Exciter SX Piston

My buddy had a Phazer that was beserk , it had that SX cut. He had it ported/piped/clutched before he even picked it up, then he took it apart, and went even more radical. It had everything on it you could buy. Thing idled like a chainsaw on steroids! The rings and pistons only lasted max, 600 miles. Had to carry spares on weekend trips to my house at Houghton Lake.

He always had at least 2 sleds with him, sometimes 3. Lots of fun though!
 
toydoc said:
When you do a round intake cut (Phazer SX piston) on a Exciter,
the intake window is open to long and it will push your fresh charge of air / fuel back out the intake and not into the top of cyl.

Most piston mods from a reed motor to a piston port motor are not the same.
With a reed intake, it stops back flow with the reed.
Piston port stops it with piston intake skirt.
Thats why you do a flat cut, and not much of one
Click to expand...
x2 Well said !
 
No, back yard blows, somtimes I make out. Wife still works at Ford.

Going up to Houghton Lake tomorrow to pay for a beautiful catheral ceiling our builder did in knottyy pine. To tall for me. I thought we were done w/him after he built the gambriel garage this summer. Guess things aren't that bad...

Those guys are mostly retired, Fedokovitz is still there. John Lavera in the model lab turned the last set of Wisecos for me 10+ years ago.
 
dsc577 said:
I'm using Wiseco pistons in my Exciter and there is no cutout.
Click to expand...
x2
I have mounted Wiseco pistons in a few Exciter engines and there has not been any cutout in them.
 
Last edited:
I wanted to revisit this. I've been fighting a hanging idle with this sled. Granted I can't get out and give it a good run, but on the stand it is being a real pain.

It was mentioned that the port stays open too long pushing the intake charge back out. I'm finding traces of fuel even in the airbox. So, I'm suspecting these pistons might be the culprit.

I'm up to a #50 pilot with the pilot screw completely closed. This is the best I've gotten it so far. It doesn't seem to need the choke though. Although, the choke will get it to idle down to normal.

I'm wondering if I'm going the wrong way here and it has too much excess fuel to burn or should I throw a #60 at it to see what happens. Thoughts on this? I'm sure I will figure it out eventually, but wanted to see if anyone might know.
thanks
 
1. Clean up among all the funky fuel and oil lines that Yamaha put on these sleds.
Delete the whole Oil Injection system including the oil pump.
Run 1:40 premix instead.

2. Completly disconnect the warming system to the carburettors.

3. Disconnect the T.O.R.S.-system from the carburettors.
remove the powerjet function and parts from the carburretors.

4. Jetting: Updated jetting for the Yamaha Exciter-I ( 87 / 88 / 89 / 90 )
Pilot jet : 40
Main jet : 320
Air screw : 1.0 turn out ( +-½ Turn )
Slide : 3.0
Needle jet : 480 P-6
Needle : 6FL68 ( Yamaha part # 239-14116-68-00 )
( And of course all the things regarding the "Power Jet" system is deleted ! )

5. Set the engine idle speed to 1600-1800 Rpm

:2strokes:
 
Thanks Lasse,
I was thinking of trying a 40. Worth a shot anyway.

Lasse said:
1. Clean up among all the funky fuel and oil lines that Yamaha put on these sleds.
Delete the whole Oil Injection system including the oil pump.
Run 1:40 premix instead.

2. Completly disconnect the warming system to the carburettors.

3. Disconnect the T.O.R.S.-system from the carburettors.
remove the powerjet function and parts from the carburretors.

4. Jetting: Updated jetting for the Yamaha Exciter-I ( 87 / 88 / 89 / 90 )
Pilot jet : 40
Main jet : 320
Air screw : 1.0 turn out ( +-½ Turn )
Slide : 3.0
Needle jet : 480 P-6
Needle : 6FL68 ( Yamaha part # 239-14116-68-00 )
( And of course all the things regarding the "Power Jet" system is deleted ! )

5. Set the engine idle speed to 1600-1800 Rpm

:2strokes:
Click to expand...
 
