Forgotten Era Speed Hill Climb 350 Morini MKII

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72degrees
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Re: Forgotten Era Speed Hill Climb 350 Morini MKII

Post by 72degrees »

At last conditions in the garage are pleasant enough again to tempt me out there so a little more progress has been made. A 10 degree mandrel bend would have been too much for the header pipes and I couldn't find them in the right diameter anyway. Just slightly more bend needed of the last sections ('up' on the front and 'in' on the rear) to get them to marry up with the twin inlet silencer. Definitely a bit by bit try and offer up job which would have needed taking the bike on a trailer to a specialist at labour rates I didn't fancy. Nothing ventured, nothing gained. I knew I should really pack the pipes with dry sand and cap them off before attempting bending them and I wasn't sure I could get enough heat in to them without an oxy torch. Anyway, my large propane burner that I use for flame throwing the weeds on the veggie patch got the sections needing tweaking glowing cherry red (a bit hairy while clamped in my vice without setting fire to the work bench) and by using a breaker bar inserted in the silencer end of the pipe for extra leverage I was able to get them to move. The front pipe worked best as it was a shallow angle. The rear was already a fairly tight radius and so inevitably kinked oval a tiny bit. Not too badly and you can't see it as it's under the engine. It will still be far less restricted than by the standard weedy 250 pipes. Perhaps I will get some kind of weird stepped pipe resonance effect at certain rpm?

I'd already started it up jury-rigged with this system but the silencer at a jaunty angle that would be useless for riding. Seems to have a bit of a flat spot now just off idle which it didn't have while being 'run in' mounted in the road 2C (with an NLM stainless 2:1 system). Using the same carbs (also same ignition pickup, but relying on the OEM transducers that came with the barn find 250 rather than the NLM module on the other one). Might be OK once really warm as I don't like to subject my neighbours to it being run for too long on a 'race' exhaust system. Last minute tweaking of the idle mixture before Hartland may be in order to get better progression and I'll go armed with different idle jets.

Single seat still not finished. Well the mounting structure is, but it looks awful with exposed brackets required to brace it. I might not have time to fabricate a neat alloy sheet tail piece but I've made sure I can revert to the standard seat if necessary. The 125H tank paint finish is not very good (brush applied) but given the condition it arrived in it serves its purpose. The front will be resiliently mounted with a through bolt and cut down demijohn bungs. The rear will be restrained on the cushioned frame mountings by a couple of sewing machine rubber drive belts.

I agonised over what rear tyre to fit to go with the racing Dunlop on the front. Dunlop classic racing tyres are very hard to come by now but new stock Avons are available The first two versions of the Morini hill climber were 350 cycle parts with 2.15 rear rims, and the Rotarini used a 350 rear hub/carrier persuaded in to a 250 swing arm with a spoked rear wheel that could accommodate a meaty KR124. 2Cs don't seem to like oversize tyres and Avon don't recommend putting their 100/90 Roadrunner R2 (available in race compound) on less than a 2.15 rim, whereas the 2C rear is only a 1.85. So in the end I went for an AM26 Roadrider 90/90 in 633 compound (the excellent Dennis Trollope had one in stock) . It looks a little skinny by modern hill climb standards, but the overall width is only 5mm less than a 100/90 Roadrunner R2. The proof of the pudding will be first run up Hartland, but while there won't be much rubber on the road in a straight line it has a lovely profile which should give a nice contact patch when laid over - which is what matters.
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72degrees
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Re: Forgotten Era Speed Hill Climb 350 Morini MKII

Post by 72degrees »

Well the 2:1 system is on properly. I remembered to take the centre stand off first as you can't get the mounting bolt out with system in place. Sounds OK, but even just making small start line test launches up the drive I was reminded that I need to rig up a heat shield. The system came with some nice stainless clamps with nuts welded on which I remembered to slip on the rear pipe first. I shall make a shield from a 45 degree 2inch alloy mandrel bend split down the centre (leaving a spare in case of mishaps). Quite a warm day so the progression was better even half warmed up. It's still rather noisy though, particularly when the row is only shielded by a 125 tank. In fact that might be making it worse as the front is yet to properly secured. Seems to be coming from the front cylinder top end, so more in hope than expectation I'll try re-checking the rocker arm side play and valve clearances.
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72degrees
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Re: Forgotten Era Speed Hill Climb 350 Morini MKII

Post by 72degrees »

I decided to ditch the single seat for now. A slightly anxious moment when finding that with the 125H tank mounted as far forward as it can go the '82 2C seat is rather snug against the rear of it and creases the cover slightly. Never mind, it will do for now. The rear pipe now has a heat shield. Not quite as efficient as the version I lashed up with jubilee clips and spire nuts for the NLM 2:1 on the 375, as the natty clamps/mountings seem to conduct a bit more heat to the shield. Doesn't get anything like as hot as a bare pipe though and shouldn't burn boots. Just got to put the rear racing number plates on and lock-wire things (sump plug, bar grips and to be on the safe side the exhaust port nuts - to jubilee clips also butted up to a head fin). Tomorrow I shall check the rocker gear for side play and valve clearances in hopes of reducing 'rattle' a bit, but once above idle the fruity 'silencer' drowns it out anyway. It's pretty much ready for Hartland Quay now, so I have time to unearth the 250EXC and make sure that is still going OK for the lad.
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72degrees
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Re: Forgotten Era Speed Hill Climb 350 Morini MKII

Post by 72degrees »

Well it's as ready as it's going to be for Hartland Quay on Sunday. The 125H tank is still a work in progress so I haven't adorned it with badges. Brush applied Hammerite smooth seems a bit inclined to chip and it really needs rubbing right back again and a final coat applying.

