So Continental have got back to me:-
"Hi Richard
Sorry to say that we don’t have a fitment for your bike, nor do we make the ContiGo anymore.
ATM is about the same as bar as you guessed and generally modern tyres would run at a higher pressure than they did in the 1980’s.
I can’t give you an official answer but if it were mine I would try 2 bar front and rear then up to 2.3 in the rear if fully loaded.
Kind regards, David Humphreys, Conti Tyres UK (Two Wheel)"
So looks like I will be upping the pressure until either it handles ok or the tyre goes pop!
Again I bought these as they are tubed type not tubeless. Don't remember them being harder to put on than in the past but I have invested in some tyre soap. (see my youtube channel if you want to see how I did it).
As always, thanks for all of the helpful replies.
p.s. If I ever need new tyres I think I will be getting ME22s.......................
Tyre pressures?
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Parker3865
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Re: Tyre pressures?
Morini 250 2c rebuilt from a box of bits.
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julianharty
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Re: Tyre pressures?
Richard,
my local bike shop's mechanic happily and repeatedly pumped up my front tyre to over 110 psi (7.5 bar) to convince the bead to seat, I suspect that even if you were to run 3 bar you're unlikely to blow the tube or the tyre. I'll check what I'm running on my 250, probably well over 2 bar in the front and more in the rear tyre. I'm riding it up to and including the national speed limit
my local bike shop's mechanic happily and repeatedly pumped up my front tyre to over 110 psi (7.5 bar) to convince the bead to seat, I suspect that even if you were to run 3 bar you're unlikely to blow the tube or the tyre. I'll check what I'm running on my 250, probably well over 2 bar in the front and more in the rear tyre. I'm riding it up to and including the national speed limit
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Parker3865
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Re: Tyre pressures?
Julian, thanks. Hit 75 ish the other day and it felt insecure around a bend (not sharp, it was the A12).
Morini 250 2c rebuilt from a box of bits.
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julianharty
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Re: Tyre pressures?
So, my tyre pressures were a bit lower than I'd expected when I checked (I've not ridden the 250 for about 10 days).
The front had 2 bar (28 psi) and the rear 1.8 bar (26 psi) according to the hopefully accurate new 40 psi range pressure meter I had to hand. I've increased the rear to 2.2 bar but not yet tried riding it like this. FYI the bike's overdue a service, including cleaning the petrol tank tap filters as one tap is blocked again - one of the perils of resurrecting the bike including derusting the tank, etc. I'm using Conti Attack tyres with tubes.
The front had 2 bar (28 psi) and the rear 1.8 bar (26 psi) according to the hopefully accurate new 40 psi range pressure meter I had to hand. I've increased the rear to 2.2 bar but not yet tried riding it like this. FYI the bike's overdue a service, including cleaning the petrol tank tap filters as one tap is blocked again - one of the perils of resurrecting the bike including derusting the tank, etc. I'm using Conti Attack tyres with tubes.
Re: Tyre pressures?
Really? 
When trying to seat the bead into the wheel rims of my 125H the tyre fitter (BSB experience) took the Heidenau 2.75 x18", with inner tube to 80psi/5.5 Bars and declared "Enough! Cast wheels produce shrapnel and safety cages don't contain it." We then applied more soap and a strap band to the circumference of the tyre and after a further 5 attempts, the bead popped into the rim at 60psi/4.0 Bars. You will also see that even at maximum load, there is a warning not to exceed 41 psi, with 2.75 x 18 tyres, moulded into the side wall of Michelin tyres that I am using at present.
If your wheels are the same as those fitted to the 125H (Grimeca cast wheels) 2.75 x 18 front and 3.00 x 18 rear, the recommended tyre presures, solo, are 1.6 kg/cm², 23 psi, or 1.6 Bars for the front and 1.8kg/cm², 26psi, or 1.8 Bars. As I am 85 kg/13.3 stones wringing wet, I usually use the pillion pressures of, 1.7 kg/cm², 24 psi, or 1.7 Bars for the front and 2.0 kg/cm², 28 psi, or 1.9 Bars. These pressures are the same for the 250 single cylinder machine that uses the same wheels.
I have experimented, with up to 28 psi in the front and 32 psi in the rear and with these pressures the bike handles like it's on 6" stilletos and the front "washes out" when pushed through a series of corners. So, I have reverted to the recommended pillion tyre pressures with the 125H.
I also have 2.75 x 18 WM2 front rim and 3.00 x 18 WM3 rear rim, on spoked wheels, on a Ducati 450 MKIII. Using either Michelin Pilot Street, or Continental ContiGo tyres, 28 psi in the front and 32psi in the rear works fine. Again, any higher pressures, when riding solo and the whole machine feels skittish and the front can "wash out" through a series of corners. If intending to do some twisties, I usually drop the front pressure to 26 psi and the rear to 30 psi and then it sticks very well.
Finally, check your tyre pressures every time you go out, you don't know when you will have a slow puncture and tubed tyres are more suceptable to air leaks than tubeless tyres. Tubes can be used in tubeless tyres.
