Coffman Pipe and Jetting

[Fathom]

I've got a 650 SN with a Coffman pipe. Can someone tell me what the jetting specs should be or lead me to a link? The Coffman site seems to be kaput.

 

[Mouthfulloflake]

everything you need is here young Jedi

 

[Fathom]

Thanks Mouth.:biggrin:

 

[Mouthfulloflake]

just in case you didnt find this one..
http://www.x-h2o.com/threads/2940

 

[Fathom]

I had found all those posts during my search before asking:biggthumpup: Nevertheless, I'm still seeing a pretty wide range. I know it's called tuning.:smile:
125 and 138 Main
115 and 120 pilot
2.0 n/s
and a 115g spring
Did you figure out if yours was running fat ot not? I could split the difference.
Can you tell me where your adjustment screws are? I'm trying to troubleshoot a rich running 650.

 

[Mouthfulloflake]

Mine had 138 main, 120 pilot.

msd enhancer, mariner head ( 185 psi).

ran 87-93 octane with NO problems, made GREAT power.

no idea wherethe screws were though sorry.

Im also at 1400 feet above sea level.

those were very safe jets I think, it could have been leaner, but it pulled to 7200 RPM with an old supercamber impeller.

it made REALLY good power for a 650. so I never tried to tune it any better.

I had found all those posts during my search before asking:biggthumpup: Nevertheless, I'm still seeing a pretty wide range. I know it's called tuning.:smile:
125 and 138 Main
115 and 120 pilot
2.0 n/s
and a 115g spring
Did you figure out if yours was running fat ot not? I could split the difference.
Can you tell me where your adjustment screws are? I'm trying to troubleshoot a rich running 650.

 

[jetskiking]

Try the 125 main and the 115 pilot with that needle and seat and spring. Thats the combo I ran on a stock 650 motor and that pipe. Thats also what coffmans recomended. It ran great:biggthumpup:

 

[Fathom]

Thank you both!

 

[Water Worx]

There is no such jet as a 138,either 137.5 or 140.

 

[Mouthfulloflake]

There is no such jet as a 138,either 137.5 or 140.

really?

I guess my eyes suck then...
maybe a 133 then?

hmmm, now I will have to find it and see, im curious.

 

[Fathom]

Do tell.

 

[Fathom]

Now that I have had the chance to verify my jets, can someone tell me what the pop-off pressure should be with this setup? We verified it to be around 45 psi. Seems a little high but need confirmation.

 

[Water Worx]

really?

I guess my eyes suck then...
maybe a 133 then?

hmmm, now I will have to find it and see, im curious.

Yeah I cant read the # on the jets anymore,(getting old sucks) but I do know that Mikuni jets go in 2.5 steps.:biggrin:

100,102.5,105,107.5,110,112.5,115 etc etc

 

[beachedflunkey]

Now that I have had the chance to verify my jets, can someone tell me what the pop-off pressure should be with this setup? We verified it to be around 45 psi. Seems a little high but need confirmation.

What were your jets again? You might want to keep that popoff and go back to am oem fa.

 

[Fathom]

I think it was 115 pilot and 125 main. I wrote it down on a bar napkin somewhere. Don't you remember? I do want to use the OEM F/A. Derm said he may have one but we haven't got to that point yet.