Author Topic: 750 DOHC Project (Read 26708 times)

somesuch · « **Reply #75 on:** May 22, 2012, 06:57:20 AM »

BTW, plastigauge the motor with the old bolts, this way the new bolts get torqued only once.

ljonny18 · « **Reply #76 on:** May 25, 2012, 01:14:30 AM »

@somesuch - good tip, thanks a lot !!!

-------------------------

Ok, most of my parts have now arrived. There were some (I think seals that were not possible to get hold of as they have been discontinued ... I will have to look into this further as and when I get to them etc ... ) :

Hopefully progress can start to now pick up again

somesuch · « **Reply #77 on:** May 25, 2012, 07:34:53 AM »

let the progress begin

how are the gear dogs/slots/shift drum/shift forks?

somebody was selling Viton valve seals on the cb1100f.com for very cheap, they hold up to heat much better than stock

ljonny18 · « **Reply #78 on:** June 26, 2012, 10:53:52 AM »

Quote from: somesuch on May 25, 2012, 07:34:53 AM

let the progress begin how are the gear dogs/slots/shift drum/shift forks?

somebody was selling Viton valve seals on the cb1100f.com for very cheap, they hold up to heat much better than stock

@SomeSuch - they all look alright, I will check the all again properly (according to my book

) before I put them back in !!! Cheers !

ljonny18 · « **Reply #79 on:** June 26, 2012, 10:54:19 AM »

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

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

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 (www.sayonara-cycles.de) 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

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.

Roach Carver · « **Reply #80 on:** June 26, 2012, 11:55:45 AM »

looking great. That gold is my favorite CB color.

ljonny18 · « **Reply #81 on:** June 26, 2012, 12:05:11 PM »

Quote from: Roach Carver on June 26, 2012, 11:55:45 AM

looking great. That gold is my favorite CB color.

Thanks man

although im not sure if I will keep the gold color :S

ljonny18 · « **Reply #82 on:** July 11, 2012, 01:38:02 PM »

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 ...

ljonny18 · « **Reply #83 on:** August 20, 2012, 03:08:27 PM »

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

ljonny18 · « **Reply #84 on:** August 20, 2012, 03:10:17 PM »

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

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

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:

ljonny18 · « **Reply #85 on:** August 20, 2012, 03:28:25 PM »

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:

ljonny18 · « **Reply #86 on:** August 22, 2012, 05:02:12 AM »

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

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

Engine cases ready for re-assembly:

ljonny18 · « **Reply #87 on:** August 22, 2012, 05:02:56 AM »

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

New bearings and seals for the shaft:

and back together

ljonny18 · « **Reply #88 on:** August 22, 2012, 05:03:47 AM »

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.

ljonny18 · « **Reply #89 on:** August 22, 2012, 05:04:30 AM »

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

(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:

ljonny18 · « **Reply #90 on:** August 23, 2012, 11:57:03 AM »

Next step.. more cleaning

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:

ljonny18 · « **Reply #91 on:** August 23, 2012, 11:58:49 AM »

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:

ljonny18 · « **Reply #92 on:** August 23, 2012, 02:53:29 PM »

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

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

ljonny18 · « **Reply #93 on:** August 23, 2012, 02:54:45 PM »

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

ljonny18 · « **Reply #94 on:** August 23, 2012, 02:55:41 PM »

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

ljonny18 · « **Reply #95 on:** August 23, 2012, 02:57:11 PM »

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.

ljonny18 · « **Reply #96 on:** August 24, 2012, 09:51:35 AM »

Bottom end complete - all sealed and torqued up and looking good

All wrapped up while I continue other jobs and eventually move onto the top end:

ljonny18 · « **Reply #97 on:** August 24, 2012, 09:52:55 AM »

I have spent some time previously cleaning the cylinder up, and now it was time to prepare the cylinder head for cleaning and inspection, which is not looking too hot at the moment:

The first step was to remove and inspect the valves:

ljonny18 · « **Reply #98 on:** August 24, 2012, 09:53:58 AM »

The next step was to remove (and bin) the chain tensioner ...

and start the cleaning process:

ljonny18 · « **Reply #99 on:** August 27, 2012, 01:09:10 AM »

I now have all the top end all cleaned up, along with the engine casings / covers. I am really happy with the results, especially considering the state it was all in before:

before:

after:

Cylinder Head:

Cylinder:

Casings and Covers:

Most of these parts will be being painted...

News:

Author Topic: 750 DOHC Project (Read 26708 times)