Topic: Few quick questions about wiseco 836 drop ins

[creepxstreet]

The F2 spigots are larger than all of the other CB750 heads.....those insulators will be a bit loose on your head unless it is an F2. Where did you get new F2 insulators....CMSNL etc?

I got 77/78 k model rubbers from vintagecb750.com

[creepxstreet]

Any suggestions on break in? Most of my engine knowledge is related to turbo Subaru stuff so it's slightly different. Those you break in hard as possible. Preheat the oil, start it, tach it out in first second and third then coast down in every gear is first start up procedure haha. As much pressure and vacuum on the rings as possible. I doubt a 40 year old motorcycle engine is similar. Any tips? Break in oil? Just something with a bunch of zinc. Was planning on running rotella 15-40

[PeWe]

I have read a tecnical thesis where a student wrote that the hard break in is better. It is during the first 20 miles when the rings will be grinded by the honed bore surface and get a good seal.
It is in Swedish but possible to copy and paste into google translate. 
https://pure.ltu.se/portal/files/34487725/LTU-EX-2011-34427149.pdf

The thesis is based on http://www.mototuneusa.com/break_in_secrets.htm
And show that the hard break in will give better result.

Warm up engine and drive stepwise with hard pulls, release throttle and let engine decelerate hard. It is now the rings will be "grinded by the honed rough surface. Repeat the hard pulls with total release of throttle. I did up to 4000, then 6000, 8000.....

I saw my old pistons where I took it very easy the first 1000km's when I really wanted to twist the throttle. It looked like the site show.

On thing I think is unclear.
Why is mineral oil so important and not syntethic?
My car MUST have fully synthetic and had that from the very beginning. I'm sure that Ferrari, Lamborghini, Porsche, Aston Martin etc use fully synthetic oils from the very beginning too. (I used mineral oil in my CB750)

[SOHC4 Cafe Racer Fan]

Make sure you do some progressive pulls under load and allow the motor to go through heat cycles.  Do not baby it, but do not be a WOT rev monkey either.  Some people break in on a Dyno, but find yourself some long open road to do it. 

Run 500 miles, drain and inspect oil.

[creepxstreet]

Alright all of my parts have arrived and I'm going to start assembly tonight. Anything else I should look at first?

[PeWe]

Sure you have all parts?
I did a total restore of the entire bike. Engine opened, new crank bearings, clutch, new primary chains with tensioner (Reinforced chains, primary as cam), NOC RC 836 pistons, restore head at the same tuner that ported it over 30 years ago with new valves etc.

I have to pull engine again to add better rods. I should have done that investment when I like revving the engine. I plan lightened crank with better ords and undercutted trans gears....
I did not have a tacho from 1982, tunded engine season 84 and I did not have too see the constant red line area. I have tacho now and at last dyno run it was revved up to close 10k rpm

Your engine will most likely give around 80-85whp or even more.
The last dyno shown here is 80+ whp with a moderate cam. Carbs are Mikuni TMR32, head has 34mm inlet valves.

[SOHC4 Cafe Racer Fan]

Sure you have all parts?
I did a total restore of the entire bike. Engine opened, new crank bearings, clutch, new primary chains with tensioner (Reinforced chains, primary as cam), NOC RC 836 pistons, restore head at the same tuner that ported it over 30 years ago with new valves etc.

I have to pull engine again to add better rods. I should have done that investment when I like revving the engine. I plan lightened crank with better ords and undercutted trans gears....
I did not have a tacho from 1982, tunded engine season 84 and I did not have too see the constant red line area. I have tacho now and at last dyno run it was revved up to close 10k rpm

Your engine will most likely give around 80-85whp or even more.
The last dyno shown here is 80+ whp with a moderate cam. Carbs are Mikuni TMR32, head has 34mm inlet valves.

Good advice from PeWe.  For each step of assembly, lay out all of the parts you will need before you get into that portion of assembly.

[creepxstreet]

Since I never posted pictures of this head and it will be a few months before we can see them again, these were pre final cleaning btw.

[creepxstreet]

Another question, I have 4 rings in the ring kits. 1 oil control ring, one second ring, and 2 identical top rings. 3 grooves in each piston. Is the top ring a double ring or is there an extra top ring in case something happen? Instructions with the rings made no mention of the 4th ring and there's no info on wisecos website about it.

[HondaMan]

Another question, I have 4 rings in the ring kits. 1 oil control ring, one second ring, and 2 identical top rings. 3 grooves in each piston. Is the top ring a double ring or is there an extra top ring in case something happen? Instructions with the rings made no mention of the 4th ring and there's no info on wisecos website about it.

I'd call that a "bonus ring"!

I've twice broken those top rings during install. Or rather I should say, they broke as soon as I started spreading them. Both times they had defects that caused the break. The first one was approx. a 1/3-2/3 break, the other was almost half and half. In both cases, the defect was plainly visible after the break, so maybe look closely and see if there might be a defect in yours beforehand? Maybe they've had enough break that they started sending a spare? Who knows...?

