Mon nouveau Flat, qui pue et qui péte !!

Bel engin, (même si je compte deux roues de trop), je me réjouis de voir ça, on est passés pas loin de chez toi il y a 2-3 semaines avec les fondus du Belgaz et Jackerda!

Au plaisir de te croiser dans ta jolie barque!

Jagbruno a écrit:Bel engin, (même si je compte deux roues de trop), je me réjouis de voir ça, on est passés pas loin de chez toi il y a 2-3 semaines avec les fondus du Belgaz et Jackerda!

Au plaisir de te croiser dans ta jolie barque!

Pas que se croiser !!
mais pas avant mi 12 debut 01 !!

BlackFish a écrit:

Jagbruno a écrit:Bel engin, (même si je compte deux roues de trop), je me réjouis de voir ça, on est passés pas loin de chez toi il y a 2-3 semaines avec les fondus du Belgaz et Jackerda!

Au plaisir de te croiser dans ta jolie barque!

Pas que se croiser !!
mais pas avant mi 12 debut 01 !!

Ah, ben quand tu voudras, c'est vrai que la route de Rochefort à St Hubert, ma 75/5 a aimé...

Tout (et des fois n'importe quoi) a ete fait sur ces motos pour les fiabiliser... Maintenant, en connaissant un peu les moteurs Ukrainiens, il y a moyen de fiabiliser le Dnepr d'origine mais il ne faut pas trop compter sur les pieces d'origine. Un moteur refait a neuf pour 500 Euros, c'est bien. Mais si tu dois le refaire tous les mois, c'est moins bien... Il y a un principe avec les Dnepr (et les anciennes Ural pre-2002): c'est qu'il faut prendre le temps d'apprendre sa machine. C'est un peu comme une cox, les memes pannes reviennent tous le temps et les memes solutions peuvent regler definitivement les memes problemes. Au debut, c'est chiant mais apres quelques mois, la moto se fiabilise (a force d'etre reparee) et on arrive meme a anticiper les pannes.
Est-ce que tu as une transmission sur la roue du side par crabottage ou un differentiel? Meme si le differentiel est theoriquement bien mieux, il amene aussi son lot de probleme (et tu ne peux plus lever le side en roulant ).

Pour ton gain de couple, si je peux te donner un conseil, roule comme il est presentement. C'est une machine homogene avec laquelle tu vas reapprendre a rouler cool. Des que tu essaies d'ameliorer le moteur (comme beaucoup de monde au debut), tu perds cet equilibres et tu te retrouves avec un attelage plus coupleux ou puissant, certes, mais avec une tenue de route plus aleatoire et des freins toujours anemiques. La, au moins, elle n'avance pas, elle ne tient pas la route et elle ne freine pas. Donc tout baigne! Tu verras dans un an ou deux ce que tu en penses mais je peux te garantir que tu prendras ton Dnepr pour te promener et le gain de puissance ou de couple ne sera qu'un lointain mauvais souvenir. Mes 2 centimes comme disent les riris.

j'ai un pote qui a un attelage dniepr dans le garage, c'est panne sur panne et emmerde sur emmerde... pour le fiabiliser faudrait le revendre d'après notre meccano local ...
Bon courage et bonne balade avec ton joli attelage.

flattwin66 a écrit:j'ai un pote qui a un attelage dniepr dans le garage, c'est panne sur panne et emmerde sur emmerde... pour le fiabiliser faudrait le revendre d'après notre meccano local ...

Toi, tu sais encourager les gens...

palica a écrit:

flattwin66 a écrit:j'ai un pote qui a un attelage dniepr dans le garage, c'est panne sur panne et emmerde sur emmerde... pour le fiabiliser faudrait le revendre d'après notre meccano local ...

Toi, tu sais encourager les gens...

