My "new" old Bicarburatore

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hugomez
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Re: My "new" old Bicarburatore

Post by hugomez » Sat Nov 01, 2014 10:19 am

Morning,

Perfect day in Amsterdam, sunny, not cold at all, ideal for a motorcycle ride.

At 8.30am I was already with the bike in the lift of the building to test it on the street.

Result:
Only one cylinder was running, the left one. The right cylinder only gave me a few "puff", but after that no more.

I have check and there is spark at both sides, but the right one is much weak that the left.

Now the bike is at my flat again and sadly I have no more time today to spent on the bike :(

I guess I will have to check the ignition.

Aiaiaiaiaiaiiiiiii
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tony mooring
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Hugo's loss of spark.

Post by tony mooring » Sat Nov 01, 2014 2:21 pm

UJH, Just wondering about the modification you made to Hugo's flywheel. Does it matter where the cam is according to the magnets around flywheel?? Maybe this could be the problem with Hugo's loss of spark on the right cylinder if the flywheel outer has been re-arranged on re-assembly. (if you know what I mean).

Lars
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Re: Hugo's loss of spark.

Post by Lars » Sat Nov 01, 2014 3:51 pm

tony mooring wrote:...Does it matter where the cam is according to the magnets around flywheel??
It does matter. It matters a lot.
The cam must be in exactly the same position relative to the magnets as before the modification.

I am sure David (UHJ200) put some marks to indicate the correct position of the wheel in relation to the hub. But it is something to keep in mind for Hugo if he ever separates the two.

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Re: Hugo's loss of spark.

Post by tony mooring » Sat Nov 01, 2014 4:13 pm

Hi Lars, But it is something to keep in mind for Hugo if he ever separates the two. That was the object of the exercise, to separate the two in order to adjust the contact breaker points to their correct positions without all the fumbling through the flywheel slots. I assume that's what Hugo has done before he took his bike out for the trial.

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Re: Hugo's loss of spark.

Post by Lars » Sat Nov 01, 2014 5:25 pm

Hi Tony, in that case it could very well be the cause. Good point.


Hugo, did you separate the the hub from the flywheel? Were you aware that it had to go back in the same position? It is not completely obvious, so it would be easy to overlook.

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Re: Hugo's loss of spark.

Post by hugomez » Sat Nov 01, 2014 6:14 pm

Hi Tony and Lars,

Thanks for your replies. I can confirm that David (UHJ200) assembled in the correct position the flywheel/hub after the fantastic job he did with the rivets/screws at the hub of my flywheel.

I didn't remove the flywheel/hub when I adjusted the points a few days ago. The all purpose of the job that David did on the flywheel was to make easier for me the adjustment of the break points, but the other day I didn't removed the flywheel from the hub because still I want to make some marks at the hub to match with the A and O marks of the flywheel, to know where they are when the flywheel is removed. (Have this any sense?)

Hugo
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tony mooring
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Re: Hugo's loss of spark.

Post by tony mooring » Sat Nov 01, 2014 6:52 pm

Hello Hugo, Yes, that makes sense O.K. If you could borrow some letter punches that would be good to mark the hub with an A and O. You will have to check your points gap and electrical connections. Check that the HT lead is making good contact in the coil because the coils are vertical and a lead may have come loose. Good luck.

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Re: Hugo's loss of spark.

Post by Lars » Sat Nov 01, 2014 9:35 pm

Hi Hugo, yes, follow Tony Mooring's advice above. In particular, set the points at max 0.3 mm as the factory suggests, and see if the spark looks more normal then. You can even try 0.2 mm and see if it makes a difference.

It did work before, so try to analyze what could have changed in the process.

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Re: Hugo's loss of spark.

Post by hugomez » Sat Nov 01, 2014 11:46 pm

Hi Tony and Lars,

I spent a little time on the bike after dinner to check a few things. The first was trying to fix a little air leak I had at the left cylinder (the cylinder that was working today). The air leak (or lack of proper seal) was between the cylinder and cylinder head. I put a second metal gasket rim at the cylinder head and now I can't hear the air coming out. During the test this morning, burned oil was coming out by that join. In the place I tried to solve the problem tightening more the nuts of the cylinder head, but still was not enough doing it. Now adding the second rim seem to be ok.

The second thing I did is about the electric "issue". Well, before start touching the ignition I started by the easiest part to check, the spark plugs. The side that was giving a good spark this morning was the left, and the one that didn't was the right. I have swap the spark plugs, getting the nice surprise that doing this I get good spark at the right side. Then the left had a poor spark.

