DOT Head mixed information

[MikeyVeitch]

Tell me if I am wrong because I and getting lots of mixed information

Gsxr 750 f 85, g 86, h 87. Not Dot

gsxr 750 j 88, k 99. Is a dot.

’Teapot’ refers strictly to gsxF engines?

do the short stroke 748cc engines have bigger valves than the longstroke 749cc engine?

if so, are they as big as the 1100/1200 valves?

do the short stroke 748cc engines have a steeper carb/intake angle than the longstroke 749cc engine?

Is the Dot - shortstoke - j/k - 88/89 the right 750 head for my bandit 1200 shenanigans?

what compression am I looking at if I was to place this head onto my FACTORY 1157cc pistons and barrel set?

ps, if I get mixed replies… I’m going to shoot myself but on a serious note, I appreciate any reply’s that you lads and ladettes give me

:)

[Swiss Toni]

A member posted a comprehensive breakdown on Dot heads a while ago. Everything you need to know. Do a search. 

[DAZ]

5 hours ago, MikeyVeitch said:

Tell me if I am wrong because I and getting lots of mixed information

Gsxr 750 f 85, g 86, h 87. Not Dot

gsxr 750 j 88, k 99. Is a dot.

’Teapot’ refers strictly to gsxF engines?

do the short stroke 748cc engines have bigger valves than the longstroke 749cc engine?

if so, are they as big as the 1100/1200 valves?

do the short stroke 748cc engines have a steeper carb/intake angle than the longstroke 749cc engine?

Is the Dot - shortstoke - j/k - 88/89 the right 750 head for my bandit 1200 shenanigans?

what compression am I looking at if I was to place this head onto my FACTORY 1157cc pistons and barrel set?

ps, if I get mixed replies… I’m going to shoot myself but on a serious note, I appreciate any reply’s that you lads and ladettes give me

To the best of my knowledge :

f,g,h, l,m, not dot 

j,k dot 

gsxf = teapot 600/750 only earlier 750 shortstroke dot head 

dot head 750 has bigger valves than long stroke 750 - short stroke+bigger bore have more room for valves than long stroke small bore 

Not sure if exactly same size as 11/1200 but not far off  28.3 inlet/25 exhaust 

yes the head has a steeper port angle approx 15° which makes the important "short turn"  bottom port wall turn into the chamber less acute and better flowing

yes the 88/89 j/k gsxr head is the best of the stock heads - but only because they have the best cams 

chamber size is one of many things which determine compression, but you are looking at +1 to +1.5 increase in compression the dot head chamber is approx 4cc +/- smaller than the bandit 12 so look at 9.5 to 10.5/11:1 

this is to the best of my knowledge and I stand to be corrected

 

Edited August 15, 2023 by DAZ

[Upshotknothole]

First gen 750Fs were short stroke 748cc engines as well, but the cams were pretty mild compared to the GSXR cams.

Teapot refers to 600 and 750 Fs, the 1100s are "power screens."

"Dot" heads actually have dots cast in the fins on either side of the head, makes them easy to spot.

I had a threat not too long ago asking similar questions regarding what's needed to do the swap. Shouldn't be more than a few pages back if you look.

Essentially it's a quick and easy way to wake up a bandit engine. You have to use the bandit cam sprockets on the dot cams, new head gasket and O-rings. I've heard different compression ratios, 10.5:1 up to 12.5:1.

It will move the carbs higher up than any other head, so expect issues with the fuel tap, especially if it's a 7/11 or similar. The stock intake rubbers on the dot heads are the best for fitting Mikuni RS carbs, and Suzuki has discontinued them, so join the rest of us in trying to find replacements.

All the benefits of the head swap disappear if you start doing any real engine work to the bandit. If you do a 1216 kit or any head work, better off with the stock head and swap the dot cams, or GSXR 1100(tappet heads only, no shim heads) cams or power screen cams.

What bike are you doing this to? We like photos here. Hope that helps, and definitely search the forums. They've been talked about a lot in here and the occasional build thread.

