Slow warming up

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72degrees
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Joined: 31 Aug 2007 21:24
Location: West Midlands

Slow warming up

Post by 72degrees »

The 375/2C hasn't been used much of late, partly because it has become very slow to warm up.

It starts OK, usually on just one 'choke' but sometimes needs two, but it takes ages until it will pull away cleanly with both off. I prefer not to warm it up for ages at home first as I used to, as my new domicile is in a much quieter area. The Husky 401 is obviously no trouble at all being EFI and the 57 Gilera 175 might just need the slots on the air cleaner closed down a little for a while when first setting off. No way round that first burst of noise when the Morini fires up with starter jet open but if I try to ride off too soon it is liable to stall or needs one choke on for at least a mile. Handlebar choke operation might allow for 'partial' enrichment suppose, but seems a bit of a faff to rig up assuming the parts are available.

The 375 (L5 cam, high CR - no base gaskets) runs PHB28s and I'm wondering if going a size or two larger on the idle jets might help. I misremember what size are in there - must check.

Don't think it's gunge in the 'progression circuits' as it is fine once fully warm and then even idles slowly and reliably. The Dellortos are the pair I bought new in 2017 so shouldn't be at all worn.

Oh well, must drop the float bowls, establish current settings and search for my little container of spare jets.
3potjohn
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Re: Slow warming up

Post by 3potjohn »

Well worth taking photos of bits, carb settings etc and sticking in a note ( well that is what I do on this iphone).
A little wise voice says just write in a book.
John
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72degrees
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Re: Slow warming up

Post by 72degrees »

Indeed.
I am reading back through the 'Forgotten Error' saga in hope of a clue. but no confirmation of what idle jets are in there. There is an underlying theme in that, of slow warming up though. Noise is not so much of an issue when waiting in the queue for the start line.
norbert
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Re: Slow warming up

Post by norbert »

After fiddling around with the setting of two 501 with diferent camshafts, exhaust and filter systems at the same time I decided to note the dates with an Edding on the float chambers (needle, notch, atomizer, and the jets). For me the most reliable way while you are looking for a good setting. And when you found it, you´ll remember it because you see it every day opening the petcock :wink:

I also sometimes need two chokes for starting. After firing up I have to take the first one off immediatley, the second one stays for a while. Usualy I take it off after having past the first traffic light on the way to avoid starving waiting for green light.
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72degrees
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Re: Slow warming up

Post by 72degrees »

norbert wrote: 30 Jan 2023 12:22 After fiddling around with the setting of two 501 with diferent camshafts, exhaust and filter systems at the same time I decided to note the dates with an Edding on the float chambers (needle, notch, atomizer, and the jets). For me the most reliable way while you are looking for a good setting. And when you found it, you´ll remember it because you see it every day opening the petcock :wink:

I also sometimes need two chokes for starting. After firing up I have to take the first one off immediatley, the second one stays for a while. Usualy I take it off after having past the first traffic light on the way to avoid starving waiting for green light.
Cunning!

This needs to run much longer before I can take off the choke - unless your first traffic light is a lot further away than mine ;)

Seems I have pondered on this before:

http://www.morini-riders-club.com/forum ... 374#p35374

My guess is 42 idle jets, but the experiments with Pollini elbows and filters have muddied the waters. Too cold still to go out and check. I will wait until I'm ready for a warm up ride to do the long overdue oil change.
norbert
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Re: Slow warming up

Post by norbert »

Dulcinea (501) wears 90° Polinis as well. The main jet is only 115 meanwhile Rocinante (also 501) with 350 filterbox has a 130 main jet (and another position of the needle (both X1, 268T atomizers with 42 and 45 idle jets).
So it seems that the Polini filters are working a bit leaner, although my exhaust systems, both 2in2 are quite diferent in my bikes (bigger diameter in Dulcinea without interference tube)
Vitesse
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Location: Crowcombe

Re: Slow warming up

Post by Vitesse »

I have never understood why they need one choke to start. Mine is the same. Either one will do it but never both. There must be a sensible answer???
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72degrees
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Re: Slow warming up

Post by 72degrees »

72degrees wrote: 30 Jan 2023 12:41 My guess is 42 idle jets, but the experiments with Pollini elbows and filters have muddied the waters. Too cold still to go out and check. I will wait until I'm ready for a warm up ride to do the long overdue oil change.
I guessed wrong.

45s

Appeal to spare set of PHBH28s - also on 45s.

I could swear I at least tried 42s at some point, but can I find them. Moving house hasn't helped. At least I now have a shed and they may turn up during the great redistribution of bits in boxes that now permits.

Oh well, I'll order and try a pair a couple of sizes bigger, in the interests of science.

I gave the 57 Gilera 175 priority in the oil change queue on a fine day last week. Based on the colour of the Silkolene mineral oil that came out of that I definitely need to get the Morini done.

Also need to do the Husky 401. Fancy 15w-50 full synthetic (recommended Motorex) and a new filter required! Is there no end to the expense of running a 'fleet' ? ;)
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