Forgotten Era Speed Hill Climb 350 Morini MKII

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Forgotten Era Speed Hill Climb 350 Morini MKII

Postby 72degrees » 25 Nov 2015 10:51

After having both our bikes stolen last year (KTM 350SXF and Yamaha YZ450F) we have been sharing a KTM 250 EXC this year but miss having a bike each at meetings where you can't share. I used to ride the 2C/375 years ago but it has too much sentimental value after 32 years to risk throwing it down the road going up a hill. I built a replica of my first Morini hill climber (from 1981) in 2008 based on a 77 Strada, but even with the borrowed 375 engine it was not very competitive in the new Forgotten Era championship as it was up against 1000cc machines. The rules have now changed and there's an up to 400 award. With the lad riding (he was second in the 250 championship and got in to the top ten run off a couple of times on the KTM) it might stand a chance and also pick up some points in the 350 class if we stick to Sport pistons.

So the 77 Strada engine that lived under the bench since 2008 has been unearthed with a view to going in to an incomplete and fairly rough late 2C I just acquired. A horror photo of the state of the inside of the 350 engine is below. After finally getting to the crank it looks like it was on borrowed time despite running reasonably well before it was taken out. One crank journal ridged and the shells badly scored, so as long as it hasn't already been reground beyond return it may as well also have a roller timing side main bearing conversion. The head I swapped from the 375 will need an exhaust port job.

I'm sure I'll find the boxes with all the valve gear I removed eventually but the budget is already growing faster than anticipated so a couple of possibly daft questions. Is the 250 rocker gear the same as 350? Presumably 250 heads use smaller valve sizes?

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Re: Forgotten Era Speed Hill Climb 350 Morini MKII

Postby EVguru » 25 Nov 2015 14:54

72degrees wrote:I'm sure I'll find the boxes with all the valve gear I removed eventually but the budget is already growing faster than anticipated so a couple of possibly daft questions. Is the 250 rocker gear the same as 350? Presumably 250 heads use smaller valve sizes?


250 valve gear is the same as 350 and 500 as well (pretty sure). 501 has a spacer and longer rocker shaft because the valve guides were moved further apart to fot bigger valves.

250 head is the same casting as 350, but with a smaller inlet seat and valve.
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Re: Forgotten Era Speed Hill Climb 350 Morini MKII

Postby 72degrees » 25 Nov 2015 15:14

EVguru wrote:
72degrees wrote:I'm sure I'll find the boxes with all the valve gear I removed eventually but the budget is already growing faster than anticipated so a couple of possibly daft questions. Is the 250 rocker gear the same as 350? Presumably 250 heads use smaller valve sizes?


250 valve gear is the same as 350 and 500 as well (pretty sure). 501 has a spacer and longer rocker shaft because the valve guides were moved further apart to fot bigger valves.

250 head is the same casting as 350, but with a smaller inlet seat and valve.


That makes sense. Rats - now I remember that the head I swapped also has a crack between the valve seats and a stripped thread on one rocker cover screw. Oh well, I suppose NLM can sort that all out together. They had to repair a similar crack when they re-did the port on the other head on the 375. They said they'd never seen it on a 350 head before. Must be that revving it to the red on the 250 tacho it has ;)
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Re: Forgotten Era Speed Hill Climb 350 Morini MKII

Postby EVguru » 25 Nov 2015 15:40

If you go big bore, you can fit 500 heads. Bengy used fit 500 heads anyway, relieving the top of the liner to clear the valves. I used a set of ex Bengy barrels modified (quite crudely) that way for Pete's racer. they cleaned up with the 402cc conversion.

If you have a valve seat done, go with a Bronze material (Trojan is very good). It gives the valves a much easier time and the expansion coefficient is almost the same as Aluminium, so they tend to stay in place!
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Re: Forgotten Era Speed Hill Climb 350 Morini MKII

Postby 72degrees » 25 Nov 2015 17:12

I'd like to keep it at 344 ish so that it's strictly legal in the 350 class though a CR even a bit higher than a Sport might be good.. Hill climbing is one of the last speed disciplines in which there is an actual 350 class - hence the 2011 350SXF. If I can get a Morini anywhere near the power that (standard about 37BHP at the rear wheel) was pushing out I'd be very happy :) - though I don't think I can get down to the 100Kgs dry weight!
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Re: Forgotten Era Speed Hill Climb 350 Morini MKII

Postby EVguru » 25 Nov 2015 17:19

First of all measure the stock compression, it might not be as high as you think, even using the swept volume + combustion chamber volume / combustion chamber volume formula.

