Weird issue

[Mekanix]

Trying to find some from around here. For some reason it cost's 30$ shipping from the states to Canada for a single jet

Trying www.[B]winnerscirclecanada[/B].com/
Seems to have everything cheap enough and should only take a day or so shipping.

 

[Sportster-2001-951C-Stock]

$30, oh man, tell me that's not normal. Sheesh, I buy stuff from England and the delivery is free. I've bought stuff from www.jamestowndistributors.com before, I think he carries Mikuni and Winderosa, not sure what else.

Call someone and tell them put it in an envelope, how does that cost $30? There's some other places I bought Mikuni stuff from as well, cycle something place had springs listed on ebay.

I'm pretty sure my jets weren't authentic Mikuni but I didn't care, looked exactly the same except for the larger orifice.

 

[Mekanix]

2.63$ a spring 5$ a jet from winners with 5$ shipping for everything I'd need.

 

[Sportster-2001-951C-Stock]

There ya go, that's reasonable pricing.

 

[Mekanix]

Easy enough,

I have two 80's two 95's two 67.5 pilots and two 65 pilots and a fuel selector on the way. Should be here Friday

 

[Mekanix]

Did some more troubleshooting tonight

Removed red wire. No change in running while in or out of the water and voltage is nice and solid with no ac ripple at all. ( noticed that if unplugged and you measure voltage coming out of the Reg that it put's out lots of AC and DC voltage, like 30 of each but with 0 current. As in it wouldn't even light up a light bulb. Must need the battery to activate it)

Measured the resistance going across the ignitor pickup, (in spec)

Replaced the MPEM, harness Whole daam grey and black boxes No change

Took the water regulator apart, Well its looks good and is air tight in any way I could test it. I didn't notice anything that it did different after reinstalling it.

Checked compression. Odd its actually at 165 each hole. Started at 158 just after rebuild but thinking maybe just a bit of oil in there is helping out.

Could this be carb or mechanical?

If mechanical could it be:

Rotary valve seal
Crank seal's
Mag to crank case gasket
Rotary valve seal
Carb gaskets

 

[Sportster-2001-951C-Stock]

Easy enough,

I have two 80's two 95's two 67.5 pilots and two 65 pilots and a fuel selector on the way. Should be here Friday

Good job. I still vote for a carb that's too fat. For whatever reason.

 

[Mike99]

Back in post 4 you mentioned that your rotary timing was running advanced. You stated you could not set it correctly. If i remember correctly, the valve needs to be flipped over, and then you can set it up correctly. Others who actually have a rotary valve should chime in here... I have reeds.

Seems to me the valve timing is critical, and could cause all kinds of funky running issues.

Mike

 

[Davidgsx]

Yep, put mine in upside down once, no worky!!!


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[Mekanix]

Back in post 4 you mentioned that your rotary timing was running advanced. You stated you could not set it correctly. If i remember correctly, the valve needs to be flipped over, and then you can set it up correctly. Others who actually have a rotary valve should chime in here... I have reeds.

Seems to me the valve timing is critical, and could cause all kinds of funky running issues.

Mike

Worked fine with that the way it is for a while. Also. Its an SBT valve which is symetrical. Can't flip it over. Its the same on both side :-(

This is a new issue that came on gradually.

Going to the lake to try some things.

 

[suke]

Worked fine with that the way it is for a while. Also. Its an SBT valve which is symetrical. Can't flip it over. Its the same on both side :-(

This is a new issue that came on gradually.

Going to the lake to try some things.

Interested to hear what you find out as I have the same issue. Pretty much identical. I gave up on trying to solution a fix as it'd likely send me down a rabbit hole of me throwing parts at it. I'm terrible at troubleshooting stuff. LOL!

 

[Sportster-2001-951C-Stock]

Yep, put mine in upside down once, no worky!!!


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Nearly as much fun as a cam cut with too much retard.

"This is a new issue that came on gradually."

Always best that way, like a slow grinding away of a critical component buried deep in the crankcase.

 

[Mekanix]

News.

Its the mag carb somehow.


Just playing around I had both Ls screws all the way in and started at very low idle out of the water to see how the low end is working. I can turn the pto carb Ls screw out 1-2 turns and not much diff in the way the engine is running. It just quiets down a bit.

But on the mag, anything more than 1/8th drops the idle way down and starts 4 stroking like crazy.

Wth!! Do I have to set the pop off higher on this carb vs the pto side? Or does it sound like a leaky needle and seat ?
Maybe the return line on this carb is clogged or the one line between the two??



What should I try?


