Newbie CB750

Twinstar Joined: Feb 06, 2012 Posts: 169 Location: Germany

Hi all, sorry i have not updated this thread for a while, this is not because I have been to lazy to do so. but because I have hardly made any progress that is worth posting :S

As mentioned in my previous post, I have received pretty much all of the parts that I require re re-building the bottom end of the engine. I cannot start the re-build until I have got ris of all the old gaskets from the engine casings, which is not as easy / nicer job as I had hoped Sad

The gaskets are in the same state as the rest of the motor was and im guessing they have never been replaced. I have read a few tips / tricks to speed up / make removing old gaskets easier, however I decided to just play it safe and slowly keep at it with regular breaks to not risk damaging any of the surfaces etc .... im making (although v-slow) progress Smile

This is the last gasket I have to get rid of:

In the meantime (between gasket fighting) I have managed to start working on some more cosmetic jobs, including sourcing an older (SOHC) tank which I managed to get from Sayonara Cycles ([URL="www.sayonara-cycles.de"]www.sayonara-cycles.de[/URL]) who have some nice bikes - have a look.

The next step for the tank, is to try and get it to fit on my later (DOHC) frame - this will require some fabrication, although (I think/hope) will look good when its done - I love the look / old school style of the older CB tanks... if it does not work, I will have to go back to using the prigional tank and re-think my plans / ideas.

I also managed to get access to a welding machine and finally got my seat unit braket welded up to the frame:

There is a long metal piece (Dowel ???) tightly fitted through the middle of the seat bracket and frame and then all welded up, so it is very strong Smile

I am quite pleased with the result, and hope it looks good once I have (tried) made a custom seat to fit.

Thats about all I have so far... I hope to be finished with the gaskets this week depending on time, give the motor a final cleaning in the parts wash, and get started on the bottom end re-build again.

Posted: Tue Jun 26, 2012 7:42 pm

Nice work! Cliff.

Posted: Wed Jun 27, 2012 1:53 am

Cool project. There's gasket remover available here in the states that comes in a spray can that works fairly well. Perhaps you can get it where you are too. I usually wind up spraying it into a cup and use a small brush to just dab it onto the gasket I want to remove. It's pretty nasty, caustic stuff so be extra careful if you try it. It removes paint as well so watch out for that....

Good luck,
David

Twinstar Joined: Feb 06, 2012 Posts: 169 Location: Germany

txscbf1100 wrote:

Cool project. There's gasket remover available here in the states that comes in a spray can that works fairly well. Perhaps you can get it where you are too. I usually wind up spraying it into a cup and use a small brush to just dab it onto the gasket I want to remove. It's pretty nasty, caustic stuff so be extra careful if you try it. It removes paint as well so watch out for that....

Good luck,
David

Hi, thanks for the info. I have read about such remover and even using paint stripper to remove gaskets. My problem is that I am currently based in Germany, and its not possible (due to both environmental laws and nonsense rules etc...) to buy and use such products (even glues etc...). There are a lot weaker alternatives but these have proved to be pretty useless Sad

I am pretty much finished now with the gaskets, but next time I will do a bit more homework on such products, and see if I can save a lot of time / effort with such jobs !

Thanks for the advice / input, its much appreciated Smile

Posted: Wed Jun 27, 2012 11:43 am

Sorry to be the bearer of bad news but from what i have read on this web site the SOHC tanks will not fit on a DOHC frame without a lot of work (cut and weld job).

Hope it all works out for you as from the initial posts you are being very meticulous and thorough. Best of luck and keep up the excellent work.

Gordon

Twinstar Joined: Feb 06, 2012 Posts: 169 Location: Germany

ozgordy wrote:

Sorry to be the bearer of bad news but from what i have read on this web site the SOHC tanks will not fit on a DOHC frame without a lot of work (cut and weld job).

Hope it all works out for you as from the initial posts you are being very meticulous and thorough. Best of luck and keep up the excellent work.