There was a bit of side play in the rockers, particularly on the front pot, but despite sounding better when first started up it's still a bit noisy at idle once warmed up. I think it may actually be the worn gear bushes that I couldn't get new replacements for (particularly the layshaft 1st gear ) as it's much worse with the clutch cover off.

The progression carburation isn't quite right still so the main target will be to actually get to the top of the hill without stalling it on the first hairpin.

A chalk and cheese photo of it next to the 250EXC before loading up. Don't laugh too much.
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corsaro chris
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Re: Forgotten Era Speed Hill Climb 350 Morini MKII

Post by corsaro chris »

Hi Pete;

That's a nice competition number they've given to you - do you get to keep it all season or is it just for Hartland?

Good fortune on the hill anyway, and keep smiling, I'm sure that stalling will be the last thing that happens once it's warmed up - it's not a 1200...

CC
"I'll use the Morini"
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72degrees
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Re: Forgotten Era Speed Hill Climb 350 Morini MKII

Post by 72degrees »

corsaro chris wrote:Hi Pete;

That's a nice competition number they've given to you - do you get to keep it all season or is it just for Hartland?

Good fortune on the hill anyway, and keep smiling, I'm sure that stalling will be the last thing that happens once it's warmed up - it's not a 1200...

CC
Heh, hadn't thought of that. 344 is actually the number Duncan will be riding it with. My permanent NHCA 350 number is 314. We will be swapping bits of white tape around between runs.

Riding it by the seat of the pants with no tacho will be interesting on this gearing. I must remind Duncan that it hasn't got a rev limiter. He has never ridden a four stroke without one before - never mind one with a right hand gear shift. I suspect he will hate it but he may still end up quicker than me on it.
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Tanshanomi
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Re: Forgotten Era Speed Hill Climb 350 Morini MKII

Post by Tanshanomi »

Loving this project!
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Re: Forgotten Era Speed Hill Climb 350 Morini MKII

Post by MickeyMoto »

Laugh? Indeed, the KTM is a bit of a joke next to the svelte Morini...
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Re: Forgotten Era Speed Hill Climb 350 Morini MKII

Post by MickeyMoto »

Laugh? Indeed, the KTM is a bit of a joke next to the svelte Morini...
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72degrees
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Re: Forgotten Era Speed Hill Climb 350 Morini MKII

Post by 72degrees »

MickeyMoto wrote:Laugh? Indeed, the KTM is a bit of a joke next to the svelte Morini...
Svelte is one word for it. Hardly the most photogenic Morini ever nailed together.
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72degrees
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Re: Forgotten Era Speed Hill Climb 350 Morini MKII

Post by 72degrees »

Well, mission accomplished. It actually managed to get to the top of Hartland Quay hill not just once but nine times. Not exactly fast, but then I wasn't really expecting it to be and on a brand new rear tyre it took the first few runs to trust the grip. Given it is only a 90/90 it was surprisingly good. So good, that on the lad's last run on it he complained that he had touched the 2:1 system down on a left hander. The rear pipe does go rather low on a 250 frame. We then experimented and discovered that the footrest had touched down hard first and folded up enough for the pipe to kiss the tarmac. To be fair, I don't think Morini really envisaged the 2C as a sporting machine. He hated it after his first run but by the end of the day said it was great fun as there was "no pressure to put in a good time". As he hadn't ridden a bike at all since July he wasn't up to his usual pace even on the KTM and only got down to a 27.59 on that. His best run on the Morini was a 31.95 and I managed a 31.98 (but four seconds slower than him on the KTM). Mixing 2T and 4T twin, LH and RH gear change is obviously easier for a youngster and I confess to feeling much more at home on a low powered wee vee than a power valve 2T that wants to wheelie at the slightest provocation these days.

The extra large rear sprocket (44 with a 14T front) means the top run of the chain is very close to the upper chain guard and as the 520 chain was a cast off from the KTM it has a tight spot so had to be set a bit on the loose side. This meant it was clattering against the guard going over the vicious bumps at the finish. As it seems to go OK I will now treat it to a new chain and if necessary modify the guard mounting to raise it a tad. The Konis and Paoili forks are a bit on the stiff side so it skipped across the bumps with the engine note changing as the rear tyre briefly went in to the air. Taking a sensible line to get it upright before the worst of them prevented more than a slight twitch of the handlebars though and no other course is so bumpy. The handling is otherwise just as you would expect from a 2C.

