Monthly Archives: June 2015

Bandit 250 engine,assemble around the valve

Because the piston fits into the cylinder, I will assemble the head.

I kept shim and valve lifter in the paper cup and I will return it to the original place.
If I do not return it to the same place the valve clearance will change.
I have to make sure not to make a mistake.
I am writing a place into a the paper cup.

By the way, the valve clearance examined on the net is ↓.
It is quite wide.Moreover, the allowable range is wide.

Because Cub is around 0.05 mm, it is about 3 to 4 times.
Because the port is long in the longitudinal direction, the valve will also become longer and linearly expand.
The other day I did the valve rubbing, but I can only sharpen at 1/100 units at most.
So has no influence.

I do air blow one by one and assemble it.
I am careful that I fly it and do not lose it.

Bandit 250 engine, add notches to the sleeve, and!

A strategy to put a piston in a cylinder first, and to let a piston pin go through later.
I failed, so I made a notch in the skirt of the cylinder.

I sharpened it with a sander, but can sharpen it fast.
It is a feeling that it collapses rather than sharpen.
The casting will be such feel.

The piston pin is now passed.

But, centering the core, matching the piston and the hole of the connecting rod,it is difficult to pass the piston pin.
The oil ring will soon get out of the sleeve.

And a thing to put Retaining_ring of two cylinders of the middle in is difficult.
I failed several times.I bent three of the eight oil rings.
There was no choice but to reuse it.
If the sealant dries, I wipe it off once again and am repetition that I paint already once.

And …

At last it entered!

I’m about to cry.
This song is flowing in my head.

Bandit 250 engine, piston rings do not fit

The cylinder was completed.
I have assembled a piston ring on the piston and assembled a piston on the connecting rod.
I try to put a piston in the cylinder, but it does not fit in.

This piston ring is tight with tension.It protrude from the ring groove by default.

I cut empty cans and made it a piston ring compressor.

But the cans are also fit together and it will not fit in.
I used an aluminum can, but it is thin.
It might have been successful if it was a thick can, such as a spray can.

The piston ring compressor I have can not be used dimensionally.

I polished the chamfering of the skirt of the sleeve smoothly, but there is no effect.

I decided to put in a piston first.

Oh my god!
Piston pin can not be passed through.
Also the liquid gasket has dried up.

A full day passed just to put a piston.
I want you to return the time.

Bandit 250 engine, I carve the escape of the intake valve

Since the escape of the intake valve is carved in the upper part of the cylinder, I made it with leutor.
The left side is the genuine cylinder, the right is the self made cylinder.(It is a photo on the way of carving.)

I tried putting a piston.


I also confirmed the rattling feeling at this point, but there is no rattling feeling.
It was rattling when it was an old cylinder.
It’s a really nice feeling.

Bandit 250 engine, valve lapping

Because bowling was completed, I perform the lapping of the valve.
I removed the valve and observed the valve face and valve seat.It is receiving damage.

This is a valve seat.

This is the valve face.

I attach a valve compound and do lapping.
The sucker is called a valve octopus.

There are 16, too.

I completed the work in a few hours.

Bandit 250 engine, boring

The brim of the sleeve protrudes from the upper surface of the cylinder block.
(I designed it like that.)

So I reduce the top surface of the cylinder together.This work is called surface polishing.
It is a unique name for sharpening the joint between the cylinder head and the cylinder.
Originally, polishing is to grind with a grindstone.And cutting is to sharpen it with a knife.
But, as in this time cutting is also called face grinding.

It turns around with a Pick test,pick up the center coordinates.

As a result, I found that the bore pitch was 61 mm – 90 mm – 61 mm.

I will prepare the boring head.
The chip uses a thing for castings.

With this scale it is possible to adjust the protrusion amount of the blade with 1/1000 units.

And, I prepare a cylinder bore gauge for measurement, too.

And I do boring.My aim is φ 49.00 mm.
I make φ 48.995mm with boring.Then I make 49.000 by honing.

The animation of a series of processes is this.

Bandit 250 engine, press fitting of cylinder sleeve

This is the completed sleeve.

I will put this in the cylinder block.

I push all genuine sleeves with a hydraulic press and remove them from the block.

I failed one and broke.

I could somehow take.
This is the block that removed the sleeve.

The second cylinder from the left in this photo was scratched when pulling out.
So I scraped off the part which swelled of the wound at Leutor.
The cylinder which damaged the sleeve did not have any scratches.

And I degreasing the sleeve and block which I made.Then I painted the sealant and press-fit.

I put in with hydraulic press.

It is complete!

The top of the sleeve protrudes from the top of the block.
I am designing like that.

I sharpen this and make a flat.

Bandit 250 engine, machining the sleeve with a lathe

I finished drawing the drawing. The next is production of the cylinders.

I sharpen it with a manual lathe.

