Simmy's Naked Turbo Project

Thanks, missed that pic!
The 900 is pretty roomy "down there", but equally, the airbox hole is massive too, and there is some clearance between the xj900s tyre and the swingarm to get the hot gasses up. Altenatively, the 900s swingarm could be persuaded to fit, and this has loads of room - where the monoshock lived.
So the oil checkvalve is needed to stop the hot oil seeping through the pump - both of them...

 

I just re-read the ride reviews from that Cycle Guide road test of the Turbo. This Larry Works guy seems to agree with me.

By all rights, the Seca Turbo should be up near the top of my list, since it’s based on one of my favorites, the XJ650 Seca. But it’s not. The Turbo Ls appealing in its own way, but any resemblance between the Turbo’s Rocket Boy looks and the smooth, balanced styling of the XJ ends at the fact that each bike has two wheels and four cylinders. Beyond that, how each 650 approaches street duty is as different as night and day. The normally aspirated Seca makes up speed in comers, while the Turbo—though not as top-heavy as the Honda CX Turbo — feels somewhat ponderous in the twisties. Not enough to keep you from going fast; just enough to make the straights seem more attractive. Call it plain pigheadedness, I won’t argue. But a real turbocharged Seca, one without the slab-sided plastic, would suit me to a T. —Larry Works

 

Awesome build! Well done throughout.

This is exactly what I wanted to do with my RJ (in the late 80’s!) I remember that article - agreed!





There’s a couple XJs locally on Craigslist now....might have to make some room with the FJs...

 

Thanks @fj1289
I hope to have a major update in another week or so.
Paint and graphics are done just need some clear-coat then I can put the body pieces back on.

 

The XJ650SecaLJ/RJ Hybrid is complete.
This project took me exactly 4 years from start to finish.
Actually its 99% finished, I need to refinish the handle bar switches, already bought new decals for this.










Here is the parts list in addition to a Seca Turbo:

FZ600
front wheel, axle, brake rotors, calipers, forks, fender

XJ650RJ
fork crowns, headlight and bracket, instruments (RJC electronic tach),mirrors, signals,
oil level switch & diode pack,
tank, seat, tail piece, side covers, tail light, rear fender, frame tabs, rear section of frame,
valve cover, oil pump covers, grab handles

XJ700N
rear wheel

XJ900RK
rear shocks

Aftermarket Stuff
Walbro GSL395 fuel pump
BoostValve boost controller
Check valve in oil scavenge line
Venhill SS brake lines
Bridgestone BT45's 110/90-16 & 130/90-16 (same size as Radian)
RaceTech fork springs
Barnett clutch springs
BDesigns.ca custom decals

 

Wow! Great paint job!!!

 

Extreme like!

 

Beautiful sleeper. The casual observer would never guess there's a turbo on it.

 

Exactly, I thought about tarting it up with Turbo badges but this is better to keep the deception.
It’s still a numbers matching Turbo, if I play with more displacement I will build another motor and leave the original alone. It sure is lighter.

 

You did say your color choice would be unique, and that it is.
Looks awesome!

Tony

 

Thanks for the compliments guys. I’ll be honest and admit I had planned to paint this silver in homage to the 2 bikes it’s founded on but with some green tint. At the painter’s I started looking through the paint samples and saw the metal flake greens and couldn’t resist.

 

That turned out great. I love the color you picked out. Just the right amount of metal flake in the paint. Not long till riding season. I hope to see it person soon.

 

Wow! That is pretty. No way any of the modern bikes look any better than that. The lines are just right, thank you Yamaha, and your colors and accents accentuate those lines perfectly. As smooth and nice as Norton Commandos. Well done Sir!
John

 

Lookin good Simmy!

 

Thanks John, though this is the 1st time I’ve heard smooth and Norton Commando in the same reference, LOL, they look good but riding those things is like putting a wet finger in a light socket.

 

Very nice. Understated, I like that.
Cheers, 50gary

 

I have the Seca horn bracket and the Turbo frame is tapped for the bolts but the weight of it is a rude joke. Eliminating that and removal of the centre stand saves a lot of weight. I’m sure by lowering the bike with 16” wheels the stand will scrape in corners.
It’s only there for the pics.
That 16 on the front really quickens up the handling and the 16 on the rear raises the revs by 250 RPMs which helps to bring on the boost sooner, this based on cruising at around 5 grand, boost hits hard at 6.

 

As for the riding I cannot comment but the lines are right and smoothly blend. Looking at more modern, and many others not so modern, they have too much styling and are trying too hard. These are "just right", what should be there, what needs to be there and just nice, not too light, not too heavy looking. And they just "fit" the rider when on them.
John

 

No doubt about it, the 650 seca has something nice about it and you've added to that, so hats off!