Good health, Bill
There really is a "42 Carat .......!"my local bike shop's mechanic happily and repeatedly pumped up my front tyre to over 110 psi (7.5 bar) to convince the bead to seat,
When trying to seat the bead into the wheel rims of my 125H the tyre fitter (BSB experience) took the Heidenau 2.75 x18", with inner tube to 80psi/5.5 Bars and declared "Enough! Cast wheels produce shrapnel and safety cages don't contain it." We then applied more soap and a strap band to the circumference of the tyre and after a further 5 attempts, the bead popped into the rim at 60psi/4.0 Bars. You will also see that even at maximum load, there is a warning not to exceed 41 psi, with 2.75 x 18 tyres, moulded into the side wall of Michelin tyres that I am using at present.
If your wheels are the same as those fitted to the 125H (Grimeca cast wheels) 2.75 x 18 front and 3.00 x 18 rear, the recommended tyre presures, solo, are 1.6 kg/cm², 23 psi, or 1.6 Bars for the front and 1.8kg/cm², 26psi, or 1.8 Bars. As I am 85 kg/13.3 stones wringing wet, I usually use the pillion pressures of, 1.7 kg/cm², 24 psi, or 1.7 Bars for the front and 2.0 kg/cm², 28 psi, or 1.9 Bars. These pressures are the same for the 250 single cylinder machine that uses the same wheels.
I have experimented, with up to 28 psi in the front and 32 psi in the rear and with these pressures the bike handles like it's on 6" stilletos and the front "washes out" when pushed through a series of corners. So, I have reverted to the recommended pillion tyre pressures with the 125H.
I also have 2.75 x 18 WM2 front rim and 3.00 x 18 WM3 rear rim, on spoked wheels, on a Ducati 450 MKIII. Using either Michelin Pilot Street, or Continental ContiGo tyres, 28 psi in the front and 32psi in the rear works fine. Again, any higher pressures, when riding solo and the whole machine feels skittish and the front can "wash out" through a series of corners. If intending to do some twisties, I usually drop the front pressure to 26 psi and the rear to 30 psi and then it sticks very well.
Finally, check your tyre pressures every time you go out, you don't know when you will have a slow puncture and tubed tyres are more suceptable to air leaks than tubeless tyres. Tubes can be used in tubeless tyres.
Good health, Bill
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julianharty
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Re: Tyre pressures?
Bill,themoudie wrote: ↑01 Sep 2024 23:13 Really?
...my local bike shop's mechanic happily and repeatedly pumped up my front tyre to over 110 psi (7.5 bar) to convince the bead to seat,
We then applied more soap and a strap band to the circumference of the tyre and after a further 5 attempts, the bead popped into the rim at 60psi/4.0 Bars.
...
Thank you for this key idea to use a strap band around the circumference. And also for your experiments with tyre pressures on the 125H, etc. I suspect they'll also suit the 250 even though it's much more powerful
and slightly heavier. And as I also have a 125 H waiting in the wings I'll follow your recommendations in terms of tyres and pressures for it when I build it.Re: Tyre pressures?
Aye Julian,
My pleasure and beware the 125H ignition hex!
Leonard (125H) has his running now after modification to the polarity of the ignition trigger coil wiring, having had the old trigger coil fail and replaced, with a new one. The same man modified mine in the same way and for the same reasons and yet it still refuses to advance the ignition. Idles beautifully!
However, Leonard then was knocked off his 125H on a roundabout by a MAMIL!
I am still investigating going down the replacement route of either part or all of the alternator/ignition system, so keep an eye on the thread in the Singles section of the forum. All the best with the 250C.
Good health, Bill
My pleasure and beware the 125H ignition hex!
Leonard (125H) has his running now after modification to the polarity of the ignition trigger coil wiring, having had the old trigger coil fail and replaced, with a new one. The same man modified mine in the same way and for the same reasons and yet it still refuses to advance the ignition.
Idles beautifully!However, Leonard then was knocked off his 125H on a roundabout by a MAMIL!
I am still investigating going down the replacement route of either part or all of the alternator/ignition system, so keep an eye on the thread in the Singles section of the forum. All the best with the 250C.
Good health, Bill
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julianharty
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Re: Tyre pressures?
There has been an imported 125H for sale on eBay over the last few months. It might have finally been sold. Anyway, it might help address the ignition issues by providing another comparison.themoudie wrote: ↑02 Sep 2024 16:32 Aye Julian,
My pleasure and beware the 125H ignition hex!
Leonard (125H) has his running now after modification to the polarity of the ignition trigger coil wiring, having had the old trigger coil fail and replaced, with a new one. The same man modified mine in the same way and for the same reasons and yet it still refuses to advance the ignition.
However, Leonard then was knocked off his 125H on a roundabout by a MAMIL!
I am still investigating going down the replacement route of either part or all of the alternator/ignition system, so keep an eye on the thread in the Singles section of the forum. All the best with the 250C.
Good health, Bill
Re: Tyre pressures?
Aye Julian,
£500 or Offers. I was tempted, but with other "black holes" in the workshop, I resisted the temptation, this time.
Good health, Bill
£500 or Offers. I was tempted, but with other "black holes" in the workshop, I resisted the temptation, this time.
