New Engine Build, 2014
For 2014 Im building a new engine with a hybrid of Honda Single Cylinder RFVC parts. The Honda RFVC engines range form 400cc to 650cc and many of the parts can be interchanged to produce different engine architecture.
Crank cases & Gearbox
For my latest engine, Im using the crank cases and gearbox from a Honda XBR500, as the gearbox features closer ratio's than the trail based bikes. This will suit my road bike better and will make gear downchanges more controllable, with less rear wheel slides into the corners!
Crank shaft
Ive used a 1985 XL600R crankshaft and balancer shaft for the engine. This is a relatively short stroke 75mm crank, which is both significantly lighter and nicer manufactured than the later XBR500 / NX650 cranks which featured heavy crank webs.
I pondered using a crank with an aftermarket 'hot rod' connecting rod which Id built onto the original Honda shaft. Comparison of the OE Honda Rod and Hot Rod version showed that the aftermarket rod was relatively thin around the small end eye, so Ive stuck with the OE Honda rod which should handle higher revs with more reliability.
The crank also features the shorter generator taper which will suit the lighter XL/XR600 AC generator.
I have removed the backlash gear off the balancer shaft to reduced friction, at the expense of a little more gear noise.
Cylinder
Brand new NX650 Cylinder with 10.5:1 Wiseco 100mm forged piston.
Cylinder Head
This engine features a hand ported XL600 twin port intake head. Pete Eccles tuned the head for a special intake that takes 2x34mm RGV250 flatslide carbs. To run the engine in, Ive fitted the OE intake manifold and twin 33mm round slide carbs as the jetting will be closer to whats needed.
The valve seats were recut and new Kibblewhite race valves and race springs fitted. Titanium valve retainers taking care of the heft valve spring retention.
This head features a 'fifth' decompression valve which has been renewed. I am unsure if this will ever get used or how reliable it will be but I dont see any reason to replace it at the moment.
Ive fitted the Phil Joy cam and stellite welded followers for reliability. The cam is very similar to the HRC works race cam so should work well with the higher comp piston.
Clutch
OE Honda NX650 clutch basket and primary gear with Kibblewhite heavy duty clutch springs. New OE clutch plates.
Clutch cover
Lightweight Magnesium XL600R
Generator Cover
Lightweight Magnesium XR600R
Exhaust
One off HRC big bore header pipes and Bike-it chrome silencers with removable baffles. Now 2into2 design. Loud I should think.
Engine build sequence is ......HERE
For 2014 Im building a new engine with a hybrid of Honda Single Cylinder RFVC parts. The Honda RFVC engines range form 400cc to 650cc and many of the parts can be interchanged to produce different engine architecture.
Crank cases & Gearbox
For my latest engine, Im using the crank cases and gearbox from a Honda XBR500, as the gearbox features closer ratio's than the trail based bikes. This will suit my road bike better and will make gear downchanges more controllable, with less rear wheel slides into the corners!
Crank shaft
Ive used a 1985 XL600R crankshaft and balancer shaft for the engine. This is a relatively short stroke 75mm crank, which is both significantly lighter and nicer manufactured than the later XBR500 / NX650 cranks which featured heavy crank webs.
I pondered using a crank with an aftermarket 'hot rod' connecting rod which Id built onto the original Honda shaft. Comparison of the OE Honda Rod and Hot Rod version showed that the aftermarket rod was relatively thin around the small end eye, so Ive stuck with the OE Honda rod which should handle higher revs with more reliability.
The crank also features the shorter generator taper which will suit the lighter XL/XR600 AC generator.
I have removed the backlash gear off the balancer shaft to reduced friction, at the expense of a little more gear noise.
Cylinder
Brand new NX650 Cylinder with 10.5:1 Wiseco 100mm forged piston.
Cylinder Head
This engine features a hand ported XL600 twin port intake head. Pete Eccles tuned the head for a special intake that takes 2x34mm RGV250 flatslide carbs. To run the engine in, Ive fitted the OE intake manifold and twin 33mm round slide carbs as the jetting will be closer to whats needed.
The valve seats were recut and new Kibblewhite race valves and race springs fitted. Titanium valve retainers taking care of the heft valve spring retention.
This head features a 'fifth' decompression valve which has been renewed. I am unsure if this will ever get used or how reliable it will be but I dont see any reason to replace it at the moment.
Ive fitted the Phil Joy cam and stellite welded followers for reliability. The cam is very similar to the HRC works race cam so should work well with the higher comp piston.
Clutch
OE Honda NX650 clutch basket and primary gear with Kibblewhite heavy duty clutch springs. New OE clutch plates.
Clutch cover
Lightweight Magnesium XL600R
Generator Cover
Lightweight Magnesium XR600R
Exhaust
One off HRC big bore header pipes and Bike-it chrome silencers with removable baffles. Now 2into2 design. Loud I should think.
Engine build sequence is ......HERE
Hi. Where have you bought the brand new cylinder for NX650 and how much does it cost? By the way, you are doing great job. Pleasure to see it... :)
ReplyDeleteHi Filip,
ReplyDeleteThanks for the kind comments. I think I had the cylinder as part of a batch of spares I bought along with the speedway front pipes. I would check David Silver Spares if you needed a new one but it may be more economical to renovate an old Dominator item.
Cheers
Adam
Hi are you still building xbr engines?..i need one rebuilt.....
ReplyDelete