 

Thanks @Minimutly and @Fuller56 , I agree the 650 Seca (550 too) has stood the test of time the best of all the XJ's from the 80's.
How many Turbos would Yamaha have sold if they had built this instead of that fiberglass abomination?
Perhaps they should have offered both and let the market decide.
The idea of a turbocharged middleweight to compete with the litre bikes I think was lost on them.
The Turbos were just a fad to display their latest doo-dads.
In all honesty they are a crazy thing to ride.

 

And a special thanks to you Len, without XJ4ever this project would have been very difficult if not impossible.

 

Not to take anything away from your project, which looks fantastic, but my experience with the Turbo Seca is that the lower compression ratio and weight resulted in less "spirited" performance at low speeds (where the 550 and event 650 seca would win out). However, keeping the turbo spooled at highway speeds, power would be easily accessible. At those speeds, the fairing would help tremendously, even if the speedo ran out of room (in US at least).

As far as "sleepers" go, I do like the Seca looks a lot more than the Maxim. That paint job and decals really looks like it could have been a factory option, so hat off. I don't know if the market should have approved in the 1980s (insurance costs were a big factor as well), but it helps to have a stock Turbo Seca as a foil

Hopefully the front end swap helps a lot compared to the 650 Turbos (I never got mine to feel quite dialed in even after cartridge emulators). How's it handle?

 

I agree with this, back in the 80's when I rode a Seca Turbo my bike was always a match for anything from about 70-100 mph, including 1000 Interceptor & FJ1100. It seemed everyone I rode with had either of those. I next acquired a CBR1000 Hurricane and was able to pull ahead.
Being from Canada and riding too often in the cold I am an advocate of fairings but I can also appreciate the streamlining. I think the fastest unfaired bike I had was the MT-01 which was good for almost 150 mph, now that was fighting the wind.

This comment will have to wait as I've only ridden it about an hour. It's stable that's about all I can say for now. Really looking forward to riding some curvy roads.
Shedding all that weight has to improve the off-boost performance.

 

Curvy roads in Ontario? Tell me where they are.

 

Actually the Eastern part of Ontario has some amazing roads, but I get your point it’s all 3 hours away. Farm country where you and I are is all plotted in squares, boring.

 

I spent some time digging into my spare motors Easter weekend.
I tore down my spare 650 Turbo and the 900 I have.
I thought about making a 738 with the original motor in the bike now by simply installing 67 mm block & pistons.
Instead I've decided to keep my original 653 and build a bigger motor on the side.
I can take my time and still have a running bike to ride, maybe do the motor swap next winter.

The 650 Turbo was stored outside without the clutch cover so there was rust even inside the motor.
Even the oil pump drive chain had rust.
I didn't take any pics of the main bearings of the Turbo motor but there are deep scores in the main journals.
I've included some pics below of the 900 and there are a few which are questionable and should probably be replaced.
I've read here that the colour code of the bearing shells has not been correlated with a number?
Can someone fill me in on that? @chacal lists blue, black, brown, green, yellow so I assume this is 1-5?
I'm planning of course, to go through the plasti-gauge process and verify the tolerances.




here's a pic of the 900 oil pump next to the 650T.
Drive gears I believe are the same I think, 25T but the driven gear on the 900 is 30T and the Turbo is 23T.
Chains are obviously different length so I'll need a new one here as the Turbo one is rusty.
The shaft in the pic is from the Turbo, you can see the rust.


I verified the lower cases are pretty much identical, at least where the oil pumps mount.


I'm undecided on which cases to use, leaning towards the 900's just because the crankshaft was originally fitted to them.
I snapped 2 of 3 bolts removing the primary chain guide out of the Turbo cases so that would need to be cleaned up.
I will heat the 900 before I remove them. Turbo's guide was ready to break in 2 pieces.
The 900 cases have the boss for the oil feed to the turbocharger, just not drilled and tapped for the check valve.
I'm pointing to it with the screw driver. I think they all have this boss.

So the plan is to build the bottom end with the 900 cases and the 900 crank, 650T oil pump and oil pan.
I need to keep the physical dimensions of this motor the same since there is just enough room between the petcock and #1 carb hat.
The 900 pistons are shorter which helps my case, I believe the barrels are the same height.
I'll have a look at the rods, obviously need to use the 900's as the bolts go in from the top, otherwise the bolt heads would hit the cases with that 60.5 mm stroke.
I'm just curious if they are the same length.