Gordon

Thanks for the post ! I already have the (SOHC) tank and the (DOHC) frame so am aware of the difficulties Sad

You are right, a cut and weld job is required !!! The question is if it is worth it or not. Usually I would so not, however as I already have the tank I may give it a try and see what happens, worst case I have to scrap this idea and go back to the original tank.

I have seen the mod done before on a couple of bikes which gives me a little hope Smile

Posted: Thu Jun 28, 2012 11:22 pm

Well if your up for it do it as that how new and interesting designs are created and at the end of the day your making your bike with your design and it always feels better when its done that way. Just tends to cost more Laughing

Twinstar Joined: Feb 06, 2012 Posts: 169 Location: Germany

ozgordy wrote:

Well if your up for it do it as that how new and interesting designs are created and at the end of the day your making your bike with your design and it always feels better when its done that way. Just tends to cost more Laughing

Very very true !!! Keep posted to see how I get on and if it works or not (or looks any good) Smile

Twinstar Joined: Feb 06, 2012 Posts: 169 Location: Germany

For anyone interested, I will be doing my best to document my 1983 CB750 F project in (more) detail on the following blog:

http://www.jonathan-williams.co.uk/CB750Project.php

I wil however continue to update this thread as usual until the completion of the project, the blog is mainly for my own personal documentation / diary ...

Twinstar Joined: Feb 06, 2012 Posts: 169 Location: Germany

Sorry (again) for the late reply... I have had not much time recently as I have been travelling back to the UK for holidays, visit friends and family and to attend weddings etc.

Waiting for the ferry in France:

Arriving in England:

Quick stop on the way home from visiting friends Smile

Twinstar Joined: Feb 06, 2012 Posts: 169 Location: Germany

Sorry, back on topic ... I have however found some time to get in the garage and do some work on the bike, but just have not had a chance to update the thread, until now Smile

I had already ordered a lot of engine parts that I "knew" I would need (gaskets, seals, bearings, chains etc etc) but before I could cpontinue, I had to check / test all "other" important motor parts to establish what else needed replacing / renweing. This was a pretty long process (over a week) sat in front of the internet, my manual and all relevant to establish what was good and what was not. It took so long (I guess) mainly becuuse it wa the first ime I have ever done a engine re-build, and also becasue I wanted to get it right (the best I could), hence doing it "by-the-book" :

Once all required parts had been ordered, I used the time while waiting for them to be delivered doing smaller yet important little jobs such as removing any old remaminign gaskets, generally cleaning parts up read for re-assembly and checking all engine casing threads to check they were all good - they were not Sad

I found three broken threads in the motor housing which I guess is not too bad ? These threads needed repairing which was the next job:

All fixed and as good as new:

Twinstar Joined: Feb 06, 2012 Posts: 169 Location: Germany

The lower primary chain tensioner was worn down to the metal (on the edges) :S which I am guessing "could" have had something to do wit the original knocking noise I discovered when I first got the bike started as the primary chain also seemed a bit slack when I first opened the engine casings ??? in any case a new chain and tensioners have been purchased.

I fitted both the primary chain tensioners (upper and lower) to the enigine casings as one of the first jobs before the re-build:

and out

onto the top tensioner

The wear on the top tensioner was not as extreme as on the bottom, however you can see the difference:

Twinstar Joined: May 24, 2012 Posts: 33 Location: UK

Hi mate, one tank trick i have seen online not in the flesh i must add is to paint the bottom section of the tank one colour (say the same as the frame) so Black for example. Then maybe add in a contrast pinstripe of say white then the top of your tank in the main colour you want. Seems effective in a photo (see below)....could look shite in real life mind you!?

Love this thread, keep it up.

Twinstar Joined: Feb 06, 2012 Posts: 169 Location: Germany

Tiki-Al wrote:

Hi mate, one tank trick i have seen online not in the flesh i must add is to paint the bottom section of the tank one colour (say the same as the frame) so Black for example. Then maybe add in a contrast pinstripe of say white then the top of your tank in the main colour you want. Seems effective in a photo (see below)....could look shite in real life mind you!?

Love this thread, keep it up.

