An update and preparation for the Piston Rally

Maestro, SEI-V

An update and preparation for the Piston Rally

Postby penman » 15 Sep 2017 16:36

My 1978 Morini 500 has been a work in progress for some months now. When I first re-commissioned it after some 20 years hibernation, I put the carbs in the ultrasonic tank, but I tried to avoid replacing any parts in view of the potential need to change jet sizes, etc. For all I knew the existing ones could be right or wrong. In the event, I had to replace the starter jets which were badly corroded and thoroughly varnished up as well. The bike started and idled very well and ran pretty well, the only issue being hesitation coming off idle or going from the over-run back on the gas. I have to say I was slightly disappointed by the general performance, but I had nothing to compare it with.

The original needles were X1, which agrees with the Blue Book, but stripping it down again, I saw they were quite worn and in fact one was slightly bent. The atomisers were 262T, the BB specifies 264T, not sure what the difference is. The pilot jets were 52, BB specifies 50 and a few people have recommended 45. So, I ordered new needles, 264T atomisers and 45 pilot jets. Going over rich on progression is a common reason for that off-idle hesitation in my experience, so a slightly smaller pilot jet seemed like a good idea. I re-checked carb balance and was slightly disappointed to find it pretty well spot on, that would have been another good reason for hesitation!

Well I have to say that the bike is transformed! I can barely believe how much difference this has made. The hesitation has completely gone and it feels a lot more "gutsy" in the low and mid-range. Of course I've made three changes, so I'm not quite sure which has made all the difference. I'm not arguing though!

I've also given up on the original rear shocks which are basically shot. One minute they have no damping and are bouncing around like a pogo stick, and the next they are rock hard. Add to that the fact that the chrome has gone on the springs so they look bad and it was time for a change. I fitted the Hagons with adjustable damping. I'm pretty skinny and I often find rear shocks are a bit too harsh - backing the damping off a couple of clicks makes an awful lot of difference for me. I'm pleased with the Hagons and the back of the bike is behaving a lot better now.

I am off to Spain for the MC Piston Rally next week and I have been hoping to use the Morini this year for a change. The last couple of years I've been on my 750 Bonneville, which has proved itself to be well suited to the terrain (with the same Hagon shocks) and I'm hoping the Morini will be just as much fun. It has much better brakes than the Bonnie and that will certainly be appreciated up in the mountains! Now with the extra bit of grunt I seem to have found, I feel a bit happier about tackling those very steep hills! I shall report back on how the Morini performs.

Regards to all,
Joe.
1980 Moto Guzzi V50 II
1978 Triumph T140 E Bonneville
1975 Triumph T160 Trident
2014 BMW F800GT
1978 Morini 500
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Re: An update and preparation for the Piston Rally

Postby 72degrees » 15 Sep 2017 17:55

Hmm, adjustable damping shocks eh? I wonder if I could get away with that in the 'Forgotten Era' championship? The Konis are definitely rather on the stiff side. The 2C/375 could also probably benefit from a pair. I've run 350 shocks on it for years but the Marzocchis currently in use are past their best. I was thinking just the other day that the least satisfactory aspect of this bike is the rather harsh ride. Not a lot can be done with the 2C Paoili forks other than cunning mods with the 'spacers' and experimenting with ATF capacity, but more modern rear shocks might help a lot.
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Re: An update and preparation for the Piston Rally

Postby penman » 15 Sep 2017 21:32

I'm sure the Hagons are not the only shocks with adjustable damping, but I've found them good for my purposes, and the price is acceptable - have a look on the Hagon website. There are about 10 clicks from softest to hardest, plus the usual preload adjustment for the spring. Needless to say, they're a bit more pricey than the fixed variety! I first tried them on the Bonneville, which still had the original Girling shocks which were working but probably a bit tired and not great in the first place. It really transformed the handling, so I invested another £200 for the Morini, with an even better result because the Marzocchis were really shot. I'll be able to give a full "road test" after the Piston Rally!

As for the front forks, I have experimented endlessly with different weights of fork oil and it's not difficult to soften the damping a bit if you need to. One bit of advice is that you need to stick to one make of oil - the grades don't seem to translate well from one make to another! I mix SAE 5 with SAE 20 in various proportions to end up with what I want. Fiddly and messy, but it does work!
1980 Moto Guzzi V50 II
1978 Triumph T140 E Bonneville
1975 Triumph T160 Trident
2014 BMW F800GT
1978 Morini 500
penman
 
Posts: 286
Joined: 08 Mar 2016 09:20
Location: Milton Keynes

Re: An update and preparation for the Piston Rally

Postby norbert » 15 Sep 2017 22:28

Hey Joe,

having been there several times you will know that Asturias y Cantabria is made for the morini :wink: surely you will have great fun with that bike over there, and even more with better brakes.

A disfrutar y que te vaya bien!!!
norbert
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Location: Lübeck/Germany

Re: An update and preparation for the Piston Rally

Postby huub » 16 Sep 2017 11:37

Hmm, adjustable damping shocks eh? I wonder if I could get away with that in the 'Forgotten Era' championship? The Konis are definitely rather on the stiff side


koni's are adjustable , but you have to take them off the bike to adjust them
(remove springs , compress them to the max , and you should be able to adjust them by turning the shaft)
but koni's are not exactly state of the art..
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Re: An update and preparation for the Piston Rally

Postby 72degrees » 16 Sep 2017 12:24

huub wrote:
Hmm, adjustable damping shocks eh? I wonder if I could get away with that in the 'Forgotten Era' championship? The Konis are definitely rather on the stiff side


koni's are adjustable , but you have to take them off the bike to adjust them
(remove springs , compress them to the max , and you should be able to adjust them by turning the shaft)
but koni's are not exactly state of the art..


I had a pair of Koni "Dial a Ride" shocks years ago. To be fair I don't think the springs are right on these anyway. They came on the Spanish barn find 250 and had been bodged to fit. The Hagons I had made up to my spec. for the Rotax/Morini years ago worked pretty well. I may try a pair of the adjustable ones on the road machine first. They can be quickly swapped to the 'racer' if they show promise.
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