The FCR carbs. are a excellent next step,even if thats all you plan on doing I would highly recommend the FCR carbs. on a bike with just a pipe.The performance you gain when jetted properly is outstanding.Lyle

 

Where can u get them? and how much? I want to do something else but dont want to dig into motor.

Even though my motor has been bored over once for stupididy of yamaha shop.
Thanks Rudy

 

TEAMSPARKS (Lyle),
Do the FCR carbs come jetted from Sparks? If they do, do you know what the jetting is set up for. I am assuming that is the jetting would be set up for the Supercharger air box. Is it possible to have them set up for a Pro-flow flange / foam filter / outerwears cover / no air box lid setup. This is the way i have to go, due to the long manufacturer time for the Supercharger air box. I know i have asked you several questions, and dont want to be a pain in the rear, but you currently are my information source regarding the Spark 690 kit. I have been having a hell of a time trying to contact Sparks over the phone to try and get some answers to my questions.
I highly appreciate all the information that you have provided so far. Thanks for your assistance.

herbdon

 

The FCRs do come pre-jetted for the application for which they will be used on.

 

I got my FCR carbs from Carb Parts Warehouse. I think the price was about the same as from Sparks. The carbs had a couple problems fitting but easy fixes. The biggest problem was with clearance to the stock exhaust pipe. When I went to the Sparks Exhaust it was like it was made for it.

I have a twist throttle so the pull was not so bad.

Other problems:
I needed to add a 3/16" spacer to the rear gas tank mount.
I used a fender washer to space out the top frame rails to clearance the throttle cam.

I dynoed at the same place as KingRaptor's 686 on a Dynojet 248C car dyno with just my FCR's, the Sparks exhaust and a custom built Air filter(no airbox) and actually had nearly the same torque curve throughout the entire engine speed range before he rejetted. He was pretty lean I think.

 

Nakedryan- give us the numbers please!

 

If someone has a website to post the torque and hp charts I'll send them the file.

This was tested on a car dyno and due to the large rollers I am not sure how accurate the numbers are. Basically, I have used it to compare KingRaptors and my ATV's. I plan to run the same setup on a ATV dyno to find out though.

I checked with Dynojet and they said that the horsepower should be higher on an ATV dyno. I will try to check that out as soon as possible.

 

NAKEDRAYGUN, I would like to here your comments on the carbs. and pipe. Lyle

 

Overall I think they're great especially for the desert and dunes riding I do.

If I had my choice I think I would have picked a smaller venturi carburetor.

I think the velocity at lower engine speed is a little too low for the stock engine.

From everything I have read the common error when switching from CV carbs to conventional carbs is increasing the venturi size. The proper way is to use the same or smaller venturi carb.

In general I have not had any severe driveability problems but I would have preferred a smaller carb.

 

Teamsparks,

I have a question for you. I ordered the 690 kit through my local shop about 4 weeks ago and still haven't received it yet. Curtis said everthing was in stock except for the cam. Do you know when the cams will be in, because I need to get my motor back together so I can practice a little before the first national.

Thanks