| Drivers Gallery Foekema-Kreidler 50cc-Racing |
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| Latest update January 16, 2003 | |||||||||||||||||||||||||||
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Put Tweewielers | This is the name of a byclicle and moped shop in Haarlem of Henk Put. Henk is after more than 10 years still the Dutch recordholder in the 250cc and 50cc sprint. The 50cc is not real, for he didn't drive it himself. He gave his 50cc HPS Kreidler to Henk Willmse to drive. However this site has the most interest in 50cc we will have a also a close look at his 250cc Yamaha, because of the very sophistcated technology. Also because there are many sprintdrivers who still are very jalours on his super fast engine. I have name another person in this matter who is responsible for some very important electronic working details, like the Lachgas injection. Frits Hofman who is an employe in a Dutch Space Laboratory, is more wellknown as the man who made a real working, with 16.000 rpm running, mini 6 cylinder Porsche engine. Read more in the description of the engines below. First the fast times on the 250cc and still the Dutch Record: 1/4 mile 10,46 sec with an endspeed of 218 km/h (135 m/h)(1984) 1/8 mile 6,612 sec with an endspeed of 173 km/h (107 m/h)(1991) The power needed for that we calculate at about 100 hp. No WR because that is of the Englishman Mike Hand on his incredable, with Nitro blowed 2-cylinder Honda. The 50cc speed was under the current WR: 1/4 mile 14,63 sec with an endspeed of 149 km/h (92.6 m/h) The current WR of Jan Nijhuys is 15,36 sec. The WR runs every year organised in Elvington had ended when the airfield was sold by the government. After that running a WR was most times a private matter, which is very expensive. Henk was sprinting from 1972 till 1991 and started on a Kawasaki 89cc which he bought from Jos Smit, also a succesfull Dutch driver. The number of compatitors in the 250cc becomes lower, that's why this class ended in 1992. The last year of the 50cc class was 1979. The reason was that standard bought engines, with some little changes were much faster. Why spend a lot of time in homemade specials, when you ca buy it easy. That why there are only a few homemade sprintspecials. Henk become more times Dutch champion and still have some Dutch records, look at the website www.explosion.nl look under Records. Henk still has his both engines and when I asked if he would like to drive again, the answer last not long. I hope there will be events in the near futeres to see him drive again. The 50cc HPS Kreidler The bike was build by Jan de Vries, who run the bike also before Henk bought it. The complete bike weights no more than 35 kg. The fuel was carried in the main....of the bike. The very tiny front suspension was made by Henk after he bought the bike. The 50cc Kreidler is a watercooled VanVeen racing engine from 1972 with dry clutch and rotating valve inlet, 28mm bing carburator and a 5 close ratio gear. Electronic ignition of Kröber. The power was about 18 hp at 16.000 rpm. Yamaha TZ 250cc The bike was build by Frits Hofman. The rohrs were high quality Chroom Molybdeen steel of Reynold. (wellkwon in the bicycle sport) The total weight 78 kg is very low. The engine is a Yamaha TZ 250cc racing engine with dry clutch. The 6 close ratio gears were changed to a standard 5 gear, with is commended automaticly by airpressior. The electronic ignition was from Daleman. Piston driven inlets with two 38mm carburators and yet the hightech part, the special devellopped computer controled Lachgas injection. The power needed for that speed should be about 100 hp by 14.000 rpm. A number of the rundata were logged every new run, to analise afterwards The tuning of the lachgas injectie was a very delicated matter. The system is actuated by the nozzle .......... At the same time extra fuell has been injected. How much depends on the temperatur. A wrong decision was mostly the end of the engine that day. But when it works well than the power grows spectaculairy. The NOS Lachgaspressoir was also used for the shifting system.  Henk and his Record Sprint engines, extremely low build, as you can see.  Henk in action on his 250cc Yamaha  The fastest 50cc sprinter, original build by Jan de Vries (2x WorldChamp.50cc)  The VanVeen Kreidler cylinder 18 hp, 149 km/h op 402 meter  Cylindertuning as usual in racing of the 70th .  250cc HPS Yamaha highend sprinter 1991  Between the caburators and the cylinder de Lachgas pressure chamber, just for 100 hp
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