Carburation wasn't too bad once well warmed up so fortunately the lad didn't have to learn the art of coaxing a Morini through a flat spot.

The clutch is still a bit grabby and sudden, which caused him to do a lurid wheelie off the line on one run. It has new plates and springs and I thought I had got the end float perfect but I'll have to check it again. The centre and basket were a bit notched, but I dressed them with a file and they are no worse than those on the 375 engine, which has a nice progressive action. Still, you only use it once on a run.

Engine noise didn't seem any worse at the end of the day after a few severe thrashings but riding without any indication of rpm is more difficult than I thought. The 'seat of the pants' doesn't seem to properly calibrated for this gearing. I might rig up the tacho for the Curborough practice day next Saturday as that features one of the longest straights we do and I don't want to be over revving even in 6th. The digital shift light system is pretty low on the list of priorities.

It is, however, at least with me riding it, hopelessly uncompetitive even in the up to 400 Forgotten Era championship, as that includes a couple of late 80's over-bored to 280 Yamaha 250 two strokes that aren't that much slower than a modern YZ250. Too many 350s to pick up the odd point in the capacity class (lots of pesky KTM 300s that are as quick as 450 4Ts) so it's very much a case of just riding for fun and trying to set PBFTBs (Personal Best For This Bike) which will be guaranteed at each hill I do this year at least :)
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72degrees
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Re: Forgotten Era Speed Hill Climb 350 Morini MKII

Post by 72degrees »

You can see why the lad managed to touch down the rear pipe on a left hander. A 'race' 350 2:1 does hang rather low on a 250 frame. I've nipped up the footrest pivot bolts so they don't fold up quite so easily. Can't see it being a problem for me to be fair. If it was more competitive I'd get a nicely tucked in custom system made up. Being a gangly lad, if I raise the footrests any higher his knees might touch his elbows :) Looks a tiny bit better from that angle, but a single seat would make it more 'purposeful'.

Now trying to rig up a mounting for the cable driven tacho somehow without using the plastic instrument housing. Anyone got any bright ideas other than mine of crude brackets and big zip ties ;)

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Re: Forgotten Era Speed Hill Climb 350 Morini MKII

Post by 72degrees »

Tacho rigged up. Cunningly mounted on the original binnacle screw positions with hand molished alloy brackets and big zip ties. Looks a bit rough, but it works and isn't going to fall off. The tacho head is rotated so that the start of the red line is at 12 o'clock. That way I can just tell the lad to rev it until the needle is straight up. It gives it a slight Aprilia Moto 6.5 appearance but I'll be happier giving it the beans through the gears down the finish straight at Curborough on Saturday now. On reviewing the chain, it seemed to be more a question of tension than anything else and it will do for now. I'll be getting a new 520 one for the 375/2C and as that will do far more miles I'll save the pennies for a while on the 'project'. I'm trying not to add up the total cost so far. After fitting the 38T 520 rear sprocket on the 375/2C carrier I'll leave it off the bike and carry it in the hill climb spares box for now. It would make gearing for very long straights quicker by just swapping the carriers. The advantage of a 6 speed box though is that you can just keep changing up, so fine tuning of overall ratio isn't so vital ;) I made sure the wheel on the project was as far forward as it can go with a 44T, on so with luck I might be able to take up the slack within the available adjustment.

I've treated it to a pair of NLMs natty stick on 3D tank badges. The wrong colour (though it's such a mongrel what is?), but at least they cover the badge mounting holes on the 125H tank.

My entry for the events at Loton Park on Easter Sunday and Monday has been accepted it seems, so I get the chance to see if I can get it to the top there this year.
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72degrees
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Re: Forgotten Era Speed Hill Climb 350 Morini MKII

Post by 72degrees »

To be fair, revisiting my gearing Excel I've probably got plenty of rpm in hand in 6th even at Curborough. Even on the tuned YZ450F on near perfect gearing we could only just about hit 90 through the speed trap! Flat out in 4th is probably the best the 350 will manage.
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72degrees
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Re: Forgotten Era Speed Hill Climb 350 Morini MKII

Post by 72degrees »

My prediction about the gearing was proved spot on at Curborough yesterday. Just nudging 9000 across the finish in 4th so about 75. It was pulling tiny wheelies off the line on 14/44 but I still might source a 13T gearbox sprocket from Italy for it, in hopes of using 5th next time I'm there. It has to be said that it doesn't seem to go quite as well as the 375 with genuine L5 cam. I really must check exactly what the cam timing numbers are on this one. The 375 has an NLM ignition module and 'scooter coils' though, which may help. I have a spare module so might rig that up. The transducers are pretty obviously the original ones from 1982 and spent years in a Spanish barn.

The rear Avon is well and truly scrubbed in now and even I had the left footrest touch down on 'the kink' on one run. No timing, but I'd guess I managed about a 44 (the same as I can in an road legal 1997 MX5). Hopelessly slow and I can't see me breaking the 70 second target at Loton next weekend, but it is a delight to ride.

Now sporting tank badges but definitely what the old motorcycle press would call 'cobby' looks ;)
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