Bah, moi dans les jours qui viennent je rentre une Bonneville 1972 (genre vilain petit canard) dans le salon pour la torréfier un petit coup pendant l'hiver...je viendrai prendre des cours de 'fiabilité' chez toi ;-)



et je vais lui mettre ça pour commencer :

Je pense qu'il faut considérer aussi ces motos comme des motos de collection, et rouler d'une façon qui leur est adaptée : Souvent les gens veulent rouler sur autoroute avec, ça n'est absolument pas fait pour, 90 / 100 km/h semble être leur limite. (je parlais pas de la Yonf, bien sur )

Mick13 a écrit:Je pense qu'il faut considérer aussi ces motos comme des motos de collection, et rouler d'une façon qui leur est adaptée : Souvent les gens veulent rouler sur autoroute avec, ça n'est absolument pas fait pour, 90 / 100 km/h semble être leur limite. (je parlais pas de la Yonf, bien sur )

Euh, tiens ma 75/5 non plus ne se sent pas du tout concernée par ce que tu viens de dire...

palica a écrit:Tout (et des fois n'importe quoi) a ete fait sur ces motos pour les fiabiliser... Maintenant, en connaissant un peu les moteurs Ukrainiens, il y a moyen de fiabiliser le Dnepr d'origine mais il ne faut pas trop compter sur les pieces d'origine. Un moteur refait a neuf pour 500 Euros, c'est bien. Mais si tu dois le refaire tous les mois, c'est moins bien... Il y a un principe avec les Dnepr (et les anciennes Ural pre-2002): c'est qu'il faut prendre le temps d'apprendre sa machine. C'est un peu comme une cox, les memes pannes reviennent tous le temps et les memes solutions peuvent regler definitivement les memes problemes. Au debut, c'est chiant mais apres quelques mois, la moto se fiabilise (a force d'etre reparee) et on arrive meme a anticiper les pannes.
Est-ce que tu as une transmission sur la roue du side par crabottage ou un differentiel? Meme si le differentiel est theoriquement bien mieux, il amene aussi son lot de probleme (et tu ne peux plus lever le side en roulant ).

Pour ton gain de couple, si je peux te donner un conseil, roule comme il est presentement. C'est une machine homogene avec laquelle tu vas reapprendre a rouler cool. Des que tu essaies d'ameliorer le moteur (comme beaucoup de monde au debut), tu perds cet equilibres et tu te retrouves avec un attelage plus coupleux ou puissant, certes, mais avec une tenue de route plus aleatoire et des freins toujours anemiques. La, au moins, elle n'avance pas, elle ne tient pas la route et elle ne freine pas. Donc tout baigne! Tu verras dans un an ou deux ce que tu en penses mais je peux te garantir que tu prendras ton Dnepr pour te promener et le gain de puissance ou de couple ne sera qu'un lointain mauvais souvenir. Mes 2 centimes comme disent les riris.

Slt,



Oui, et ?,,,,tout et n'importe quoi, deux cylindres fonte made RFA
deux pistons complet made RFA 4 sièges et 4 guide + 4 soupapes de mêmes origine
que les cylindres et pistons (VAG pour ne pas le citer) avec les roulement et spy SKF
le tout pour 500 euro !!! + MO self made,,,,,,(le tout possible de 650 a 900cc)

Pour l'électrique, 100 euro pour une dynamo en 12v/40amp,,,,(169 pour du Bosch)


Différentiel asymétrique 19/11, tu peut lever la roue

Maintenant oui, si tu paye un potier qui te compte une heure pour une passe au tour
sur une longueur de 20 cm,,,,,,,,alors cela peut chiffrer
(note qu'il ma bien fait rire, le sus dit potier, quand il écrit qu'il ni a pas de garantie
sur les joints et les pertes d'huile !!!, en plus je doit l'avoir vexé quand je lui ai demandé
si il ne confondais pas « gravité » et thermosiphon )
Ici, en Belgique, la garantie légale est de deux ans,,,,,,même sur les joints
alors sur un side de moins d'un an,,,cqfd,,,même en France

Cette histoire de perte d'huile relativise la nouvelle fiabilité des Ural
d'autant qu'ils sont assemblés a la main et le défaut de fonderie coupable
étais visible a l'œil nu,,,,il semble que le ratio qualité/rendement est en pleine
évolution chez eux aussi !!; et puis franchement, vendre des side « tous chemins »
et ne pas avoir sur toute la France un axe de pont de stock,,,,,,,,,,,

Cela dit, je ne suis pas en recherche de puissance ni même de vitesse
mais de confort d'utilisation

flattwin66 a écrit:j'ai un pote qui a un attelage dniepr dans le garage, c'est panne sur panne et emmerde sur emmerde... pour le fiabiliser faudrait le revendre d'après notre meccano local ...
Bon courage et bonne balade avec ton joli attelage.

