Turbocharging my 82 XJ650 Maxim

wouldn't NOS be just as much fun

 

maybe a cam swap would give you the extra ompf you are looking for

from info overload
SOME TANTALIZING THOUGHTS: although we have not----and do not know of anyone who has---there may be opportunities for performance gains via cam-swapping between different models. Here is what we can say with surety:

b) all XJ650 (except, perhaps, for the Turbo models), XJ700 non-X, and XJ750 model cams will interchange. Here's the lift variances between them:

Intake:

* 650 models (except Turbo): 8.50mm
* 700 non-X models: 8.80mm
* 1981-83 750 models: 8.80mm
* 1984 XJ750RL models: 8.80mm

Exhaust:

* 650 models (except Turbo): 7.80mm
* 700 non-X models: 8.30mm
* 1981-83 750 models: 7.80mm
* 1984 XJ750RL models: 8.30mm


Since the cam lift durations and overlap specifications are not available for all models, we can only (for now) guess what those differences are; however, it would be reasonable to speculate that the 700 non-X and XJ750RL cams are the "hottest" of the bunch, followed by the 1981-83 750 cams, and lowest on the totem pole would be the 650 non-Turbo cams.

Although camshaft design and swapping is a real black art, as not only are lift, durations, and overlap issues involved, there's also cam-timing considerations as well as the interaction between all those factors and cylinder size, air flow into and out of the cylinders, etc. to account for.

Please note that in order to correct (or enhance) other design parameters or issues, it is sometimes best to swap out ONLY the intake OR the exhaust cam (rather than both)......so much depends on the engine and bike in question, the intended usage, rpm power range desired, etc.

Like we said, a black art....... Remember, "hotness" in camshafts, just like beauty, is in the eye of the beholder, and it depends on whether your definition of "hot" is "low-end power", "all-around power", "high-end screamer", or some other variation of the above.

If anyone has any experience with cam swaps on these engines, please let us know what you did, and how it worked out!!

d) XJ900RK and RL cams----these we just don't know about. We BELIEVE (but cannot assure you) that they will interchange with all XJ650, XJ700 non-X, and XJ750 engines. If so, they are probably the "hottest" cams available.

 

Never doubted your qualifications, just looking for answers to the "what if" questions I have . Much rather understand a reason as to why not, then just blatantly accept a reason. Only real carb experience I have is from single carb small engines.

Thank you for your response, time to chew this over

 

Manbot is giving you some good info. I watched him go through his build and he's a pretty sharp guy. A lot of folks don't realize everything Yammy did to build the turbo AND make it reliable. The differences, some have been noted included stronger pistons, rods, heads, lower initial compression to help fight soaring heat which in turn presents you with massive detonation, both a sound type detonation sensor mounted at the front of the engine as well as a pneumatic/electric boost sensor off the surge tank(that MUST be checked for correct output on any used unit & corrected) that were wired to the ECM which uses code to interpret the info and demand raising or lowering of the timing. I spoke with factory guys who told me that Yammy did the Destructive testing at 22PSI yet only signed off on a max of 14 (with their stupid turbo-stall inducing "powerup kit") for the general public.

Any BS carbs (Yammy 650 Turbo specific) that you find today will require a complete and I do mean complete rebuild including shaft seals etc. to prevent leakage. I've done dozens and dozens of set and individual carbs and the rebuild of my set took approx 4 hours since they all have to be separated which means removing the butterflies. Then upon completion, you'll need to Red locktite the butterfly screws and deform the ends to prevent the ingestion of any loos screws....probably wouldn't be a good thing for you engine.

I like the carbs because to me, it's simple. I restored mine 6-7 years ago and it still runs like a champ but I'm sure that there are other ways such as FI to skin that cat too.

FWIW: I run 18PSI using a boost controller so I installed a R6 ('99-'02) pump in place of the stock pump. It makes something like 42PSI so it's comfortably higher than my boost pressure.

I just wanted to pass off some info that might make your build easier or more successful.....so good luck!!

jeff

 

The rarity of that bike... if i could get my hands on one I'd probably sell all 5 of my xj650's and my cars