Topic: The truth about CB750 intake seats

[MRieck]

 To the point....they are soft as a grape. The 550's are a close second. I have had literrally 100's of seats cut by 3 machinists using Serdi machines and the concensus is the same.....they suck. They do not cut "clean" but instead want to smear than tear. Awful but workable. I do have a NOS CB750 head with clean intake cuts. First off the 45 width is all over the place from the factory but they are a shiny cut. I think heat cycles effect the seat. Cutting the seats with the Serdi helps as I have rebuilt heads I've done and they have held the 45 width more consistent. The exhaust seats are good on both heads.
 I'd recommend changing the intake seats if you want a top notch head (especially if you are racing it). My next head for my bike will have this done for sure.
 Just wanted to share some long time observations. I'd love to hear feedback from people that have worked with the Serdi and these heads.

[scondon]

 I never mess with that stuff. I just send mine to someone who knows what they're doing

[MRieck]

I never mess with that stuff. I just send mine to someone who knows what they're doing

That just made me crack up bro.

[Jerry Rxman Griffin aka MuthaF'er]

PM

[754]

A single grade of carbide, will not be ideal for all materials.

 could be the rake..

[MRieck]

A single grade of carbide, will not be ideal for all materials.

 could be the rake..

3 different very professionals indicate otherwise. Also....new cutters used in many cases. they stink....that's the fact.

[754]

Did you discuss with the Serdei rep, or go to the website??
or just the other professionals..



I have gotten into huge (putting  a shop out of business  )troubles, relying on a suppplier/distributor for advice on carbide/tooling selection. Problem that could have been solved with 1 call to the actual company reps, for what its worth..


They sell equipment that has a reputation for cutting precision valve seats.. tell them its not.. its in their best interest to help...

[MRieck]

Did you discuss with the Serdei rep, or go to the website??
or just the other professionals..



I have gotten into huge (putting  a shop out of business  )troubles, relying on a suppplier/distributor for advice on carbide/tooling selection. Problem that could have been solved with 1 call to the actual company reps, for what its worth..


They sell equipment that has a reputation for cutting precision valve seats.. tell them its not.. its in their best interest to help...

It is not the machine 754....it's the seats. as I said...the exhaust cut perfect (as do all modern seats). i appreciate what you are saying but you can't shine a turd brother. One of the shops are multiple USA funnybike champs(5 times) etc. These are hard. seasoned veterans......all of them. The seats stink. I'll change them for my next project and let everybody know the difference.

[MRieck]

PS....I'll be using a NOS 750 head. It will be "seasoned" in the oven for 3 or 4 cycles. There is a reason for that too.

[bwaller]

Try a little marinade on that newbie while you bake it Mike, it'll be yummy.

No argument here, and as I mentioned better seat materials await.

[MRieck]

Try a little marinade on that newbie while you bake it Mike, it'll be yummy.

No argument here, and as I mentioned better seat materials await.

I was thinking of using some of your maple syrup Brent......only the the best you know. As a plug........Brent's maple syrup is truly awesome....really.

[scondon]

I was thinking of using some of your maple syrup Brent......only the the best you know. As a plug........Brent's maple syrup is truly awesome....really.

    Straight from the motherland. Too good to waste on the kids

[mark]

They're plain ol' cast iron. So soft, in fact, that my 250/350 twin factory manual recommends leaving the valves installed when wire-brushing carbon from the head - to avoid scratching the seats.

Have you considered grinding vs. a cutter?


my 2¢

[MRieck]

They're plain ol' cast iron. So soft, in fact, that my 250/350 twin factory manual recommends leaving the valves installed when wire-brushing carbon from the head - to avoid scratching the seats.

Have you considered grinding vs. a cutter?


my 2¢

You are reading my mind......for the 45 cut it might be easier. The other angles would be fine on the Serdi. I know in the past the 60 and 30 degree cuts were made with Neway cutters and the 45 ground.

[HondaMan]

They're plain ol' cast iron. So soft, in fact, that my 250/350 twin factory manual recommends leaving the valves installed when wire-brushing carbon from the head - to avoid scratching the seats.

Have you considered grinding vs. a cutter?


my 2¢

You are reading my mind......for the 45 cut it might be easier. The other angles would be fine on the Serdi. I know in the past the 60 and 30 degree cuts were made with Neway cutters and the 45 ground.

Interesting: that's what I just finished doing on one of the Hondaman Special heads, and on a 550 head (that actually had a raised seat). I couldn't get a "light enough" touch on the 45 to make it a clean cut, so I just cut above it and below it, then ground it. The 550 seat did cut a little cleaner: the 750 seats "feel" like a Briggs & Stratton engine! The old 305 Honda and 450 Honda were similar, as I remember...

I don't get to use any nice Serdi tooling, just my semi-stiff wrists and long pilots...