what jets in my 670??

[tys670]

i have a 97 formula z with a 670 motor out of a 98 summit.ihave a set of force pipes k&n pods and a shortys cover on my sled but dont know what jets to run in my carbs?can anyone help me out i usually just ride around edmonton and area.

 

[4extreme]

i have a 97 formula z with a 670 motor out of a 98 summit.ihave a set of force pipes k&n pods and a shortys cover on my sled but dont know what jets to run in my carbs?can anyone help me out i usually just ride around edmonton and area.

On the BRP site the `98 670 X had a 350(pto side) and a 340(mag side) for main jets. Seeing how you have K&N`s and other mods that would allow more air I would start with a size alittle bigger and start jetting down as necessary. Any mods you do, you`ll always have to re-jet to get it to run better. Better to start on the rich size than the lean side, fuel is cheaper than rebuilds, goodluck.


also for the stock `98 670 X
Needle Jet NJ-224-AA-8
Pilot Jet PJ 55

if its just the summit( no X)
main 380(pto) 370(mag)
Needle Jet NJ-224-AA-2
Pilot Jet PJ 75

 

[Summitric]

1998 Ran 2 Different Sizes Of Carbs, We Found Out... 44mm And 40mm. The One Size Carbs Ran 340/350 Like 4extreme Said, The Other Size Carb Ran 410/420 I Think It Was.... We Ran Into This When We Added Pipes Onto One And The Jetting That Was Recomended Was Way Out To Lunch.... Then With A Little Research Found This Out.

 

[4extreme]

What was the reason for two different carbs?

 

[SLEDBUNNYRACING]

PTO side runs hotter so they run it a bit fatter.

What was the reason for two different carbs?

 

[4extreme]

PTO side runs hotter so they run it a bit fatter.

that`s the reason for different jetting...They had to sets of carbs for the same sled, maybe one set was for the 'X' and one set for the plain summit.( my guess)

 

[Summitric]

I Believe It Was A Mid Season Change As The '99 Had The Smaller Size Carbs With The Smaller Jets. The Dpm's Were A Slightly Different Design Too. I Think The Early '98 Release Had The Bigger Carbs.... That Is Why Guys Were Trying To Find The Bigger Carbs For Their Modified '99 670x Summits..... I Just Happened To Have Both Sets Now(picked Up A Complete Set Of Carbs With Cables And Handlebars And Everything At A Swap Meet For $75.00..... Smokin' Deal. Detuning My 670x, So Going Back To Stock Carbs(with Tricks And Ufo's Etc.) To Make It More Driveable For The Kids.

 

[99summitx]

I Believe It Was A Mid Season Change As The '99 Had The Smaller Size Carbs With The Smaller Jets. The Dpm's Were A Slightly Different Design Too. I Think The Early '98 Release Had The Bigger Carbs.... That Is Why Guys Were Trying To Find The Bigger Carbs For Their Modified '99 670x Summits..... I Just Happened To Have Both Sets Now(picked Up A Complete Set Of Carbs With Cables And Handlebars And Everything At A Swap Meet For $75.00..... Smokin' Deal. Detuning My 670x, So Going Back To Stock Carbs(with Tricks And Ufo's Etc.) To Make It More Driveable For The Kids.

My stock carbs are 44mm on my 99
350 pto
340 mag

 

[Summitric]

My stock carbs are 44mm on my 99
350 pto
340 mag

SORRY, I HAD THEM BACKWARDS....THE '99 670X IS A 44MM CARB AND THE '98 WAS A 40MM CARB..... SORRY I HAD THEM BACKWARDS IN THE PREVIOUS THREAD.... SO YUP, THE '99 670X IS 340/350 LIKE 99SUMMITX SAYS.

 

[renegade x]

In 98 they had a regular 670 summit and a 670x model also.The regular 670 had 40mm carbs the 670x had 44mm.In 99 they only had the 670x and it also had 44mm carbs.Hope this helps.

 

[Summitric]

Yup, You're Right!!!!!

 

[rsaint]

i have a 97 formula z with a 670 motor out of a 98 summit.ihave a set of force pipes k&n pods and a shortys cover on my sled but dont know what jets to run in my carbs?can anyone help me out i usually just ride around edmonton and area.

I had a 98 670 with twin crankshop pipes k n filters and shorty cover and ran 460 470 jet size i would start there.

 

[Deano670]

I must ask this question, everyone who has commented on this topic is doing things the exact opposite of the way I've always done them(not that your wrong) But Ive always jetted richer on the mag side and leaner on the pto as I've always found the mag side to run warmer do to the fact that its further away from the flow of water from the pump. Mt two cents

 

[Summitric]

I must ask this question, everyone who has commented on this topic is doing things the exact opposite of the way I've always done them(not that your wrong) But Ive always jetted richer on the mag side and leaner on the pto as I've always found the mag side to run warmer do to the fact that its further away from the flow of water from the pump. Mt two cents

HEY DEANO.... THEORETICALLY THE PTO SIDE WILL RUN HOTTER DUE TO THE CLUTCH AND HEAT TRANSFER TO THAT SIDE..... ALL THE PIPE MANUFACTURERS AND TUNERS RECOMEND PUTTING THE BIGGER JET ON THE PTO SIDE TO MAKE IT RUN RICHER, THUS HELPING KEEP IT A LITTLE COOLER, CLOSELY MATCHING THE TEMPERATURE OF THE MAGNETO SIDE. MY EGT GUAGES HAVE ALWAYS SUBSTANTIATED THIS.... CURIOUS AS TO YOUR SUCCESS WITH RUNNING WHAT YOU DOO???

 

[stevel]

Have your brother Deion do it for you lol , Hi Tyson .

 

[renegade x]

sumitric your correct.

 

[Deano670]

sumitric your correct.

Well Im glad YOU cleared this up for us!!!!!

 

[KORE]

In my 96 670 i was running 400pto and 390mag, my clutches are not getting hot enough that I cant touch either, even after a good pulled. turns out a set of new plugs fouled, pto side and the mag side was on its way. After rejetting to 370pto and 380 mag ill know the difference. for my sled any way.

 

[renegade x]

Well Im glad YOU cleared this up for us!!!!!

Sorry can't type.