1998 mxz 670 question

[tonycug]

have a 1998 670 that i picked up and have been fixing just needed some hep with jetting checked out what it has in it right now and its got a 640 on mag side and 660 on pto side main jets not sure how the number work still new to the sport i live in edmonton alberta does anyone know where i could get some info or if anyone could explain how to tune carbs would be great also its got aftermarket pipes and after market air filters on carbs thanks everyone

 

[tonycug]

here are some pictures of my sled

 

[tonycug]

here is another pictures showing the pipes i have on it

 

[pistonbroke800]

What's done to the engine? I had a mildly modded 670 and I ran 420/430 mains in it. Your jets seem huge for a 670. A stock 800 come with like 480 mains

 

[lloydguy]

I'm at 380/370 if I remember correctly. with my 670. That doesnt look like a "s" chassis bulk head to me.

 

[neilsleder]

PM Deano670 on here he knows his 670's. Or do a search for Mad Motorsports and get his number and give him a call

 

[neilsleder]

I'm at 380/370 if I remember correctly. with my 670. That doesnt look like a "s" chassis bulk head to me.

I think its an old Polaris you can see the hood in the top left corner.

 

[tonycug]

ya its a polaris body with a 670 motor its kind of rough but was in my budget thanks for all the help will see if i can get it running right

 

[tonycug]

also if you look in the picture you can see that i put a clear plastic tube from the bottom tube to the top one that goes to the gear for the water pump was told that was a good way of doing it and fill it with oil because the sled does not have a oil injection pump has anyone else ever done that and is it the right way to do it? thanks for your time guys and thanks for the help

 

[tonycug]

here are some more pictures of my sled not the prettiest machine out there hopefully it gets me a few good rides this year

 

[Modman]

Nice looking wedge chassis.

1) I would get two of the same pods on your carbs, you could be sucking in different amount of air using 2 different filter styles.

2) Your oil injection line from the bottom of the oil cover is correct, just make sure you fill up that line with injection oil from time to time, it will still use oil to lube the water pump bearings and you will have to top it up every now and then.

3) Check your plugs but I would think those jets are wayyy to big. Most of the carb'd 670's (non-Hac) models ran around the 400 mark, once you get to 520's they jump up by 2 number sizes, but still, 640's are big jets, unless there is something about it you are not telling us. I can't imagine your fuel consumption with those jets, you'd be lucky to get 40 kms out of tank, it if even runs well. You need to do a plug reading and see what the plugs tell you.

4) Looks like it has a t-stat delete on it, make sure you warm it up well before riding and after lunch breaks, otherwise you are at risk of cold seizing that motor. Normally there was a loop system that runs off the top of the head (where the little coolant block off plate is). You don't have this so your motor is at risk for cold seize if it gets a big slug of cold coolant all at once.

I have some jets for those carbs if you want them.

 

[tonycug]

thanks for the help will let you know what i find

 

[goodngrubby]

My last 670 was close to the same setup as yours.....Gagner pipes, K&N pods, and oil injection delete with a shorty cover. If those are still the stock 44mil Mikuni carbs, you should be running 420-440 jets. Like Modman suggested, I'd flush the mix-matched pods, and buy some new ones. Try and get them both up at the same angle, because snow will accumulate on the one laying horizontally.

 

[tonycug]

thanks for the advice good will try that and see how it works thanks for athe advice