Does anyone have any idea of performance increases from head work on an M750/carb? I want to increase my performance as much as possible without it being visible from a tech point of view. Any other ideas on inobvious power increases would be helpful. I'm hoping to be able to get about 70hp and still appear stock. I've already done the K&I, rejet and cans thing.
head work
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2,326 Posts
I would look into some new keihin carbs (39mm for your bike). You can get a kit from www.ca-cycleworks.com for around $740 bucks (he is also a dml member). With that and a new sprocket you will definitely feel the difference.
Check these guys out:
http://www.moto-one.com.au/performance/750ss_900carb_cams.html
I've heard BCM and MBP do good head work.
70 hp may be within reach.
http://www.moto-one.com.au/performance/750ss_900carb_cams.html
I've heard BCM and MBP do good head work.
70 hp may be within reach.
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3,178 Posts
imho, waste of $ on a 750. don't do it unless in racing class and not allowed to bump displacement.
the problem with 2V heads is that they are bent. normal heads bend in an up and down fashion to help curl the flow of air/gas to straight on top of the valve and then into the combustion chamber. our heads do that.
but our heads also have this wierdo right to left bend. the trick is to eliminate / minimize this without screwing up the flow numbers. it is pretty easy to "bubba-ize" the heads and not get any power out of them.
a real good head porting is a few thousand bucks.
another problem is that the engine cases of pre 1998 750s are safe up to 75 hp. a superbike prepped 750 with carbs and head work can get to 80.
what I would do if trying to be ultra sneaky is get a 900 engine and put the 750 clutch stuff on it so it kinda looks the same. then remove the belt covers and the inner pieces, as the 900 covers are different. just tell folks you took the belt covers off and say they run cooler or some such crap.
what i'd really do is bolt in a 900 motor and FCRs and leave it with that.
oh, and if you're really mean, bore the engine cases and run a 4mm overbore for 984cc...
;D chris
the problem with 2V heads is that they are bent. normal heads bend in an up and down fashion to help curl the flow of air/gas to straight on top of the valve and then into the combustion chamber. our heads do that.
but our heads also have this wierdo right to left bend. the trick is to eliminate / minimize this without screwing up the flow numbers. it is pretty easy to "bubba-ize" the heads and not get any power out of them.
a real good head porting is a few thousand bucks.
another problem is that the engine cases of pre 1998 750s are safe up to 75 hp. a superbike prepped 750 with carbs and head work can get to 80.
what I would do if trying to be ultra sneaky is get a 900 engine and put the 750 clutch stuff on it so it kinda looks the same. then remove the belt covers and the inner pieces, as the 900 covers are different. just tell folks you took the belt covers off and say they run cooler or some such crap.
what i'd really do is bolt in a 900 motor and FCRs and leave it with that.
oh, and if you're really mean, bore the engine cases and run a 4mm overbore for 984cc...
;D chris
Chris,
I can't bump up displacement. I want to be competitive in lightweight twins against SV's. That will be tough, though a lot of mods are allowed. However, ultimately that will be dependent on as much as I can get out of the motor plus lots of suspension work, corner speed and balls. I want to keep the work on the motor invisible to run in a lower class for fun and need to keep the changes invisible without going too far. I need to keep the stock parts on the outside. I was thinking bigger valves, port and polish, lighter flywheel and have my tuner do a little cam work. I want to go between classes without doing anymore questionable engine work than anyone else. I did look @ that Aussie sight and was really impressed. Do you have access to bigger valves for a carburated 750?
I can't bump up displacement. I want to be competitive in lightweight twins against SV's. That will be tough, though a lot of mods are allowed. However, ultimately that will be dependent on as much as I can get out of the motor plus lots of suspension work, corner speed and balls. I want to keep the work on the motor invisible to run in a lower class for fun and need to keep the changes invisible without going too far. I need to keep the stock parts on the outside. I was thinking bigger valves, port and polish, lighter flywheel and have my tuner do a little cam work. I want to go between classes without doing anymore questionable engine work than anyone else. I did look @ that Aussie sight and was really impressed. Do you have access to bigger valves for a carburated 750?
You need to send your heads to MBP. Messing with your heads without a world of experience is asking for garbage. Get some pistons from BCM. The head package from MBP will include a switch to FCR carburetors and short manifolds. The full Monty head job will include four new valves, new seats, guides, collets and extensive port work including welding. That will put you in the 80hp plus range.
908,
Eighty horses on a sixty horse 750? Are you sure you aren't talking about a 900? How do I get hold of BCM? Do they have a website, telephone, etc. I ran into a vintage guy @ Putnam park this summer and he said he got an extra 18 ponies from headwork and I though it was BCM. Are they from the northeast. His guys were from Mass or somewhere around there.
Eighty horses on a sixty horse 750? Are you sure you aren't talking about a 900? How do I get hold of BCM? Do they have a website, telephone, etc. I ran into a vintage guy @ Putnam park this summer and he said he got an extra 18 ponies from headwork and I though it was BCM. Are they from the northeast. His guys were from Mass or somewhere around there.
G
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·Depending where you are.......you could also contact Manley Cycle in the midwest....and prolly Evoluzione in Simi Valley on the west coast.....
If you get brave and try to port them yourself, here is a tip. Bring the intake side to a near polished state then sand blast the intake side ports. This will add little bumps that will help lower the rpm range and aid in fuel atomization. Polish the snot out of the exhaust side!
http://www.mbpducati.com/
Pricing is all going to depend on who does it, and how far you want them to go...
--Fillmore
Pricing is all going to depend on who does it, and how far you want them to go...
--Fillmore
Thanks. Sorry to hear about the crash. Sounds like it shook you up. I broke my collarbone @ Grattan in July and it took 5 seconds off my lap time for a while. Other than that I've discovered many other ways to crash (4 last year , one @ triple digits, 1 this year). Sometimes it's a mystery, other times you push your luck against a cattle guard one too many times.
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