few questions

ok i got a 1981 xj 650 engine with no carbs, wiring and stuff like that.

i got the bike with just frame and engine now i wanna use it for a project im starting.

ok the question is how much power can be added from port and polishing the intake and exhaust? i ported them and i took off a lot of excess material and gasket matched them.

next is what carbs can i use? do they have to be for a 650 (i got YICS and i know i need carbs for the YICS) or can i use any carbs?


also i need wiring harness and can i use any or does it have to be a xj 650 also?

i ask these questions cuz im finding a ton of parts i could use but none happen to be for a xj650.

i had someone email me saying they have a xj 650 parts bike close to me but they havent got back to me and im in a hurry to fire this thing up so any help would be great.


thanks guys

 

I'm not as much of an expert on this as I would like, but I believe you can use the carbs from some other XJs. In partiuclar 750s. I believe they are the same. I don't think YICS makes any difference in the carbs themselves. It's a passage in the heads and just affects how you synch them.

There are some that I'm pretty sure you can't use. 650 Turbo carbs are pressurized and XJ700 carbs are also different. Hitachis I think.

I'm sure we'd all love to hear about your project.

Greg

 

well then in the case of hearing about the project.

the engine isnt going back into a bike but i plan on making a mini rail, for those of you who dont know what it is.

a mini rail is a smaller size of a sand cart but a smaller scale like a go cart with a lot of ground clearence.

when i start the project its gonna be setup like a go cart with about half a foot of ground clearence and independant suspention all the way around using a arm setup.

my plans is to use a 84 subaru independant suspention off the back of the subaru which is a diff and cv setup. then just basicly im just gonna use part of a drive shaft to weld in the shaft drive off the XJ 650 engine.

it dont need to be percise since its going on a offroad mini rail.


once i get everything dont im gonna extend the a arms and cv shafts so i can get more ground clearence and probley use 21 inch coil over shocks.

ive been doing my homework on the project and i got the basic idea for a frame and all. i just need to start gathering steel tube and the like for the frame.

when the idea first came to me was when a friend told me he had a older yamaha frame and engine sitting at his house and ive been wanting to do a mini rail for a period of time now.

now i wanna make sure its clear the bike when i got it was in no condition to restore the frame had been tweaked and almost nothing left on the frame so this was a ideal project engine.

as i hear the 81 XJ650 is good for 71 hp stock and im unsure of the tq the engine makes. with the accel coil packs and my hand porting the head im sure when i first get it on the frame it will make good power but im not gonna stop there. i basicly just wanna get it done before i start making it better.

i plan to use a turbo possibly and or 900 barrels and head. my goal is to make around 130 hp on the mini rail and have good ground clearence.

later on down the road i plan to make a full size sand rail with a taurus SHO engine like a member of another forum im on has made.

for those of you who dont know about the SHO ford had yamaha make a engine for them in a car that was suposed to compete with corvette at the time called the GN-34 but it ended up in the taurus. the SHO is a 3.0 or 3.2 liter v6 and the 3.0 made 220 hp and 200 ft lbs and the 3.2 made 220 hp and 220 ft lbs of tq. there has been a lot of things said about the SHO engine like when yamaha made the engine it was oringionally making 300+ hp and ford de-tuned the engine because they didnt want it to compete with their fleet car mustang. funny thing is the SHO in stock forum can beat mustangs up to the 05 GT's but with some mods the engine can easily beat 05 GT's

in my opinion yamaha makes a excellent engine and ive been a fan of yamaha for years, hell the SHO takes to boost better then any other car engine ive seen. when yamaha made their own car, 3.5 liter making 400 hp and revs to 10k rpms which was i think 93' i was shocked.

all the yamaha engines ive seen including the SHO seem like you have to want to kill them for them to die.

if anyone wants i will post pictures of my progress as i get some. right now i got the XJ650 tore down and im going threw checking it out to make sure its gonna be in good running order. the engine got 30k miles on it so its had a good run before it was wrecked in 91.

if anyone wouldnt mind i would be open for susgestions including good mods for power and such.

thats about it for now.

good day all

 

I did some digging around on XJ 650 carbs when I was looking for a donor. Yamaha lists a different part number for the pre-82 (pre-YICS) Maxims.