I took a brand new spark a have and replaced the one that seem not to be ok, now both side have a nice spark.

Now I have a few questions:

Is it possible that this morning the right cylinder didn't work because a bad spark plug?

Is it possible that because another ignition problem, a good condition spark plug was broken?

Perhaps the unburned fuel/oil broke it?

I have to say that the spark plug that give the poor spark was only use in previous tests, it was practically new, perhaps 10 / 15 kilometers made with it. Is it not strange that it stop working fine after so little use?

What can be the reason that break a spark plug?

Sorry to ask so many question but I am very curious.
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tony mooring
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Re: Hugo's loss of spark.

Post by tony mooring » Sun Nov 02, 2014 12:26 am

Hugo, It would appear that the 'no firing' on right cylinder must have been faulty plug. Plugs can foul up at any time. I always ride with spare plugs. In the old days plugs used to 'whisker up' but these days the plugs are manufactured to a better degree and it's not often you get trouble. Take your faulty plug to 'an old time' garage and ask them to put it on their sand blasting machine and get them to check plug after. It may be just oiled up and that was your problem.

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Re: Hugo's loss of spark.

Post by Lars » Sun Nov 02, 2014 8:49 am

I agree with Tony's comments and observations. I have had similar experiences with spark plugs.

The only thing I can add is an answer to your second question: No, spark plugs are never damaged by a defective ignition system. Not directly, at least. Instead, they get fouled up by the resulting misfiring in the cylinders. Unburned fuel and oil mixed with soot particles get pushed under high pressure into all the little crevices of the plug and causing it to fail. Once cleaned up, as Tony describes, they are usually good to go again.

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Re: My "new" old Bicarburatore

Post by hugomez » Sun Nov 02, 2014 2:17 pm

Hi, thanks Tony and Lars for your replies about the spark plugs.

I just arrived home after a few hours with the BIcarburatore at the neighbourhood.

Today after around 10 meters pushing the bike it started, both cylinders working. The engine was very accelerated so I stopped to close the air screws of the carbs to see if I managed to reduce the revolutions. The smoke that was coming out the silencers was HUGE, I was even worried that somebody could call the police.

While I was inside the white cloud tuning the carbs screws, I could see that a lot of burned oil was coming out from the pipes at the join with the cylinders.

Once the engine revolutions drops a bit, I sit on the bike and start my ride. The smoke continued very intense for around 10/15 more minutes.

I was hoping that this oil was unburned in the pipes from yesterday, and it was confirmed when the smoke reduced a lot, coming out from the silencers a very reasonable amount, normal amount I would say for a Rumi that has a 4% oil mixture at the fuel. Also the drops coming out from the join between the pipes and cylinders reduced drastically (but not completely)

The rest of the time no more crazy amount of oil came out of the silencers, and also not oil was coming out from the little hole of the cap/screw at the top of the upper half. I mention this because in previous tests the oil was coming out by there, because of the vacuum effect when the leak from the halves to the cylinders.

Keeping all these details in consideration I would say that during the complete test I did today there was no leak from the inside of the gearbox to the cylinders.

However not everything have been good. The bike was not going well, because of a bad carburation setting, or a bad ignition setting. So I spent most of the time pushing the bike, riding 30 meters, stopping (usually because it has no power) and trying again and again.

The carbs have the same settings they had in previous tests, and I have to say that in some of the previous test the bike was not going bad. The only thing that is not the same is the float bowl, and the float and needle inside this. The float bowl I had in previous test was a replica and I installed on it a brand new 6.5gm plastic float. When I sold that replica float bowl, I left the 6.5gm float and needle on it.

The float bowl I have right now in my bike is an original one. It was coming already with a float bowl and needle from the previous owner, but I didn't check the "size"of it or the position of the needle. I will check once my girlfriend is not at home to do not upset her with the smell of the fuel.

Can be the float bowl the reason of that very bad performance?, probably not, right?, I wonder if perhaps having a wrong needle position and a wrong float size, a lot fuel is coming inside the carbs. Could it be?

During my test, I removed the sparkplugs to see them and they where both very wet, too rich of fuel.

I am happy that during the test there was not signal of leak from the gearbox to the cylinders, but I guess until I do not have a proper ride with the bike I won't be able to confirm if the join of the halves will resist or not.

Now I am going to rest, very tired for pushing the bike that much.
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Lasse
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Re: My "new" old Bicarburatore

Post by Lasse » Sun Nov 02, 2014 3:22 pm

Even when reading about all your troubles, I will heartily congratulate you with the results!
It looks like you have eradicated the leaks between gearbox and motor.

