Simmy's Naked Turbo Project

The turbo tank looks NOTHING like the 750rl

 

750rl


Turbo

 

Thanks. I'm interested. If you have a pic available, please send. We may be at the vintage show in June. Going to check out local B&Bs for availability.

 

Definitely an interesting project! FYI...if you transfer the boost pressure sensor (used as a secondary timing safety) be sure to check the output voltage. According to the manual, it's supposed to be at 2V but I NEVER found one reading at 2V until I adjusted it. The problem is that with too high a voltage at rest, it will begin retarding the timing early never allowing you to max your power!


Jeff


FWIW....I run 18psi on mine since I completed several years ago....a blast to ride!

 

How did you adjust the boost pressure sensor?
I read what you did to get more boost, makes sense and I plan to follow that.
Did you alter the turbo compressor side?

 

If you take a look here, you'll see how the boost controller is configured:
http://s808.photobucket.com/user/jeffkushner1/library/Yamaha 650 Turbo Boost gage and controller?sort=3&page=1

You will also see pics of the check valve that I installed on the oil return line. The factory scavenge pump has one but it fails over time so I modified this valve and installed it....there's enough room but you'll need to trim the ends of the valve to fit.

As I remember, the boost pressure sensor has a strain gauge (that measures the pressure) that once you use a razor knife and open the box, you can gently bend it to raise or lower the output voltage...yeah, I was kinda surprised too but it worked! No worry if you mess up...if you shop on fleabay, you can get them for 20 bucks.

I rebuilt the turbo using the kit from Jerry at Gpop shop and I called him when it seemed like I had leftover parts. He explained that the kit is designed for several models so I was ok. I did nothing to modify the factory turbo but I was VERY careful in rebuilding it. You must index the impeller (the turbine and shaft are one piece) to the shaft before disassembling or you will have to send it out to get professionally balanced. It spins at 212K rpm so any imbalance will lower overall boost and very possibly can destroy it.

Slip a fender washer behind the stock blowoff valve in the surge tank & it will raise the blow off from 14 to 21PSI...once you have the controller installed, you run the bike and carefully set it so that it opens at 18psi.....the OPEN point is what you are searching for since that will open the bleed off from the turbo....

jeff

 

I just bought 2 motors however I haven't picked them up yet.
One is an XJ900 and the other is a 650Turbo.
I haven't given up on the idea of grafting the 900 block and pistons onto the turbo bottom end, for an XJ740 Turbo.
What these motors will allow is a mock up in parallel to my task of reviving the actual bike back to life.
This spare turbo motor is very rough and could be seized as I was told. That's fine, all I need it for is to get one (2 actually) of the crank throws to top dead centre, fit the 900 barrels and one piston and measure the volume of the resulting combustion chamber.
This is what I'm anticipating:

1. the 650 cases will need to be enlarged to accommodate the 900 sleeves. No problem with a Dremmel.
2. the 900 block will need to be shaved down a considerable amount to achieve 8.2:1 CR of the stock turbo. The problem with this is that I can't take this off the top as it will compromise the YICS passages but more importantly the recessed keeper for the cam chain guide. This means machining from the bottom of the block which also means removing the sleeves, then shortening them and reinstalling.
3. the 900 block looks to have the boss for the knock sensor cast in and just needs to be threaded

My big concern is, after removing the sleeves and pushing them back in will they be distorted beyond serviceability?
The 900 has 49,000 kms so I'm hoping the pistons, rings and bores are good for use.
The Turbo had stronger forged pistons but I'm willing to bet the 900 pistons will be up to the task.
Anyone have any water to throw on my plan? I suppose if the 900 motor checks out good I could go that route but I'm still planning to use the 30mm turbo carbs and turbo head, this would require shimming the barrel to lower the compression, making the motor even taller than a stock 900. There's over 8 mm difference in the stroke between the stock 650 and 900 so the turbo air pipes might not fit right. I'm thinking the carbs might work better on a 740 versus an 853.

 

Turbo engine

XJ900 engine

 

Simmy,

You might want to wander over to the Turbo Forum and do a search. Looking under the Seca 650 section, I found 4 pages of threads for a "Seca 900" search.....http://tmioa22687.yuku.com/directory#.WTfUu-srLcs

A couple of the guys have done it and know the idiosyncrasies of that exact project. One guy, Positive Pressure was the one that "took me under his wing" and taught me all I didn't even realize that I didn't know about turbocharging but he got angry at someone or something and deleted all his posts....a real shame because it was a treasure trove of information....just gone, poof!


P.S. on the 650 turbo forum, I use the screen name "eradicator".

jeff

 

Yes I read everything I could on that forum. There was one guy posting in broken English describing motor swaps into his XJ-Turbo. XJ900's, and parts there of, I really got skeptical when he said he tried the XJ700-X motor in his Turbo. There are so many questions concerning that mod I wouldn't know where to begin. Frankly, his posts read like the over-active imagination of someone with a pound of knowledge and a ton of BS, maybe I'm mistaken here. Without pics it didn't happen, right? Not sure if its the same guy you're referring to. As you say, he taught you a lot.
I have some mechanical experience building my XJ911-X motor. In that case there were already FZ911's put together so I was pretty confident it was going to work. There was a surprise in the way the XJ-X water pipes mounted differently than the FZ but other than that it went together pretty easy.
I read your posts over there and learned a lot. Seems relatively simple to extract more boost, and cheap at that!
I will be calling on your experience when that time comes.
There's already a ton of knowledge here, much of the electrical mods, eliminating the Atari and such I believe I can work through with the electrical experts here, XJ550H, Rooster, K-Moe come to mind.
I'm not too proud to admit I will need help with this. I know the end result will be a keeper.