The 900 has 9.6:1 CR which I will need to drop to about 8:1.
the 650 Turbo is 8.2:1 and the Kawasaki Turbo was only 7.8:1.
I'll be using 650T heads which I plan to dish out around the edges to match the larger bore.
Ideally I can get some forged pistons made and I'm going to ask for a quote from https://www.jepistons.com/
I believe they could make exactly what I need to drop the compression without adding extra base gaskets.
We'll see what that might cost.
I could go 1 mm larger to 68 mm and clean up the cylinders with a fresh bore job.
I just ordered a low mileage 650T cylinder head from eBay.

 

I used an XJ900 engine and installed forged pistons from JE pistons using stock compression. I used the XJ650 turbo oil pump and chain gear which allowed me to use the scavenging port of the 650 oil pan. You can definitely tap the port next to the oil filter, I did. I get 150 hp on a conservative tune. Your biggest limit on these bikes is the ridiculously low gear ratio, but you'll get to 125-130 mph really fast! My plan is to modify the middle gear. I found the right combo of gears to make it possible, but custom middle gear will be $.

 

Awesome info @skylrk62 are you saying you kept 9.6:1 CR?
If you don't mind, can you send me a PM and tell me what kind of money 4 custom pistons run?
Or just respond here, I don't care.

In my case I think the limiting factor will be the 30 mm carbs and the small valves.
My gear ratio is now even shorter with the 16" rear wheel on it, that's all ok as it brings on boost sooner!

 

I'm not 100% on the ratio being exactly, but within .1-.5 of the original. I believe it cost me $800-850 for a set of custom pistons (JE part no# WD-05702). This was in 2017, so it may be more or less now? I fuel injected my bike, so I can't help with your carb setup.

 

That is a great price for forged pistons.
I don't think it's worth the attempt to rebuild this motor then taking the chance of melting it down with the OEM 900 pistons.
Definitely the way to go.
My challenge will be to order the exact piston I need so I can put them straight in with the desired CR.
I'm planning to put it together first with the stock 900 pistons, modified combustion chamber in the head and see what the CR is.
Then I could tell JE how much deck height to take off the piston. Going up 1mm in the bore will throw these calcualtions off though.
I've even thought about ordering a 68.5 mm block and pistons from Germany.

I would expect your fuel injection and inter-cooler probably tolerates higher pressures than my basically stock set up will allow.
What bore size did you go with?

 

Stock bore, but had special modern improvements. I'll send you specs in a private message.

 

Now that's just not playing the game...
Anyway, for @Simmy , why use the 650 turbo head and carbs? Is it that the 900 ones bigger and will foul the petcock?
I know the carbs are bigger, but are they taller?

 

Hi @Minimutly I'm posting this from the Yamaha Turbo manual, I'm pretty much stuck with these carbs.
The 900 head is physically bigger as it carries another bearing support but the Turbo has special cams with less duration, and they won't fit in the 900 head.
I'm not certain if that is for performance with turbocharging or emissions with turbocharging. Suspecting the latter, I would think longer duration combined with pressurizing things might dump unburned fuel out the exhaust, this would not be good for emissions but also likely not good for the turbocharger, I'm just guessing.
On the Turbo forum there is mention of running an XJ700N exhaust cam retarded 3 degrees but I've not been able to learn anything more about this.
The exhaust valve has 16G (the Turbo model designation) embossed on the surface, I'm not sure if it got some exotic metal to withstand the additional heat or its simply a different size than the other 650/750 valve.
So pretty much resigned to the puny carbs and inlet/exhaust valves.

 

You could do the traditional suck-through design and use a single large carb?

 

Just remember, if you plan on going over 100 hp, you'll most likely need a custom lockout clutch.

 

Now we're getting carried away with things @skylrk62 , you're a bad influence.
When it comes down to it there is a reason I love riding thumpers, nothing better than the soothing pulse of simplicity.

 

Yes I can see why you wouldn't want to change the carbs. It may not be the end of the world, since the air going through them is denser, and more air just needs to be higher pressure to recover any losses. You could regrind the 900 cams - the turbo cams have less duration - probably to keep low speed torque up and use less fuel. The downside is you will lose performance on boost. I get the "keep it simple" thing too.

