Author Topic: 78 CB750F "Modular-ish" cafe build? (Read 59327 times)

madScientist · « **Reply #50 on:** December 20, 2012, 04:16:35 PM »

Quote from: CB750 Cafe Racer Fan on December 20, 2012, 04:05:33 PM

Purrty looking motor.

Thanks!

So I'm building this thing in my house. We had friends over last night and I couldn't help but show off the internals of the motor...

I'm pretty proud of it.

SOHC4 Cafe Racer Fan · « **Reply #51 on:** December 22, 2012, 10:40:38 AM »

I wish I had the mechanical talent to do an entire motor rebuild. I simply don't have the experience and confidence to measure wear on the internal parts or patience to deal with frozen studs as well as a host of other issues. I'm better with the rougher/less skilled (turn a wrench) portions of the build.

madScientist · « **Reply #52 on:** December 22, 2012, 01:40:45 PM »

A lot of it is being able to determine what you cant / shouldn't do and farm out. Assembly isn't terribly hard as long as you follow the instructions. Go slow, double check what you're doing, proceed. I have the SOHC manual and the Clymer. I read the sections in both of them twice before i start.

You can do anything you put your mind to!

madScientist · « **Reply #53 on:** January 18, 2013, 09:52:11 AM »

Whoa...I didn't realize it's been almost a month since i posted.

Progress has been slow but steady. The lower part of the engine is back together. I'm probably going to have to pull the clutch cover though. The arm doesn't act right.

With my fiance's help I got the lower part of the engine set down in the bike. I also went through the gauges. Changed the faces because they were very faded. I painted the needles to make them prettier. The BA9's were swapped out for blue LED's. I hooked it up to a car battery...looked pretty cool!

The wiring harness connections have been swapped out for new ones courtesy of vintage connections. I put in a solid state voltage regulator and a blade type fuse box. Also going to order a solid state rectifier. I have a Dynatek ignition in it that I put in about 6 years ago but I'm thinking of swapping it out for a Pamco. That will be later though. If anyone's interested in a Dynatek let me know.

As of late I've been in contact with THE Mike Rieck about working over the head. Probably going to have that shipped out next week for his midas touch. I'm probably getting a Megacycle 125-65 from him as well. I cannot thank him enough for his help and guidance.

The 836 kit will be ordered in the next couple weeks as well. I'll be using the Dynoman kit. The machine shop I use for my car engine builds said they'd bore. hone, and bead blast the cylinders for $100.

I'm very anxious to have to old girl back together.

Left side of the engine on the stand

Right side

Couple shots of the bike

madScientist · « **Reply #54 on:** March 27, 2013, 10:34:47 AM »

So it's been awhile since I've been able to get anything done on the bike but i did get a LOT of stuff ordered and shipped.

The head, cam, and rockers have been shipped to Mr. Rieck for a stage 2 port, valve guides, and valve job. He's also sent the cam out to Megacycle for a 125-65 grind and the rockers for a hardweld treatment.

The JE 10.5:1 pistons have been installed. The jugs bored and honed and painted a satin black. The APE studs were put in and the jugs installed.

I pulled the front wheel off as I found a leak under both the fork legs that i have to sort out. I probably didn't get the hex bolt tightened down enough.

I still have a lot I can do while I wait though. I plan to get the master cylinders rebuilt, switches cleaned up, tank stripped and prepped for paint, electrical sorted (pamco to be ordered in the next week or so). Still a lot of things to get sorted out.

I think I'm going to go with Mikuni RS34's for the carb package. I have the stock F2 insulators however they aren't very pliable and was considering getting aftermarket ones. Mike mentioned there are aftermarket boots out there but not sure of the quality. I'll do a little research and probably start a post for opinions.

77cb750f2 · « **Reply #55 on:** March 27, 2013, 01:13:19 PM »

Looks great so far. Looking forward to seeing the finished product!

madScientist · « **Reply #56 on:** March 27, 2013, 01:24:38 PM »

Thanks! The biggest challenge is getting time to work on it. I"m anxious to get it done though. Shooting for the beginning of May.

Bankerdanny · « **Reply #57 on:** March 27, 2013, 01:53:30 PM »

Are those Norman Hyde M bars?

madScientist · « **Reply #58 on:** March 27, 2013, 02:49:12 PM »

Yes they are! I am not a fan of clubmans or drags and after seeing them on Tweakin's bike in another thread I really liked them.

