(Another) Dot head question!

[Swiss Toni]

After all the kerfuffle about these heads, I decided to dig mine out. I was always under the impression it was out of a GSXR motor. Now I'm not so sure! The valve sizes on mine are:

Inlet: 27.49mm 

Ex:  26.37mm

Cast beneath the head  is Pat No (pattern or patent)? 771502.

Painted under no 4 inlet is: 2-317

So, does this give any indication whether this is a GSXR or Teapot head. Also, any info what's on the cams, and lift, would also be useful!

Have both heads the same size inlet tracts?

Edited April 25, 2017 by Swiss Toni

[fatblokeonbandit]

dose it look like this?????

 

[Swiss Toni]

Yes Gary, it does. As I said, I know it's a Dot head. What I don't know is where it's from!

[fatblokeonbandit]

Only 2 places a 750 J/K or teapot 750's they are all the sameish,  some say the inlet is steeper on the gsxr but ive had a gsxf and a tpot one and apart from the colour they looked identicle...

[Fula28]

Well , from memory both 750-j,k & Tea pot heads casting is same! High inlet tracts , Causes carb interface issues on slingshots,(  Frame) if your doing hybrid,  Just cams are  different (Sorry no idea on lifts) but we all know Gsxr cams are best ones for peak power once dailed in on slotted sprockets . 

 

[Swiss Toni]

Will have to look at cam specs to narrow it down then!

[fatblokeonbandit]

Apparently the cams from the gsxr750's with dot heads have a B stamped on the right end

 

very unscientific I know, but a few years ago I measured a box full, a pair with the B mark definitely came from a DOT head gsxr.???

 

Edited April 25, 2017 by fatblokeonbandit

[Dezza]

1 hour ago, fatblokeonbandit said:

Apparently the cams from the gsxr750's with dot heads have a B stamped on the right end

 

very unscientific I know, but a few years ago I measured a box full, a pair with the B mark definitely came from a DOT head gsxr.???

 

Why do you think this is unscientific? You measured diffierent cams from different sources and then compared the resulting data. Admittedly if you wanted to publish a paper on it you would have to get ~10 randomly selected cams per source and then measure those in a double blind way and do a proper statistical test on the data but that isn't exactly practical for OSS purpose. Your approach goes way beyond 'opinion' so should be applauded.

[Swiss Toni]

I agree! At the least, it's something to look out for! I have the cams from the Dot head, and I'm thinking I maybe have a set of J/K 750 cams off 'That Site' somewhere in the corner of the man cave. Will post results. 

[fatblokeonbandit]

1 hour ago, Dezza said:

Why do you think this is unscientific? You measured diffierent cams from different sources and then compared the resulting data. Admittedly if you wanted to publish a paper on it you would have to get ~10 randomly selected cams per source and then measure those in a double blind way and do a proper statistical test on the data but that isn't exactly practical for OSS purpose. Your approach goes way beyond 'opinion' so should be applauded.

Its not scientific as I didn't keep a note of which cams came from which engine, the only ones im sure of are the "B" ones, the rest came from 2 x b12's a gsxr 1127  and a power screen

[Swiss Toni]

Ok Gary. How's about this?

I found the J/K cams. Stamped into the right side of the cam, between the cam wheel and the first lobe is:

27A  IN.  

180 degrees opposite this is: R1

Cast into the cam, on the left side are the letters B and 180 degrees opposite, C. 

Base circle: 28mm. 

Lobe height: 33mm. 

Ex cam: (Stamped) 27A EX.  R1 ect, 

(Cast):   R and C. 

Now, the cams that came off the Dot head. 

Inlet cam stamping same as J/K cam on right side, but cast in letters on left side are: C and 1. 

Ex cam stamping a same as J/K,

but now cast-in numbers are: B and 8. All base circle/lobe heights same on all 4 cams. 

[fatblokeonbandit]

have a look at the very right hand outside  edge of the cams next to the notch, and see whats stamped there,  the cast marks are just that apparently casting marks for the blanks before grinding

[Swiss Toni]

I've looked. There's nowt there! 

[fatblokeonbandit]

that's odd, all the cams in the picture had a letter stamped on the end, ??

[Swiss Toni]

I'll have another look. If there's any markings where you say they are, they'll be mighty faint!

[Swiss Toni]

Ok, had another look with the magnifying glass. Dot cams have very faint markings on end. One is half a B, the other looks like a G but may also be B. Egay ones have no markings on ends whatsoever. Still black finish, so not worn. Strange!

[Roger P.]

When I went looking for hotter cams, I happened to find a ratty 89 Slingshot sitting in a breakers yard in Edmonton, Alberta, about 2500km west of me ( I was visiting family). I stood by as the cams were removed from the motor, and they were stamped B (intake) and G (exhaust), so that's about as authoritative as it gets I suppose. My K4 Bandit intake cam was stamped W. The 88 DOT head GSXR cams are both B, and reinforces the statement that the 89 had a softer exhaust cam than the 88.

 

According to the manual I have, 91 750's are stamped A, except for Sweden which are stamped C on the intake.

Edited April 25, 2017 by Roger P.

[clivegto]

http://old-skool-suzuki.proboards.com/thread/1546/oilcooled-camshafts-specs

I thought this was intresting.

[Swiss Toni]

That's interesting, Roger! Clive's link pretty much confirms your findings. Cheers lads!