Restoration of a 1990 R100gs

Hello All

I am a "diyer" and have decided to rebuild my GS which had been looking a little tatty and with around 80k on the clock was I feel going to start letting me down in a big and expensive way. My rear wheel would also not revolve backwards so some inspections were necessary

I am happy to post details of my mechanical adventures to include photos so as to share the journey - if any one is interested. As well as looking on line (eg Chris Harris & Boxer 2 valve videos) I also refer to Haynes, Clymer and when my concentration permits, Snowbums articles.

Other than reference to these resources, accumulated knowledge through rebuilding my R100rt (which I have owned for the last 16 years and love) and rebuilding and converting an r65 in to a bobber, I have no other experience. Accordingly, I don't expect this journey to be entirely straight forward and I am happy to share my mistakes as well as my successes in the hope that sharing my frustration may at the least be a little cathartic if not informative. As I have no formal training please do not rely on any thing I may do as indicative of how you should approach your own repairs.

The story so far is that the bike has been fully stripped, the frame powder coated and I have painted (with hammerite smooth coat) the triple trees and fork bottoms. I have also:

1. Replaced the steering head bearings
2. Polished the front wheel
3. Replaced the front disc with a Siebenrock 320mm disc
4. Replaced the brake pads -note I have not rebuilt the caliper as I rebuilt it about 6 months ago.
5. Rebuilt the forks - all seals replaced, new stanchions and new gaiters.

Things I have learnt:

a) The bearing races are difficult to remove - when I replaced them on the swing arm of my rt, I welded a bead around the race which forced the race to contract. The races then just fell out. On the triple trees, I used a cycleworks puller -really the only bit I needed was the split washer as once it expanded I could drift them out.

b) I replaced the bearing on the lower yoke by putting the lower yoke in to the freezer for a few hours and then heated the bearing with a butane torch. The bearing just slid right on and did not need to be struck (never a good idea to hit bearings). I greased the bearing when it was still hot which really helped to get the grease in to all the individual rollers. Please note that I adopted this procedure having watched one of Chris Harris' videos which are extremely useful.

c) Hammerite smooth looks the business - when several coats are sprayed on. It is hard to distinguish from the powder coated parts. It obviously doesn't wear quite as well and of course an appropriate primer must be used when spraying on to alloys.

d) to get the fork gaiters on, soak the bottom end in very hot water -also I noted there was a hole in the top of the gaiter (to allow air to escape when the fork is compressed) but none at the bottom. Should water ingress it would therefore have no means to escape. I blocked the top hole with black gasket sealant and used a hot drill bit to put new holes in the bottom of the gaiters - I guess this means some dirt might get in but that is how the original gaiters were set up and I never had a fork seal fail nor had the lower ends of the original fork stanchions suffered any corrosion.


I am not sure how to safely upload photos from my computer but would like to know how to do so, so I can post photos of the project as its going along. I see the post image icon but it refers to a url link so am not sure with me not being too computer literate.

Cheers for now

David

Good man! Looking forward to it.

"I am not sure how to safely upload photos from my computer but would like to know how to do so, so I can post photos of the project as its going along. I see the post image icon but it refers to a url link so am not sure with me not being too computer literate."

Follow this route: Go Advanced/Manage Attachments/Choose File/Upload/Close this window/Preview post ...

Photos of project to date as referred to in my initial email - thank you Oblertone

Once he learned a new trick he thought he'd try it again!

Further photos - bobber R65 project completed and R100GS prior to commencing works.

If you have removed the swinging arm bearings I would replace them with the stock taper roller fitted to the mono bikes - it is possible, but needs a shield at the back to hold the grease and spacers somewhere - the information is out there somewhere.

Have a good look at the pivot pins too, as there is every chance the bearings have been turning on them, particularly the drive side.
Moteren Israel make slightly oversize pins which hold the bearings a bit tighter.

Decent pads help the brakes a lot, EBC HH 100s are excellent, and any decent brake shop will be able to sleeve your M/C down to 11mm, if you want a brake that works.
FWIW the highly touted Lucas/TRW pads were the worst pads I have ever fitted to a bike, but some folks like them.
Soft braided lines will give you a nice feel to the lever and a more progressive action.

Your bike seems to have a rather extreme angle on the drive shaft which will cost you a fair bit power, and with a dry drive shaft the heat will dry out the UJs PDQ.
Emerald Isle make a rebuildable drive shaft and solid bushes for the pivot joint in the paralever, worth fitting if you intend doing and serious work on the bike.
The splines at the rear of the drive shaft need the best lube you can find, at least 60% moly, or they gall and lock the suspension, which doesn't do the UJs or the gearbox bearings any good.

