pics wanted for cutting the head

[hannesd]

hello guys,

would anyone have some pics as to see how to setup the head onto a lathe, securely and how fast to spin it? (i gues that last question depends on the specific tool you're using to cut the head,right)

i haven't been able to find some specific pics of a gasser head on a lathe

thanks guys.
Hannes.

not that it makes any difference but it's for my 2001 gasser 200

 

[Jakobi]

I'm no help mate I'd imagine you'd utilize the thread for the spark plug hole though.

 

[HenrikSchmidt]

I'm no help mate I'd imagine you'd utilize the thread for the spark plug hole though.

That's what i normally do, if the plug are centered and axial with the head..
On a gasser top I would do it like that.
Set up a piece of scrap metal (a little bigger than a sparkplug) Cut a sparkplug thread(M14x1.25) on the scrap piece, screw on the head and start cutting away

If you already have a axle with a sparkplug thread, you need to true it in the lathe before cutting, to make sure you're cutting the head even..

Good luck with the project..

 

[Diggs345]

Id like to see this too , iv been getting some tooling and toolholders for my lathe , now i just need to get some practice in before i attack my head

Henrik , how do you go about reprofiling the combustion bowl after you have reduced the sqish band ?

 

[HenrikSchmidt]

I would set it up in my CNC Lathe, and draw it up in the cad/cam system first, it'll help me alot on caculating the chamber volume

I do not have any photos, but I found a similar tread on this subject:http://www.gasgasrider.org/forum/showthread.php?t=11970&highlight=head+mod&page=8

Here, he is using a milling machine instead of a lathe, but he is still holding the head by the thread in a chuck like the one on your lathe.

On a manual lathe it's going to be a little more tricky, since its very hard to make a curved shape on a manual lathe.
I think, I would make up a cutting tool with a fairly big radius, and carefully try to "copy" the original shape of the head by working both axes of the lathe, one at a time, with very small steps.

 

[Diggs345]

Thanks for the reply , my plan is to get hold of some old two stroke heads to practice on first

 

[HenrikSchmidt]

good idea..

best if you have the bike to test the effects of the mod.

I'm also playing with 50cc 2stroke moped engines, and it gives you good tuning knowlegde for very little money

 

[Jakobi]

I would set it up in my CNC Lathe, and draw it up in the cad/cam system first, it'll help me alot on caculating the chamber volume

I do not have any photos, but I found a similar tread on this subject:http://www.gasgasrider.org/forum/showthread.php?t=11970&highlight=head+mod&page=8

Thats my head

 

[hannesd]

That's what i normally do, if the plug are centered and axial with the head..
On a gasser top I would do it like that.
Set up a piece of scrap metal (a little bigger than a sparkplug) Cut a sparkplug thread(M14x1.25) on the scrap piece, screw on the head and start cutting away

If you already have a axle with a sparkplug thread, you need to true it in the lathe before cutting, to make sure you're cutting the head even..

Good luck with the project..

so just by holding the head thrue the spark plug hole would be sufficient?
there will sure be some imbalance because of the piece sticking out of the head, where you atache the head to the frame...

i'll cut an axle with that M14x1.25mm and see how fast i can spin it.

meanwhile, any pics of that setup are still welcome (to give me more self confidence,first time cutting a head)

ciao, Hannes.

 

[hannesd]

found this :

 

[Harry]

Hi Have a look at these photos of when I machined my head. I used an old spark plug with the hex machined off. Can not recall lathe speed?

 

[Diggs345]

Hi Have a look at these photos of when I machined my head. I used an old spark plug with the hex machined off. Can not recall lathe speed?

Nice one , how did you machine the bowl out ?

 

[HenrikSchmidt]

It does not need to be spinning really fast.
i woud say 4-500rpm should be fast enough, you're never gonna meet the cutting speed of your tool anyway

you will not have any problems with the balance at that speed..
you need to make sure that the head is running true before cutting, not for the balance, but for the precision of your head..

 

[hannesd]

Hi Have a look at these photos of when I machined my head. I used an old spark plug with the hex machined off. Can not recall lathe speed?

and the rubber bands around the head go there for reduction of the sharp noise,right?
allso, did you use the spark plug with or without the washer between the spark plug and the head?

did you do that on a manual lathe?

thanks allready

Hannes.

 

[Harry]

Correct the rubber bands are to stop it 'chattering' I left the bowl and took 1mm off the mating surface. I am not 100% sure but I think I removed the plug washer.

 

[(F5)]

Correct the rubber bands are to stop it 'chattering' . . .

You what? How does that work? (I'm self taught, read badly, as my tutor was a muppet)

 

[wrench]

You what? How does that work? (I'm self taught, read badly, as my tutor was a muppet)

"chattering" is caused by excessive vibration, a by product of the machining/cutting process and causes an annoying noise. If you get too much vibration you will get an extremely rough and uneven depth cut pattern.

The rubber bands act as a damper and "absorb" the vibration.

 

[hannesd]

Correct the rubber bands are to stop it 'chattering' I left the bowl and took 1mm off the mating surface. I am not 100% sure but I think I removed the plug washer.

was that off an ec 200/250 or 300, you cut 1mm?
i'm curious as to what difference it might make.
i'd like to do it properly as to get the most out of my 200,but have some doubts to cutting the bowl with probably a manual lathe, def not CNC...

Hannes.

 

[Diggs345]

Its not just a case of turning 1mm off , you need to do a solder test on the squish band to find out the correct amount to remove, you also need to correct the head volume to keep the compression ratio right .

 

[hannesd]

Its not just a case of turning 1mm off , you need to do a solder test on the squish band to find out the correct amount to remove, you also need to correct the head volume to keep the compression ratio right .

yes i realize,but if it's too hard to shape the bowl on a manual lathe,i'd go the lazy way and just measure the squish now and make sure not to shave the head too much so compression would go skyhigh.
i could get it done by a pro, you'll say, yes true, but therefor i'd have to find one in the area, wich i have no clue to.
plus most of all i'm a do it all yourself kinda guy, so id be more satisfied if i could achieve improvement if i did it myself.
some of you will understand my vision, others will say, don't bother trying

thanks for all the input so far ,

ciao Hannes.