Topic: help with 850 kit cycle x?

[Milunchbox12]

Whose running this kit? What other parts have you installed ? What cam did you use?
Jimbo

[PeWe]

For hotter cams, ported head and stiffer springs is a must. OEM ports, moderate cams. Check http://www.satanicmechanic.org/megacyclecam.shtml  Other cams on the top left.
If you want good torque at low rpms or if you can live with an engine that wake up after 6500rpms.
There are some cam talk in several threads.

[Milunchbox12]

If it says good for big bore or 836 kit do all think it would work for an 850?

[PeWe]

836 or 849 must be very similar. The 849 kit is the salvation for people like me with 836 where the bore has become beyond spec. Possible to bore another 0.5mm and continue with same cylinders. Good price too.

The CR is most important here. Different piston domes. I use NOS RC pistons with wider domes that need wider chambers as my head has. My chambers machined flat surfaces widing to 65mm fits the piston domes very well, rather large flat surfaces close to each other, squich band if I have understood it correctly.  https://www.rbracing-rsr.com/squishcalc1.html

Cam depends on how you will use the bike. City driving and touring, avoid the hotter cams that probably work better with much larger displacement. Nervous idle, stable around 1400-1600 rpms.

I'll use Megacycle 125-20 coming season, IN lift 0.388" (most spec are wrong saying 0.338"). Rather hot cam (idle wise) due to the overlap, I'm curious how my bike will behave on low rpms. Maybe something between my Action Fours SS-1 (nice tourer cam) and CX-7 (screaming high rpm cam, much loader sound from my 4-1).

One good thing is the frame kit that make it possible to change cam and time it without pulling the engine out of the frame. PM forum member 754. Easy to install when engine and carbs are mounted, enough to remove tank and ign coils to cut frame and install the adaptors.

Dynoman sell old Russ Collins cam profiles. DP295 might be something. (Not if head is not ported)
Or a Megacycle cam as I think is of highest quality. Check with forum member MRieck. He can port the head, larger Inlet valves and do all other stuff needed.

APE has also a complete range of hot stuff for our SOHC engines. Lightened crank with better rods, cams, valves...

Ported head is still the bottom end here. Not ported head, no idea to use a hot cam.
Cam with description "bolt right in stock engines" like CX-1, Megacycle 125-05 might be the choice then.

[Milunchbox12]

Pewe are you doing an it kit on your bike?

[PeWe]

No specific kit the 3 steps below, carbs if there is money left to spend 
- 836 since many years, 3:rd 836 piston setup installed 2013.
- Ported head with over size IN valves, 34mm (std 32). The tuner used F2 Inlet valves, 33.5 usually available to K head.
- Hotter cam.
- Carbs Mikuni VM29 (Smoothbore).  Ported head more important than better carbs. My std carbs took the bike to same top speed as the Smoothbores did.

But the engine have plenty of new parts internally, gaskets, sealings, O-rings for the entire oil route from pump to head very important, bearings, all chains changed to Heavy Duty, primary included (not that important unless max tuned or race use).
All tensioners new too, clutch with springs...  Replaced all these parts for 2:nd time

It cost some to restore an engine.
Some people use the cheap 836 piston kit from eBay, seller based in Thailand. With this a moderate cam if more is wanted. Budget version

[theslayedsaint]

Would love to hear how you like it after its all together. I'm rebuildibg engine right now on my cb750 with same 849cc pistons. Just dropped the head on. I'm going to be running the web cam 63a.
Almost eveything is new engine so hoping for this thing to really come alive.

[Milunchbox12]

Slated saint let me know how works for you.

[Sam Green Racing]

Lunchbox, it would be a good idea to tell people what you want from the motor.
Are you going to race it, drag race it, land speed race it or use it on the road?
Different components suit different types of racing and different tracks better.
If you're using it for the road, you can quite easily loose your licence with a stock motor.

Sam.

[Milunchbox12]

Sam. I'm making a old school looking drag bike.  I don't want a ton of power just a little more.  I need rings and is a 77 the cylinders have a rough spot from when it was stuck. I figured why not go with an 850 kit. Any advice is greatly appreciated.

[Milunchbox12]

Sam also to clarify it's just a street bike. Nothing fancy.

[theslayedsaint]

Looks great! Mine is going with a little more "cafe racer" look. Also I was wanting more push off the blocks so not sure if that cam would be a good idea for you.

[Milunchbox12]

Nice bike slayed. When are you going to run the engine?