You'll never get a piston port engine to run right with a reed valve cut like in that pic.
With that cut the intake is open more than it is closed. The piston can't stuff the cylinder properly and much of the charge will be pushed back at the carb. Crankcase pressure will be less than with a straight cut so again, full charge can't be delivered to the cylinder. When you close the throttle that unused charge is still there and the engine will use it up before settling in to idle. Not to mention it is still having the same issues with charge intake and delivery while the throttle is closed. Trying to jet that thing will be a never ending nightmare.

Get those pistons out of there.

BTW, I completly dissagree with Lasse on the oil/fuel lines, oil injection and elimination of TORS.

Elimination of the PJ system does make things simpler and Yamaha did it on the late Exciters althogh I've never had issues with the PJ system in a trail application if you run with the stock airbox.

opsled
 
Thank you opsled. That was the kind of insight I was hoping for. I appreciate you sharing that knowledge. I was hoping to get it a little closer than it is. I am trying to sell the sled and it really does run good, but the run-on is annoying. I hate to stick money into new pistons if I can avoid it.

opsled said:
You'll never get a piston port engine to run right with a reed valve cut like in that pic.
With that cut the intake is open more than it is closed. The piston can't stuff the cylinder properly and much of the charge will be pushed back at the carb. Crankcase pressure will be less than with a straight cut so again, full charge can't be delivered to the cylinder. When you close the throttle that unused charge is still there and the engine will use it up before settling in to idle. Not to mention it is still having the same issues with charge intake and delivery while the throttle is closed. Trying to jet that thing will be a never ending nightmare.

Get those pistons out of there.

BTW, I completly dissagree with Lasse on the oil/fuel lines, oil injection and elimination of TORS.

Elimination of the PJ system does make things simpler and Yamaha did it on the late Exciters althogh I've never had issues with the PJ system in a trail application if you run with the stock airbox.

opsled
Click to expand...
 
toydoc said:
When you do a round intake cut (Phazer SX piston) on a Exciter,
the intake window is open to long and it will push your fresh charge of air / fuel back out the intake and not into the top of cyl.

Most piston mods from a reed motor to a piston port motor are not the same.
With a reed intake, it stops back flow with the reed.
Piston port stops it with piston intake skirt.
Thats why you do a flat cut, and not much of one
Click to expand...
opsled said:
You'll never get a piston port engine to run right with a reed valve cut like in that pic.
With that cut the intake is open more than it is closed.
The piston can't stuff the cylinder properly and much of the charge will be pushed back at the carb.
Crankcase pressure will be less than with a straight cut so again, full charge can't be delivered to the cylinder.
When you close the throttle that unused charge is still there and the engine will use it up before settling in to idle.
Not to mention it is still having the same issues with charge intake and delivery while the throttle is closed.
Trying to jet that thing will be a never ending nightmare.
Get those pistons out of there.
Click to expand...
I totally agree.

:2strokes:
 
OPSLED while i know you know your stuff ...........i must say that the TORS on all exciters is the first thing i remove if it has not been done yet on eveyone that come threw the shop ............me owning one of these sleds and haveing every problem under the sun with it i got to know them quite well the oil injection is one to be desired i agree mine was direct injected to the intake wil others i have own where stock with no problems ............power jets on the yamahas Get ride of then the cause too many burn downs stock box or not ........i still have them on my 86 vmax but that sled i am not worried about .........

when i get one in the shop i check for all the updates and TSB's and then do my own thing ..........i will never cut a air box like yamaha said ..........but one thing is for sure everyone of my customers are much happier with the sleds when i am done with them ............speeking of EX 570's just got a virgin 87 in to be worked on with only 1500 miles on it ........this thing is pretty .............

the piston cut pictured ..........junk i do not know how that sled even runs stock pistons with 2mm off the intake side skirt is all you need for a trail rider ............

on a side note i hate Wiseco pistons ..........but they work very well in the Exciters
 
I will agree Mike that the TORS switches on the roundslide carbs like the Exciter's and Vmax 540's used were very problematic. I can understand just eliminating the system on those because of that. Carb switches for them are very expensive and there are two in the system to give trouble. The button type single switch system used on all butterfly and racked carb applications is a different story. Simple to adjust and reltively trouble free. Probably 1 reason you never saw a roundslide on a Yamaha after the Exciter.

