Ontic's 1981 R80G/S build-up thread

[Sibbo]

The timing has to be out mate, those things are a doddle to start if things are right .The right maggy ? How about installing a coil if all else fails ...a few of the Brit bike boys do it . A better spark at low revs .

Good Luck !

Originally Posted by ontic

thanks mate, yep, twin cylinder 2-stroke. Last time I wrestled with this bloody engine I got it running OK- the carby is very simple and has minimal adjustment- I cleaned out the choked up header and got a better seal between the carby and the block, all horribly difficult tasks involving working space- having removed and put back on the carby throttle linkage the idle and starting settings were bit off but it was finally starting and running OK. This time I went out and there was no spark. So the next day I got another Lucas SR impulse magneto out of my spares (Lucky!) and swapped it on. Nice bright spark, timing seemed about right (just after TDC). Trying to adjust the timing is a RPITA.
Along with 5 liters of fresh premium I took a near new fully charged bike battery out and spent the day hand cranking to get the flywheel going and then pressing the Dynastart button. I also liberally used about a 3rd of a can of 'start ya bastard' ether spray.
Occasionally it backfired a litte, and a fair few times it almost ran. Almost. Clean the plugs, air the engine, try some different settings, try again... and again and again all day. My back still hurts from all the cranking.
No joy.
Next time I am going to lug out the battery from my truck with the hope that the extra speed of turning the engine over will get it to fire. It felt like a bit more crank over speed might have done it. I have a feeling that once I get it running it will burn out the damp old cobwebs from the engine and will actually allow me to tune the carby on the fly in order to get the settings a bit better.
If this doesn't work then I am going to have to try to free the seized-up tiny little slotted screw on the end of the maggy drive shaft, facing away from me, right up the back of the engine in the really inaccessible bit, and start blindly playing with the timing a little bit (the timing marks on my flywheel are rusted off)

It is such a simple engine, and the people who get them running well can start them with a hand flick of the flywheel. Mine has never done that and has been the bane of my boat ownership- but no doubt it is something really really simple.





Anyway, back to bikes.

I just tried Rucksta's suggestions and there is no perceivable play in the shock mount or anything else other than the final drive.
With the final drive empty of oil, rolling the wheel forwards and backwards produces a very slight difference in sound. Forward just sounds like a smooth rolling bearing, backwards introduces a very slight rumble. I am only hearing it because I am actually looking for it and all this is with my ear as close as possible to the final drive, ie it is very quiet.

A question,
just to open up and have an investigation within the final drive, then put it back together does one need new gaskets or seals or anything?

Work ran late tonight so I couldn't get much done, but I must say I am absolutely loving having a TIG welder.

[ontic]

Originally Posted by Rucksta

The outer I've only seen in two sizes thick & thin 0.15 & 0.7 mm I think they were.
Despite the listings this is all I've been able to get my hands on.

Fortunatly there is a stack of them and they seem to pound thinner with use so I can always get close emough by swapping in new for old. 2 x 0.15 would be a good start.
Last I bought were $8.00AUD each onshore.

I'd leave the inner shims alone as they set the lash on the crownwheel & pinion and I'm not qualified to do that.
You may be better with bearing blue than me but even the input seal is a challenge I don't tackle but the big seal is easy enough but you'd know if you needed it as it would visibly leak oil.

Unless you remove the small bearing or the bush there should be no need to play in here if it was set up right and it's not broken or eliptical on the bush / small bearing as suggested.

If the FD required more than a simple outer shimming I send mine of to Ray Peake for a complete job.


Be aware there are at least two diffenent bearing setups on G/S FDs
Mine is an 09/82 and has the brake cam shaft running in a brass bush at each end. Later versions have a tube running right throug the two halves. Extenaly there is little difference but the early type appears to have a 'cap' over where an axle would go through on the right hand side (if it had an axle) later models have what looks like a continuos casting instead of the cap.

Mine has a steel stub axle and a tapered small bearing,
Later versions have an alloy stub axle and a needle bearing. This is based on a total sample of two final dribves I've seen the inside of.

A popular modification was cut additional grooves in the brake cam shaft to use double 'O' rings each side.
Factory did this shortly before the change in the drives oabout the same time the rubber inserts went into the forward brake spring

Great post,
thanks.
From the previous owner apparantly the final drive did have a slow leak- I never really saw a fresh leak as I have hardly ridden this bike, all I saw was the old remnants of a leak on the right side of the final drive.

Originally Posted by Sibbo

The timing has to be out mate, those things are a doddle to start if things are right .The right maggy ? How about installing a coil if all else fails ...a few of the Brit bike boys do it . A better spark at low revs .

Good Luck !