You can leave the base gaskets out and/or shorten the barrels (at the base is best) to get more compression.
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Re: Forgotten Era Speed Hill Climb 350 Morini MKII

Postby 72degrees » 10 Dec 2015 16:39

Progress report.

Crank, rods, timing side crankcase and one head dropped of at NLM.

The good news. The crank is badly scored but the shells are standard so it should clean up with a regrind.

The bad news - a call from Ollie just now: the inlet valve guide in that head is toast and a replacement isn't currently available.

So plan B is to whip a head off the seemingly low mileage 250 engine and see what the state of that is, with a view to getting a 350 inlet valve seat put in to one (or both if a check reveals the guides on the other head from the 77 350 are as bad) of those. I'll get a video of that engine running first though, as possibly someone may be in the market for a sound 250 twin lump minus heads. Unless one of you has a spare 350 head in good nick (or even better a 500 pair) hanging around?

Makes me wonder now what the state of the guides is on the original 76 head left on the 375. It had a port job and crack between the valve seats fixed - errm, 20 years ago but I can't remember if it was treated to new guides.

Looks like this project is going to take longer and cost more than anticipated. Oh well, I just collected the KTM 250EXC from a refresh with new piston, mains and rod kit. 2T motors have their advantages. At least that whole job, including labour, cost less than just the parts required for a partial gearbox rebuild and new clutch basket/primary gear on the YZ450F (that got stolen not long afterwards :( ).
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Re: Forgotten Era Speed Hill Climb 350 Morini MKII

Postby EVguru » 10 Dec 2015 21:50

I've got some NOS valve guides somewhere.
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Re: Forgotten Era Speed Hill Climb 350 Morini MKII

Postby 72degrees » 11 Dec 2015 08:28

EVguru wrote:I've got some NOS valve guides somewhere.


Any chance you could be persuaded to sell a pair ?
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Re: Forgotten Era Speed Hill Climb 350 Morini MKII

Postby 72degrees » 05 Jan 2016 19:02

Update.

The head problem is not quite resolved yet but there is a plan B, C and even D.

All new bearings fitted with ease (oven and freezer) in to the LH crankcase and the gear cluster (teeth, bushes, selectors and dogs all good enough for me) seems to have gone back in OK after finally correctly identifying the variant (Table 4A not 4 in the parts list I found and not as in the original Harglo blue book either). The one with a toothed washer/shim, that also helpfully bore witness to having been up against a seeger clip - so that clinched the position after I'd temporarily lost track of where it went. I found (after having been given a tip) that a large zip tie strategically wrapped round the cluster helped to keep things in place as I j-j-jiggled. Also that a particular sized, very sturdy, KTM/Husaberg original parts cardboard box made a perfect cradle to support the case on. Can't check end float or selection until the RH case comes back from the crank regrind and roller bearing job via NLM but I plan to do a 'dry but oily' run of those without the crank in first. Everything seems to spin round OK for now though. Presumably the correct end float relies on a centre gasket being fitted? This engine had none (nor the vital copper washers). The manual I'm using talks about applying a coat of silicon sealant to the mating faces - but surely this must be in addition to gasket 21.01.57?

Next job is to reassemble the oil pressure relief valve (as you can imagine, given the state of the inside of the cases as shown in the photo above, it needed a very thorough cleaning) and fit a new crank supply oil seal in to the clutch/side cover. I think I'll replace with a DPSM (ADP) type as that's what was in there and Barnwells can supply the 15247 size required.

I must get round to taking a video of the 2C engine running (pretty sweetly) before I drop it out and then start removing unnecessary ancillaries. Got to find a very small petrol tank that can be adapted. Should have kept the Puch Gran Prix moped one that I modified in 1981 and used again in 2008 and not sold it on Ebay. At least I kept the cast front wheel from FE hill climber MkI that has a race wet Dunlop - though I suppose it might be getting a but age hardened by now. Time and budget dictate that I will have to start off using the exhaust system it came with. A 2C 2:2 in surprisingly good condition except that someone has hacked off the back half of both silencers and welded on 'straight through' cans that can be repacked MX style. Now they have been. it sounds (with the 250 engine) not bad - but I'm sure it will rob the soon to be sport pistons, L cam and PHBH28 carbed 350 of some top end. If it shows promise at the first event I'll treat it to a 2:1.

Might not be ready for Hartland Quay on 20th March, but I hope to have at least fired it up by then and if necessary I'll borrow the intakes and carbs from the 2C/375 to see if it does.
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Re: Forgotten Era Speed Hill Climb 350 Morini MKII

Postby EVguru » 05 Jan 2016 22:24

I think the centre gasket was deleted to improve oil tightness and replaced with sealant.