Demande a ton pote a quel heure je peut passer pour le soulager de ses malheurs

Mick13 a écrit:Je pense qu'il faut considérer aussi ces motos comme des motos de collection, et rouler d'une façon qui leur est adaptée : Souvent les gens veulent rouler sur autoroute avec, ça n'est absolument pas fait pour, 90 / 100 km/h semble être leur limite. (je parlais pas de la Yonf, bien sur )

Vi vi, 90 c'est la bonne limite comme le macadam est celle des utilisateurs lambda des 1200gs
ou des nouvelles XTZ yam ou la ligne droite pour les amateurs "amateur" de R1

C'est clair qu'il faut prendre en compte les limite de la bécane, mais sans oublier
ses propres limites personnelles

BlackFish a écrit:

flattwin66 a écrit:j'ai un pote qui a un attelage dniepr dans le garage, c'est panne sur panne et emmerde sur emmerde... pour le fiabiliser faudrait le revendre d'après notre meccano local ...
Bon courage et bonne balade avec ton joli attelage.

Demande a ton pote a quel heure je peut passer pour le soulager de ses malheurs

Pareil !

Désolé,j'ai déjà envoyé un MP,chuis doué pour les emmerdes.

battez vous pas, le premier qui me donne un kit krauser je lui file l'adresse du propriétaire du Dniepr .

NB:Uniquement pour Richard, je peut te filer des parpaings pour que ton armoire ne se casse pas la gueule

BlackFish a écrit:
Oui, et ?,,,,tout et n'importe quoi, deux cylindres fonte made RFA
deux pistons complet made RFA 4 sièges et 4 guide + 4 soupapes de mêmes origine
que les cylindres et pistons (VAG pour ne pas le citer) avec les roulement et spy SKF
le tout pour 500 euro !!! + MO self made,,,,,,(le tout possible de 650 a 900cc)
Pour l'électrique, 100 euro pour une dynamo en 12v/40amp,,,,(169 pour du Bosch)
Différentiel asymétrique 19/11, tu peut lever la roue

Comme tu as l'air de bien connaitre les Dnepr et d'avoir fait tes devoirs, il nous reste plus qu'a attendre ton tuto et tes premieres sorties en Dnepr 900...

Moi, les motos russes, tres peu pour moi

Tiens, si tu te debrouilles aussi bien en anglais qu'en usinage:

There is good news and bad news. The good news is a Dnepr engine can be bored and stroked to a much larger displacement and modified in other ways to produce significantly higher horsepower and RPMs. The bad news is, like any engine mods, it will be expensive proportional to the extent of the mods. Performance costs money, how fast do you wanna go?

Starting with the case, I first looked at oiling. Can't make big RPMs and horsepower without sufficient oiling. Most of the bearings in the Dnepr bottom end are roller, which do not require high volumes of oil or high pressure. They are in fact all lubricated by splash/mist except for the front main bearing which gets a trickle of oil from the main pressure feed to the crank. Only the rod bearings are fed by the oil pump, and they are the only non-roller bearings. They are split-shell babbet type bearings, which require pressurized oil. I'll get back these later.

The oil pump appears to have sufficient volume to supply more oil if its passages are enlarged and radiused and the pressure relief spring is shimmed. Looking at the front bearing plate you can see the main oil gallery coming up the left side from the oil pump (bottom of first photo). The oil enters a slip joint in the bearing plate in front of the main bearing. Note the groove around the inside of the opening in the first photo. The crank spins inside this opening with very little clearance. Most of the oil passes into the nose of the crank and goes through the centrifuge and then to the rod bearings through internal passages in the crank. Since there are no seals on the sides of the slip joint, some of the pressurized oil seeps out both sides. On one side it lubricates the front main bearing (second photo), on the other it runs down to make a 2 inch deep puddle in the bottom of the timing cover, bathing the oil pump gear in oil which is then transfered to the crank and cam gears. This puddle of oil eventually overflows into the sump through 2 holes in the bearing plate. There is a second oil gallery in the bearing plate that runs from the center to the edge at about 10 o'clock in the first photo, it feeds the oil pressure sensor in the case (see the hole in the third photo, dead center). This, if enlarged for added flow, can be used as a source for external oil lines for oiling the rear main bearing and running hydraulic lifters. Yeah, I said hydraulic lifters