First finish the outer diameter and drill a hole with a large thick drill.Then spread that hole with a spiral turning tool.
This video ↑ is drilling a hole.

The lathe became covered with cutting chips.
The knife shown in this photograph is a spiral turning tool.The direction is different.

It took 2 hours to a single cylinder!
It took a whole day, and my booger turned black!
I am tired!

Bandit 250 engine, Exposes a drawing of the sleeve

As a result of measuring the inner diameter of the cylinder, it was 0.02 mm ~ 0.03 mm widened, so boring is necessary.
But, oversize piston is abolished both one over and two over.
Put the oversized and a little can Bore up.
I can expect a little power up, but the dream collapsed fleetingly.

Although I examine the diversion of other car models, Bandit is impossible because the bore is the biggest.

So I have no choice but to make sleeves.
I decided to remove the sleeve.Even boring is troublesome.

I will pull it out with a manual hydraulic press.
When was removed, the block side was scratched.
This is all right if I scrape it off in Leutor.

This is a removed sleeve.

The escape of the intake valve is dug in the upper part.

First of all, I took off only 1 cylinder, and I measured dimensions and drew a drawing.
In this way ↓.

Those who are suffering from bad condition on board Bandit 250, are free to use this drawing without permission.
The outer diameter is mating tolerance becomes m7, but if it is m7 it will be φ55.011 to φ55.041.
The actual measurement here was φ55.100, but in this case the fitting tolerance is u6 or u7.It is a bit too tight.So I changed it without permission.

· No escape of valves.
· The inner diameter is 1 mm smaller.
(Press fit into the cylinder block and boring to finish it to φ49.00.)
· Since the brim comes out of the block, it needs a surface research.
Please pay attention to this.
(Even if there is a problem, I will not take responsibility.)

As usual, I ordered the Dense Bar.I bought 60φ.
So brim will remain cast.

I am able to use it which was rolling at the edge of the factory.

Next time, I will cut out 4 sleeves with my hands.

Bandit 250 engine, cause of rattling noise

There was no abnormality around camshaft, so I decomposed everything on the waist.

The oil seems to have been replaced frequently.So the piston is not so seriously damaged.
I think this distance is reasonable because this car is about 25000 kilometers driving.

The state of the head.
When I bought it, the rubber packing inside the carburetor was deteriorating.And it was sucking gasoline from a strange place.
It was very thick, and a condition was bad.But, the deposition of carbon is not so bad.
Because I ran a little after I overhauled a carburetor, It may have removed it.
There is one cylinder with less carbon and burnt.Well, a carburetor car is such a thing.
There was not the sedimentation of much carbon in the exhaust port either.It is a normal condition.

This had much mileage and ran a long distance with having thick air-fuel mixture.
Therefore, I think that the valve sheet is bitten by the carbon and it is rough.
So, I think I will do the adjusting.

The state of the cylinder is such a feeling.
I think that there are many oily looks.
It is not so bad.

I considered the cause of the noise.
As a test, I removed one piston from the engine and inserted it.Then, it moved around 0.5 mm of rattling to the left and right.
When I measured the cylinder with the cylinder bore gauge, the diameter was spread from 0.02 mm to 0.03 mm.
It was gradually worn out,so I do not understand it judging from an eye either.
I can see the piston ring gaps from above.It will suck the oil.

The cause is either abrasion of the cylinder or abrasion of the cylinder + piston.

Later I ordered a new piston and compared it.And it turned out that the piston was not so abrasion.
Later, I removed the cylinder sleeve from the block, but the outside diameter was φ55.10.
For normal press fitting, I think that it is about φ55.03 to 55.06.
Possibly press fit charges are too big and may influence that residual stress is let loose by a secular variation, and the inside diameter spreads a little.

Cylinders do not usually decrease so much.

Even if I measure the cylinder of a car that ran for about 100,000 kilometers, it has not decreased so much.The connecting rod metal metal does not often decrease in the same way, too.
During running, the inside of the engine has become gooey with abundant oil, so the parts are floating on the oil film.
My image feeling like grasping the slimy eel.
I think that quantity of abrasion of the piston side is a fact when I say with this engine.

The combustion chamber was operating for a long time with the carburetor setting in a different state.
Therefore, it was eating combustion gas with a lot of HC (hydrocarbon).As a result, a chemical weak cast iron sleeve may have worn over the piston in preference.
I have watched the sleeve which the inside diameter spread through very much in SR400.
Perhaps that might have been running a long distance with a different carburetor setting.

Then, where does the performance of the engine properly setting carburetor deteriorate from?
I think that it is desolation of valve face and valve seat.

The valve contact surface is always hot and dry during operation.
When it comes to lubricants, there is only carbon which is a byproduct of combustion.
The valve always rotates little by little during operation and the seat and the face fit the sharpen together.
But, when large carbon particles or the like comes in, it gets dented and the sealing becomes worse.

Therefore I want to do the grinding of the valve.