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Post by finntv on Jul 9, 2014 13:53:55 GMT -5
 I had to remove the carburettors because the engine was not running on both cylinders. The rear cylinder started to fire only when the choke was almost full on. Now they are thoroughly cleaned and ready to go on the bike again. But what caught my eye was the rubber adapters between the carburettors and the cylinder heads. There was a built in restriction in the middle of the rubber adapter. Diameter of the restricted hole was 27mm, when the carburettor connection i.d was 36,5mm. There was a metallic 'washer' embedded in the rubber, with a nice taper (in the adapter) on the carb side, but completely square surface towards the head. Does someone know what is the purpose of these? I had the bike restricted to 33HP five years ago, but that was done on a dyno and a throttle cable stopper was put on the lower cable by the carbs. Finntv NTV650P -95 K1100RS -97 |
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Post by finntv on Jul 10, 2014 7:49:05 GMT -5
Figured it out: My bike was imported as second hand from Germany by the previous owner. In Germany they have very progressive insurance system based on the engine output. Obviously the insurance is much cheaper for a bike with max 50hp. Therefore most of the german bikes have been restricted. I had a look what www.mobile.de had to offer and out of 120 NTV's for sale approx 40 was 'full output' versions. New rubber adapters can be found from a local bike parts store for £18 per pair. However the problem still remains: my bike is very reluctant to run on the rear cylinder. Now it's off only at idle. On power both cylinders are working. Occational ignitions on the rear cyl also when idling -> it sounds like a Harley :-) Finntv NTV650P -95 K1100RS -97 |
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Post by finntv on Aug 21, 2014 23:54:13 GMT -5
Finally I have my NTV running smoothly!
Had to take off the carburettors once again and the reason for no-idle of the rear cylinder was a glogged idle jet. Todays petrols are bad for motorcycles if you have to keep the bike standing over winter. When it dries out in the float bowls, there is a hard resin formed it to small cavities and orifices. This resin is so hard that carburettor cleaner cannot melt it away and compressed air is not strong enough to clear blocked orifices. The only way is to use metal strings to poke through the blocked passages (don't use very hard materials or too much force). For the next winter I'll try to fill the carburettors with special 'Small engine gasoline' which is alkylate-based and therefore not as volatile as the standard pump-gasoline.
The lesson learned: When you have all jets unscrewed from the carburettor, DO NOT forget to make 'see-through' test. In my case sun was not shining through one of the idle jets at all.
Finntv
NTV650P -95
K1100RS -97
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Post by Jake on Aug 22, 2014 4:08:13 GMT -5
Well done Finntv, I’m glad you’ve finally got you’re carbs sorted.  I must admit I’ve often wondered about the ‘additives’ that are put in petrol and whether they differ from company to company. Does the additive package in Shell petrol differ from Texaco or BP and which package is better for the carbs and fuel consumption or performance etc? For a long time I would only use 97 or 98 octane petrol in the NTV because the engine seemed marginally smoother. But with the higher cost of petrol nowadays I generally use 95 octane and the additives contained in the Shell ‘fuelsave’ package seems to suit the bike fine, because MPG has improved and the engine still seems smooth..... I suppose there are additives that you can buy at a car shop that you can put in petrol to help keep the carbs clean, but I’ve never tried them out.....  www.halfords.com/motoring/engine-oils-fluids/fuel-oil-additives |
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I had to remove the carburettors because the engine was not running on both cylinders. The rear cylinder started to fire only when the choke was almost full on. Now they are thoroughly cleaned and ready to go on the bike again. But what caught my eye was the rubber adapters between the carburettors and the cylinder heads. There was a built in restriction in the middle of the rubber adapter. Diameter of the restricted hole was 27mm, when the carburettor connection i.d was 36,5mm. There was a metallic 'washer' embedded in the rubber, with a nice taper (in the adapter) on the carb side, but completely square surface towards the head.
