Another 900 GTS story. The Black Pig

"The generator light is always on. "

I'm not a expert on the GTS but isn't the light supposed to stay on ? the Darmah had that strange little red reverse relay that put the light out because it was confusing on the GTS i thought ?
 
I think you ar correct light on when charging
Test with Meter
12 volts across battery + -
14.4 volts across battery + - engine running
 
They do say if you use the new Suflex clutches you should use the matching springs. I couldn't see the point but its poss they are better balanced strength wise ?
 
My Surflex springs are a different free length to the standard ones. Material type apart, the thickness and number of coils directly relate to the rate so I'd say that they were not the same. Once you've established that it lifts evenly then check that the amount of movement at the lever/cable/actuator is adequate. see if the actuating arm is hitting the cases. You might be running out of adjustment if the pushrod length total is wrong. (There are at least two total lengths on different models that I've heard of) A sticky clutch plays havoc with gear selection.
So far as the brake goes have a look where the shoes are catching. It will be at one leading edge and might be adjusted out by spinning the actuating spindle round 180degrees to make a slight difference in the way that wear on that has affected the interface with the shoes, or even the shoes themselves. At a pinch you might grind a bit off the shoe to delay that actuation or add a bit on to put the process in a 'new place'. Small changes can make a big difference. (a tight spoke can pull a drum out of round) and remember that you are working at the far end of normal movement once the drum is skimmed.
 
The latest 'Classic Bikes' has a Commando restoration where they mention having
skimmed the drum, but they talk about fitting fatter linings to compensate. I am surmising that that is to maintain the relationship between the actuator pivot point and braking surface. That might be your answer, but you may still have to find someone with a big lathe to have them turned down to the correct size.
 
Thanks Guys,
The clutch problem is exactly as Paul predicted. I couldn't believe how uneven it lifted and the solution of backing off and loctiting the spring screws has entirely levelled it up. I guess the best solution would be a new set of springs, but let's see how this performs now.
I think the problem with the starter is that one of the brushes was not pushing against the commutator as it's cable was snagged. I've cleaned up both brushes and commutator, but one of the brushes is pretty worn.
I'm trying to locate replacements. There are a number of suppliers on ebay but I can't find brushes of the same dimensions yet.

Martin - good advice on the back brake. I think what I'll do is get the engine back together and give it a bit more of a run with lots of brake applications. Then I'll take out the back wheel and have a look at what's occuring.
 
I managed to get some new brushes for the starter motor - from Greece!!
I couldn't find the reference number but there's a Greek company Autotek who lists all the brushes by size and starter make. So I ordered 2 Fiat JSX Brushes. What actually arrived was 2 boxes of 4 brushes - so having fitted 2 new ones I can supply 3 other Marelli starter motors with Brushes! And now the starter works! Shout if you need some brushes for your GTS starter. Not sure if they fit the Darmah.

So after sorting the clutch and starter out I thought give her a bit of a warm up and drop in to see Bill of Performance Red, my local (and hopefully sympathetic) MOT tester. Bill ooed and aahed all around the bike and I nervously waited for the test of the non existent back brake. Here's the fateful moment when Bill tries to get a reading on the brake test....

MOT2.JPG


We discussed the value of time to settle in new drum brake linings - and she passed the MOT!

Not all is quite right though. The gearchange is much improved now that the clutch is working - but it's still heavy. And worse - it sometimes jumps out of gear. I'm hoping that this is down to the selector box adjustment and not to do with the selector forks. A small (45 degree) adjustment on the selector box screw seems to make a big difference to the gear change characteristics. If there's a definitive method for setting this up I'm all ears.

Then Pat dusted his Darmah off and we did a few miles, stopping every now and then to adjust carb and gear selector settings. Here's Pat having a fiddle.
photo.JPG


One other thing - maybe for Paddy. My front brake with Paul's excellent calipers is working fine. However all the action occurs right away as soon as the piston is acted up by the lever - which I can hardly reach. It bites within about 5 mm of the rest position. Is is possible to adjust the piston in the master cylinder to allow it to move a bit more?
 
Daft as it sounds, you might have the wrong lever. The 'bumpy-bits' that push against the piston can vary quite a bit. I remember a case years ago where a company were selling chinese 'carbon' levers for R1s which had a tendency to make the wheels lock (allegedly) because the slight difference in pivot position and 'bump' changed the way it all worked. Paddy will know what is interchangeable and what isn't. (I have a suspicion that you might have fallen foul of the 'what was on the shelf on the Friday when it was built' syndrome)
 
Well done great effort! who said "ye canny make a silk purse from a pig ear" ? it is great seeing classics restored to their prime if not better than factory release and not just wiped with an oily rag stating I want to keep it original:cool:
 
