Jetting question for 700 Red Heads

S

sr522re

New member
Joined
Feb 18, 2011
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52
Age
47
Location
Zeeland, MI
Looking through the Stock Spec Pages, I found that the stock jetting specs for my 2001 SX700R are 1 - 145 and 2/3 - 143.8. I assume this means that one carb has a 145 main jet, and the other two have a 143.8 main jet. Is this correct? Also, which one has the 145 in it?

Also, looking at Turks jetting specs, he calls out a 142.5 in all three carbs for trail riding. I realize that his spec is based on some modifications like the head gasket mod, but shouldn't I worry about running too lean at 142.5?

My biggest confussion is with the stock specs using 1 size main for one carb and another size main in the other two carbs. I assume Yamaha does this for a reason, but shouldn't this same reason be carried over to the specs that Turk provides? I'm just hesitant to put the same 142.5 main in all three carbs if Yamaha felt there was a reason for two of the carbs to be leaner.

If anyone could shed some light on this topic I would certainly appreciate it.

And believe me, I'm not questioning Turks knowledge at all, I'm just trying to understand the reasons behind it better... My sled is still completely stock, but I'm thinking about the head gasket mod and some clutching work before the snow falls. Just don't want to mess anything up with jetting.

Thanks in advance!

C
 
sr522re said:
Looking through the Stock Spec Pages, I found that the stock jetting specs for my 2001 SX700R are 1 - 145 and 2/3 - 143.8. I assume this means that one carb has a 145 main jet, and the other two have a 143.8 main jet. Is this correct? Also, which one has the 145 in it?

Also, looking at Turks jetting specs, he calls out a 142.5 in all three carbs for trail riding. I realize that his spec is based on some modifications like the head gasket mod, but shouldn't I worry about running too lean at 142.5?

My biggest confussion is with the stock specs using 1 size main for one carb and another size main in the other two carbs. I assume Yamaha does this for a reason, but shouldn't this same reason be carried over to the specs that Turk provides? I'm just hesitant to put the same 142.5 main in all three carbs if Yamaha felt there was a reason for two of the carbs to be leaner.

If anyone could shed some light on this topic I would certainly appreciate it.

And believe me, I'm not questioning Turks knowledge at all, I'm just trying to understand the reasons behind it better... My sled is still completely stock, but I'm thinking about the head gasket mod and some clutching work before the snow falls. Just don't want to mess anything up with jetting.

Thanks in advance!

C
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The jetting from the factory is fairly conservative, WOW thats easy to say....
You may want to stick with the 143.8 as the fuels have changed over the years and is not what it used to be. Yamaha has what is called staggered jetting due to the way the water flows through the cooling system and they staggered the jetting so that it wont cause any issues per Yamaha engineerings thoughts. If I am NOT mistaken if you sit on your sled 1 cylinder is on the left(by the clutch) and #3 is by the recoil,(if I have it wrong it is opposite.

sr522re I see that you are new here, Welcome aboard, and dont worry about ruffling Turks feathers... Unfortunately he is no longer with us... He has moved onto greener pastures, er um, snowier mountains.... RIP Turk.

The staggered jetting is not a huge issue as the jets are only one jet size larger or smaller depending on how you look at it.

Your sled will respond well to a set of reed spacers as the reed block covers the "front" transfer or boost port. If you have rode this sled before you notice a burble sound around 5000-5500 rpm, with the reed spacers this will eliminate that and help with the motor getting the proper amount of air flow and will slightly improve the mid range response.
 
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I have like 9000 miles on 142.5 mains and lowered the needles 1/2 position as well no problems whatsoever.There is still lots of piston wash.I also am running a single layer head gasket and reed spacers which is a nice improvement.I will give a word of caution in that I ride a lot of tight trails and off trail and never hold it wide open acrossed a lake for miles or anything like that.In fact I don't think I've ever held it wide open for more than a 1/4 mile or so.You need premium fuel with all the mods listed.
 