The rear main bearing gets the least oil and does the most work. This bearing supports the entire weight of crankshaft & rods plus flywheel and clutch. There is no oil delivery to this bearing other than splash/mist (see 2 photos below). This is not unusual, Harleys and British twins are the same, but if higher RPMs and horsepower are to be made, this bearing needs more oil. The easiest way to send more oil here is to run an external line (i.e.-automotive steel brake line) into the flywheel housing and drill a hole between the seal and bearing (see screwdriver in second photo) to attach the line. The line would have to have a restrictor orifice built into it to limit the amount of oil delivered, otherwise it would reduce oil pressure too much and the volume of oil would probably overcome the seal and cause a leak. A suitable size Mikuni main jet could be used as an orifice, and placed in one of the fittings in the external oil line. I'd say an orifice of .020-.030 inch would work here, all that's necessary is a constant trickle of fresh oil.





The next area where more oil is needed is the lifters. The stock lifters are cast iron and run directly against bores in the aluminum crankcase (see first photo below). Although aluminum is a reasonably good bearing material, in order to hold up well the surfaces must be polished and a good oil supply must be present. The Dnepr has neither of these requirements at the lifters. There is no direct oiling, the lifters themselves look prehistoric, and the bores they run in are far from smooth. Eastbloc can tell you about Dnepr lifter failure

To fix this, the first step is to ream out the lifter bores to appropriate size and install a set of bronze liners in them. These liners are used in racing engines to repair worn lifter bores and reduce friction. Fortunately, the size of the Dnepr lifters is comparable to Chevy V-8 lifters. This means that the bronze liners and a variety of lifters (from stock hydraulic to full race hydraulics and solids) are available cheap. Reduction of friction is important in the lifters if a more aggressive cam profile will be used due to increased side loading (more on this later). After the bronze liners are installed and a choice of lifters is made, the holes can be drilled in the case for the external oil lines to deliver oil to the lifters. One hole must be drilled through the top of the case (see second photo) to intersect each lifter bore at the area where the oil holes in the lifters will be. Since the bronze liners will be a precision fit with the new lifters, there will be very little oil pressure escaping around these lifters. Use of solid tips on the pushrods will keep oil from pumping out the tops of the lifters. What oil does seep out from here will run down the pushrod tubes and lubricate the rest of the valve train, but external return lines will be necessary from the heads to the sump, because the stock returns are too small. This extra oil circulation in the heads will also help carry away heat. These photos show the oil pressure sensor (on the right), this is where external oil lines will get their supply.





Next I'll address the limits of what can be done to the rest of the engine to increase displacement. There are several limiting factors: the rods, the cast iron crank, the thin cylinder walls and the location & angle of the pushrod tubes.

The Dnepr rods are junk and the bearings are worse. They are the worst looking rods I've seen in any engine.....ever. These alone are the biggest limiting factor as far as performance, especially for increased RPMs. The rods and caps don't match and the bearing shells don't line up (see first photo below). The bolts are small and weak-looking, and I've seen better sand castings done in high-school metal shop. I think one of mine is bent, or else it was cast that way (see second photo, looking down the beam).





Normally, rods are not a big problem, they all work the same way and alot of rods are made in similar sizes. So if you don't like your rods, usually you can find rods out of some other engine that can be made to fit. This is done alot in racing to accommodate stroker cranks, to reduce "rod ratio" (rod angle) for high RPMs or simply to get a stronger or lighter rod. Crower has a listing of their available rods with sizes and weights here: http://www.crower.com/sp/gs_rods.shtml The abbreviations on the chart are: Total Weight, Rotating Weight, Reciprocating Weight, Center to Center Length, Big End Bore, Big End Width and Wrist Pin Size.