Glawster said:
Not all is quite right though. The gearchange is much improved now that the clutch is working - but it's still heavy. And worse - it sometimes jumps out of gear. I'm hoping that this is down to the selector box adjustment and not to do with the selector forks. A small (45 degree) adjustment on the selector box screw seems to make a big difference to the gear change characteristics. If there's a definitive method for setting this up I'm all ears.
Click to expand...
I'm not guaranteeing this will work as it's many years since I last adjusted one. :o
Turning the selector box screw rotates a small eccentric inside the selector box. Watch the gear lever as you adjust it, you will see that it moves up and down. Note the position of the adjustment screw when the lever is at it's highest point. Now turn the screw to find the lowest point of the lever and note the position of the adjuster. Now turn the adjuster back to halfway between those two points. This should give you the midway position with equal gear lever travel in each direction. It may need a little tweak one way or the other for best selection but it should give you a good starting point and a position you can use as a reference.
Nice to see these two bikes out on the road :)
 
ref the brake lever, does yours have a little grub screw in the front? that adjusts the gap between the end of the lever and the m/c piston (i think!)
 
Derek - thanks for the tip on the selector box. Yes, it moves just as you say so I set it halfway - and to be honest I think this is where it already was. It seems that a very small movement significantly affects the character of the gear change.

Martin - Good point about the bump on the brake lever. I tried filing a little bit off and it moved it fractionally. I'll take a bit more off and try again. Anyway I bought the lever and master cylinder assembly from Paddy, so I'm sure it will be subject to a 5 year warranty.

Neil - it does have the little grub screw to take out the free play, but if you continue screwing it in then it moves the piston with the risk of the brake binding.

Anyway, with this nice spring weather I took it out today and did about 50 miles, two up with my wife on the back. She really isn't a motorbike fan, but I think she felt a bit left out. I'm only using up to 4,000 rpm but I have to say the handling is great once you get used to the length of the thing. It did drop out of gear, but only twice. I won't bore you with many more photos on this thread, but I can't help posting another couple...

Here's one old girl on the Sharpness Canal at Saul Junction. First bit of fresh air she's had in 14 years!

8-3-14.JPG


Here's a pair of old girls enjoying the sunshine.

Picture1.jpg
 
If that is all the snagging then you have done well! They are both looking well but there is only one you can tinker with in the garage.

I snuck out for a spin too! I was seconded for a trip to MIL's who is still receiving delightful letters from HMR&C after losing her husband last year, the latest being a letter informing her ever greater amounts were being extracted at source from her pension which sent her into a spin.

Anyway, had a great walk along the beach and finally got out for a ride. They have salted the roads around here so I am not sure what will be left of the bike when I look this morning, even though it was dry.

One comment from Tony Brancato about 28 years ago; Try not to let the revs drop below 3,000 and never never when under load as there isn't a whole load of oil squirting around for the bottom end at low revs. It doesn't give you a whole lot to work with when running in, but it's enough.
 
I suppose its possible that by having all new components with Goodrich lines instead of rubber you have made the front brake a bit too good :)
I have heard of this when people are using single disks with 15mm piston master cylinders but not with twin disc.
Are the front calipers releasing fully ? The piston seals should pull the pads well off the disc which should give you the take up slack on the lever. ?
 
Excellent thread*, and many congratulations on the restoration!

My very first Ducrappi was a black and gold 860GTE. I liked it. After a few trials and tribulations followed by a period of relative calm, it all ended in tears one day when the alternator nut came loose, allowing the woodruff key of the rotor to bust a piece out of the end of the crank ...

* Gotta admit I've only just come across it - I don't look here too often as there isn't normally a lot of Bevel talk. And then I tend to only look in the Vintage section. My bad ...)

Craig
 
Hi Craig,
I'm glad you found your way here as you gave me plenty of great tips on the Motoscrubs Forum when I was refurbishing my Mk3 250.
There a small but enthusiastic and knowledgeable Bevel group on here and I benefited from loads of help from them. Mostly the posts are in the Projects section and I'm sure your input would broaden the knowledge base. Anyway I've learned a lot about Bevel twins in the last 6 months, but mostly how much more expensive they are than singles. I'm certain you will know Barry Jones of Classic Ducati? His pithy comment was "You'll need deep pockets to put that heap right" and he wasn't wrong!

Paddy - my calipers came fully refurbished by excellent Mr Vacant Possession. How can you question their effective operation? I'm going down Martin's route of filing a bit off the lever where it touches the piston. It's slowly coming within reach...

And another nice ride today in the Cotswolds - 120 miles now covered and it's becoming addictive. I'm not sure if anyone knows the road from Stratford to Cheltenham through Broadway and Winchcombe, but it's one of my favourites. I'm sure the suspension on the old banger gives a far superior ride to my previous GT1000. It's a delight.