Later cases used a rubber sleeve like the oil pump feed on the upper internal case bolt in addition to the copper washers.

Arexons Motosil D is available from Amazon.co.uk.
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Re: Forgotten Era Speed Hill Climb 350 Morini MKII

Postby 72degrees » 05 Jan 2016 22:57

EVguru wrote:I think the centre gasket was deleted to improve oil tightness and replaced with sealant.

Later cases used a rubber sleeve like the oil pump feed on the upper internal case bolt in addition to the copper washers.

Arexons Motosil D is available from Amazon.co.uk.


Ah, that makes sense.
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Re: Forgotten Era Speed Hill Climb 350 Morini MKII

Postby 72degrees » 07 Feb 2016 15:05

One step forward two steps back. Crank work done but it needed new rods as the big end eyes had gone oval :(

Once all the bearings had been fitted (including timing side roller conversion) I decided a trial assembly to check gearbox function was wise. With the benefit of hindsight I realise that although this engine was a runner before I extracted it I never actually checked that the gearbox worked.

I'm pretty sure I got the cluster back in correctly (the type shown in table 4A of the parts list with toothed washers) and it seemed possible to get it in to all the gears by spinning the main shaft and manipulating the selector drum before I put the selector mechanism back on. The selector and detent plates seemed to be sitting correctly when the mechanism was back on so I went ahead and put the cases together without the crank or cam (with dowels and screws) and tried to get all the gears. All seemed OK until I tried the higher gears (> 4th I think) when it bound up. There was a fair amount of end play on both shafts when in neutral, but what's acceptable?

I'll check everything again but first a sanity check on the detent spring. The parts list and workshop manual gearbox diagram show the spring (42 in the image) as having a bend in the last section that is located in the groove in the stopper plate peg. Yet the illustration of it assembled makes it look as if it should be essentially straight before assembly. My spring has no bend as in the parts list and It certainly puts a lot of pressure on the detent plate once located, perhaps too much?.

Oh well, I may have to just chuck the bottom end at NLM but I wanted to do most of the work on this build myself.

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Re: Forgotten Era Speed Hill Climb 350 Morini MKII

Postby 72degrees » 17 Feb 2016 19:42

Well the spring is as it should be so I had another go after making sure the shafts, selector forks, drum and selector mechanism were all really well coated with lubricant this time. Fitted a 'good used' bush from NLM in to the second gear pinion on the layshaft. Significantly less wobbly, but not worth changing the other bushes (not so bad) on the basis of that one I reckon unless new ones could be obtained. A dry (but oily) run without crank or cam gave much better selection this time so today put it together properly. A bit of scare when the crank went tight at first with preliminary tightened case screws but after quickly putting the primary drive and oil pump gear on reasonably tight with the old nut it snugged up against the drive side bearing properly and freed off nicely. Still good and free once the case screws were tight so looking good.

I have a new type ring nut (and special tool) to put on before going any further. Looks to be a self locking type so am I right in thinking best not to use any Loctite on the thread for fear of it getting under the oil pump gear and preventing it turning in extremis?
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Re: Forgotten Era Speed Hill Climb 350 Morini MKII

Postby 72degrees » 20 Feb 2016 19:28

Progression_1.jpg
Progression_1.jpg (254.42 KiB) Viewed 26194 times

More progress than in this photo today. Oil pump, primary drive and clutch cover now back on. I even managed to get the kickstart spring wound up correctly. Next stage is a quick check on clutch end float but I'll probably leave final clutch assembly until the bottom end is in place in the bike. Lighter to lift in to place without the top end on and I still remember the cunning dodge required to get a 350 rear cylinder and head on when in a 250 frame.Time to order pistons and start preparing the heads and valves. I hope I can find the pushrods from the cylinder that I pinched the head from for the 2C/375. Fingers crossed they are in a box in shed #2 along with the rocker gear.

I might have a preliminary investigation of the cam timing soon. I know I can't do it properly until the top end is back on, with the clearances set appropriately, but a bit of a trial run with a degree disc while watching/feeling the cam followers might be interesting as the cam is a bit of an unknown quantity.

The sparks department (including stator and rotor) on the project bike 250 can do for a first start attempt in due course. That starts amazingly easily, so the components must be in at least reasonable condition.

I think I'll temporarily borrow the PHBH 28s and intake rubbers from the 2C/375 to quickly know it lives again and it will have to make do with the 2C 2:2 exhaust system until I can tell if it shows enough promise to justify throwing even more cash at it.
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