com/index.cgi?action=display&board=engine&thread=779&page=1
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carbs
May 11, 2009 18:56:35 GMT -5
Post by honda on May 11, 2009 18:56:35 GMT -5
Hello EVERYDAYBIKER The most likely thing is the choke slider things are stuck/seized. Going off a cyl when cold also suggests rich mix/flooding. When the engine starts to warm it may come back on to that cyl as the fuel doesnt "drop out" as badly at temperature. A common problem with this type of carb. I wouldnt worry too much about what model they are origonally from. I have the same bigger 650 engine setup. It runs fine on the 600 carbs. The carbs from Revere, Transalp, A/Twin, Deauville are basically the same. A higher rpm misfire such as this is usually rich mixture. The richer the lower down the rpm range it will start. Carburated race engines often suffer from this as the builder is usually attempting to keep the mixture rich enough to stop valve damage, or seizure in a 2 stroke. It becomes apparent when competing in a sport where the altitude alters greatly or from the coast to inland. A poor spark/ignition problem such as leaky ign leads or poor coil usually happens further down the rpm range on big throttle openings, right in the torque range as the engine has the largest amount of air per stroke thus the most dense mixture. This is the most dificult time for the spark to jump between the electrodes thus the weakness shows up as the spark faulters. A blue or blue'y white spark fires. A red or pinkish spark is not good even it it will jump 10mm in the open it wont fire in the density of the cylinder. Sticky slides usually give either intermittant poor idle or downright poor power or both. Remove the air filter, reach in and see if they move freely. Diaphrams with holes in them simply dont go correctly at all. Regards D
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carbs
May 15, 2009 18:06:03 GMT -5
Post by everydaybiker on May 15, 2009 18:06:03 GMT -5
Thanks both. I assume the choke sliders we're talking about are the main throttle slides / pistons? I'll certainly check that.
I checked the colour of the plugs a while back - the rears were a mid to light tan colour, the fronts a little lighter - which I thought at the time was indicating perhaps slightly lean on the front cylinder, but I could well be wrong.
FYI I'm getting around 60 to the gallon doing my daily 150 miles, 130 of which is motorway usually around 75/80mph. I guess this figure may not mean much because it's sitting at around 5000 revs which is within its 'happy' range.
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carbs
May 17, 2009 17:53:34 GMT -5
Post by honda on May 17, 2009 17:53:34 GMT -5
No the the choke slides are the things at the end on the the choke cables at the carbs. The other slides are controlled by constant depression via the diaphrams on top. They seldom seize.
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carbs
May 26, 2015 8:42:22 GMT -5
Post by dutch7 on May 26, 2015 8:42:22 GMT -5
Hi i have just replaced my diaphragms on my 99 650nt but i have lost top end power.......i have had problems with carbs for a while even got them tuned at honda, but still had problem of getting to 65-70 and the wind made the bike faulter, sound silly i know, anyway i decided to change the diaphragms.....any clues...
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