100 Cubic Inches of Fury!

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Chip Birks
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Re: 100 Cubic Inches of Fury!

Post by Chip Birks » Wed Jun 06, 2018 6:27 am

Spent a few minutes yesterday setting up rocker geometry. I have a set of used old SCAT 1.4 rockers for it. I got everything looking really good, however i ran into a little bit of a problem. Apparently this set of rockers was machined on the aggressive side of 1.4:1. Total valve lift should be .551", based on advertised lift at the lobe of .394. What I saw last night was .595 at the valve, and .403 at the lobe :shock: Which means my rockers are measuring out at around 1.47:1. I need to check a few things, but I don't believe I have enough spring height to actually lift that high without causing a few problems. I'm looking now at having to grab a new set of rockers asap. I'm looking at 2 options, new SCAT, which is what I have currently in my 2276, or CB. Anybody have experience with both that makes you lean one way or the other? There is a $10 price difference between the 2, so price doesn't really sway me at this point.

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Kalle
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Re: 100 Cubic Inches of Fury!

Post by Kalle » Wed Jun 06, 2018 6:53 am

Thats exactly my experience with the Scat rockers I have used. They do give you a little more than advertized and if I remember correctly the first set I used gave me 1.45 and the other 1.48. I later replaced them with JPM 1.55 rockers since the lobes on my mild JPM cam would allow it. WIth the 1.55`s I had a total lift of 0.0510 on my mouse engine. The mild cam in combination with the small valves and the lift made the job easy for the CB650 springs. I just "compensated" for the mild set up with more boost :D

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66brm
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Re: 100 Cubic Inches of Fury!

Post by 66brm » Wed Jun 06, 2018 7:33 am

There is a thread on tos about a current issue with the cb 1.3's where the tips are chewing up very early, no reported issues with the 1.4s which have hardened tips. Scats 1.4s need to be checked for the tips being out of parallel with the shafts, some need to be reground to correct, but otherwise good reports. It's the usual after market crap shoot really. I personally went with cb's and two sets of lash caps to find a set of eight that I then polished to get them smooth due to surface pitting...

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Chip Birks
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Re: 100 Cubic Inches of Fury!

Post by Chip Birks » Wed Jun 06, 2018 10:32 am

Kalle wrote:
Wed Jun 06, 2018 6:53 am
Thats exactly my experience with the Scat rockers I have used. They do give you a little more than advertized and if I remember correctly the first set I used gave me 1.45 and the other 1.48. I later replaced them with JPM 1.55 rockers since the lobes on my mild JPM cam would allow it. WIth the 1.55`s I had a total lift of 0.0510 on my mouse engine. The mild cam in combination with the small valves and the lift made the job easy for the CB650 springs. I just "compensated" for the mild set up with more boost :D

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Kalle
Gosh! .510 with a 1.55 ratio! Those cam lobes must have been darn close to round! I'm sure your valvetrain loved it! I don't have the expectation that this engine will go years and years without the occasional spring change, the cost savings from not running race fuel at one event will close to justify the new springs :D But .600 lift seems pretty excessive. I'll probably go with the CB set, they seem to be built pretty stout.

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Chip Birks
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Re: 100 Cubic Inches of Fury!

Post by Chip Birks » Thu Jun 07, 2018 9:13 pm

I'm going to go with some new CB 1.4s. Aircooled.net is local to me and has them on the shelf. I'll pick them up tomorrow. Waiting on a package from CB as well, that should have the last bits needed to button this thing up. It should be here Saturday.

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petew
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Re: 100 Cubic Inches of Fury!

Post by petew » Thu Jun 07, 2018 10:32 pm

What's the advantage of ratio rockers over a big cam profile?

bug66
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Re: 100 Cubic Inches of Fury!

Post by bug66 » Fri Jun 08, 2018 6:32 am

petew wrote:
Thu Jun 07, 2018 10:32 pm
What's the advantage of ratio rockers over a big cam profile?
Easier on the valve train I guess. less movement on the lifters and pushrod.
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madmike
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Re: 100 Cubic Inches of Fury!

Post by madmike » Sat Jun 09, 2018 5:29 am

Yes it seems to mellow out the harsh movement if that makes sense?
I had W120 cam with stock & 1:25's and the fk 10 with 1:4's are way better :wink: :lol:

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Chip Birks
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Re: 100 Cubic Inches of Fury!

Post by Chip Birks » Sat Jun 09, 2018 12:05 pm

Wifey left me home with a sleeping sick baby so she could ride her bike. So i moved operations into the kitchen and have just finished assembling/shimming my new CB 1.4 rockers at the kitchen table. Got them all setup, and now am ready to take apart, clean, lube, and reassemble. Then its back to the engine to see just how accurate CBs grinding process actually is. Fingers crossed!
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Chip Birks
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Re: 100 Cubic Inches of Fury!

Post by Chip Birks » Sat Jun 09, 2018 5:38 pm

Well, it appears that this under sell/over deliver thing is an industry wide thing. The new CBs measure out at 1.50, giving me .606" at the valve! Gonna have to knock the top off of the guides for clearance, and get rid of my newly installed titanium retainers in order to get the needed spring installed height. Gotta love it.

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buguy
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Re: 100 Cubic Inches of Fury!

Post by buguy » Sat Jun 09, 2018 6:38 pm

Weird. I didn't know the rocker arm to the valve tip was supposed to be off center? Are they all that way? My stocker was off to the right side of the valve and I figured it was just done wrong.

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Chip Birks
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Re: 100 Cubic Inches of Fury!

Post by Chip Birks » Sat Jun 09, 2018 8:12 pm

buguy wrote:
Sat Jun 09, 2018 6:38 pm
Weird. I didn't know the rocker arm to the valve tip was supposed to be off center? Are they all that way? My stocker was off to the right side of the valve and I figured it was just done wrong.
I thought it was a little strange too. But makes sense.

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buguy
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Re: 100 Cubic Inches of Fury!

Post by buguy » Sat Jun 09, 2018 8:18 pm

Agreed. Makes sense.

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rubenski
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Re: 100 Cubic Inches of Fury!

Post by rubenski » Sun Jun 10, 2018 1:31 am

Isnt that to get the valve spinning? And lubing it that way?
Better to be blown than to suck!

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Chip Birks
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Re: 100 Cubic Inches of Fury!

Post by Chip Birks » Sun Jun 10, 2018 1:35 am

Yes

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