Topic: Frame mod cb 750

[PeWe]

No turnin back now mate

Almost...
But it look turned back 
Look really good and more technical than before 
Tight fit. I had to grind the paint off completely. Pipes at rear cut were slightly oval which caused extra tight fit. I had to grind extra and used valve lapping compound under the clamps that I rotated around to grind them to looser fit. The lapping compound is still visible not cleaned.

The front cut area can probably be covered by a thin layer of primer but I think I'll use copper paste to rub into the metal surfaces. Maybe use heat gun and give it a burn into the metal to avoid future rust. I'll might find something else.

Soon continue to make the top end work I need to do.
It will be much easier to switch cam... and mor fun...
Cam timing: It must be possible to have bike on a jack/wood support (I have no center stand)
Rotate the rear wheel with 1:st or 2:nd gear in to move the crank (no plugs). Degree wheel on ignition side and no need of open alternator cover.

[Nic]

When I did mine one of the rear frame tubes must have moved a bee's dick after the cuts and it was a wrestle to get the last rear clamp on, while I could get them on with a lot of effort I decided to cut the bottom of the triangle, I then fitted all 4 clamps, tack welded the bottom triangle, took the whole H section off and finished welding the bottom triangle, the clamps fit very easy now.
 It was only out .5 mil but it made it hard to get the last rear clamp on. Out of round tubes would be more drama than what I had to go through. Good luck with that.
I took my gear selector cover and alt cover off to do cam timing. It wasn't too much effort. I left the alt wiring connected and just suspended the cover to the frame with some wire. Only a small amount of oil came from the gear selector cover. My engine won't even turn over by the points nut so I did it via the alt.
The biggest PITA I reckon is using the hex key on those 20 bolts, after a while it get's to be quite painful and slow so I welded hex keys into 1/4" drive sockets and made a Tee bar from a 1/4" drive extension. The way to go. While I was at it I made up another socket with the #3 impact bit.
Frank used imperial bolts unfortunately, my only complaint.

[timbo750]

Nic, glad you mentioned this. I cut ny frame on the weekend and noticed the frame moved slightly with the rear cuts also. I was not going to do anything about it as I was only cutting pre powder coating, but now I will definitely try to fit first and will cut and weld the lower if I need to.

Project 1 CB750 - http//forums.sohc4.net/index.php?topic=126864

[Nic]

Nic, glad you mentioned this. I cut ny frame on the weekend and noticed the frame moved slightly with the rear cuts also. I was not going to do anything about it as I was only cutting pre powder coating, but now I will definitely try to fit first and will cut and weld the lower if I need to.

Project 1 CB750 - http//forums.sohc4.net/index.php?topic=126864

I wouldn't weld up the triangle on yours until I had the bike together, ie, with engine in and wheels on so that all the stresses that will be on the frame are before you fit the H section. So I reckon cut the bottom triangle and get The H section powder coated as two pieces and weld it back together later.

[chewbacca5000]

These things are freaking awesome you rock star!  Another thing to ad to my MC wish list.  Nicely done.  Now when are you going to make a kit so swap out entire engines at a will? 

[754]

The oval or out of round tubing, was certainly a surprise, had not considered that. Please tell what year /month, that frame is.
 Best to measure the tubing before hand. Powdercoat will need to be partially sanded off.. The triangle brace in the middle, would have to pull the tubing on some frames, a lot of pieces coming together, and that is probably welded after everything else.
 Thanks for the detailed. Info, and report.

[PeWe]

The oval or out of round tubing, was certainly a surprise, had not considered that. Please tell what year /month, that frame is.
 Best to measure the tubing before hand. Powdercoat will need to be partially sanded off.. The triangle brace in the middle, would have to pull the tubing on some frames, a lot of pieces coming together, and that is probably welded after everything else.
 Thanks for the detailed. Info, and report.

The ovalness was not that much, needed some additional grinding compared with front. The clamps fits like machinery parts. My bike was imported to Sweden October 1976, frame no 25795xx.

One very interesting detail here. My frame was also a little bit out at rear. I thought the frame had built in stress forces after a minor crash back in the days. Easy to bend by hand and fit the clamps.

My procedure:
I started to measure and drill the 2 holes on each side on the triangular bracing. Test mounted the brackets and tightened the screws.
(I had to shorten the upper part of the brackets about 3mm when I had done holes for grounding my ignition that interfered with the lower hole for the bracket.)
Removed the brackets and cut the bracing in the middle of the 2 holes. Then cut frame pipes. Front cut first, then rear. I used hose clamps just for sure as guide for the tiger saw. I had a cloth covering the engine and KN filters plus a piece of alu to protect the bike for the blade. (Harness,, carbs etc must not get hit by a blade going wild)

About the bolts... I bought a cheap allen tool, inch
http://www.biltema.se/ProductImages/10/large/10-1020_l.jpg

Clamp bolts are close to the allen mm heads
I use a screw driver like this: http://img.directindustry.com/images_di/photo-g/screwdriver-type-ball-end-allen-keys-88203-6477155.jpg
Inch allen tool for final torque

[PeWe]

....................
I took my gear selector cover and alt cover off to do cam timing. It wasn't too much effort. I left the alt wiring connected and just suspended the cover to the frame with some wire. Only a small amount of oil came from the gear selector cover. My engine won't even turn over by the points nut so I did it via the alt.
.................................