A good safety item for a trail sled in my opinion.

I just don't like blanket statements about dumping TORS and/or oil injection without a reason why. Most of the TORS issues I've seen were from missadjustments made by the operator. A missadjusted throttle system can lead to a sled that takes off without a it's rider. A functioning TORS will stop that from happening.

As for oil injection, I have no idea why some want to junk or modify the best system on the market. Must be like TORS. Lack of understanding how it works. That and those like Bender and Dynotech trashing the system back in the early 80's for flawed reasoning. They were/are wrong... Yamaha had it right and never changed thier system design. It was a ghost problem that was never there.

opsled
 
Well, between you guys and the conversation we were having on FB I tore it down last night. Some joker put Wiseco pistons from an SRV in there. :o| I'm sure they thought they were doing something good. Anyway, i want to thank everyone again. Glad I finally just bit the bullet so to speak.

TORS, I do think it is a good idea. I've had it on both Phazers and now Exciters. Can't say I've ever experienced a problem. It actually did it's job once when the carbs on my phazer started to freeze up. That being said it wasn't uncommon for these to get unplugged and disconnected. I think the earlier versions probably experienced some issues.

Oil injection, I like to keep it for the basic reason that mixing fuel on a sled is a PITA. The exciter oil pump does require adjustment at the pump itself. They will fall out of spec after some time. Usually just a simple shim adjustment. Again, that's just my preference.

Now whether you stick with the factory injection or go to direct injection it just has to be what puts your mind at ease. Both ways work and if it works for you keep doing it. After endless research myself I'm convinced the autolube does vary from 100:1 to at least 50:1 so in theory direct injection makes sense. That being said I have never heard of a failure caused by the stock system either. Just a matter of personal preference I guess.
 
yes you are right the oil injection mod is up to the owner ............i do not care either way that was the way i got mine ..........but look at all the yamis they all had this set up so it must work .........11,500 miles on the old 2000 vmax 700 with that system and never a problem still runs like new ..........well 1500 miles since i had it apart to freshen the motor but then again it really did not need it just did it because i had it apart ...............plus i think it helps having some oil in the carbs with the gas during storage keeps the moisture under control ..........
 
I guess you anti THORS guys have never seen a sled take off on it's own. Buddy disconnected his, the throttle stuck, and away she went! Hit a bunch of stuff. Some idiot goes over to see if it'll start, and away she goes again headed for a house, it rams a stack of docks on it's final ride to the scrap heap. If you don't think they're functioning right just plug the wires together to verify.

Direct injection, I just like it. Lets me have a more constant rpm to delivery ratio, look at what other manufacturers use. Don't tell me about their reliability problems, Yamaha does have superior motors. Every time I pull my carbs there is oil present in the inlet tract. To each, his own.

But, as ususal, I can be, and often am, wrong. I have proven this time, and time again.

Remember, I always want the best for everyone! I got nothin but LOVE.

Good Luck, John
 
not really anti TORS it is there for a reason ..........for all my personal sleds that are disconnected i have a tether on those machines my phazer still works and so does my 700 and they both have tethers too which i wear all the time
 
DI oil injection works. No doubt.

Problem is that people think DI changes the fuel/ratio in comparison to the stock system.

It doesn't......

Hook em up how ya want but I have more reasons for leaving it stock that are valid than reasons to change it. Yamaha knows them too. That's why they use what they use.

opsled
 
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