Bankerdanny · « **Reply #59 on:** March 27, 2013, 03:42:40 PM »

Me too. They look like a great compromise between clubman bars and superbike bars. I have a eBay seller that carries them saved in my favorites for when it's time to go handlebar shopping.

madScientist · « **Reply #60 on:** March 27, 2013, 05:30:26 PM »

It might be the same guy I picked these up from. He was fast and good to work with.

madScientist · « **Reply #61 on:** April 24, 2013, 06:19:45 AM »

Work has been keeping me busy so I haven't had a lot of time to devote to the F. However I've received lots of packages in the mail :-D I think I might be in trouble as my fiance is starting to wise up as to how much I have in this sucker. Oh well easy come easy go.

On Monday I received the JMR head. If you could box up awesome and ship it that would be what I received. This thing is gorgeous! The ports are much improved from what I sent out. He even smoothed out my messing up of one of the valve guide collars. That guy is a magician! I took some haphazard pictures and will take better ones once I go out and get some clay. Right now I have it mocked up on the jugs.

So the list of things I've picked up...

Mikuni RS34's
Megacycle 125-65 (thanks Mike!)
Megacycle hard welded rockers (Thanks again Mike!)
JMR Head (yeah you know...)
Pamco (wired up and ready to go)
RK 530 Xring chain (gold for +5 bling)
Few other odd's and ends.

I think I have everything to largely put it back together...all except time.

I also started addressing the tank. It was pretty rusty on the inside and when I was stupid kid I put a Kreem liner in it without first getting it derusted so it was nasty. About a week of MEK got the liner largely out but the rust looks like it's a little beyond my help. I was going to run diluted muratic acid through it but figured it might be best left to the hands of a professional. So I dropped it off at my favorite radiator shop. They are going to hot tank it and promised me they'd get the rust out. They're also going to give it a good media blasting as it's going to head off to the painter when it's done.

I'm going to be out of town on business for the next couple weeks which sucks but I think when i get back I'm going to have to take a few days off to see if I cant get it back together!

Fuzzy head photo

SOHC4 Cafe Racer Fan · « **Reply #62 on:** April 25, 2013, 09:14:49 PM »

That JMR head is a thing of beauty. I am heading that direction. Love the new black F motor!!

iron_worker · « **Reply #63 on:** April 26, 2013, 08:28:40 AM »

Quote from: madScientist on April 24, 2013, 06:19:45 AM

So the list of things I've picked up...

Mikuni RS34's
Megacycle 125-65 (thanks Mike!)
Megacycle hard welded rockers (Thanks again Mike!)
JMR Head (yeah you know...)
Pamco (wired up and ready to go)
RK 530 Xring chain (gold for +5 bling)
Few other odd's and ends.

$$$$$$$$$$$$$$$$

IW

brandEn · « **Reply #64 on:** April 26, 2013, 08:35:32 AM »

nice!

madScientist · « **Reply #65 on:** April 26, 2013, 07:48:35 PM »

Thanks guys!

The pocket book has taken a hell of a hit over the last couple months. There is light at the end of the tunnel though...

madScientist · « **Reply #66 on:** May 03, 2013, 03:21:02 PM »

Preparing to check the piston to valve clearance and do an initial degree of the cam to check fitment and what not. I put modelling clay on the #4 piston for the clearance check and went to checking the degree of the cam.

After some significant cursing i got the cam chain on...i apparently didn't know or get the "trick" but i eventually got that sucker on there. Found true TDC. Went to install the valves and realized I had no tappets. The previous ones I had were junk and neglected to pick up new ones so I'm in a holding pattern until they arrive. Mr Rieck is shipping me some.

Meanwhile...since I have to wait to make forward progress...I ordered a spectra fuel filter and an Earls oil cooler. I have a lockhart but I just dont like the look of it. I cant put my finger on it but something about it just rubs me the wrong way. Plus I've never used a Lockhart and have used Earls on all my race cars. So in a week or so the Lockhart will be in the "selling stuff" post I'll start. I have a lot of odds and ends as well as 2 complete carb racks to pawn off...

Still haven't heard from the radiator shop on the tank. Hoping I hear from them Monday so I can get everything off to paint by Wednesday...next weekend at the latest.

I found myself trolling Joker Machine the other day while procrastinating on a project at work. Not a good idea...I ended up ordering tappet covers and axle adjusters.

OPINION TIME!!!
Lets talk exhausts...I have my choices zeroed down to either a MotoGP Werks or a Cycle X 4-2-1. I'm aiming for stainless or otherwise polished for both systems. What's everyone's opinion on these two? Do you like the sound? Performance increase? Too loud (if possible)? Oil changing a b**ch? Which, overall would you prefer.

I think I'm leaning towards the cycle X because it looks like changing the oil can be accomplished with the pipes installed versus the MotoGP's that have to be removed. Thoughts?

madScientist · « **Reply #67 on:** May 08, 2013, 05:32:49 AM »

Spent a few hours last night degree-ing the cam and dont like my numbers.