 

You already know who NOT to listen to....your BS detector is working perfectly<LOL>. Unfortunately, the guy I'm speaking of has been gone for a couple of years now. A real shame. From what I gather, the basic crank blocks of the XJ 650, 750 & 900 are nearly identical and much different then the FZ engines. I've "heard" that the 900 cylinders will slip right onto the 650 crank but since I learned how to extract more power than the running gear can really cope with, I never found a need to try it myself but like I said at the beginning, I like seeing out of the box projects go through the development then implementation stages.

If you've read what I've posted over there, then you pretty much know what I know....but knowing to look for help is the smartest of qualities that not all men possess!

jeff

 

When you remove and reinstall the cylinder liners you will be heating the block and taking advantage of the difference in expansion rates. That will prevent damaging either the liners or the block.

 

I'm liking my Turbo even more now. That discarded body work weighed a ton!
I need to weigh everything coming off and compare it to the RJ stuff going on to see how much lighter it will be.
There's a big steel cantilevered bracket holding the headlight way out there. I can't wait until that and the Atari are gone.
If anyone is interested in the entire Turbo fairing let me know, I'll package it up in one bundle. I can even provide the mounting tabs.
Just completed a major project on the house (painting) which was taking all my time. Now that winter is approaching I hope I'll get more time for this.

It's barely noticeable in this pic but the top cooling fin on the head is broken. I will get this welded up when I have the head off.

I toiled with the idea to get it running the way it is, before tearing it apart for mods and cosmetics but there is so much stuff I would need to handle twice that I've decided to tackle everything all at once.

I've decided to go the 740 big bore route using the pistons and block from the 853 motor and bottom end from the 650 Turbo.
This way the carburetors will be positioned in the same place. That 900 stroke would be nice but I'm worried about any misalignment in all the Turbo equipment that extra 8 mm might create.

 

Sometimes, "easy" is not a bad thing! Besides, 100cc is a 100cc.....and size matters!


jeff

 

I'm optimistic the extra displacement, extra boost as you've done and shedding 50 lbs of fiberglass will liven er up.
Besides, this is incredible fun!
I've just located some nice chrome header pipes from an XJ700. I read here the ID is slightly smaller on the Turbo pipes to speed up flow to the turbo.
I'm doing this purely for cosmetics but the added displacement should compensate for this.
My last Seca I went for the blacked out look as much as I could. This one I'm going for as much chrome as I can.

Jeff how much boost can you get with the OEM fuel pump? I see you're using an 00-02 R6 pump and seems to be everyone's choice.
At this point I'm unsure if my pump still works.
I spent 1/2 an hour removing body panels, that's virtually all I've done so far, except shoving another back wheel on it which holds air just to roll it around.
So far I have collected:
donor XJ650RJ
donor 900 motor
spare Turbo motor and spare boost sensor
FZ600 forks, wheel, fender and brakes
XJ700 rear wheel, header pipes, crank end caps and horns (yay more chrome)
mint condition RJ 9" headlight, speedo, electric tach, blinkers, tail light & fender and idiot light bezel
RJ gas tank, side panels, seat, tail piece
new gas cap.
And I dug out the shorter side stand I modified for my sidecar bike when I rode it solo.
The 16" wheels lower a 650 Seca about 1" in front and 3/4" in rear.

 

Hey Jeff, I'd like to ask you a couple of questions about the turbos, but your inbox is full............can you send me a note? info@xj4ever.com

Thanks,
Len

 

Opps...I cleared out my inbox.

I'm not sure of the max boost with the stock pump but Yamaha used a unique check valve/fuel pressure regulator arrangement that allows for higher boost with a lower pressure pump. Only recently, someone said the output pressure of the 99-02 R6 pump was only a few PSI but I can tell you, it works great all the way up to 21PSI.

So honestly, I don't know because I never put an actual gauge on the line but I have read that the stock pump is approx 14.2PSI which certainly should get you to some good boost numbers, especially if you take the time to make sure you have a good mating surfaces between the wastegate and the turbo to prevent leakage. That's one of the major "leak points".

jeff

 

Simmy, I meant to tell you that the mirrors from the stock fairing are VERY rare & hard to find so if your rubber boots are in good condition, please endeavor to save them. They would be worth the money or just to provide to someone that needs them some day.

Also, they say that 7 pounds of weight savings is equivalent to One BHP...so if you've cut 50lbs, you've just "added" 7BHP to your rear wheel! At least that's the thinking I used when shaving weight when we raced.

jeff

 

In car racing, they say that for every hundred pounds you shed, you gain a tenth in the quarter mile.

"Adding power makes you faster on the straights. Subtracting weight makes you faster everywhere."
Colin Chapman

 

Rubber boots are partially disintegrated so no use to a restoration project.