But you are running WAY TOO RICH - & I guess it must be because of the float, sitting in a wrong position.
Generally speaking, the level of petrol should be just a tiny tad UNDER the mainjets - with the bike on the level.
The carb needles should be in the mid position, to start with.

& Please remember, every time you adjust the points gap, you change the firing point somewhat.
Even if the RUMI motor is quite tolerant of firing points, I would recommend you to have your ignition (points start to open) approx. 1.7 mm before dtc.
And with all your new ignition parts, which are in perfect order, I would NOT go under 0.3 mm in points gap.

About plugs: Yes, even new modern plugs can be "temperamental".
The time I had my two RUMIs, I used NGK "Iridium" plugs, which never fouled up, and always gave dependable starting.

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Re: My "new" old Bicarburatore

Post by hugomez » Sun Nov 02, 2014 5:09 pm

Hi Lasse,

Thanks for congratulate me for the result regarding the leak between the gearbox and the cylinders. I am also very happy for it but as I mentioned, I won't be sure until I can have a proper ride, riding a good speed for a constant period of time making at least a few dozens kilometres.

I have to apologies about my comment before about the float, I was wrong. I have check it and inside the float bowl I have the same float and needle I had in my previous float bowl. When I wrote that I didn't remember changing the float, but after had a look into the bowl and see it I remembered changing it. Again, sorry.

I guess the focusing point now should be the ignition, at least at the moment.

Thanks Lasse,
Hugo
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Lasse
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Re: My "new" old Bicarburatore

Post by Lasse » Sun Nov 02, 2014 6:14 pm

Hugo, wet & sooty ignition plugs normally Means one thing: - overly rich mixture!
You also described too much smoke, also an example of too much gasolene, leaving the cylinders more or less unburnt...

Considering you do not have sticking needles, or way too large mainjets, I am still convinced about the level of fuel must be too high inside the floatbowl.
Quite easily controlled, just by taking the chokes & needles out of the carbs. and shining a torch inside the openings, WHILE OPENING THE PETCOCKS!
If you see petrol running out through the openings the needles occupied before dismantling - then you KNOW the floatlevel must be too high.

In rare instances, you will experience a float with a microscopic hole in it, allowing fuel to run inside the actual float, thereby making it heavier.
Try to shake the float, and listen if some fluid is inside it.
A too heavy float, obviously, will allow more fuel to access the bowl, and make the mixture too rich.

To me it seems strange, if the ignition should make the motor run rich?
OK. if the firing point is MUCH to late, you might get unburnt fuel out in the exhaust - but personally, I dont believe you sat your ignition that bad...

But the worst scenario comes here, sorry.
Considering EVERYTHING of ignition & carbsettings are 100% spot on, the only thing that could give a hell of a lot smoke, & oily plugs: Gearbox oil!

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Re: My "new" old Bicarburatore

Post by hugomez » Sun Nov 02, 2014 6:29 pm

Hi Lasse,

The Huge amount of smoke was only happening at the beginning of the test today. I think it was because the dried oil that was inside the pipes and silencers from my previous test. Once the pipes and silencers got very hot, all that dried oil burned, but after all it was finally burned, the amount of smoke reduced drastically.

Right now, at this precise moment I do not think there is a leak from gearbox to cylinders, what I am experiencing right now is a very low power on the engine and a very rich mixture (the spark plugs are wet).
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Re: My "new" old Bicarburatore

Post by hugomez » Sun Nov 02, 2014 7:18 pm

Hi Lasse,

I want to add something else to my last reply.

During the test this morning I removed the spark plugs twice and both times they were wet and dark.

I didn't touch the mixture screws of the carbs, they were all the time one turn and a half out, I leave it like that, however the air screws of both carbs I have been moving all the time (always trying to have at both carbs the same position) , sometimes to reduce the revs of the engine, sometimes to the opposite direction trying to see if getting more air I could get the engine performing better and getting stronger.

When I arrived home I didn't check the spark plugs. Now I took them out of the bike and not wet and dark as they were during the test, actually the one of the right cylinder is completely dry and light brown. I will take photos and post it here.

Very confuse at this moment. I will set the ignition as you suggested for the next test in the street.

Good night ;)
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Re: My "new" old Bicarburatore

Post by hugomez » Sun Nov 02, 2014 7:46 pm

Here the photos, but probably difficult to read, because no one of them was brand new for the test today.

One of them I even used at the test of Saturday when only one cylinder was working. The other I took from the box of spark plugs, I check this morning and it has a nice chocolate colour so I put on the bike for the test.

Another thing I did today in one of the times I removed the spark plugs to look at them, was to clean with a piece of cloth and also with sand paper.