The stock #80 spring at stock settings, 18 mm preload, on the Ohlins works well at the rear, fork springs which give around 10% more rider sag at the front complete the set.
With them in the forks you will need little compression damping, but a bit more rebound , which can be dialed in with the fork oil as the damping is in separate legs.
FWIW the single adjuster on the Ohlins sets both comp and rebound damping, something it seems few have discovered, and those that have discovered that there is no such thing as a truly progressive spring are even rarer, so be careful who you take suspension advice from!

Have fun , and don't take anyone's advice too seriously , everyone gets different results from the same thing and everyone thinks they are right!

Snowbum has a tech site which covers just about everything mechanical in great detail , and is compulsory, if not particularly easy, reading for most things mechanical / electrical.

Richie Moore at Moorespeed ? specialises in these bikes, he has some good bits and advice, and he has the runs on the board too, his sidecar bikes sweep the field.

Thank you for your message Beemerboff.

I replaced the bearings with stock BMW - I have a story to tell about replacement of stock pivot bearings on the bevel drive with an aftermarket part which did not work out! I caution against the use of the solid pivot with grease cup as a replacement - I had a cup split on me and it got caught in the drive shaft - I will elaborate more in another instalment during the build. Needless to say I did not over torque - the part failed and is IMHO a bucket of sh*t and should not be on sale - better to replace the bearings every 10k or 15k -much safer -trust me I 'm a lawyer!

I have replaced the pads with decent stock. I will note your suggestion on pads however and try them noxt time. Not sure what you mean by sleeving - do you mean the rear drum as integrated into the back wheel?

The angle of the bike is somewhat lessened when I park my 18st on it! and has a good geometry with the front. It is an ohlins shock which was designed for the bike. I have replaced the driveshaft previously and it is the rebuildable type with grease nipples on the UJ's. It has rubber bushes in it which can be replaced - I thought I was buying the best (spent over £450 on the shaft) and it will have to do for the moment - will look up Emerald Isle than in another 40k (which will only take me about 3 years -less if I don't use other bikes so much) so many thanks for the recommendation

Richard is a good source of information and his high spec bikes are not dissimilar to what HPN can do - also Gary at BaMW in Derby is getting mentioned quite a bit.

Many thanks for your suggestions which are very useful indeed.

Kind wishes

David

Just found this thread Dai. Tidy mun , I look forward to following this.

Tinytim said:

Just found this thread Dai. Tidy mun , I look forward to following this.

Click to expand...

Many thanks - I hope to make some progress with the gearbox this week

Gearbox - "every man must know his limitattions" - Dirty Harry

Hello

I previously tidied up the gearbox and wanted to replace the 2 main seals (input and output) as well as the lever seal.

I used a puller from Cycle works -photo attached and after a bit of effort got the flange off and removed the housing.

I gave the box a good inspection - selector forks seem fine as does the nylon wheel and pawl springs. I note that the layshaft helical gear has some wear but should last a few thousand miles yet.

In terms of the output seal, the flat side must face out c/f where the seal is used on gearboxes for other models. Haynes recommends pre shaping the seal to allow for the speedo drive but Clymer makes no such mention. I did not pre-shape so time will tell which book was correct.

Removing the old gasket was the usual pain but got her nice and clean before putting the new gasket on.

I think in the long term I will look for a reconditioned box -preferably one with a kick start but what I have will certainly do for the moment.

I have also stripped, replaced all seals and gaskets and rebuilt both carburettors as well as replaced the main seal in the engine as well as the clutch - with a heavy duty oil resistant one. Replacing the main seal was expensive due to the cost of the tool to fit it but I decided to buy the driver due to the very limited tolerances on the seal depth.

I am considering whether to make any modifications to the engine, in particular,:

1. An asymmetrical cam shaft and
2. High compression pistons.

Has anyone carried out either of these modifications and what did they think?

I also run a Yamaha Super Tenere and I think that no matter what modifications I do, the old girl will never keep up with a S10 (or of course modern GS) - am I worried? - Of course not. What I want my GS to be is a solid workhorse - capable under arduous conditions and relatively uncomplicated should she breakdown in foreign pastures where garages may not be so sophisticated - perhaps a hallmark of a capable adventure bike?

Thank you reading this and of course, comments are welcome.

David

Great write up David, I’m hooked

Oldrat said:

Great write up David, I’m hooked

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Many thanks

Engine mods.
I have built a few warm motors over the last few years.
A couple of 860 seibenrock ones with the 336 cam,,very nice,powerful and revvey.
An 1070 with enduro cam(299??) very torquey and as fast as you’d need from a gs.
Two Rs spec motors,heavy and light flywheel,with 328 cams and Richie Moore pistons.
Plus a couple of R100gs just with the RM omega pistons.
Also a Rs with RM pistons and 40 mm delorto pumpers(Oe cam).
The High comp pistons combined with the cam make for a really nice motor,lots of mid range and willing to rev out.
The next warmish motor I build for a special will have the pistons,cam and the rorty forties.