[DAZ]

4 hours ago, Upshotknothole said:

All the benefits of the head swap disappear if you start doing any real engine work to the bandit. If you do a 1216 kit or any head work, better off with the stock head and swap the dot cams, or GSXR 1100(tappet heads only, no shim heads) cams or power screen cams.

The main issue with dot heads and a 1216 kit is more to do with an acceptable compression ratio, most big bore  kits raise the compression to 12 or 13 to1  with the std 1200 head so the smaller combustion chamber of the dot heads pushes it way to high for road use and I would also be wary of piston to valve clearance with the pop up dome on pistons and shallower chambers bringing the valves lower in relation to the cylinder block deck 

[wraith]

All been answered above and is good info, so all I will say is for bolt on power a DOT head is worth doing. B12 respond well with a DOT (have one myself) and I understand the 1127 and 1052 respond well to them as well. 

Only down side is depending what your fitting the head/engine into the carb angel can course a problem. 

My B12 engine with DOT head and gsxr cams runs very well but being in a gsx1100et frame I had to lift the rear of the tank a bit to clear the gsxr750 38mm carbs (also worth fitting as far as I'm concerned )

[Joseph]

4 hours ago, Upshotknothole said:

The stock intake rubbers on the dot heads are the best for fitting Mikuni RS carbs, and Suzuki has discontinued them, so join the rest of us in trying to find replacements

RS carbs are compatible with Bandit intakes thanks to being the same size as Bandit carbs 

[MikeyVeitch]

8 hours ago, Upshotknothole said:

First gen 750Fs were short stroke 748cc engines as well, but the cams were pretty mild compared to the GSXR cams.

Teapot refers to 600 and 750 Fs, the 1100s are "power screens."

"Dot" heads actually have dots cast in the fins on either side of the head, makes them easy to spot.

I had a threat not too long ago asking similar questions regarding what's needed to do the swap. Shouldn't be more than a few pages back if you look.

Essentially it's a quick and easy way to wake up a bandit engine. You have to use the bandit cam sprockets on the dot cams, new head gasket and O-rings. I've heard different compression ratios, 10.5:1 up to 12.5:1.

It will move the carbs higher up than any other head, so expect issues with the fuel tap, especially if it's a 7/11 or similar. The stock intake rubbers on the dot heads are the best for fitting Mikuni RS carbs, and Suzuki has discontinued them, so join the rest of us in trying to find replacements.

All the benefits of the head swap disappear if you start doing any real engine work to the bandit. If you do a 1216 kit or any head work, better off with the stock head and swap the dot cams, or GSXR 1100(tappet heads only, no shim heads) cams or power screen cams.

What bike are you doing this to? We like photos here. Hope that helps, and definitely search the forums. They've been talked about a lot in here and the occasional build thread.

Bandit 1200 engine

has full gsxr 1127 1992 gearbox and clutch.

I have a shim head also from the 1992 engine, would this be better to use for top end power than the Dot head?

[wraith]

I'd go for the DOT head, as I believe the 92 gsxr head won't increase the compression on a b12 motor so you'd only gain would be cams which you can put gsxr (non shim) cams straight into the b12 head or DOT head. 

If you're using any other cams apart from your standard b12 cams you will need to swap the cam sprockets and use your b12 cam sprockets.

[Upshotknothole]

4 hours ago, MikeyVeitch said:

Bandit 1200 engine

has full gsxr 1127 1992 gearbox and clutch.

I have a shim head also from the 1992 engine, would this be better to use for top end power than the Dot head?

Use the dot head for now. If you ever replace the pistons and bore it out, stick the 92 shim head on it. The 1100 head will work with the higher compression pistons and it's supposed to be the best flowing of all the heads, you just give up aftermarket cams. Or you can use the stock bandit head, get it ported, and use aftermarket cams. Really depends on how much money you want to spend. The dot head is the cheapest and easiest upgrade if you've already got it.

[MikeyVeitch]

2 hours ago, Upshotknothole said:

Use the dot head for now. If you ever replace the pistons and bore it out, stick the 92 shim head on it. The 1100 head will work with the higher compression pistons and it's supposed to be the best flowing of all the heads, you just give up aftermarket cams. Or you can use the stock bandit head, get it ported, and use aftermarket cams. Really depends on how much money you want to spend. The dot head is the cheapest and easiest upgrade if you've already got it.

