Dot Head to 1127

[cranky1350]

Hi all, Fitting a 750 dot head to a L model 1127.

Does anyone know how much this will raise the compression ratio ? 

Any tips or tricks ? 

Any potential issues to look out for ?

Thanks in advance 

Cheers Cranky 

 

[no class]

Whoooo are you...who , who, who , who

[TonyGee]

1 hour ago, no class said:

Whoooo are you...who , who, who , who

I reeeeally wana know !!!! 

[wraith]

Didn't this thread come up about 2 weeks ago?

And welcome to OSS

What's wrong with your 1127 head?

[clivegto]

1.5 to 2 points, measuring stuff is a good idea. 

[Wagola]

3 hours ago, no class said:

Whoooo are you...who , who, who , who

Who the hell are you.......

[manden]

11:1 - 11.5:1 depending on block and head gaskets

[no class]

you could just skim .060 off your 1127 head and get basically the same  results .

[Dezza]

18 minutes ago, no class said:

you could just skim .060 off your 1127 head and get basically the same  results .

How much for a Blandit head? This seems like a whole lot less hassle than faffing about with a head change that has other effects such as raising and changing the angle of the carbs.

[clivegto]

31 minutes ago, Dezza said:

How much for a Blandit head? This seems like a whole lot less hassle than faffing about with a head change that has other effects such as raising and changing the angle of the carbs.

Maths, every engine is different. 

[wraith]

53 minutes ago, Dezza said:

How much for a Blandit head? This seems like a whole lot less hassle than faffing about with a head change that has other effects such as raising and changing the angle of the carbs.

On that site, anything between £90 and £190 for a stock b12 head 1127 head good luck with that 

[clivegto]

2 hours ago, no class said:

you could just skim .060 off your 1127 head and get basically the same  results .

B12 one flows best from what I have been told with side by side comparisons. 

[Dezza]

I asked as 0.06" =  approximately 1.5 mm, which seems quite a lot to me, but I know relatively little about this

[Dezza]

1 hour ago, wraith said:

On that site, anything between £90 and £190 for a stock b12 head 1127 head good luck with that 

Already have Blandit 12 head, just like everyone else on here .

[HWB]

28 minutes ago, Dezza said:

I asked as 0.06" =  approximately 1.5 mm, which seems quite a lot to me, but I know relatively little about this

Exactly ! I asked a couple of weeks ago this same question, having an 1127 head and a *dot*head id go with the free +2 point compression instead of taking off 1.5 mm which is kinda crazy tbh, you would hit the lower fins with that much material taken off. Can take .03 off and hit the 12.5 mark easy if you really want to fron the dot. Best thing you could do tho is to measure everything to be certain of what numbers you have

[no class]

my old  kat 1052 motor had gsxr1127 pistons and  cylinder block..no base gasket ...... cases bored to accept the larger sleeve diameter ...which will make it 1109 cc....1127 head skimmed @.060”  .... do not remember the exact valve to piston clearances  .... intake cam was advanced 2 degrees ( which improved the low end torque )  the comp ratio was ... if I recall correctly ...in the 11:7 -1  zone .  this motor was quite stout back in the day . As Clive mentioned .... measure your particular set up .... do your calculations ..... and as far as skimming .060” off a stock head , it works .

[wraith]

Been told the b12 heads flow better and you get better porformace from a ported b12 head than you do with a 1127 head? 

Just what I've been told 

[Gixer1460]

6 minutes ago, wraith said:

Been told the b12 heads flow better and you get better porformace from a ported b12 head than you do with a 1127 head? 

Just what I've been told 

They may do as stock - so do the shimmed 'GSXR heads! But a ported head of any type should address the limitations to pretty much flow as good as they can, whatever the initial flavour!

[JohnnyB12]

Hi from Newbie JohnnyB12,

I wanted to do this too. Put a gsxr750K head on a gsxr1100N that had stuffed camshafts. 

You must remember that the dot head has a large diameter spark plug hence short lands between the plug hole and valve seats. A  super high CR would possibly generate enough heat to cause cracks in these short lands and ruin the head.  I was going to add a spacer under the cylinders to bring the compression back to standard. Erroneously I bought a 2mm spacer and calculated the resultant CR to be around 9.6 to 1.   Should've bought a 1mm spacer instead.

[Gixer1460]

EH?  AFAIK The plug thread size is same as all oil cooled GSXR's - 12mm. Cracking between the plug and the valve inserts is well known in 4V engines and doesn't affect the use of a head at all - not unusual to see multiple cracks across all cylinders. Don't work about the CR causing cracks - worry about the CR and the quality of the fuel you are using with high CR's . . . . . . detonation is the thing to worry about -it'll eat plugs, pepper a cyl. head, overheat valves and melt holes in pistons but the valve seats will still be sitting there!

Edited August 11, 2021 by Gixer1460

[manden]

I have 10mm plugs in mine

[Gixer1460]

30 minutes ago, manden said:

I have 10mm plugs in mine

No need to shout about being small and not normal LOL!

[manden]

Haha