Problems installing Andrews x3 camshafts

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In our "great and powerful" country, there's a major problem with machining. Many don't want to take on such work; it's easier for them to bore car cylinder blocks and generally focus solely on cars. And some want to do this work for big money, but they don't have the skills or understanding of what needs to be done.We have a problem with motorcycle culture in general, and vintage motorcycles are a real disaster. So, to be on the safe side, I'd rather reduce the cost, take measurements myself, and adjust if necessary... That's our reality.
 

This is why I suggested adjusting the piston dome rather than the cylinder head. You can grind the tops off the dome on a belt sander, going slowly and measuring as you go. You would be surprised at how close you can get them to each other even with a "primitive" solution.

There is also the risk of sending out the head and it being tied up at a shop for a indeterminate amount of time. I like to do as much as possible on my own, that way I can control the timeline and know my parts are safe.
 

I completely agree with you; this work in the workshop could really drag on for months. They don't ride a motorcycle anyway. And if the compression ratio needs to be reduced, it's definitely better to trim the piston. I had a project with an 83mm piston, but it's on hold for now.But in my case, I need to either reduce the combustion chamber or increase the piston protrusion. According to my calculations, my piston's 0.2mm shortfall from the cylinder block plane is about 1 cm³. I'd rather reduce the combustion chamber than reduce the shortfall to 0. I once had a piston banging against the cylinder head at high RPMs. Better safe than sorry. 

Could you tell me where, in your opinion, it's best to trim the excess weight from the piston? The difference in MTC pistons is up to 5 grams. I don't like that.   

 

To reduce piston weight and make them equal weight I grind on the underside along the ribs or on the lug around the wrist pin hole. Below is shown the old style MTC 80mm that has the round cast lug around the wrist pin so I had to grind along the interior ribs to equalize the weight (to within 1 gram) You can also drill a additional oil hole for the wrist pin and chamfer the holes.

 

You have a square cast lug so you can grind a lot off the edges to equalize them. I just use a rotary tool (Dremel) with a 1/4" carbide bit.

 
Thanks for the info.I'll do that.Isn't it dangerous to remove (grind down) the internal reinforcements? The piston is quite heavy for its diameter, after all. That's usually how much the original factory cast pistons on high-mileage cars from the 1980s weigh. 

Any "square" edge is a potential "stress point" so radiusing the edges shown may in fact increase the reliability

Then they (MTC) leave us no choice...We'll cut without waiting for peritonitis.)))I don't know how that sounds in English or if the joke is clear.

v.f. wrote:

Isn't it dangerous to remove (grind down) the internal reinforcements? The piston is quite heavy for its diameter, after all.

Grind on the edges but not remove (I had to because of round lug at wrist pin) where Wookie marked up is where I suggest to grind the most. You can probably make a 6mm bevel on each side and still be safe.

Wookie58 wrote:

Any "square" edge is a potential "stress point" so radiusing the edges shown may in fact increase the reliability

 

Thought I was crazy... 



🤪

Daveo was that pic taken on a vibrating massage table - Lol

It's not very clear in the photo, but the piston wall is clearly thicker on one side than the other.So yes, you'll have to remove it little by little and carefully.Although, in any case, the piston weight seems excessive to me for this engine. And the life of the connecting rod small end certainly won't increase...The forged pistons I have now weigh 280 grams, and even then they seem heavy to me. I replaced the piston pins during the rebuild; there's no wear, but traces of wear are visible.