Thanks for the post. I have also seen and noticed this method, and you are right, it does create a good effect !!! I also like on these bikes (the CRD bikes for example) is that the bottom of these tanks (later k series) are not straight / smooth and have different lines in comparison to the earlier k series tanks - this techniques seems to overcome this issue neatly and well, and also allows for you to move the ignition down to and build into the bottom of the tank which (I think) is also a nice touch (you can see it in the picture you attached) Smile

Glad you like the thread, thanks again, Jon.

Twinstar Joined: Feb 06, 2012 Posts: 169 Location: Germany

In the meantime, yet another clear up ready for the re-build. I know I keep going on about it, however I personally find that making some (although in my case limited) space and getting everything (tools and new parts) in place and accessible really helps speed up the process and also reduces frustration and mistakes. Saying that, I am also aware of some amazing projects that have come out of the smallest and most unorganised sheds Very Happy

Bootom end engine parts waiting on the shelf for new parts:

Engine cases ready for re-assembly:

Twinstar Joined: Feb 06, 2012 Posts: 169 Location: Germany

I have bought a new primary chain as I was not sure as to what condition it was in (im guessing bad) and I dont have the correct equipment to test / measure it correctly. Therefore I thought (like with most other parts im unsure of) to go new. Next was to check the primary shaft assembly. I have bought new bearings for the shaft, but wanted to check that the rubbers within the shock absorver bady were good, as if not I guess they could make for a "snathcy" feel between the clutch and gearbox during riding....

Ready for dismantling and inspection:

The rubbers looked (surprisingly) good. After taking them all out and inspecting them, none of them seemed damaged, and when assembled, they were tight with no free play. back together again Smile

New bearings and seals for the shaft:

and back together

Twinstar Joined: Feb 06, 2012 Posts: 169 Location: Germany

Next up, gearbox...

I stripped the gearbox shaft (my camera ran out of battery at this point so missing some pics), again replacing worn bearing and seals. I checked each gear for damage, but all looked great !!!

One thing I had not done was to remove the gear change / selector mechanism. I was not going to do so, as I thought I could just leave it in peace and place without disturbing anything, however I had both a new oil seal, and main bearing for the change drum, so had to take (most of) it out after all... Plus it was in need of a good clean.

My make shift parts wash:

and out:

Once out, I gave it all a good clean, fittend the new bearing, seal and also return spring (as mine was looking a little old) and re-fitted the mechanism which went a lot easier than expected.

Twinstar Joined: Feb 06, 2012 Posts: 169 Location: Germany

I had a little time between jobs, so decided to prep the connecting rods the new (green) bearing shells and new connecting rod nuts and bolts Smile

(see earlier posts re checking and getting the correct (color / width) connecting and main bearing shells).

old parts:

new nuts and bolts:

and bearing (left) :

fitted:

Twinstar Joined: May 24, 2012 Posts: 33 Location: UK

Nice work, i see you have gone for the aftermarket gasket set, I was looking at this too as it's soooo much cheaper.

I have read that the aftermarket gasket between the cylinder head and the barrels can sometimes leak and the genuine gasket is recommended. Although that single gasket costs as much as that complete set!

Be interested to see what you think? Maybe compare the old gasket with the new one if it's not in bits?

Twinstar Joined: Feb 06, 2012 Posts: 169 Location: Germany

Tiki-Al wrote:

Nice work, i see you have gone for the aftermarket gasket set, I was looking at this too as it's soooo much cheaper.

I have read that the aftermarket gasket between the cylinder head and the barrels can sometimes leak and the genuine gasket is recommended. Although that single gasket costs as much as that complete set!

Be interested to see what you think? Maybe compare the old gasket with the new one if it's not in bits?

Yeah, I went for the aftermarket kit mainly because it includes so much for such a good price (even if not all of it is used etc....), however its good you have mentioned this, as I have also read a few negative comments re the aftermarket kits, although I have also read a lot of very good comments too. Re the Cylinder gaskets, I am still not 100% sure if to go with the aftermarket gasket or not !?!? I guess I will have to do a little more research !

If you or anyone else has anymore info on this, or links to any articles / user experiences, they are much appreciated !