 

I didn't want to admit it but I had huge disappointment with this Turbo last weekend.
The previous weekend I changed the oil and restarted the bike and warmed it up, checked the level, everything was finally finished.
It was cold and wet so I shut it off, put the cover on and waited for a warm day.
So a warm day came last week and I decided to go for a good ride. I made it 5 doors down the street and it quit.
Walked it back home totally pissed.
It would start just barely and run on a couple cylinders, #4 was cold.
In my mind I'm thinking please don't be plugged idle circuits in any of the carbs.
It just wasn't getting enough gas to rev up.
Tonight I took the tank off and hooked up my aux tank with transparent gas lines so I could see what is going on.
This bike has 2 gas lines to hook up, one feeds the fuel pump and the other one returns excess fuel pressure from the regulator.
The lines were empty of gas so I followed the trick from @ManBot13 - put the sidestand down, put it in gear, turn it on and hold the starter button.
When you do this nothing runs except the fuel pump. I had to run the pump like this for several long minutes until I go all the lines full of gas.
I thought maybe the pump was just cavitated. Once I got enough gas the bike started up and I warmed it up and had it idling but I could tell its not right.
The new Walbro fuel pump I bought is just not pushing the fuel anymore, it was flowing a ton of fuel through the bike, now there's barely a trickle from the return line.
This has to be it. I'm going to test it on the bench just to be sure but this sure feels like a win to me!
I ordered this on-line a year ago from Summit Racing, I'm hesitant to get the same thing again but it fits nice and I know they perform when they do work.
Oh yah my new Turbo head arrived today, looks to be in nice shape, all exhaust studs accounted and clean threads on the intake side.
The cam caps came with it to, most of the heads on eBay are missing them. No cams though, I think the cams from the swamp rat motor are ok.

 

I got thinking about my fuel pump a little more.
The fuel system starts at the petcock and the Turbo has a positive shut when in the off position.
From there it goes through a metallic style fuel filter from Chacal straight into the fuel pump.
I eliminated the guts from the fuel check valve just before the carbs so I shut the fuel off when stopped.
Needless to say, in the 100 kms I've ridden it I already forgot to switch the fuel back on and had the motor running a short while like that.
So the question is, do you think I damaged this fuel pump by running it with the gas shut off?
There is no difference in the system from OEM except different pump. The Yamaha pump would tolerate this, will the Walbro?

 

this might explain things better. When the fuel is shut off the pump will see hydraulic lock, will it stop spinning or pull its seals apart? The pump is good for 130 LPH, mine is delivering probably .5 LPH.

 

I bench tested the pump with the filter in place, slight trickle of gas coming through.
I took the filter out of the hose and the pump just gushes.
Seems this little fuel filter was causing the issue, strange because it was allowing strong flow when I first assembled everything.
The petcock has a filter but I'd like something better in front of the pump.
I'll see what Canadian tire has. I'm sure glad I don't need a replacement pump.
And to the safety cops, yes this was stupid - potential sparks next to open fuel containers.

 

I wouldn't rule out the pump just on this alone. Bad pump will still move fluid when there is little/no restriction. You have the means to test PSI on the output side?

 

Yes I have a gauge. Is there any harm dead-ending it for a second?

 

I can't say for 100% certainty but I wouldn't think it would cause harm if done briefly for testing. Pump is already suspect anyway i.e. a known good filter should not reduce a pumps output like that. I assume the filter is not clogged?

 

It is somewhat common, at least in my experience in the automotive repair industry, to check a fuel pumps dead head pressure. Obviously you don't want to hold it there for very long but just check to see the maximum pressure said pump is capable of

 

@jayrodoh @Chitwood thanks guys, I'm going to see what the pump is capable of when I get home today.
Back on Page 19 of this build I did a pressure test and had the pump reaching 22 psi.
I agree with Jay, questioning the pump now, something has changed as it was pushing fuel through that filter before.
When I first had it running from my auxiliary Motion Pro fuel tank last fall I had the return line stuck into another gas can on the floor.
I had to change this to discharge back into the Motion Pro tank, otherwise it would empty the Motion Pro after 2 minutes of idling it flowed so much gas.
The pump is supposed to flow 130 LPH @ 15 psi so it should flush a full Seca gas tank through in about 10 minutes.
Very frustrating, when reviving an old machine you don't need problems from the new stuff bolted on.

 

If it pumps 150 l/s, and your not using that flow, where does it go? I assume a regulator and waste return?
How clean was your tank?
Normally pumps have strainers in front of them, not filters. If the pump is pushing into injectors the filter is before the injectors, after the return.

 

excess fuel just gets dumped back to the tank, see the schematic on page 22.
I dead-ended the fuel pump on the bench, see pic below, it actually decayed a bit, it was 60 psi


I took the filter out of the circuit and I'm back on the road. I went for a 30 km stretch and got into the boost a few times, ran without incident.

except I have a persistent oil drip from the oil connection at the turbo.
I tightened it up but that didn't fix it. I'll have to take it apart and see if the gasket is set right.

 

I hate oil leaks. And y'all know why.

 

Glad you figured it out, crazy that the filer is causing issues. Is it super fine mesh? Maybe it’s not rated for pressurized applications and is putting strain on the pump.