Lightened Gudgeon Pin



FurryOnTheInside

Well-Known Member
Joined
Sep 23, 2013
Messages
3,192
Likes
517
#4
I’ll get a postage price if your interested? Give me some time and I’m going to see what I can take from the piston as well
View attachment 81548
Very interested! It's one of the very few things that can't be done on my coffee table using small/cheap tools.

I was able to remove only 1.5 grams from inside the piston (non windowed) so I resorted to grinding a little off the con rod (for an unknown weight reduction) to reduce the reciprocating mass. This was enough, along with the 3/8" holes in the crank cheeks, to get perfectly reasonable balance up to around 7000rpm, but it is a little bit shakey above that speed. (That might be the timing as much as the balance though. I have a stock CDI with 1.2mm offset magnet key.)

You can add three of these beauties to the parcel with my two Jaguar designed CDIs! ;) ;)
 
Last edited:

HeadSmess

Well-Known Member
Joined
May 17, 2010
Messages
3,004
Likes
320
#5
oh i does like a nice carbide drill... though they arent quite as impressive as watching a T-drill take out a 50mm hole at 100mm deep in a matter of seconds.

idea with the piston...looks like theres at least a bit of meat around the bosses so you could run an endmill through, putting two flats on the side of the piston.... though looking at the clip grooves...maybe not. (on a 48 at least)

make a split bush clamp so you can ensure concentricity, and you can bore out the back of the skirt a bit, until you meet the bosses (wife...shes a stunner!)
 

jaguar

Well-Known Member
Joined
Nov 25, 2010
Messages
3,454
Likes
435
#6
You should sell them. Most everyone with a china girl engine has too much vibration. This will lessen the vibration.
 

Stoneman

Active Member
Joined
May 20, 2017
Messages
689
Likes
168
#7
You should sell them. Most everyone with a china girl engine has too much vibration. This will lessen the vibration.
I have been, I’ve just got to work out the drill bits.
I’m talking to the tool sharpener about it as the edges dull real quick, I’ve just hooked up a mister for cooling so I’m hoping the bits will last longer.
The carbide bits here are quite expensive.
 

jaguar

Well-Known Member
Joined
Nov 25, 2010
Messages
3,454
Likes
435
#8
Let us know the cost (including shipping) and how to pay. I assume they come from Australia.
 

Stoneman

Active Member
Joined
May 20, 2017
Messages
689
Likes
168
#9
I’m on my way to see him today with another 2 bits needing sharpening so I get get an idea what it’s actually costing me.

Will do though and yes from Australia. . It was all thanks to your web site :)
 

Stoneman

Active Member
Joined
May 20, 2017
Messages
689
Likes
168
#12
Getting good feedback with these pins

I’m having issues with the drill bits lasting that is making it very hard to gauge how much they are worth, so I’m sorry to anyone waiting

For example I just had one drill bit shapened for $20AU and got one pinned drilled
When the bit was new I got 7!

So I’m not sure if it’s the sharpening guy or the angles still need to be worked on for optimal cutting
 
Last edited:
Joined
Jul 6, 2011
Messages
60
Likes
5
#13
My experience, is that NOTHING cuts like a new blade or bit.

Chain saw blades are great examples....
They cut excellent when brand new, and are short lived when sharpened.
Dosent matter if I sharpen, or the pro sharpens, there never as sharp as new.
 

Malort

New Member
Joined
Apr 21, 2018
Messages
6
Likes
1
#16
As I mentioned, I don’t know the dimensions of the stock pin. I’d need to know the existing hole diameter and OAL of the pin.
Insert style boring bars can work in a hole as small as .180”, and solid carbide bars can go much, much smaller. The limiting factors here would be the length to diameter ratio of the hole, and the available RPM of the lathe. Carbide doesn’t like running too slow.
 

Stoneman

Active Member
Joined
May 20, 2017
Messages
689
Likes
168
#17
The boring bars I’ve used wouldn’t have a chance with hardened steel

Haven’t looked at a carbide bit but I can’t spend all day drilling one pin..
 

Street Ryderz

Well-Known Member
Joined
Oct 14, 2016
Messages
2,660
Likes
537
#18
The boring bars I’ve used wouldn’t have a chance with hardened steel

Haven’t looked at a carbide bit but I can’t spend all day drilling one pin..
I don't see any sign's of cutting fluid being used? even wd-40 would prolong the life of the bits greatly,When drilling the cranks if cutting fluid wasnt used even with the tungston carbide bit you might get half a hole done and the bit would be garbage,with the fluid I bought two bits this year and have done 12 holes allready and there still fine cutting clean.
 

Stoneman

Active Member
Joined
May 20, 2017
Messages
689
Likes
168
#19
I don't see any sign's of cutting fluid being used? even wd-40 would prolong the life of the bits greatly,When drilling the cranks if cutting fluid wasnt used even with the tungston carbide bit you might get half a hole done and the bit would be garbage,with the fluid I bought two bits this year and have done 12 holes allready and there still fine cutting clean.
Different metal streets, I’ve learnt a lot since buying the machine and cooling is one of the first along with cutting angles and relief angles for good chip removal.
I have drilled the cranks with no fluid and the bits are fine

Here’s the mister
image.jpg
 
Last edited:

Malort

New Member
Joined
Apr 21, 2018
Messages
6
Likes
1
#20
Nice job on the MQL mister, much less mess than flood coolant.

Couple thoughts on this. As you're finding out, carbide drills don't like opening up existing holes, they much prefer drilling from solid. All carbide drills are not created equal and there are tools designed for high hardness steels. OSG Tap & Die has tools that will drill into the 60's HRC, and I've seen demos of their tools drilling and tapping files. Many other companies have similar tools, but I'm not familiar with distribution in Australia. Word of warning, as the technology increases, so does the price.

Maybe consider trying carbide reamers. They are designed to open existing holes and can take fairly large depth of cuts. Might take a couple of different diameters to arrive at your final dimension. Or, if your finished dimension matches that of an end mill, feeding a four flute end mill with a large corner radius would cut that pin all day.

Not trying to complicate your life here, just throwing out some ideas that might work. Good luck!
 

Top