Paul - those LED warning lights are driving me nuts. Even in sunlight they're still lairy. I've tried emery papering them but it only reduces the brightness a little. Your idea of some kind of adjuster to calm them down would be a big improvement.
 
If mr Vacant can question my exotic dancing i reserve the right to question his calipers :) The only other cure might be to put your fingers in the vice and tighten it......longer fingers might do the trick ?
 
Worry worry! I haven't done mine yet but you have been inspiring me to get my finger out. Just got one more tax bill to pay next month (followed by VAT the month after) and I should be back on my feet.

I don't think it is very complicated - I'll have a think.
 
I was insomnially considering the brakes issue. A long time ago I came across the Vintage Brake site with this very useful master cylinder ratio chart So far as I can tell a 12mm Master cylinder was standard on twin disc (and an 11mm on single discs using the smaller FO5 caliper with 32mm as opposed to 38mm pistons)
The author states: For 2 piston opposed calipers, I like ratios in the 27:1 range, feeling some line and caliper flex. For a firmer lever, use 23:1. I think ratios lower than 23:1 produce a lever feel so "wooden" as to have little, if any feel.
From his chart, 4 x 38mm active pistons would give a ratio of 40.11 ( whereas the single disc app. would have 33.85) Fitting an 11mm M/C by accident would have only made the brakes even 'softer'
This is somewhat confusing, as I find it hard to believe that Brembo are so far 'out' on the 'soft' side with their standard fit. To fit in with the 'sweet spot' you would need a 14mm M/C. I suppose that it is possible that the softer size was chosen to cater for the common man and at the time? That might point the way to a possible upgrade for track work which after all, is what the vintage brake chart is aimed at.
What I think may be happening is that Paddy's suggestion of the effects of stainless hoses, coupled with the effects of a Vacant Possession 'Rain-man' quality build and a non-adjustable hand-span have simply stacked up against Glawster in this particular case.
 
The 860 and 900 use a brembo PS15 M/C with a 15.8 mm piston.
The Pantah used a PS12 which was 12.6mm Dia
I sort of alluded about the early bevels running a single front disc might have a solid brake with a PS15. but then they use a 15.8 mm rear piston with a single disc on 860/900 as well.
It might even be the way the M/C is sitting on the bars ie not in line with the throttle that is moving the lever out. I also suspect it will settle in a bit with use and the seals will pull the pistons in the caliper further back as it loosens up giving more play on the lever.
 
Martin - I hate to think of you losing sleep on my behalf. Please take it easy and have a lie in tomorrow.
Paddy - from what I can see the diameter of the piston is 12.6mm, not 15mm, so maybe I have a PS12 type? Would a smaller piston give this effect? I think it would be the opposite, yes?
All the bits are on the straight part of the bars. The problem's more or less solved by filing a bit off the lever where it acts on the cylinder. I've now got it back to a reasonably position where I can reach it..
Note I'm using the genuine Brembo cap you gave me!

OFF
DSC_0308.JPG


ON
DSC_0309.JPG
 
Oh you non believers !! I can assure you i wouldn't sell you the wrong part. No 860/900 ever used a PS12, not even the 750 GT/Sport that had a single disc and used Brembo had a solid body PS15.



The part that protrudes and is pushed by the lever is wasted to about 12.6mm, the rubber seals are a fraction up on 15.6 .;)
 
Last edited:
Ah Paddy, I could only see the bit poking out of the end. I wouldn't dare to question your integrity as the first choice purveyor of only the finest Bevel parts...:)
 
I had thought that this thread had been brought to a conclusion - but a bit of advice please.

I've now covered 600 miles and really enjoyed them. I'm just struggling to get the low speed running anything like correct. My method is the usual...
- make sure the slides lift together.
- set it running to a fast idle
- take off one plugcap and adjust the mixture screw on the running cylinder to it's fastest position.
- repeat on the other cylinder.
- slow the idle back down equally.
The front cylinder responds well to this method. The back cylinder does not. You can turn the mixture screw through a whole turn without it really affecting the idling speed. The back spark plug is very black and the end of the left silencer is black.
I thought maybe the rich running was due to the float height being too high. I increased the setting from 18mm to 21mm and also dropped the needle a notch. No difference - it's still running black.

I haven't replaced any carburettor parts beyond the gasket set. I know all parts are available but it's easy to spend a fortune on carb parts.
When I had the carbs cleaned the guy said think about replacing the floats as they had been very cruddy and might be overweight. Also I understand the needles can wear.
Has anybody got any advice on how to solve this issue without breaking the bank?
 
Oh - and we found another Italian Day yesterday - in Broadway (Worcestershire). Only Ferraris and fancy food - typical of Broadway if you know it.
Anyway we managed to lower the tone of the event a little. Aren't Morinis just great bikes?

Italian%2520Relay.jpg
 
You must log in or register to reply here.
Back
Top Bottom