The critical dimensions in this case are big end bore and big end width. Center to center length must be close, but I have a source for custom forged pistons (@ about $100 ea.) and they will make them to accommodate different wrist pin height (within reason) and diameter. These pistons can accommodate a longer rod by moving the wrist pin hole up, as long as the hole doesn't end up in the ring grooves. A longer rod reduces rod angle which reduces rod and crank stresses at high RPM. So it's OK if the rod is a little longer and/or the pin is a different size. The Dnepr rods are 140mm (5.552 in.) center to center, big end width 28mm (1.102") and big end bore 51mm (2.007"). Sorry I can't get more exact with my measurements, but I don't have a set of calipers here so these are rough measurements.

The big problem with the Dnepr rods and crank is that the big end of the rods is offset to one side by about 3mm(see photos below). This means that in order to find another rod that will work, it has to be at least 3mm too wide (31mm or 1.220" or more) so the excess can be milled off to create the offset.





There are quite a few rods that are acceptable length and big end bore, but the only ones wide enough are way too long. There are 3 alternatives to make something fit. One is to mig-weld on one side of the rods to build them up and re-machine them, the second is to spray-weld a shoulder around the crank journals to narrow them and then resurface the crank. Either of these options would require heat treating the parts afterward. The third option is to use a custom steel billet crank and any rods I want. Custom cranks are available from Crower and others, made to any specs you want including journal diameter/width and stroke. If I had unlimited money I would have a crank made to accept Subaru or Porsche rods and increase the stroke by 13mm. Yes, it will fit

One thing I won't do is re-use the original rods. As for alternatives I'm undecided. A mild increase in stroke can be gained by using undersize bearings and grinding the crank journals off center toward the outside. More stroke can be gained this way by spray-welding the outside of the journal so there's more to work with. This method can only be used for slight stroke increases up to say 2mm, more than that would require a different crank. Steve at Steve's Machine Shop (51 Burnt Ridge Rd, Liberty NY 845-295-0548) is a master crank grinder, and he can grind me whatever I want (within reason). If I had access to a good size lathe and mill I could make a billet crank myself, as well as billet aluminum cylinders and chrome-moly big-bore sleeves. Unfortunately I don't have the machines and neither does Steve.

Possible displacement could be as high as 900cc from what I can see in the bottom end. I don't think this could be safely done without a custom high volume oil pump, but that's not too tough to build if you're a decent machinist. There's plenty of room in the case for stroker clearance. The cylinders don't protrude into the case, so there's room to extend them with steel sleeves, even if the sleeves had to be notched to miss the crank throws and rods (see photo below). No biggie.



When stroking an engine you cause the piston to travel farther up and down the cylinder. If your cylinder sleeve is long enough on the bottom, you can simply put a "stroker plate" under the cylinder, its thickness 1/2 that of the stroke increase, and allow the piston to travel both higher and lower in the cylinder. On the Dnepr you can only go so far with this without running into another design limit.....the pushrod tubes and their angle. Due to the angle of the pushrods, the farther you move the head from the cam the lower the angle will become until the pushrod hits the bottom of its hole in the head or the inside of the pushrod tube. However I think it would be OK if the head were no more than 6.5mm (13mm stroke increase) farther out. If this were a problem, the wrist pin could be moved higher with a custom piston, which would keep the head in the original position while moving the piston lower in the cylinder. This would require a steel sleeve that would extend further into the crankcase. There is plenty of room to do this, especially if the sleeve is notched for crank/rod clearance at the bottom. It would also be necessary to use rods that have small bolt heads (such as SPS 12 point) for maximum clearance.



All this bottom end work is expensive, and it takes alot of stroke increase to cause much increase in displacement. Stroking increases torque due to increased leverage on the crank, but the longer the stroke the more centrifugal force you get, so your top RPM will suffer. And once the bottom end is built, the entire assembly including the centrifuge, pinion gear, flywheel and clutch must be balanced so it will all stay in the engine where it belongs. Boring the cylinders increases displacement quite a bit, and for less money (up to a point).

