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GS674R Jetting help Needed (Pics Included)

  • Thread starter Thread starter ashdricky
  • Start date Start date
A

ashdricky

Guest
So I have finally completed the 555/650 conversion, and now I need direction on jetting my cv32 carbs. I was told that they came off of an 850 so Im almost certain there will be jetting issues. for an exhaust we have a few options as we intend to fabricate mufflers to follow the lines on the tail section, will be using 4-2 system or a 4-1-2 system with a crossover under the oil pan. also we will use the stock airbox, with a large k&n auto filter.
these are just our current ideas and nothing is really set in stone at this point so any advice or direction is welcome.
Thanks-Rob
PS-I would like to thank all of the members who contributed to this build, Nerobro, Suzukidon, Dansofield, Rapidray, Boontonmike, Seanspecht, and many others who freely shared their knowledge.
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I'd maybe start with a 650 stage 3 Dynojet or the like kit. Ray might have some factory pro needles, which apparently are even better than the Dj needles but I have never used em so i don't know.

I know you said you'll be using the box with the kn filter, but if you do go Dynojet, at least in the kits I've used, there are two sizes of larger main jet. I'd think the smaller of those two sizes would be where to start.
If you want to go factory pro needles, and then jet with larger Mikuni jets, start around 5-6 sizes up on the main, needle clip toward the point (again, I don't know how rich those FP needles are tapered) a slot and see. The main needs to be right first. You should be able to get it running/idling well on the stock pilot jet size with three-ish turns out on the mix screws.
I'd take a look at the carb sticky thread, and compare jet sizes from the 850 and 650 carbs and see how much different they are besides the main, pilot and such. The air corrector jet may be much larger.

Also, have you checked to see if those carbs are offset the same as your ports?
I could swear the are, but I may be wrong. The exhaust side isn't the same as the larger bikes...
If you need different gang planks, let me know. I have a set from a set of 550/650 carbs.
 
By the way if you really and truly are planning in this being a race bike or heavy track time bike, and not so much a street bike, you may want to look into a set of smaller RS carbs or something like that. Ray would know. The CVs are great for the street, but they're absolute schit for racing.
 
Have you had any head work done?

Are you running 550 or 650 camshafts?

Are you certain you can obtain a K&N filter for the '77-'79 air box?

If you are running a fairly stock engine, little or no head work, no hi lift profile cams, fairly normal exhaust, stock air filter, etc. then I would not go to a Dynajet kit, etc. they are for pods. A near stock exhaust (read some restriction here) does not need a Dynajet IMO, maybe a St 1, but nothing more.

I am running a 4-1 exhaust, stock cams, stock air filter and all I have had to do to get perfect running is go one size larger on the mains and raise the needles by removing the white plastic washer and replacing it with three thin metal washers to give a slightly richer mixture on the needle.

Be aware there are two different lots of settings for the 650 engines. The G and E have different settings. The G flows more air through the filter and therefore requires 5 sizes larger main jets.

The E main jet is 97.5 as opposed to the G which is 110. Maybe you could go with the 110 mains as a starting point, I am using #100 mains in mine.

The air jets are different between the two models as well with the E model needing larger jets at #175 with the G only using #160.

Unless you have done stuff inside the motor that requires richer settings then I would not alter things too much until you get it running.

Just my 2cents worth as I cannot remember all that you have done to this motor. All my comments are from experience as it took me about 6 months to get the teething issues out of my engine and get the carbs set properly (my big issue was looking for problems that didn't exist). Hoping to save you that trouble.

Good luck with it.
 
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Thank you don, we dont know what exhaust we will use yet, possibly an uncorked 4-2 setup, Im told ignition kill will burn exhaust packing, as far as the airbox we are using one from an 81 650 to match the cv32 carbs, i have the 550 cams in right now, and no head work was done except bead blasting to remove the carbon build up.

Cafekid I sent you a PM regarding the gang planks
 
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