Are the heads for 1100 and 1200 interchangable? Or all years of the 1200 interchangeable? Might be replacing my head. Mostly can only find 1100 heads. And the one descent looking one from a 1200 is from and 86 apparently with a engine code of 38Y00, mine is a 1990 with engine code 36Y00. Visually they all look the same. Idk if there's and small variations. My shop manual doesn't having any information that would suggest they are different. Can't get a clear answer from Google. If anyone could give me an affirmative yes or no on the subject, I would greatly appreciate it.
AFAIK they are all the same but if you need more reassurance then forget Google and use something like this > https://www.cmsnl.com/yamaha-motorcycle_model16707/ which will give you all the part numbers you need. It's European but covers bikes in the USA too.
Quote from: crazy88 on October 18, 2025, 07:53:29 PMAre the heads for 1100 and 1200 interchangable? Or all years of the 1200 interchangeable? Might be replacing my head. Mostly can only find 1100 heads. And the one descent looking one from a 1200 is from and 86 apparently with a engine code of 38Y00, mine is a 1990 with engine code 36Y00. Visually they all look the same. Idk if there's and small variations. My shop manual doesn't having any information that would suggest they are different. Can't get a clear answer from Google. If anyone could give me an affirmative yes or no on the subject, I would greatly appreciate it.
Yes, they are all interchangeable. You can even put the xjr1200/1250/1300 heads on with a little bit of shaving to the outer fins of the head. The 1100/1200s were in perimeter frames where as the xjr1200/1250/1300 were in a spine back chassis so they didn't take the time to machine the tape in those
Awesome guys. Thank you for the responses
Quote from: RPM - Robert on October 20, 2025, 11:52:47 AMQuote from: crazy88 on October 18, 2025, 07:53:29 PMAre the heads for 1100 and 1200 interchangable? Or all years of the 1200 interchangeable? Might be replacing my head. Mostly can only find 1100 heads. And the one descent looking one from a 1200 is from and 86 apparently with a engine code of 38Y00, mine is a 1990 with engine code 36Y00. Visually they all look the same. Idk if there's and small variations. My shop manual doesn't having any information that would suggest they are different. Can't get a clear answer from Google. If anyone could give me an affirmative yes or no on the subject, I would greatly appreciate it.
Yes, they are all interchangeable. You can even put the xjr1200/1250/1300 heads on with a little bit of shaving to the outer fins of the head. The 1100/1200s were in perimeter frames where as the xjr1200/1250/1300 were in a spine back chassis so they didn't take the time to machine the tape in those
Are there any minor differences between them, or any advantages to using a particular model of cylinder head (I'm thinking about my 3CV with a 1350 big bore kit). I'm not after ultimate horsepower, but like Pat am aiming for most usable real world power and torque heavy, with around 140 bhp.
No, they are all the same internally. The only difference being the outside fins and at some point on the 1250/1300 models they have EGR ports on the top side of the head for emissions.
What about the cams Robert, I've read where some say the 1100 cams have a different profile and are sportier than the 1200, but then read elsewhere that they have the same part number so are all the same. Has anyone ever measured the profiles between them and confirmed they're the same.
I know the XJR 1200 was a detuned version of the FJ, it was tuned to have more torque down low and less top end HP. Not sure how they achieved that, cam timing maybe?