Stock bore on Dnepr 650 is 78mm. The max bore that can be done on a set of stock cylinders and heads will be 84mm. This requires boring the original cast-in cast iron sleeve completely out of the aluminum jug and installing a sleeve with a larger OD. This is where we run into another design limit, the location of the pushrod tubes in the head. Going larger with the sleeve OD requires machining the recess in the head larger to accept it. The pushrod tubes pass right next to this area, and you can only go out so far before you hit them. The top edge of the cylinder sleeve is the head gasket surface of the cylinder, the recess in the head has a corresponding surface that is critical.





So the pushrod tube is the limit here, and in order to have enough wall thickness at the top of the sleeve for the head gasket to seal the thickness of the sleeve in this area must be kept close to stock, which limits the actual cylinder bore to no more than 84mm. With a stock stroke 84mm yields 753cc.
Increasing the OD of the sleeve also requires boring out the crankcase to accept the bottom of the sleeve. But the sleeve doesn't need to be as thick at the bottom because there is less side thrust there from the piston. So the sleeve is cut to 1/8 inch thickness to reduce the size of the bore in the case. By increasing the cylinder bore, more room is created for the rod to swing in the cylinder, allowing more stroke. Increasing the stroke by 13mm (6.5mm on the crank throw) will give a stroke of 81mm. This yields a displacement of 898cc.

To bore and re-sleeve the cylinders there is a critical area that must be watched. The area near the top of the aluminum jug where the fins are cut away for the pushrod tubes.



This area is thin and if it is further thinned when boring for the sleeve this may cause a weak spot that will crack when the new sleeve is installed. If I had my way I'd make a billet aluminum jug that would accommodate this and sleeve it with a chrome-moly sleeve which could be made thinner than DOM steel. But once again, I don't have the machines

Compression = horsepower. Anytime you increase displacement without increasing combustion chamber volume, you are increasing compression. The stock Dnepr compression is 7.5:1, which is lawnmower level. 325/7.5 = 47cc approximate chamber volume. 375/47 = 7.97:1 compression for a 750, fine for pump gas. 450/47 = 9.57:1 compression for a 900, unless the cylinder base gasket were shimmed this would not run well on anything less than the highest octane pump gas.

Next is the cam. The Dnepr cam has pointy lobes like a Briggs & Stratton, no duration. In order to use the RPM capabilities of a built and balanced bottom end, the cam needs more duration, which causes the cam lobes to have a squarish look, like those in Harleys or British twins. As far as I know there are no performance cams available for Dnepr 650's. There are companies that can regrind cams to different profiles by grinding the base circle smaller, but the Dnepr cam's base circle isn't much bigger than the shaft.



So to regrind a stock cam it would need to be built up with spray-welding and reground, then heat treaded. It would probably be cheaper to have a custom cam made from billet steel, which could be in any profile desired. I'd probly go for something close to the cam profile in a later model BMW airhead, but the grind would have to be calculated for actual valve lift because the rocker arm ratios may be different from BMW to Dnepr. Rocker arm ratio is the difference between the length of the rocker arm on the pushrod side and the valve side. I don't have the tools to measure it here, but it looks like at least 1.8:1 on the Dnepr, which means for every .100" of cam lift there will be .180" lift at the valve. So care must be taken when designing a cam to avoid piston to valve clearance problems.



High lift/short duration cams are good for low end torque but run out of steam at high RPM. Long duration cams cause rough idling and only run well at high speed. For all around rideability, there must be a compromise. This is a Dnepr not a Ninja, so medium lift/medium duration will get the best results and allow travelling at highway speeds. That's why I said a close imitation of a stock BMW grind would be good. I'm not going to go deep into cams, there are books on the subject. I just wanted to point out what it will take to get a decent cam grind for a Dnepr.

A more aggressive cam profile is one reason for the bronze liner and Chevy lifter upgrade. An aggressive, longer duration cam will snap the valve open quickly, hold it open longer, then close it quickly. This allows more time for intake flow, thereby increasing dynamic compression. It also causes increased side loading of the lifters, requiring better lubrication and bearing surfaces. Crower sells racing lifters with the "Coolface" option, a tiny oil hole in the face of the lifter to oil the cam lobe. This is perfect for a Dnepr. http://www.crower.com/pdf/flat_tappet_menu.pdf

Last we come to the heads. On some heads it is possible to machine the original valve seats out and install larger seats & valves.....but not on these heads. Nor is it possible to go crazy with a grinder enlarging the ports because the head castings are thin and too much grinding will go through them. The valve spring pocket intrudes into the intake port causing a restriction. My approach to this is to grind out the port until I just hit the spring pocket and then metal-epoxy a valve spring shim in the bottom of the pocket to seal it back up. This gains the absolute most port area that can be gained. After this the best that can be done is to do a very clean porting job and get everything as smooth and aerodynamic as possible, then rely on a good cam to help the breathing along with a 5 angle valve job.