Good health, Bill
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julianharty
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Re: Tyre pressures?
I hope it's finally been sold to someone who'll get it on the road and ride it. I've already got a nearly complete unregistered 125 in bits to rebuild! And then it'll need some advice on suitable tyre pressures
Re: Tyre pressures?
To some degree pumping up the rear tyre makes it a slightly bigger diameter, which slightly raises the back of the bike and this in turn has the effect of slightly reducing the trail of the front wheel. Less trail means less straight line stability. For similar reasons you can get instability from high preload settings on the rear suspension, or rear suspension units that are slightly longer than the genuine ones. Or with stronger springs. Generally to improve straight line stability you want to do things that make the trail greater. In other words things that reduce the steepness of the front forks. Lower ride height at the back in your case might improve things.
At the front end a softer front tyre has a wider contact patch than if it's hard and wide contact patches on motorcycles can also cause instability in a straight line. Sometimes owners inadvertently make the fork angle steeper (less stable) by having worn out front springs, too short preload spacers, or setting the fork tubes higher in the yokes than than Mr Lambertini intended. (top yokes can also be too high due to taper roller headrace conversions etc). A higher ride height at the front in your case might improve things.
Hope my ramblings are of some use to you.
Although it was a long time ago I last had some fun riding a friend's, the 250 is a nimble, agile bike. It's excellent on the really twisty bits. I doubt if it was ever intended to excel at rock stable high speed straight lining.
At the front end a softer front tyre has a wider contact patch than if it's hard and wide contact patches on motorcycles can also cause instability in a straight line. Sometimes owners inadvertently make the fork angle steeper (less stable) by having worn out front springs, too short preload spacers, or setting the fork tubes higher in the yokes than than Mr Lambertini intended. (top yokes can also be too high due to taper roller headrace conversions etc). A higher ride height at the front in your case might improve things.
Hope my ramblings are of some use to you.
Although it was a long time ago I last had some fun riding a friend's, the 250 is a nimble, agile bike. It's excellent on the really twisty bits. I doubt if it was ever intended to excel at rock stable high speed straight lining.
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julianharty
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Re: Tyre pressures?
Good point on the effects of longer springs; my 250 2C does have longer rear shocks than standard, I fitted some relatively fancy YSS units, as sold for BMW R45 models e.g. https://www.brooksuspension.co.uk/motor ... bers-78-85 that are 320mm.
I've not noticed any instability; the fastest the bike has gone is perhaps 65 MPH (105 KPH) ish, so far. That said I've been taking it gently as I'm running in replacement piston rings in slightly worn barrels.
I've not noticed any instability; the fastest the bike has gone is perhaps 65 MPH (105 KPH) ish, so far. That said I've been taking it gently as I'm running in replacement piston rings in slightly worn barrels.
Re: Tyre pressures?
I agree with everything that bumblebee says of course if you go too far then you get cruiser handling which is fine for straight line stability but sacrifices steering response and in extreme case could be vague at low speed.
Its really about geometry, the 250 2C was certainly not designed to have straight line instability at high speeds so something is not as per initial design. If forks, steering head, shocks, wheel bearings and wheels are in good condition then any instability would be down to tyres and tyre pressures.
Its tempting to overtighten steering heads.
Mark
Its really about geometry, the 250 2C was certainly not designed to have straight line instability at high speeds so something is not as per initial design. If forks, steering head, shocks, wheel bearings and wheels are in good condition then any instability would be down to tyres and tyre pressures.
Its tempting to overtighten steering heads.
Mark
Re: Tyre pressures?
Wear in the swingarm pivot is also very often a factor. Can't remember what the 250 pivot arrangement is, but just having it tight enough may not be enough to make up for wear in there.
Wear can be hard to detect by hand because the pivot shaft is usually adjusted tight enough to remove play along the axis of the shaft, and that makes it hard to detect wear in the other direction (at right angles to the shaft) which also has a negative effect on straight line stability.
Front tyres with profiles that are flatter near the major diameter of the tyre tend to be less stable because it only takes a slight change of the "uprightness" (is that a word?) of the bike to move the center of the contact patch left or right quite a bit. The trail pulls the center of the contact patch back towards the axis of the bike and this in effect steers left/right and sets up a situation which can feel unstable. One of the other reasons pumping up a front tyre helps straight line stability is it slightly reduces the flatness of the tyre profile.
As others have noted, overly hard tyres do not grip as well as the correct pressures.
Wear can be hard to detect by hand because the pivot shaft is usually adjusted tight enough to remove play along the axis of the shaft, and that makes it hard to detect wear in the other direction (at right angles to the shaft) which also has a negative effect on straight line stability.
Front tyres with profiles that are flatter near the major diameter of the tyre tend to be less stable because it only takes a slight change of the "uprightness" (is that a word?) of the bike to move the center of the contact patch left or right quite a bit. The trail pulls the center of the contact patch back towards the axis of the bike and this in effect steers left/right and sets up a situation which can feel unstable. One of the other reasons pumping up a front tyre helps straight line stability is it slightly reduces the flatness of the tyre profile.
As others have noted, overly hard tyres do not grip as well as the correct pressures.