Yeah, thanks,
the timing is what I have been more and more suspecting. The maggy is the correct maggy for this engine from a bunch of spare parts I bought for the engine- it is just an optional improved sprung impulse-starting maggy. Spark is bright and good, heaps better than the old one. Ie, it should be good enough and something else is the problem.
Here's the relevant manual mention

The problem with setting the timing (I tried last time) is where the maggy is- right up the back of the engine hard to reach well- let alone get your head in to look at close enough at the back of the maggy to tell when the points close and open- that and the 'nut' on the maggy drive shaft is actually just one of those pathetic little shallow slotted screws that are made to not work and this screw is quite seized in place. And of course the lack of timing marks on my flywheel... all fun and games.
If I can free the the 'nut', and figure out the timing mark (hmmm, I do have spare flywheels...) then with my third and fourth hands use a torch and a mirror to tell when the points open and close I might just be able to do it!
Big battery is going to be key though. Cranking this thing gets old quick.

[One Less Harley]

here's some FD dissassembly picts for you.

[Sibbo]

Does the boat engine have a valve lifter? If it does your battery drill is a good way to get it up to speed ... then drop the lifter .A mate and i set up a similar system with a tiny little bike starter motor on a 20 hp Yanmar diesel .The pissy little starter spins it up with the lifter open then you drop it . It starts perfectly .

Assuming it has somewhere to drive !

[ontic]

Originally Posted by One Less Harley

here's some FD dissassembly picts for you.

Thanks, thats a great post with some very helpful photos.

And let me take the opportunity to post myself a note here- my shed is too chaotic for such a thing not to get lost.

Remember- Final drive has no oil in it!!

Originally Posted by Sibbo

Does the boat engine have a valve lifter?

No to the valve lifter.
I took the opportunity to buy a new big battery for my 4x4. The old one is still good enough but it is on the way out. Today I took this new 720CCA battery out to the boat (through the gale and the pouring rain). Sure enough, with this different maggy the timing was now out.
I broke a couple of prized tools getting that stupid little slotted screw loose and finnaly managed to adjust the timing. I couldn't adjust it by when the points open (impossible to see when the maggy is installed- which is how it needs to be done), but rather just had to do it off the fly-wheel whose timing marks I figured out, and from when the plug would spark- and then just shift it forward and back a little to find the sweetest spot.
With a bit of starting spray it starts and runs now. It is not perfect, and it has it's issues, but it is running and the next owner can figure it out. I'm done with that bloody engine
Tomorrow the wardrobe of sails and other extra's clogging my shed will be organised and photographed, and after one more trip out to the boat next week to take some photos and do another coat of paint it should be ready for ebay.
Can't wait.


Now, back to the G/S.
I borrowed my partners fathers little old dremel to help me do the close fitting of the subframe reinforcements so that I have a better chance of Tig'ing them successfully.
Yesterday afternoon I gave it a spin. Everything going great, just some gentle delicate sanding, until 30 minutes in the dremel makes a noise and spits a chunk of black stuff at my face out of one of the air vents and then looses power and sounds like it is only firing on one cylinder (if it had cylinders).
Dammit, I hate borrowing tools.
Pulled it apart and investigated- it seems a chunk fractured off one of the brushes and on its way out tore some little copper wires on the armature.
Double dammit.
I really am trying to avoid buying a new tool every time I have a need- but now I have to fix this one or buy another to replace it.


I still haven't put in my motobins order.
I need to be told off- I'm having very real and very dangerous temptations to get a siebenrock 1000cc power up kit.
I do not need this. Tell me I do not need this, please

other than that, as I posted in the airheads piccy thread, I had a good ride last weekend. Around 1000kms of some of Victoria's best on the 90/6. Met up with the fellas from boxerworks. No I didn't stop to take any pics, just a couple when I got there.




and this inspirational picture from the wall inside the Hotel

[Rucksta]

You need a Seibenrock 1000cc power up kit

[ontic]

Originally Posted by Rucksta

You need a Seibenrock 1000cc power up kit

LOL.
Thanks, I think. Are you still running the 1000cc kit? I've been reading a bunch of threads about these power up kits and have noted your strong advocacy, and have also come across your posts leading you towards the 1070cc kit.
I definitely don't want the 1070cc kit (?yet) but the 1000cc one sounds right up my alley and although expensive, isn't completely ridiculous.
Was it really as plug and play as it sounds? Any carby adjustments?
How has longevity been and how much more life do you expect?
With the higher compression have you had any pinging with poor fuel? (I just searched and see you are twin plugged, did you do this before or after the power-up kit?)

There is a strong likelihood that I will be riding this bike at least a small way round the world, up into SE Asia to start with and then who knows where after that (depends on a lot of undermined factors right now). Thus, I am a little concerned about raising the compression for the poorer fuels I might encounter.

A bit more power would be really nice at times, especially when loaded down and/or two-up- essentially though I want maximum torque and midrange, whatever efficiency I can get, and reasonable reliability. A decent compromise is of course OK.
Any real potential after 6000rpm is mostly wasted on me, especially if it is costing me between 2500-4000rpm.