I keep hearing people say that the 1100 shin head ‘flows well’. Is this because of factory porting / different valves?  I looked online and they seem to take the same valve size as a 1100/1200 tappet head. No intentions of doing a big bore (on this bike) so in this application, dot gives big angry cams and higher compression so will be the best option. 

[Upshotknothole]

1 minute ago, MikeyVeitch said:

I keep hearing people say that the 1100 shin head ‘flows well’. Is this because of factory porting / different valves?  I looked online and they seem to take the same valve size as a 1100/1200 tappet head. No intentions of doing a big bore (on this bike) so in this application, dot gives big angry cams and higher compression so will be the best option. 

Yeah, they just had the best porting from the factory. Decent cams, but I think the dot head cams were probably a little better.

[MikeyVeitch]

So I’m getting ready to install this head, does this rubber guide on the intake side need to be removed?

Also, my bandit 1200 rubber fit but don’t seem to king up correctly, so I need the rubbers for a dot head too?

Edited August 16, 2023 by MikeyVeitch

[IhmeJanneFIN]

This thread seems like a appropriate place to ask about my head dilemma as it revolves around dot and other heads also.

I am building boosted 1216 engine and I have in my possession 4 differend oil boilers and heads, each with it's own flaws (cheap engines so "minor" problems in these, more below). My compression ratio goal is about 8,5:1 and will be run with efi also flexfuel. Power targer around 300, but anything between 200-300 is acceptable.

 

Engines are:

-92 GSXR 1127 engine (shim head), at the moment assembled and cams look ok. Have not run when in my possession. Would rather not disasseble, so I would be able to use this in some other project as NA engine. Also shim head, so would need some rocker fork work done to use reliably in boosted engine. Have read otherwise also, so might be OK head, with just throwing new springs and titanium retainers (which also costly).

 

 

-96 B12 engine, with damaged cams and cam liners (lot of alu and metal gone due to oil starvation at the top end due to broken oil pump). At the moment completely disassembled. Lower engine parts are ok (crank, cylinders, gearbox, clutch...), only the head is toast, so no good without some alu welding and machining the cam liners to spec again and new cams. Costly, if even doable? Will take the lower end of this engine to my 1216 build, but the metal clutch basket from the 1127R with 1127F inner (4 normal springs, no diaphragm, cheaper to fit lock up and better clutch to start with than B12 alu basket).

 

 

-88 GSXR 750 aka the real DOT head and cams, with minor pitting on exhaust cam lobes and on 1 rocker. Also has minor damage on the #2 and #3 cylinders, as small bits of alu missing between valves and next to valve seat (small hole next to alu seat as there was alu stuck to it and took it out with pliers). So might need oversise valves to fix this head. Engine completely disassebled at the moment. Tempted to put big valves and stiffer springs to this head.

And finally my first oil boiler ever.

-94 GSX750F (currently 988cc Frankenstein). This engine is currently on the bike and running with the oem 750F dot head and cams. This engine might be a ticking bomb waiting to explode, so might disassemble this engine just to look how it has beared my small test runs. There is some brownish black flake seen in the engine oil, so the oilite bushings might be failing on the piston pins. But the head and mild 750F oem cams are in good condition. Would like to put stiffer springs to this one if going in use.

 

So, my question is, which of these would be my best bet for the boosted 1216cc build? All need some sort of attention, just differend kind of attention before putting to use, so would like to do the headwork only once to the best plausilble head.

 

And some backround info of build plan the help decide witch head to recommend.

 

I have obtained very cheaply a set of unused gen 1 Busa Wössner pistons with 13,5:1 compression, which I plan to run on my engine with bored B12 cylinders. Bare in mind, these pistons are originally meant for Busa, so the advertised compression ratio of 13,5:1 is not achieved with these in the oil boiler. What the compression ratio will be, I don't know yet, have to do a dry build and calculate, BUT, the Wössners have a remarkable bigger valve pockets than B12 oem pistons but have the same compression height. So in my mind, these should have lower compression ratio than B12 oem pistons, but the same deck height and squishband as oem B12 pistons?

