Topic: 410 head for 750 Pros and Cons.

[754]

 I think I am getting another 410 head, which seems to be the one to use for hopup.
Generally do they leave the chamber's alone? Which means F type pistons only ?
I am thinking  F cylinder should accompany its rather than a K cyl.
 I know the spigots are bigger than early engines and can be opened up further.
 What other pros and cons .0
 Is it common to switch back to early  style caves and keepers ?
 The older motors have a second oil drain from the F only has one ?
Is this meaning oil is pooling up there,  or ?

 I  am just wondering which heads to use in the future ..

[slikwilli420]

I asked about then when I was doing my race bike since I picked up a -410 head cheap to use. I remember someone saying the Mike Rieck would rather use a good K head for hi-po stuff. With my stage 4 K head done up, is there really anything additional a -410 head brings that I cannot get out of the K head? The valves are already oversized, and the ports are massive with all his work.

[dragracer]

I've had good success with my 410 head. We did replace the stock valve guides with APE guides. I'm still running the stock valves but replaced them with new ones when the head was done. Its ported and flows well in my opinion. And yes, the spigots are bigger than the K. I've actually got K pistons under mine so there is a loss of compression. The head was milled some but you'll never take enough off to compensate for the compression loss. I would suggest a set of Dynoman's high comp F pistons to really make the engine work as it should. I think those pistons are 970cc. I was told that JE can make any size you need with the proper chamber mold provided. There was a youtube video someone did showing an F head being molded for custom pistons. If I had to buy brand new pistons for a build when using a 410 head, I would get the largest custom piston made as possible- ummmm, I'm actually already contemplating that in the near future. A tad shy of $600 if I recall. Definitely use the F cylinder.

[dragracer]

I'm currently building a K headed engine with oversized stainless valves and the same type 72mm hi comp MTC pistons that are in my red bike. I'll be using the same size cam and header. The only big change engine wise will be the use of 34mm Lectron carbs versus the 36mm Mikuni RS carbs on the red F model. Chassis wise, this one will have a mono shock but close in setup overall. I'm curious as to how the two engines will perform in comparison on one another. K head versus 410 F head.

[sohc boy]

i had good success 754 also with the F head (ported )on my old 836 ,stock  F valves , keepers an shimmed stock springs (no failing  valve ,spring, guide, issues ),bike did double duty ,street &strip, 20 odd yr's  ,used the early K barre,l was also concerned with the oil drain back , so sleeved the blank one an drilled another drain hole ,cut face of head quite a bit  , but used longer 900 1100 F con rod ,10:5 MTC piston pokes up in chamber more ,340 L, 220 D, cam, comp ended up  11:1, 94 hp, 98oct petrol ( pump gasolina), magneto,CV carb , been building a RC big blk'd 1,055cc with  the same head for while , but time's getting short

[Old Scrambler]

Frank.........I am happy with the 410 on my Salt-Flats bike. ..........modern valves and guides for a Prelude fit well with stem-machining for length. The CB1000-1100 rods have 17mm small-end pins...........so order pistons accordingly. I started with a fairly level head-face so had minimal shaving.

Whichever bottom-end.........the late-model tranny-gears have the best ratios and shift drum.

[Don R]

 I have a low mile F engine and a spare back cut trans for one. I assume the 1100 rods need cylinder spacing and cam chain adjustment or is that only when using the 900 stroke?

[Ilja]

The f1 head has 8 drain holes and uses 8 studs as oil return.
The f2 head had 4 drain holes and uses 4 studs as oil return.
The 4 which are not used are capped off... because on the f2 head these stud holes are open to atmosphere through the fins!

So when you combine an f2 head with prev. model cylinders you will have 4 extra crank breathers through the fins. I plugged them off with a small o-ring dowel which the mls gasket compresses. (Had to take the engine apart only for this!)

F2 combustion chamber volume is 27.5-28cc. Intake and exhaust valve are quite a bit bigger, resulting in more hp potential.

Ideally would be to use it with a bigger cylinder bore (900cc +) with modified or fairly flat pistons...so you get a nice squish band all around the chamber and compensate compression ratio with displacement. 

[Ilja]

Compression ratios with 65mm cruzinis and 72mm "cruzinis" (1000cc piston flat top slight dome).
You might want a high compression piston and lathe your dome around for squish clearance.. if its not already made like that.

[Jerry Rxman Griffin aka MuthaF'er]

Ilja, Out of curosity have you measured the chamber volume of the F/F1 head and the pre-77 K heads?

[cbr954]

i mill my f2 heads .060", gets the chamber volume to about 24cc which is on par with the K heads.  It just starts to touch the seats when milled this far.

[sohc boy]

i mill my f2 heads .060", gets the chamber volume to about 24cc which is on par with the K heads.  It just starts to touch the seats when milled this far.

... same amount i milled my F2 head  .060 .. + - 25cc .. stock F2 head was around 30cc , used bushed longer 1100F rod ,machined squish band on piston , didnt change chamber shape , only debur'd 

[Ilja]

Thats exactly what I meant!  
Get some turbulence in those chambers and also keep detonation pockets away from the edge of the piston!

Ilja, Out of curosity have you measured the chamber volume of the F/F1 head and the pre-77 K heads?

Yes, but I dont exactly recall what it was... I think 23cc..