I am in a similar boat with the valve seals, what seemed to be valve seals were included in the gasket kit, although there were only 8 (16 required) and the valve stem hole appeared slightly too large - im guessing these are for something else ? In any case, the original Honda valves are (im guessing) good, however expensive (8 Euros each) !

in a previos post in this thread (feels like ages ago now) - DrOlds mentioned:

Quote:

... install new valve seals, there are viton ones available but the ones in the Veshra engine gasket kit are fine ...

and genesound mentioned:

Quote:

.... I strongly suggest trying the Viton valve stem seals from US Seal that member Jebbysan here is selling. They aren't real expensive with his special buy (about 1/2 of market price) and I think they're a newer and better compound and a better molding job than what was available when these bikes were new. These motors also tend to run quite hot and turn all the rubber parts in the motors to fossils far too quickly, and Viton stands up to it much better than the old materials of 30 years ago. See the for sale section, I think, or PM Jebbysan for details...

I think I will look into the Viton seals available and see how much it costs with postage to EU !

If anyone knows what the 8 (grey) valve looking seals are in my gasket kit, please let me know Smile

Cheers,
Jon.

Twinstar Joined: May 24, 2012 Posts: 33 Location: UK

ljonny18 wrote:

In any case, the original Honda valves are (im guessing) good, however expensive (8 Euros each) !

You think thats expensive, david silver in the UK want 19 Euros each!!!!

Im interested in the Vitron seals too so let me know how you get on. Where do you source your parts in the EU then? as I only use David Silver and the dreaded E-bay, i've been so messed about on ebay with parts though it's crazy.

Cheers

Twinstar Joined: Feb 06, 2012 Posts: 169 Location: Germany

Tiki-Al wrote:

ljonny18 wrote:

In any case, the original Honda valves are (im guessing) good, however expensive (8 Euros each) !

You think thats expensive, david silver in the UK want 19 Euros each!!!!

Im interested in the Vitron seals too so let me know how you get on. Where do you source your parts in the EU then? as I only use David Silver and the dreaded E-bay, i've been so messed about on ebay with parts though it's crazy.

Cheers

I have also used David Silvers for a lot of stuff and can recommend them !!! They know there stuff and are friendly !!! 19 Euros is v-expensive though for valve seals - thats over 300 Euros for all 16 ?!?!? can that be ?

In EU I also use "CONSOLIDATED MOTOR SPARES B.V., NETHERLANDS (CMSL)" - they deliver worldwide, are reasonably priced and are fast at sending things out !!! Although, they are only an online shop, you have to know what you want as you cant speak to anyone - not like David Silvers... the CMSL website is:

http://www.cmsnl.com/

Although, I must say, you cant go wrong wit DS especially if you are based in the UK.

Twinstar Joined: Feb 06, 2012 Posts: 169 Location: Germany

Next step.. more cleaning Smile

I pretty much cleaned all parts before reassemble of the bottom end, e.g. cleaning the crank shaft :

After all new parts had been fittet to their relevant components, and all major parts and components were all cleaned up, I started the reassembly.

First up was to bit the new main bearing shells (brown) to both engine casings (I have already fitted the rod bearings):

Not forgetting to add a bit of oil to the casings before putting the shells in place:

Top half complete:

Onto the bottom half:

And the bottom casing bearing shells fitted:

Twinstar Joined: Feb 06, 2012 Posts: 169 Location: Germany

Once all the bearing shells were in place and the engine casings were all prepared, the next step was to out all the internals (gear box, primary shaft, crankshaft etc ... ) back in.
This process went very quickly and very easily... I was (for some reason) expecting it to be a lot more difficult and time consuming than it actually was.

After all internals have been re-added, complete with new primary and cam chains:

Twinstar Joined: Feb 06, 2012 Posts: 169 Location: Germany

Because I am not very prepared, I did not have any sealant to put between the two engine casing halves, and because it was a Sunday and everything over here is closed on a Sunday I had to wrap the motor up in plastic sheets to keep it clean and protect it until I could get hold of some sealant (hopefully the following day).