Bronze liners are also available for valve guides and should be used to help reduce heat from friction, especially when running aggressive cam profiles. These should be accompanied by PC valve stem seals. The valve springs must be selected to accommodate the cam's lift at the valve without binding. Valve springs should not run more than 180 lbs. open spring pressure at full lift, no matter what the cam company says. Higher pressures do nothing but destroy new cams & lifters due to the absence of zinc and other good stuff that has been removed from motor oil in the US. The best oil still on the market for most engines is Rotella-T diesel oil in 15W-40. Otherwise the high dollar racing oils in 20W-50 are best for air-cooled engines.

The pushrods for this setup will need to be custom length. Moroso and Mr. Gasket have custom length pushrods available with solid ball ends. The pushrod length should be measured with the lifter on the cam's base circle, valve closed and the valve adjuster backed out all the way and screwed two turns in.

All this extra horsepower will generate more heat, but with good oiling, good bearings and bronze liners, friction and its associated heat is reduced. I would have my forged pistons made without the bottom (extra) oil ring groove, and also have them teflon coated. Both these things will reduce friction. It is possible to run an oil cooler, but in an unconventional way. By adding a steel coil welded to the inside of the oil sump to act as a heat exchanger, an external pump could be used to circulate ATF fluid through this heat exchanger and then to an oil cooler. The pump could be run off a small belt from the drive shaft.

So this is what can be done with a Dnepr engine and unlimited money (or unlimited access to a machine shop with the right machines). As for mine I'm still undecided, but it will most likely end up a 750 with a modified stock crank, non-Dnepr rods and custom forged pistons with a reground cam. All the stuff that can be done to a Dnepr can also be done with Ural or BMW. Performance costs money, how fast do you wanna go?

palica a écrit:

BlackFish a écrit:
Oui, et ?,,,,tout et n'importe quoi, deux cylindres fonte made RFA
deux pistons complet made RFA 4 sièges et 4 guide + 4 soupapes de mêmes origine
que les cylindres et pistons (VAG pour ne pas le citer) avec les roulement et spy SKF
le tout pour 500 euro !!! + MO self made,,,,,,(le tout possible de 650 a 900cc)
Pour l'électrique, 100 euro pour une dynamo en 12v/40amp,,,,(169 pour du Bosch)
Différentiel asymétrique 19/11, tu peut lever la roue

Comme tu as l'air de bien connaitre les Dnepr et d'avoir fait tes devoirs, il nous reste plus qu'a attendre ton tuto et tes premieres sorties en Dnepr 900...

Moi, les motos russes, tres peu pour moi

Tsiiiiiiiiiiiii!!!!!!!!!!!!!

Pas en 900
je préfère en 800, plus facile pour le retour d'huile des culasses
j'ai commandé un bloc nu histoire de de passer un hiver intéressant
et comme je n'aime pas la poterie

Fais quand même gaffe avec ta lime...

Richard de l'Aulagnier a écrit:Fais quand même gaffe avec ta lime...

Je songe a changer mon Nick pour Lime Lover...

@ blackfish

mamam a déjà monté dans le panier

palica a écrit:

Richard de l'Aulagnier a écrit:Fais quand même gaffe avec ta lime...

Je songe a changer mon Nick pour Lime Lover...

C'est vrai que tu t'es niqué avec une lime...

boxer man a écrit:@ blackfish

mamam a déjà monté dans le panier

A l'arrêt, pour voir !!!

c'est déjà le début de l'aventure

Je découvre ce fil.....
Sympa, le Dniepr, pour la gueule je craque. Mais je suis trop nul en mécanique pour tenter ce genre de challenge. Monté avec un moteur BM, et un circuit électrique Guzzi, pourquoi pas ?