Turbocharging my 82 XJ650 Maxim

Just got the turbo back from the shop. Cleaned, rebuilt, balanced, and ready to go. I plan on getting some polishing discs and making the little turbo shine.

I am collecting more parts for the fuel injection every day. Last weekend I grabbed a Venom fuel rail with injectors from a cavalier for $20. I checked and the spacing a little bit larger but it is usable none the less.

I have a WHOLE bunch more stuff to do the bike before it is ready to hit the road. I am debating on whether or not to stretch the swingarm 6 inches or so. I am also on the hunt for xj900 cylinders and pistons to drop in the bike while I have it in 1,000,000 pieces.

I am trying to have it 100% completed around feb or march...but I am sure many things will be swapped out before then.

 

If you lengthen the swingarm won't cornering ability turn to crap? Just curious.

 

I intend on reinforcing the swingarm and the frame so it should flex much less than stock. With the swapped out front end and other mods it should handle decently.

 

I have been pretty bored this weekend so I decided I would start working on the aesthetics part of my turbo. So far I have about 4 hours invested in it and im not anywhere near being done. I am in the process of removing what isnt needed on the turbo housing and sanding & polishing the housing to a chrome like finish.



Hopefully I will have time tomorrow to remove the rest of the un needed stuff and start sanding the housing. The end product should be well work the wait. Just compare the pic with the stock turbo to this pic and you should be pleasantly surprized by the progress

 

WOW what an inspiration. great colors. how much you want for it lol

 

Had today off so I spent another hour and a half or so on the compressor housing.

I still have more sanding and then a whole lot of polishing ahead of me but I like the progress so far. And for those wondering why the heck I am spending 8-10 hours on a piece of the bike that wont even be visable unless I either lay it over or someone gets on their hands and knees.. I dont know I am just wierd I guess.

 

Got some more progress on the compressor housing. Ive been spending more time at work, so my projects come to a standstill. I still have some more to be done on the center of the housing, but I got tired of working on it today. I did a 5 minute polish job with some mothers chrome polish and an old sock...I was very surprized at the outcome. I can only imagine how good its gonna look after I spend time and actually use a real polishing compound. The whole aluminum polishing thing is kind of addicting. Now I want to do my handlebar controls, and my upper triple tree, then my wheels, and forks, and valve cover, and engine sidecovers, hell screw it I might as well do the engine cases too while I'm at it.

 

*delete*

 

From your first post i noticed you said you wanted a xj750 tank on your xj650, i ran into a problem with that and put it on hold, the triple tree connected with the left of the tank, it seems the stops for the forks (part of frame) were not forward enuff for the 750 tank so moding the stops is a future project for me, maybe weld maybe drill and and a bolt into the stops...dunno yet, gunna stip the bike and have the frame soda blasted and powder coated soon! ill do the mod then. sorry i got no info on the turbo itself.

 

it's been a few years but have you had any luck with the swap?

 

Very curious what happened of this project as I just picked up a seca and planned on doing the same thing, decided to look for possible build threads

 

buy a 650 turbo save your self a lot of headache
there are other threads on this subject. the turbo motor is built different to take the stress of the turbo as well as different type of carbs
stronger parts needed or you may blow the standard 650 motor.

original poster said

 

It's not a matter of may blow, but will blow. If you want anything other than a tiny amount of boost, you have to use the Turbo engine.

 

I was hoping to use the 650 maxim engine.. 9.2:1 compression vs the 8.2:1 seca turbo compression. Also the maxim has bigger carbs and the stroke is the same from both engines. I've always wanted to mix the two together.
Looking at the specs in comparison there is almost no difference in 1/4 mile. Just wanted the xj650 to have the oompf from the seca... If I recall the Seca has the forged pistons and there is a difference in the piston crowns. It's doable.. if one has time to tinker

http://www.motorcyclespecs.co.za/model/yamaha/yamaha_xj650_turbo.htm
http://www.motorcyclespecs.co.za/model/yamaha/yamaha_xj650_maxim.htm

 

The turbo Seca also has stronger engine cases.

If all a person wants is more "oomph" the fast route is to swap in an xj750 or XJ900 engine.

Putting a turbo on the non-turbo engines has been done, but it's a dance between getting a bit more "oomph" and breaking the engine. The turbo engine is the better platform to work from, and has much more potential than Yamaha ever got out of it.

 

The comment got deleted??

 

Not by any moderator.

 

Maxim carbs won't work. Turbo Seca carbs are pressurized, i.e. the "atmosphere" side of the slide diaphragm is actually at compressor pressure, and the fuel is pumped in at 2 psi above the compressor pressure, or the bowls would never fill.

The Turbo had an 8.2:1 compression ratio for a reason, all that extra fuel/air at higher pressure/temperature will detonate. Furthermore, the TCI can sense detonation using a mic and retard timing to minimize it.

So if you don't want to use the entire Turbo Seca plant, you will at a minimum need to fuel inject the bike and make your own fuel/timing maps to handle the different operating conditions. You aren't the first one to ask about the project and there's a reason why the answer is always the same: "Start with a Turbo Seca."

I've seen one user put all his maxim parts on a Turbo Seca plant and it looked awesome. I have a turbo seca that I restored from the frame up and can promise you that it isn't just the turbocharger that is needed.

Like K-Moe said, if you want more oomph, "there's no replacement for displacement." That's what the big-4 concluded. If you want a turbo for the "cool factor" get a Turbo Seca and modify from there. If you want to start from scratch for the experience, I'd probably pick a better plant that is already fuel injected

 

I hear ya, but I would still like to humor this idea for a bit if anyone else is up for it. After thinking a bit more about it, what if one were to build a "box" around the carbs to equalize the pressure?

 

I'll humor you just to help you realize that my qualification is already well thought out:

You need a small pressure differential between your fuel inlet and you compressor pressure for the bowl of the carb to fill and your venturi to draw up fuel. If your venturi drops the pressure by 2 psi, but your compressor boosts it by 4 psi, there will be 2 psi of pressure forcing fuel back into the tank and nothing will get forced into the airstream.

Therefore you NEED a fuel pump, and a way to regulate the pressure, even if you build a "box" around the carb to pressurize the venturi (i.e. get the slide to act right).

The carb jets and needle will need to be changed for the different performance under boost.

If you start with fuel injection, you avoid all the carb issues,

Now you also need a TCI box that handles the rpm/timing AND boost pressure as an input (from a boost sensor), and perhaps a mic to detect detonation (because carbs won't be very precise in fuel delivery) for some closed-loop feedback.

Add the intake and exhaust plumbing (yamaha picked the rear of the engine for some benefits/tradeoffs), oil line and pump fittings to feed the turbo.

And you still have to worry about blowing up the engine.