[Lornce]

If you want to do a rtw trip I wouldn't recommend a 1000cc top end. Won't harm longevity, but it'll undermine the fuel range. Range is a bigger issue for travel than power, imho.

An R80 has more than enough power to negotiate anything you're likely to encounter travelling the world.

[ontic]

Originally Posted by Lornce

An R80 has more than enough power to negotiate anything you're likely to encounter travelling the world.

I totally agree with this and really the 1000cc kit would be more of a want than anything needed. However a lot of this trip might be two-up with luggage, and even though I think the R80 would do fine, particularly through the slower roads in the developing world where I will spend most of my time, it would no doubt feel a lot nicer with that bit extra. I don't mind riding a heavy bike, but I am not overly excited about riding a heavy sluggish bike.
Range? I'd like to hear how greatly the 1000cc kit affects fuel efficiency. Range per se I am not particularly worried about as I've got 45 liters fuel capacity in my Sauer tank, and anything where more would be expected will just have me temporarily strapping on extra plastic fuel bottles.
As I understood it the siebenrock 1000cc kit is a bit more efficient at converting fuel to power- which if that extra power is used enough would translate to a higher fuel use per KM, but I would not always be using the extra power.
For my use I'd be hoping for a reasonable and probably variable (10-20%) increase in fuel consumption, but if I am being unrealistic I am open for education.
Cheers,

[SOLO LOBO]

Grant and Susan were fine with 800cc's

[ontic]

Originally Posted by SOLO LOBO

Grant and Susan were fine with 800cc's

Riding two-up with everything including those jug panniers, don't tell me that bike didn't wish for hyperdrive on occasion
(makes Wookie sound)


But seriously, no doubt it is very true and I need to be talked out of this.
We'll see.

[Sibbo]

Consider yourself talked out of it .Reliability, torque and light weight are my considerations .2 up you will probably be more worried about staying vertical on shitful roads than going fast and an R80 has a fair bit up it's sleeve if you use the revs .

[Lornce]

R80G/S-PD I picked up in BC this summer fairly amazed how well it accelerated. Fully loaded 5th gear passing was a breeze. Those short gears certainly work to provide readily available torque.

I couldn't abide needlessly spinning a liter motor like that.



Besides, 60-80km/hr cruise speeds is all you really need to shoot for in most of the world.

[Rucksta]

Ontic

I went for 1000cc kit '77 S heads with a few mods, 9.5:1 pistons and Del Orto carbs in one hit.
Dual plugs came a few years along with valve seats and a mod to the squish band to adress pinging with the intoduction of unleaded fuel.

I have about 350,000 km on the bores and pistons with one ring replacement a couple sets of valve guides plus a set of guides when I did the valve seats.

Bottom end is still in good shape as are the cam and rockers.

Gear box has been trouble free.
I seem to have stopped wearing out universal joints.
I seem to be hard on the final drive but it does cop a bigger pounding since I went to USD forks 5 or 6 years ago.

I put 100,000km on the stock motor.
I did gearbox & final drive bearings as well as valve guides in the 100,000 as well as a couple of drive shafts.

With the stock motor I was always ringing it neck and got poor fuel ecomomy.
With the 1000kit I can get the response and performance I want with a turn of the wrist.

Motor will run on 91, E10 or Opal.
It runs fastest on 95.
I use 98 makes me feel better about running hot slugging it through the trees.

I average around 15- 17km /lt and have achieved 22-24km/lt running good dirt road in top gear at 80kph.

Stock motor would deliver in the 15-17 km/lt range never seeing better but sometimes returning 12.5 with the lowest ever 10.3 on a fang thru the hills.


I'm due for a new set of barrels (have been for the last 35,000ks)
I am still interested in a 1070 kit mainly for the mid range.

When I think back to what a blast this bike was when the 1000 motor was fresh and what it does now I'm thinking a fresh set of barrels, pistons & rings with a valve grind and new guides would give me back everything it had that impressed me as a 28 year old rev head.

If I went 1070 I'd need more brake and suspension upgrades as well as a higher 5th gear and posibly exhaust replacement with 38 or 40mm to get the best out of it.

The cost of the kit and associated upgrades is a bit scary .
For the same money I could have a very nice second hand enduro, a husky TE610 or a new SX85 for the budding MX rider in the family so I'll probably just go for another 1000 kit.


The Seibenrock power up kit with the standard heads and 32mm bings is reported to be a torque monster.

[Airhead Wrangler]

Originally Posted by Lornce

If you want to do a rtw trip I wouldn't recommend a 1000cc top end. Won't harm longevity, but it'll undermine the fuel range. Range is a bigger issue for travel than power, imho.

An R80 has more than enough power to negotiate anything you're likely to encounter travelling the world.

A buddy of mine gets consistently better gas mileage on a GSPD with a 9.5:1 1000cc engine. The taller final drive and higher compression make quite a difference.