In the meantime, I cracked on with some outstanding smaller tasks that needed to be done, including stripping and inspecting the clutch and plates:

And the result is (as expected) all clutch plates need to be replaced, however I probably would have replaced them all anyway at this stage Smile

I also took apart, inspected and cleaned up the oil pump:

Which was all good, however that gasket was the hardest I have had to remove so far Sad

Twinstar Joined: Feb 06, 2012 Posts: 169 Location: Germany

The following day, more goodies arrived in the post (although without checking im not sure what everything is for) :

Although, I know what these are Wink

Twinstar Joined: Feb 06, 2012 Posts: 169 Location: Germany

Old piston rings removed:

cleaning up the pistons (as best as possible) - this took most of the day :S

Half way through cleaning:

and, although not perfectly clean after cleaning, the pistons do look in good shape !!!

I managed to make some good progress and fitted the new piston rings to the pistons with no major problems. I then fitted the pistons to the connecting rods (using new clips) and finally the rods to the crank and got them all torqued up correctly Smile

Twinstar Joined: Feb 06, 2012 Posts: 169 Location: Germany

Luckily, my neighbour works at the local Mercedes garage, and managed to bring me back some "proper" motor sealant for the engine casings, so I could finally crack on getting the two halves together :

First off I put the gear box into 1st gear, and manually aligned the gear selector up to fit. I then applied the sealant to the correct surface areas of the two engine casings before putting them together. once together I torqued all the casing bolts up to thew correct torques settings.

Twinstar Joined: May 24, 2012 Posts: 33 Location: UK

Nice work, Im about at this stage now too but am stumped at how I am going to get the pistons up into the barrels?

I've seen people use piston ring clamps but they always seem to do it by dropping the lose individual pistons through the barrels from above.
Whats the easiest way to lower the barrels onto the pistons? It looks like you cant use the ring clamps so its a two man job and a tricky one at that!

Twinstar Joined: Feb 06, 2012 Posts: 169 Location: Germany

Tiki-Al wrote:

Nice work, Im about at this stage now too but am stumped at how I am going to get the pistons up into the barrels?

I've seen people use piston ring clamps but they always seem to do it by dropping the lose individual pistons through the barrels from above.
Whats the easiest way to lower the barrels onto the pistons? It looks like you cant use the ring clamps so its a two man job and a tricky one at that!

Hi, I have not got that far, and have not (yet) really thought how I am going to do this Smile

but for sure I will let you know how I do it and how it went !!! If you get round to doing yours first, please do let me know also - PS, do you have a thread / any pics of your build ? Im always interested in bike builds, especially similar ones to my own Smile

In the meantime, DrOlds has posted previously in this thread with some tips re getting the pistons into the barrels !!! I have not heard form him recently, are you still out there DrOlds ?

I will re-post his comments below, I hope they help:

Quote:

DrOlds: The deposits on the oil pick up screen look like RTV / sicilone from a sloppy job on the valve cover and / or chunks of the cam chain guides. When reassembling the front guide before setting the head on make sure it is in the correct pocket on the bottom. You can tell because you will see the little casting rib (runs front to rear) when you look down the center tunnel with a flashlight. The rear tensioner has to go in the head before the head goes on. I find it easier to use a ring compressor and put the pistons down from the top BUT if you want to use the tapes on the base of the cylinders put the pistons in first (with the rod caps off). It is a bitch trying to drop the cylinders down while putting 2 pistons into the bores while working between the studs. The big o-rings go into a groove where the cylinder liners sit in the cylinders. Dig out all of the old ones and pack the new ones in.

Quote:

DrOlds:
If you go to "supersport pictures" and SteveG's 81 CB900F thread:

http://www.cb1100f.net/modules.php?name=Forums&file=viewtopic&t=54027&start=60

On page three you can see the pistons sticking out of the cylinder before he set it on the upper half of the cylinder case. He then connected all the rods (use locktite red on the rod nuts) and assembled the case halfs after that...this eliminated all the problems with trying to drop the cylinders down while trying to get the pistons and rings into the cylinders while working inside the cylinder studs.