[PeWe]

You will open the ports more than the photos show?
I guess they need more job to match 34mm carbs and larger inlet valves. There are much more to remove in the roof, around the guides. Job close to the seat is most important as I have understood. Pocket between seat and guide.  Google image search to find other CB750 port jobs.

I have 32mm carbs and 34mm inlet valves (F2 valves that are shorter than the K valves and cause more to adjust, I have lash caps as extensions, F2 stems are also very soft mushrooming quickly)

My head was ported over 30 years ago. Chambers opened and in need of old type of pistons with wider crown to ensure CR and get the squish as intended. I was lucky to find old NOS RC 65mm.

[creepxstreet]

Back from the dead. Like most builds everything has taken its fair share of time to complete. Finally got engine done and run and ready to start. Been trying for 3 nights not to get this thing to start, I'm starting to get frustrated with it. It's close, it stumbles like it wants to start sometimes but it's like everything is very slightly out. synced carbs while cranking, getting good spark. Ignition timed correctly. My dads got a 915cc sohc straight from a rebuild at the machine shop that I verified cam timing from (generally to make sure nothing is 180.out). Everything was done by the manual, if I had an issue with anything I took it back apart and redid it. Squirted a little oil in the cylinders and put fresh plugs in it today and it tries to start, then just keeps cranking. Starting to think I've killed the starter and its not spinning fast enough. I'm also thinking maybe the rings aren't sealing tight enough to pull enough vacuum to suck fuel in. The carb throats will be wet from fuel pushing being pushed back out of the carbs.

[TurboD]

I will assure you it is not the rings.. I would recheck the timing of everything. Also try a compression check, the actual number is not important at this time, you merely want to be sure the valves are seating and that none have been bent.

[madmtnmotors]

Is one of those springs upside down?

[TurboD]

A spring flipped on either end will always be same.

[creepxstreet]

My home compression tester doeesnt fit these these plug holes. I'll bring home my leakdown tester from work on Monday and check that.

[TurboD]

A leakdown tester would be great, You do not need a gauge to verify that you have compression, you can use your finger. As you bump the engine, you simply want to be sure it has compression and holds compression for a second or two. This will rule out bent valves.

I just finished building a 836, and my combination with the cam bolted in the stock position the engine would turn over but the valves were hitting the piston ever so slightly. Had someone just bolted my setup together and hit the starter they would have some work to do.

[creepxstreet]

I was Very thorough while degreeing the cam in. Valves touched piston a couple times but I knew that's what was happening and was never rough with it, they never hit with spring pressure or anything. But I shouldn't rule that out I guess.

[TurboD]

That's good.

Something I learned many many years ago, and it has served me well when thinking through problems.

A engine only needs 3 basic things to run. Compression, fuel and spark. As long as the timings are somewhat close it should fire and run.

[creepxstreet]

Starters spinning nowhere as fast as when I first started. Definitely .It fast enough to start an engine.My garage is at the top of a large hill. I'm going to take it to the top of that and roll it down and see if it will start popstarting it like that .

[PeWe]

EDIT. The ignition can hardly be verified as correct when egnine is not running. Only if the points release when they should. Nex is that each point is not connected to correct coil or rotor is 180 degrees wrong. Coil 1-4 vs 2-3 OR ign rotor is 180 degrees wrong?
OEM ign? switch between blue and yellow wires where they are connected with main harness
OK condensors? Correctly connected with the insulators?

It should start with the kickstart at first atttemp. (after a few kicks with ign off, fuel on with choke)

[creepxstreet]

Cycle x power arc ignition. Only 3 wires and its correct. Strong spark. Nothing to get backwards or 180.TDC Mark on reluctor wheel turns an led on on the unit when it's at TDC. Set directly on tdc compression. Spun back wheel with trans in gear to get to tdc. It's perfect

As always, I appreciate all responses and help. I hope I don't sound cocky or anything.

Edit: finally broke out the advancing timing light. This unit seems to auto advance to approximately 20 degrees advanced while cranking. Anyone think that's too much? I think it may be. It's shot a few huge fireballs out the exhaust. Right now the only thing I can think is that the power arc is doing some weird advance which is why it won't start and probably gets worse when I try and pop start it, sees higher rpms and advances further.

[PeWe]

Test with stock point ignition as a fault trace measure. Possible to verify that coils , ign wires are OK.

[creepxstreet]

No change with points. Adjusted the cam chain tensioner and 15 degrees atdc and got it tighter. Deffinite improvement. I think my issue may lie in cam timing. I wonder if I didn't have my chain tight in the right spot while degreeing it. Thinking about buying a frame cut kit so I dont have to pull the engine to check.

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[PeWe]

I mounted the cam chain wrong for many years ago. Chain slack on wrong side and one cog wrong. Engine started without any problem but I heard the ticking when valves got hit by the pistons at idle. Pulled engine and did it right.