650 -> 820cc conversion

Does anybody know if this guy is on the forums?
I thought his fin repair was very nice.

 

He SHOULD be, huh???

 

Great Video - sounds 'Antipodean' maybe NZ..

 

My bad - Australian.. Does some fun Millyard-esque stuff

 

Hey David, thanks for this link. I’m new here and yes I’m an Aussie.

Great to find a place just for XJs. I have a series of videos on my channel for my current XJ650 build. Check it out and happy to answer any questions you might have. Mezzmo Engineering on YouTube.

I just posted a detailed build video of my engine that you might be interested in. The 650 is a great engine, only weak links imo is the choke port design and the big one is the primary chain and guide...

 

Welcome! Our community gets better by bringing in more enthusiasts with something to share!

 

Hey! Glad you’re here, Mezz! Your video was posted earlier in this forum and we were saying you ought to be on here. Good to see you.

I had already made this forum into a sticky so we can always find it.

excellent work

welcome aboard,
DFox

 

Thanks guys. Look forward to sharing and learning more too...

 

Great fin repair. I like the way he built them up.

 

Holy shit its mezzmo!!! I binge watched the whole custom build at 4am a few weeks ago and have been subscribed and keeping up.

 

Good to be here and glad to hear you have been enjoying my channel. My build is coming along, I think all the hard work will come together pretty quickly over the next few weeks.
Looking forward to doing the electrics and getting it running. I have a long list of Moto gadget parts about to go in so should be fun...

 

I've really enjoyed your XJ650 build videos on YouTube - addicted to them now, in fact. They are very well put together and extremely informative. While my project goal (restoring my bone-stock '82 Seca 650 to as close to showroom condition as possible) differs from yours, I have nonetheless gleaned lots of useful information from your vids, and I would encourage everyone here to check them out. Thanks for posting them, and keep up the great work. Also love the old Celica in your avatar.

 

Thanks mate, glad it’s helping you out. Yes, I have to get the Celica out again, it’s been far too long

 

I really liked your episode adapting the 900 Diversion rear wheel.
We all envy that 17" 150 rear tire.

 

Thanks mate. It does look good and only just fits after some mods....I purchased that rim and took a chance so given I already paid for it there was no way I was going to give up without a fight...
Hope to have the electrics sorted in the next week or so and then should be getting close to the first ride up my driveway....

 

Well done and thanks! I have a 900F "framy" - just an engine and frame, looking to buy a set of wheels, brakes and forks from a 900s to fit to it. Now I know they will fit. Good work, and good vid's too, easy to watch.

 

I'm addicted to your build ,your bike is looking great . Hope you keep at it.

 

Thanks mate, getting close now. The paint work has turned out well. I hope to go for the first test ride in a couple of weeks time...

 

yes, very nice. I've been looking particularly at the engine rebuild part because I want to do that to my 900 but I'm waaaay to scared.

 

You should just go for it. Take your time, watch my videos and others and you will be fine.
Plenty of good info available to help you...

 

I will. I have a starter clutch issue. It slips ONLY after the bike has warmed up. Being that I just acquired it, I'm going to ride it for a year and enjoy it before I perform open hear surgery. Is there anything in particular that stood out about the XJ motor that I should be aware of?

 

Not really. Check my full build video to get some ideas. Only thing I'd recommend is replacing the primary chain and guide if you're going for a full build. Other than that a good carby clean and you should be good.

 

Great vid. I saw it a couple of times. How long did the actual engine build take you?

 

The engine assembly in that video took me one night, around 6 or 7 hours.

 

3 things have got my build back on track - this forum, a covid-assisted early retirement, and the Mezzmo outstanding xj build came at just the right time.....

 

Using the compression ratio, bore, and stroke of a 650, I calculated an estimated combustion chamber volume. Then used that volume with the 750 stroke and @Mezzmo 's bore of 68 and it looks like his hybrid engine should have a compression ratio of around 11 (could be wrong without knowing piston dimensions). Mezzmo, do you need to use higher octane fuel in your build? Also, have you measured the power output of your engine? I would be curious to see how much more power per cc you are getting with that higher compression.

 

@Mezzmo may chime in but I believe he used the 750 barrels & head.
Aftermarket big bore piston kits are typically engineered to account for the increase in compression, meaning the piston deck height is less.

 

Hi guys, I use standard unleaded fuel. I used the 750 barrels and head. The pistons are built to big bore a 750. I tested compression at the first start and it was around 170psi.
Definitely more power than before but not measured so don’t know for sure. Still need to do some fine tuning on the carbs to get mid range right.

 

I am considering trying something similar on my 700. Did you see any significant differences between the 650 and 750 barrels or head?

 

650 and 750 barrels will interchange on the engine casings. But the barrels are different between YICS and Non-YICS heads. 750 head has a different bolt pattern for the carby boots and different cams. Other than that pretty much the same. Of course there's also the YICS and Non YICS heads.
I started with an XJ650 non yics and converted it to an 820 with YICS head. Not sure about the 700 and if its the same as the 650 or 750....

 

I watched your build and that was some really solid work with a beautiful result. You really put some impressive ingenuity, detail work, and a lot of elbow grease into that! I love the way the xj900 wheels look on your 650. Everything all painted and polished looks beautiful.

 

Thanks mate, I appreciate the feedback

 

Hi everyone. Five years ago I converted 750 cc to 819 cc by installing the Japanese repair kit with big bore pistons. This repair kit was rather cheap (about 160 bucks) and consisted of: pistons, piston rings, piston pins, circlips and head gasket.