I ran Turks jetting specs and the 1-layer gasket with reed spacers on my stock piped 700sx for 2 years before I added triple pipes & rebuilt the motor. When I pulled the motor apart to rering it, the piston wash looked almost perfect across all 3 cyls.
 
sleddineinar said:
I ran Turks jetting specs and the 1-layer gasket with reed spacers on my stock piped 700sx for 2 years before I added triple pipes & rebuilt the motor. When I pulled the motor apart to rering it, the piston wash looked almost perfect across all 3 cyls.
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I rebuilt the motor because the outer most bearing on the PTO side had lost it's seal and some balls & the motor had 5000 miles on it. NOT because the motor burned down. Just thought I'd clarify that.
 
I too have run Turks set up on my mountain max for approx 4000 mi. with absolutely no issues with stock exhaust and can. There is alot more hp to be had from the VERY conservitive Yamaha stock setup. Soc
 
Thanks for the good and reassuring information guys! I've read all of the technical information and I fully trust Turks settings, I just didn't understand the stock jetting specs and the differences between the 3 carbs. Now I understand. This sled is new to me with only one ride on it late last winter for maybe 10 miles. I upgraded from a 98 Phazer. I've been patiently waiting all year for this winter to come around so I can ride it some more. The sled is still in stock form and I haven't done any of the "free" mods yet only because I've been trying to convince myself that I need more time on the stock sled before I make any changes. I did however buy a spare stock muffler that I drilled out to swap in and out and see if I notice any gains. Maybe useless, but it was $25. Has anyone else drilled their can with positive results?

The mods I see myself doing soon would be the reed spacers since I can have them made at no cost. The head gasket mod will follow, just don't know when yet. Again, wondering if I should ride it more first to see if I want to do it. Do I have to mess with clutching if I do the head gasket mod??? I'm sure I can figure it out although it does seem confusing...

Gearing I'll probably leave stock since I will only ditch bang and trail ride with it.

Anyways, thanks again for the input. This site is definitely awesome and filled with great information. Glad I joined!

C
 
Find yourself a 51/43 helix from a rx-1 or apex and put a 4.5 gram rivet in the inner hole/ closest to the pin hole of the flyweights and leave the rest stock.This will work excellent with the above mentioned mods.
 
I would leave the stock jets in it, there's not a huge amount of power to be had by leaning out the mains. I would rather have safe jetting for cold temps and be able to hold the throttle open for as long as I want, mine melted down running 142.5 going across a lake on a cold day. Just something to think about.
 
sr522re said:
Thanks for the good and reassuring information guys! I've read all of the technical information and I fully trust Turks settings, I just didn't understand the stock jetting specs and the differences between the 3 carbs. Now I understand. This sled is new to me with only one ride on it late last winter for maybe 10 miles. I upgraded from a 98 Phazer. I've been patiently waiting all year for this winter to come around so I can ride it some more. The sled is still in stock form and I haven't done any of the "free" mods yet only because I've been trying to convince myself that I need more time on the stock sled before I make any changes. I did however buy a spare stock muffler that I drilled out to swap in and out and see if I notice any gains. Maybe useless, but it was $25. Has anyone else drilled their can with positive results?

The mods I see myself doing soon would be the reed spacers since I can have them made at no cost. The head gasket mod will follow, just don't know when yet. Again, wondering if I should ride it more first to see if I want to do it. Do I have to mess with clutching if I do the head gasket mod??? I'm sure I can figure it out although it does seem confusing...

Gearing I'll probably leave stock since I will only ditch bang and trail ride with it.

Anyways, thanks again for the input. This site is definitely awesome and filled with great information. Glad I joined!

C
Click to expand...
You are going to want to gear it.... at least one step closer to 2:1, 1.95:1 gearing works great for me and I am pretty good sized. Plus if you re-gear it will help with your stock clutching if you choose to leave that stock for now.

Remember the headgasket mod is a free mod as you are going to re-use your headgasket after it gets "peeled".
 
I ran the 142.5 all across as well(may of put the 143.8 in where the 145 was). I didnt do the headgasket mod though. I notched the reed stoppers as well.
 
Bluemonster2 said:
I ran the 142.5 all across as well(may of put the 143.8 in where the 145 was). I didnt do the headgasket mod though. I notched the reed stoppers as well.
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Did you notice any performance gains with just the jets and notched reeds over stock? Did you do any other mods worth mentioning? I'm still trying to figure out what I want to do with my sled so I've enjoyed hearing what everyone has done.

On a side not, it's still early, but I hear we're expected to have one of the worst winters in 30 years. Bring on the snow!
 
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