 

Commenting on the head porting, you can polish to complete shine the exhaust ports to the pipes, if you want, that will help extract the gases as best as possible.

But Porting the intakes, you can't do the same, you really have to know what your doing, or more then likely you will take away from the power of the engine. Head porting can't be explained, only trained in person, but the safest thing you can do to the intake ports is light deburring and little clean up work will help without the risk of hurting the power it's already making.

An expertly ported head can turn a 650 into 750's area power.

Good luck with your little sand Rail, I always wanted to do that, or build a mini Indy Car style go cart with a 1000cc or bigger engine.

 

thanks everyone for the comments.

for the head porting reply.

i understand what your saying and i have a lot of experience with port and polish on all forms of heads big and little.
me and my dremel go a long way

when i port i do a gasket match job and remove the excess factory casting (burrs) and all the way down i remove the same material.

when i was inside the valve ports i really didnt like the way yamaha has the valves set in but it was probley done to keep the heads lite as possible.


i do have a question to ask tho. tonight i was pulling the wiring harness off the frame and chopping the frame up for scrap metal and i know i dont have any sensors or whatever on the wiring harness, i have the oil sensor on the engine, alt and starter cables but no sort of sensors for the 20 some plugs i seen.

was basicly wondering what sensors a XJ650 made in 11/81 might have had?

 

Oil level, neutral light are the only ones I know of. There are many other connections dealing with the ignition and so on, might be those odd connectors you've seen. If you could perhaps post pictures of which connectors your curious about, we could help you identify each fairly easily. May I suggest you get the Haynes manual, it covers your year and model with a very good diagram. Best place to start in my humble opinion.

 

ill have to grab some pictures... i thought there would at least be a voltage regulator tho.. well like i said ill grab some pictures and get them uploaded tonight

 

both front wiring harness






middle wiring harness





and both rear wiring harness

ok now i know most of the wires like lights, coil packs , gauges, and the ones that go to the engine but there are some on there that really got me confused.

i imagine getting a haynes or something would be the best bet but as of right now i think the olny time i would use a haynes would be for this since this isnt gonna be a bike anymore and woulndt be using all the wiring.

anyways thanks guys for anything you can tell me

 

i should also ask since i am forgetting if there is a way to convert a shaft drive to a chain drive? would make this easier.

 

no reply ?

 

You can't bring the engine back to the drawing board. There's a small output shaft and a U-joint for shaft drive. It's a shaft drive engine.

Asking to convert the Shaft Drive to Chain Drive is like asking me to Convert a Carnival Cruise Ship to a Submarine ....

Sure ... we can do! No problem. When do you need it??? I got my whole crew working on it right now. Some of the parts we need are back-ordered.
Oh, yea ... one other thing. It's going to cost a little more than we wrote-down on the estimate. Can you leave some cash on account for the bribes we'll need to pay-off the inspectors from immigrations???

 

Two great links to XJ electrical knowledge, the second one actually has wiring diagrams.

http://www.geocities.com/MotorCity/Speedway/7795/

http://members.tripod.com/dave_jack/

I'm not aware of any conversions to a chain drive! Ditto as RickCoMatic posted.

 

thanks for the reply... so it sounds to me like its gonna end up using a subaru rear end haha

 

How about I send you a photo copy of the Haynes electrical schematic? PM your address and I'll get one fired off.
I also hate to be the bearer of bad news but could you get photos of the opposite side of the connectors? Wire color codes are the easiest way to determine the true identity of the connector and wires. Thanks.

 

If what your creating isn't a motorcycle; then why do you need a motorcycle wiring harness??

The bulk of the wiring is all run-back stuff to the fuse panel area or wiring associated with lighting, instrumentation, handle bar controls and several safety circuits.

It would be far easier to build the creation and wire it from scratch.

Then, you'd only need a couple of ignition related connectors which could easily be left-off the project ... replaced with soldered connections and heat shrinked.