As I said, having all this in consideration, probably is difficult to read this spark plugs.

Next time I test the bike I will mount brand new once.
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arthur lewthwaite
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Re: My "new" old Bicarburatore

Post by arthur lewthwaite » Sun Nov 02, 2014 9:41 pm

hugo looking at the plugs as in pictures the one on the right is firing and mixture about correct,the one on the left as i see it is clean and wet no carbon on it onlywet fuel which is a sign that the engine is not working(f iring)either because of lack spark or lack of compression,do a compression test.either of these could be your reason for lack of power and unburnt fuel.

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Re: My "new" old Bicarburatore

Post by hugomez » Sun Nov 02, 2014 10:19 pm

Hi Arthur,

In the test of yesterday (Saturday) I can confirm that one cylinder was not working, but today (Sunday) all the time both cylinders where working. Sometimes when the smoke was very low I put the hand to see if air was coming out from the silencers, and yes, they both were working.

As I mentioned before, in some point I cleaned both spark plugs, even with sand paper.

In my next test I will use brand new sparkplugs to be sure the reading is correct.

Thanks Arthur,
Hugo
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Ian Skinner
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Re: My "new" old Bicarburatore

Post by Ian Skinner » Mon Nov 03, 2014 12:11 am

We have all been there!!

Ian
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Re: My "new" old Bicarburatore

Post by hugomez » Mon Nov 03, 2014 9:23 am

:lol: :lol: :lol: Ian, that was me yesterday :lol: :lol:
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Re: My "new" old Bicarburatore

Post by Lasse » Mon Nov 03, 2014 10:36 am

Certainly yes, Hugo, your results are confusing...
A good idea, obviously, is to install new plugs - but why not try the Iridium type from NGK?
Giving me super results.

As I had a Bicarburatore, together with a Corsa, you may use my settings, because the motors in question are more or less comparable.
When I had the motors running really well, I had mainjets of size 90 - later to go Down to 88.
My mixture screws were two full turns out - and my ignition settings, as already told.

PS. I had a good deal of trouble in adjusting the petrol level in the floatchamber(s)
In the bike with remote floatchamber I shifted the actual floatchamber up and Down, until I reached a position, where the petrol almost trickled out of the needle orifices.
(So I had to turn the petcocks off, everytime I left the bike...)
Talking about the twincarb setup as you have (common floatchamber) - I could fine tune the petrol level, by adding or removing gaskets under the top lid.
Very clever - I would say...

Looking forward to your ultimate breakthrough & succes!
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Ian Skinner
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Re: My "new" old Bicarburatore

Post by Ian Skinner » Mon Nov 03, 2014 11:59 am

Hi Hugo

Logic tells me that as the engine set up you had was performing ok, then therefore, something has been changed that wasn't broke. For God's sake don't start changing jets and needles in the carbs, remember they were performing ok. What have you changed in the carb department. The float chamber top? If yes, does the needle seat and seal in it? I there a lump of crud in it? Tell us in detail what you have changed.

Plugs that I have used successfully for a long time in Rumis are NGK B7EVX, fire off like a fire-cracker and seem to last indefinitely!

Ian

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Re: My "new" old Bicarburatore

Post by hugomez » Mon Nov 03, 2014 7:00 pm

Hi Ian and Lasse,

The only thing I changed was the float bowl, but the rest is the same as in previous tests. Even the float and the needle inside the float bowl are the same. Ian, you are right, in previous test the bike was going strong and nice with that carbs setup.

Still I think that I maybe did something wrong with the ignition setting, I will play a bit with it and see what I find.

The sparkplugs I used during the test was a pair of NGK B9ES, but a have a pair of NGK B7EVX waiting once the engine perform correctly.

Anyway I am just testing the engine now to see if everything work, but if you guys remember, after all the search and reparations of the halves, I found that problem at the bearing area (ignition side). That issue changed everything because I want to get a replacement halves. I have new parts to mount on the engine and I want to mount them once I have that replacement halves.
All these tests I am doing these days won't be the finishing of the engine, once I have a replacement halves here I will open all again. (Hopefully will be the last time in many years)

Lasse, nice bike.
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Re: My "new" old Bicarburatore

Post by Lasse » Wed Nov 05, 2014 8:57 am

If the only change from before, is the floatbowl, then you should take a good look at the float & the floatlevel.
You have a motor "running rich" - and this can almost just stem from the floatbowl!
So, Check the petrol level of the bowl.

I cant believe, a "wrong" ignition setting should let the motor run rich - the float level simply have to be the culprit.

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