I'll try to do the cam timing without removing the alternator cover.
Degree wheel on ignition side (I'll lift off the Pamco plate and let it rest around the corner, give it more cable)
Move the crank by turning the rear wheel and gear in.

Edit again:
I'll use my small degree wheel again since it fits perfectly as I hoped after adjusting the center hole up to 14,5mm or so. There is not much more space for a bigger wheel anyway. (Brake pedal)
One more thing: Next timing session is to check how the cam was timed before removal. Piston stop is NOT possible when valves are moving! Bent valves..must be a result in my theory Piston stop is to be used before the sprocket is bolted on the cam/rocker arms mounted.
I have to turn crank to T mark on 1:4, zero the degree wheel and lock the nut. Then measure the cam.  Remove cam, do the planned job and time cam again but ~3 degrees advanced compared with before.

All easy done thanks to the frame mod kit.

[timbo750]

Nic, glad you mentioned this. I cut ny frame on the weekend and noticed the frame moved slightly with the rear cuts also. I was not going to do anything about it as I was only cutting pre powder coating, but now I will definitely try to fit first and will cut and weld the lower if I need to.

Project 1 CB750 - http//forums.sohc4.net/index.php?topic=126864

I wouldn't weld up the triangle on yours until I had the bike together, ie, with engine in and wheels on so that all the stresses that will be on the frame are before you fit the H section. So I reckon cut the bottom triangle and get The H section powder coated as two pieces and weld it back together later.

Nic, thanks for the advice. I tried lining it all up by hand and noticed both the rear frame tubes (bits still attached) move outwards and not very much. this suggests to me that I actually want to move the frame tubes inwards not the removed tubes outwards and I know I can achieve this when it all go back together. Hopefully the will be of to the powder coater today.

[PeWe]

First time removing valve cover, engine still in frame and almost everything on.
The hole in the triangle bracing is useful for dial gauge. Found that when thinking about where to place the magneto foot not needed.

Time cam need running around the bike, measure valves on 1, degree wheel on ignition side. Just veirfy when IN/EX open/close. Remove everything on head, replace long cyl studs inside valve cover one by one, use newer higher 10.9 grade nuts, check that all 4 o-rings are fresh under cam towers with rocker arms that I'll replace too. So convenient to not take out the engine.

[PeWe]

I had to test the frame mod!
Head off today
Lenghts of front frame cuts OK, did not obstruct the removal of head nuts.

Started to replace all HD studs that were over torqued due to bad torque wrench. I had to tighten 35-36Nm to move torqued nuts (26ft lbs) with my new wrench. Kibblewhite cyl studs going in. New had calibration report at 35Nm as proof. I'll torque head with 28-29Nm 20.65-21.4 ft lbs.

[BPellerine]

must feel good to be able to do that without removing the engine!and the kit is easy to use!bill

[PeWe]

Yes indeed.
This was the main reason of doing the frame mod. I had a rework to do. Check small o-rings under cam towers that were OK and replace studs when I snapped one that I replaced. Got 2:nd thought about replacing all when I read about one guy that did the same and one more stud snapped when driving that ruined the engine. Time the cam again was another thing. Advance it.

Testing other cams will be easy and fun.

[Don R]

 For the tool guys out there, a rigid brand 1" mini tube cutter will cut the tubes nicely, perfectly round and no filings.  A 3 wheel cutter would work also, most larger tubing cutters won't swing the full circle.

[750K]

Good to know Don R, I had already considered a tube cutter. Have one that's seen lots of use over the years, they work great.

[754]

Got a few kits left if anyone needs one..

[timbo750]

Just got the frame back from the powder coaters and will post photos with the frame kit installed on.

Project 1 CB750 - http://forums.sohc4.net/index.php?topic=126864

[Bailgang]

I finally got around to installing Franks frame mod on my F2 this morning, I followed Don R's tip on using a 1"mini cutter to cut the frame tubes and all went well and everything fit perfectly. Not only does the kit allow you to do top end work without removing the engine from the frame but it makes getting the engine in the frame in the first place sooooo much easier. My youngest son stopped by later this afternoon to help me swing the newly rebuilt engine back in and it went in the frame with ease thanks to the frame kit.

[754]

One concern people have had is not wanting to cut an early frame.
 With  the weldless aluminum frame kit, there is two cuts on the long tubes and one on each side of the brace. ..no further material cut off the tubing.
 Therefore, at this point, welding the frame back to stock is quick and simple. Once you start cutting off sections of tubing, good luck trying to go back to stock..
 Another concern is weight, why add extra weight to your frame.

[750K]

Hey Frank, did you ever get around to making that left side double motor mount? Just remembered it, been sidetracked with other things than motorcycles this summer and forgot all about it.

[754]

Pm sent.

[Don R]

Just a tip oval tube can be rounded with a crescent wrench, just adjust it to the correct diamater and rotate it around the oval tube, it will squeeze where it needs to, adjust as needed. It's a feel thing, so take your time.

[VB-SLE]

Got a few kits left if anyone needs one..

I would like to grab a kit please, how much would the total cost be including postage to Australia?

[754]

Will get total price for you later today, thanks.

[CB750F2]

Frank, I would like one of your frame kits. Please advise total price to Australia - post code 4807. How is payment made? PayPal? Thanks, Pat