Firstly I would need to get my pistons to fit my cylinders, to be able to check the deck height and calculate cylinder volume without the head with the wössners.

I also know the dot heads will pump up the compression as it has smaller combustion chamber than the 1127/1157 heads, so it might bring the compression right on the ballpark or go way over the target with these wössner pistons. Will have to finetune the compression ratio and squishband with spacer plate if necessary.

[Gixer1460]

I'd use the 1100 shim head in a blown engine (I have on my 1460), shim spitting is unlikely due to lower RPMS. Bandit head would cost to put right, even if it could! A dot head wouldn't work at all well blown even with a decomp plate you lose the squish so burn suffers. Personally I'd use proper 81mm turbo pistons and sell the busa ones.

Edited September 4, 2023 by Gixer1460

[Upshotknothole]

42 minutes ago, Gixer1460 said:

I'd use the 1100 shim head in a blown engine (I have on my 1460), shim spitting is unlikely due to lower RPMS.

I feel like if the urban legends about the shim heads spitting shims were true, all of the shim head 750s would have blown up years ago.

[DAZ]

My thoughts pretty much echo what @Gixer1460said above only thing I would add is check the length of the dot head valves as the chamber is shallower it may be that the valve stems are longer than the regular 11/1200 valves , as the ports are cast differently I don't see Suzuki San just milling the heads to reduce chamber volume it'll possibly cast shallower and have longer stems ,most all oversize valves I've seen for sale are for 11/1200 heads

[IhmeJanneFIN]

8 hours ago, Gixer1460 said:

I'd use the 1100 shim head in a blown engine (I have on my 1460), shim spitting is unlikely due to lower RPMS. Bandit head would cost to put right, even if it could! A dot head wouldn't work at all well blown even with a decomp plate you lose the squish so burn suffers. Personally I'd use proper 81mm turbo pistons and sell the buds ones.

I kinda anticipated this answer from you Gixer1460 , as I remember you saying on some post on this forum, that you run shim head on your build without problems. Do you think stiffer valve springs would be a good idea, or can it be run as stock condition?

B12 head is a big piece of paperweight, that I agree, there is no point in fixing that as it would be costly if even. Will keep it as spares though, as it has good valves still.

The guy I bought those pistons from (local guy to me), had been basically selling them in half price for about half a year with no luck (I had been eyeballing the listing previously), so I reckon I would not be able to sell them either with good enough price to buy new turbo designated pistons, so this is what I will run now. They do look rather decent to my eyes, though I have never held a designated turbo piston in my hands so cannot tell the difference

I need to get my block bored so I can start the dry build and calculate the CR those pistons will be in oil boiler, that would determine a lot which head to run. Would like to keep the squishband tight for better bang in the cylinder.

 

[IhmeJanneFIN]

7 hours ago, DAZ said:

My thoughts pretty much echo what @Gixer1460said above only thing I would add is check the length of the dot head valves as the chamber is shallower it may be that the valve stems are longer than the regular 11/1200 valves , as the ports are cast differently I don't see Suzuki San just milling the heads to reduce chamber volume it'll possibly cast shallower and have longer stems ,most all oversize valves I've seen for sale are for 11/1200 heads

With my dry build I will check valve to piston clearance no matter what head, as I am planning on running non oem valvetiming.

I saw bigger intake and exhaust valves and titanium retainers being sold at Abuso Racing site for quite reasonable price of 310€/set to many makes and models of bikes.

[Gixer1460]

3 hours ago, IhmeJanneFIN said:

 Do you think stiffer valve springs would be a good idea, or can it be run as stock condition?

The whole of the valve train in my engine was developed by someone much smarter than me - Kroll Turbo grind cams, dual springs with probably increased poundage, Ti valve spring retainers and caps + other secret squirrel stuff. I'd say stock (good) springs would be ok for moderate boost but increased seat pressure is good insurance if getting into the 2 bar+ boost range.

[clivegto]

The dot head valves are longer 

[BoostedRooster712]

I've learnt so much reading this thread and it took exactly one beer.