I'm pulling the carbs off again right now...

 

[Mekanix]

Could it just be the mag cylinder needle is being held open by the diaphram?
And all the pump pressure is being routed straight through the pilot just on that cylinder?

or Maybe the needle is not able to close fully with the cover on the diaphram ?

 

[Davidgsx]

Nearly as much fun as a cam cut with too much retard.

"This is a new issue that came on gradually."

Always best that way, like a slow grinding away of a critical component buried deep in the crankcase.

I just spit my drink out laughing, thank you


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[Sportster-2001-951C-Stock]

Could it just be the mag cylinder needle is being held open by the diaphram?
And all the pump pressure is being routed straight through the pilot just on that cylinder?

or Maybe the needle is not able to close fully with the cover on the diaphram ?

I think you've got it narrowed down, the fuel seems to suddenly gush like the metering needle isn't seating.

While your in there make sure the fuel return orifice in that carb isn't plugged, assuming both carbs have separate fuel return orifices.

 

[Sportster-2001-951C-Stock]

Consider taking some lapping compound to the needle seat or swapping the seat, there may be a bur on the seat causing the needle not to seal?

 

[Sportster-2001-951C-Stock]

I just spit my drink out laughing, thank you


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Or, you just finished installing a new motor in a mercruiser and the carb idle mixture is set a little lean, so it wants to diesel (thus as a result rotate backward momentarily a rotation or two) when the ignition is shut off but before you get around to dialing that in it sucks a cup of water into one cylinder and hydrolocks and you didn't know until you hit the starter and three teeth are promptly stripped off the flywheel.

So now, that motor has to come right back out, just b/c the idle mixture was a tad too lean.....

 

[soccerdad]

In my head for troubleshooting, I look at what has changed. So your compression has gone up??? Could you have a blown crank seal? Either letting air in, oil in or ??? You obviously are swapping parts (another great troubleshooting system). Did you try swapping carbs? I just don't see having to rejet if it was running well with the original jetting. My vote is something is plugged, or leaking.

 

[Sportster-2001-951C-Stock]

I just don't see having to rejet if it was running well with the original jetting. My vote is something is plugged, or leaking.

Right, I don't think we're talking about rejetting anymore since he discovered one carb seems to be gushing fuel. Although, it was a little on the rich side before this recent problem occurred and arguably might benefit from a smaller jet (don't know till you try it).

2-strokes should normally run a little rich (occasional 4-stroking in some spots) but pig rich can suck too. In my case it was worth the effort to make a jet change.

 

[Sportster-2001-951C-Stock]

One way to judge a "normal" idle speed throttle butterfly position (often a function of idle mixture) is by observing how much of the transition ports are covered or exposed to the vacuum side of the butterfly.

On a Rochester carb for instance, the transition is slotted, not two or three round holes, and the correct amount of transition port exposed to vacuum should form a square shape, ideally.

In this photo, the amount of transition port exposed is slightly more than normal:

 

[Mekanix]

Jets are on the way and would be fun to play with.

For now ive swapped the mag and pto springs.

Replaced the mag needle and seat, arm, stripped everything and cleaned the body.

Thought about swapping carb body's. But I'm waiting till tomorrow to see if my parts get here. Then ill see what new spings do.

Ive tried setting pop off and so far 38.75 mag and 38.25 pto I s what I got.
Also tried poping them off connected together and tried to set then to hiss at the same time.

 

[1983]

Take a mirror and good flashlight, then look down each carbs throat at idle with airbox all the way off. See if fuel is dribbling into throat at idle, which means needle and seat are leaking.

Rob

 

[Mekanix]

In my head for troubleshooting, I look at what has changed. So your compression has gone up??? Could you have a blown crank seal? Either letting air in, oil in or ??? You obviously are swapping parts (another great troubleshooting system). Did you try swapping carbs? I just don't see having to rejet if it was running well with the original jetting. My vote is something is plugged, or leaking.

Compression went up from probably a good break in. or just a bit of extra oil from the last time I fogged it. But yeah 165 is what I get now. But thats with the throttle wide open and the raves down.
Then again I did change the head this time because the last one was pitted. Maybe its modified ?

Don't have a set of carbs to swap, Working on that though.

Rejeting might happen later on if this issue gets fixed.

 

[Mekanix]

Take a mirror and good flashlight, then look down each carbs throat at idle with airbox all the way off. See if fuel is dribbling into throat at idle, which means needle and seat are leaking.

Rob

Did that, Saw nothing At least nothing commng out of the main jet which is where I would expect to see that.