The intake opens at 25 BTC as indicated on the card but doesnt close until 87 ABC when it should close at 52. That's 35 degrees of incorrectness and am very skeptical Megacycle misground the cam.

So I'm going to take the top end apart tonight and reset everything. I've also been trying to do the timing with only the #1 rockers in (like i do car engines). So I'm going to put the rest of them in in case there is shaft flex that would be skewing the numbers.

madScientist · « **Reply #68 on:** May 09, 2013, 05:40:06 AM »

That did it. I put the whole head together and degree'd in the cam. Ran a complete rotation to let the valves sit into the modeling clay on the #4 piston. I started taking it back apart this morning and should be able to finish that up tonight...maybe even get it together!

That CAM was the closest to spec I've ever received one. The only discrepancy was the exhaust valve closed 2 degrees later than the card and the intake closed 1 degree later. Not a big deal at all! Lobe centerlines were set at 103.75. Lift was perfect!

The CRANE's and Ford Racing custom grinds I get are typically ~5 degrees off one way or another with lift being ~.05 off in one direction or another. Makes for a lot of adjustment to get them set right...

iron_worker · « **Reply #69 on:** May 09, 2013, 07:53:50 AM »

When you were degreeing, did you set your valve clearance to zero lash?

What was causing your 35 degree error? Almost seems like that must have been a miscalculation on your part. The cam shafts would never flex by 35 degrees ... maybe a fraction of a degree.

IW

madScientist · « **Reply #70 on:** May 09, 2013, 08:43:09 AM »

Valve clearance was set to zero lash. The only thing I can figure was that, because the cam didn't have the running stress of the rockers, it was flexing some which threw off the readings.

If the cam was flexing or shifting a little it can equate to fairly significant discrepancies on the degree wheel. Oddly enough, installing all the rockers (and setting all to 0 lash) made it easier to degree since the pressure would hold the cam in place. So when the dial gauge read .004 on #1, i loosened the cam gear bolts, turned the engine to 25 BTC and tightened down...where with the single group of rockers i had to back it up to a flat point and change the by the number of degrees off.

This is pure speculation but, I think that because our cam gears are smack dab in the middle of the cam they can be prone to a tad of "wobble" if not set into a running condition. Whereas on a car engine the cam gear is at the end of the cam and firmly fixed inside the bearings.

No expert...pure speculation. Alls i know is that from hence forth on all the bike engines i set a cam in the degree will be set in a running condition (all rockers installed and ready).

madScientist · « **Reply #71 on:** May 09, 2013, 08:44:58 AM »

Oh and I totally agree that the flex likely would not have equated to a full 35 degrees...could have been total miscalculation on my part. I did it several times and each time it came to the same readings.

Doing it in full run condition worked swimmingly...lesson learned and off we go!

madScientist · « **Reply #72 on:** May 09, 2013, 08:55:35 AM »

Now you have me curious...

I have a couple of other F engines that I can test runout and wobble theories on. It'll take me a little while to get around to it though. Getting this to a rideable condition is my first goal since I REALLY want to sell off the VS1400 crazy machine...

madScientist · « **Reply #73 on:** May 15, 2013, 09:33:02 AM »

The 35 degree variance has been officially attributed to crappy instruments. The dial gauge that came in the degree kit was junk. Raising and lowering the needle never landed in the same spot. How the hell is someone supposed to get accurate measures when the gauge is junk?!

To work around the problem I set the valve lash to .04 and rotated to where the rocker touched the valve. All numbers hit where they should have. Then I remembered I had a Starrett dial gauge and did it all over again...numbers hit.
Lessons learned? Dont use crappy measuring tools...

Valve lash is set to .004 and the cam chain slack is now adjusted.

Afterwards I mounted up the Mikuni's...I will need to take them off tonight to open up the insulators a little but I couldn't resist putting them up!

Next up:

-- open the insulators
-- install ignition wiring
-- install loom
-- install the oil cooler

Getting so close to starting this thing I can almost smell it! Oh wait...thats redline assembly lube i smell...

iron_worker · « **Reply #74 on:** May 15, 2013, 10:47:03 AM »

Quote from: madScientist on May 15, 2013, 09:33:02 AM

The 35 degree variance has been officially attributed to crappy instruments. The dial gauge that came in the degree kit was junk. Raising and lowering the needle never landed in the same spot. How the hell is someone supposed to get accurate measures when the gauge is junk?!

I figured as much. ha

Good luck getting that bad mofo running!

IW

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Author Topic: 78 CB750F "Modular-ish" cafe build? (Read 59327 times)