Bugatti Typ 50 1/4 Scale model

[Vixen]

Hello Michael,

Your valve timing looks reasonable. I would not expect you to have a problem engine with these valve event timings and durations.

Mike

[ThomasM]

Hello Michael,

You wrote that you have run the engine for about half an hour with 1:50 mix without oil in the oil pan. At this point i remenbered the problems i had a few days ago when i first tried to run my model a engine. The engine behaved very difficult ( missfires, sudden stops no idle and so on ) . All of the problems dissapeared when i removed the oil out of the oil pan and changed to 1:50 mixture.

I dont want to unsettle you but it is difficult for me to believe that the exhaust can be the reason for the plug fouling. When you run the engine for half an hour it consumed a significant amount of gasoline and therefore oil. Could it be that after half an hour of running the blow by of the two stroke oil has filled up the oil pan enough for creating the problems of oil pumping and therefore the plug fouling ?

Best regards,
Thomas

[Roger B]

I agree that the valve timing looks fairly normal. You are measuring at 0.1mm opening, what is the actual valve lift? If you have a fairly high back pressure due to a restrictive exhaust the late closing of the exhaust may cause problems. I have no real feel for how the gas flows in small engines compare to full size ones but typically the late closing of the exhaust valve is to allow the inertia of the exhaust gas flow to pull the last of the exhaust out of the cylinder and create a slight vacuum to help the induction. If there is too much back pressure the exhaust will tend to obstruct rather than help the inlet flow.
Thomas's point is also valid.

[michelko]

Hi guys,
@ Thomas:
i made 0,5l fuel with 1:50 mixture. So this is just 10ml of 2 stroke oil.
While i did the recheck of the valve Timing i drained the case. Had only some Drops of a oil/fuel mix coming out. maybe that was at al 10ml. The initial oil fill was abaout 180-200ml 20W50 Oil.


@ Roger:
valve lift is 2.5mm

Regards Michael

[Roger B]

Ok, so you were measuring the timing at about 4% lift where there will not be much flow  Have you tried running with just the 4-1 pieces without the longer single pipes? it looks like there is a flange there. If the running is improved you could try larger outlet pipes.

[michelko]

Roger
you are right. The long pipes can be dismanteled. I ran the engine without them only the collector parts.
Makes no difference. Some minutes and the engine starts dieing.
Only without the whole exhaust i can keep it running.
I am a little clueless what causes this behavior.

Michael

[BillTodd]

how strong are your valve springs? …

just wondering if pressure pulses from one cylinder can push another open ?

[michelko]

Bill,
i donīt think so. The springs are pretty strong and the Exhaust has an open end so there should not be any Kind of vacuum.

The macor arrived, many thanks for yout Support.

To sort the Things out i started to make a new exhaust. Itīs a eight in nothing.

i was able to collect an ultra cheap fuelpump/filter/Regulator setup of an triumph motorbike. Some of the next steps would also be to work a little on the injection system.
Must do the waterpump also.... so much to do before i get 

Michael

[Roger B]

That 8 to nothing exhaust will make a rather different sound  I hope it helps towards solving your problem.

[Vixen]

Hi Michael,

I am sure if you are very logical in your testing and make only one change at a time, you will succeed in identifying the problems and their solution.

Good luck

Mike

[michelko]

Hi guys,
here is a Little update on the Waterpump.
Machined the housing and the cover. Came out nice. Still have to do the impeller and the shaft bearing.

Michael

[michelko]

Hi Guys,
here is a Little update on the waterpump. Just waitung for some hose Clips that i ordered.

All parts are ready machined.
 First pic is how it looks like on the original engine.

Just been curious about the flow of the pump. Not tested yet.

Michael

[Vixen]

Hello Michael

The waterpump looks good. I am sure it will work very well for you.

It looks like the water pump is driven off the camshaft drive gear train. Is there a second water pump on the far side, or is that the return pipe to the radiator.

What are you using for coolant? Water with antifreeze or one of the new waterless coolants made by Evans and others?

Mike

[michelko]

Hi Mike,
Till now i ran an electric pump sourced from the watercooling of an pc.
If the new pump is not strong enough i will use the electric one too and hide it under the engine stand.
Coolant is basf glysantin, it  is automotive stuff.

Michael

[michelko]

Hi started the production of the next generation of spark plugs.
Thinking about the electrode tip. Should this be flat or like a needle?
 Would like to hear your thoughts.

Michael