"We are standing on the shoulders of giants" (Issac Newon)

mikeyboy said:

Engine mods.
I have built a few warm motors over the last few years.
A couple of 860 seibenrock ones with the 336 cam,,very nice,powerful and revvey.
An 1070 with enduro cam(299??) very torquey and as fast as you’d need from a gs.
Two Rs spec motors,heavy and light flywheel,with 328 cams and Richie Moore pistons.
Plus a couple of R100gs just with the RM omega pistons.
Also a Rs with RM pistons and 40 mm delorto pumpers(Oe cam).
The High comp pistons combined with the cam make for a really nice motor,lots of mid range and willing to rev out.
The next warmish motor I build for a special will have the pistons,cam and the rorty forties.

Click to expand...

Many thanks Mikey

You have given me plenty to think about.

I am yet to replace a cam so should be an interesting task - I know that the cam and crank sprockets are marked and you need to align the marks when replacing the timing chain so I guess noting the position of the woodruff key slot in relation to the cam sprocket mark (assuming the sprocket is put on a new cam in the same position that it came off) will help to ensure correct timing is preserved. This is something I will have to research further before I grasp the nettle.


I think if I am going down the modification route, I will be to replace the cam and go for the Omega pistons and retain the bing carbs but with a larger main jet. RM markets a pack so I will try to contact him to discuss. Alternatively I will just fit a new timing chain and ancillaries.

What is evident is that there are a lot of highly skilled people out there who are prepared to assist an amateur like me and I am most grateful for your input.

Turning to matters more within my pay grade, I also need to try to polish up the exhaust system - something which won't involve and grey matter whatsoever (and not much expenditure) - I will post some horror to beauty pics and this will give readers a chance to consider where my life went wrong - surely it can't all be explained away by a severe blow to the head.

I have started on one section of the exhaust already, an upper manifold and have spent a couple of hours on it to date. I am using Promax metal polishing compounds and a wool pad attached to an angle grinder. I reckon it will take at least another 6-8 hours of polishing to get the system looking smart.

At least this will give me some further time to consider whether and if so, how best, to replace the cam as well as how patient can I be.

Once again thank you for your input Mikey and thanks to anyone else who takes the time to read my account.

David

Im always in awe of people who can do this. Brilliant

Great thread, subscribed.

Re high comp pistons, I've got the impression from reading other threads that they may not work so well if you are travelling in some of the less developed countries with low octane fuel.

If you go down the modification route your plan to speak to RM and get a package is sound, he will know what works with his pistons, and what you will need to do get the most benefit from them. Like air boxes and exhausts.

A previous poster on this forum had Richie's help with a warm motor, including head work, and while he could not have been happier with the motor, if the extra performance was utilised in full it only served to emphasize the shortcomings of the rest of the running gear.
FWIW CV carbs spend little time on the main jet, for just about the only RELEVANT tuning advice on Bings do a search on - Mike Fishwick Bing - and hopefully you will find his pages and sage advice.

From Kettle738 in the other thread...

Thanks for posting the reference to Mike Fishwick, found his technical bulletin here.

http://www.vintage-register.co.uk/li...CV Carbs.pdf

Mick.

B Murr said:

Great thread, subscribed.

Re high comp pistons, I've got the impression from reading other threads that they may not work so well if you are travelling in some of the less developed countries with low octane fuel.

Click to expand...

The high comp pistons can cause a bit of pinking if the timing is over advanced,I find posh fuel helps.
I would not recommend going down this route if the bike is heading for areas without a decent fuel supply.
Best off spitting with standard comp ratio

All that glisters is not gold ("The Bard")

mikeyboy said:

The high comp pistons can cause a bit of pinking if the timing is over advanced,I find posh fuel helps.
I would not recommend going down this route if the bike is heading for areas without a decent fuel supply.
Best off spitting with standard comp ratio

Click to expand...

Many thanks to those that have posted replies - clearly there is a wealth of information out there and I am a poor man!

I have been trying to polish up the exhaust system and have so far spent a few hours on one of the headers.


Below is a picture of how she looks after a few hours, alongside her dirty sister. I also attach a photo of the compound I am using and the type of pad. I got 10 pads for under £5 and the compounds came from metal polishing supplies - all through ebay.

I don't think I m going to make much more progress this week on the bike other than further exhaust polishing as I have to check the valve clearances on my S10 and as this is new to me, will no doubt take a couple of days.

I did however previously change some of the seals on the GS bevel drive and hope to post some photos of the problems I encountered along with a short narrative on my experience of after market bevel drive to swing arm pivots to which I alluded in previous postings.

Thank you for reading this post.

David