xr 600 carb/port Q's

2 replies to this topic
  • reknelb

Posted February 17, 2002 - 10:48 PM


I own a SRX 600, for those who are not familiar with it, it is a Yamaha single, 4 valve, air cooled, street bike(1986). It has individual ports for each valve, two carbs (one on each intake port), and 2 exhaust headrs that meet about 10 inches down the front. Is the xr 600 similar in design? I was thinking of doing a single carb conversion to my bike as the stock carb set-up is really odd and most people put dual CR 33mm carbs on. What kind/size do people put on XRs when they replace the stock carb? What is the stock carb? my motor has a megacycle cam, 11.5.1 Wis. piston, ported head, Tit. spring kit, and a fresh valve job. Does anyone know where to get HP #s on a xr 600? (stock vs. built motor) I'm thinking most people use the CR carbs on the SRX because they don't want to move the oil tank so a single carb will fit. I'm thinking a single carb might be better, or, I could be dead wrong. Any opinions?

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  • Victor_Venturo

Posted February 18, 2002 - 02:17 AM


The older dual carb Xr Hondas feed into a single intake port. They are setup progressive. The second carb feeds only the higher RPM and does not have an idle circuit. Setup correctly these bikes made great power and had even better bottom end. The newer single carb setup is lighter, cheaper, easier to tune, less complex and makes good power. Since Honda came out with all the single carb parts on the newer bikes it made for easy swaps. Dont know which setup was best but even the XR628 bikes that won Baja many times had single carbs in the later years.
Your setup sounds like both carbs are identical feeding the individual intakes. Is there a newer version with a single carb? That would be the ticket if you can find a setup from a wrecking yard. Maybe one of the carb companies can set you up with rebuild and jetting kits rather than trying to remanifold to a single carb.

  • reknelb

Posted February 18, 2002 - 06:46 AM


actually, the stock dual carb set up is progressive on the srx too. A mechanical carb works all the time, and a CV carb helps out with the mid-top end. The Yamaha grizzly 600 uses the same top end as my bike, with a 40mm CV carb, so a manifold is available. The HP numbers on the Grizzly are pretty low (not for a 4-wheeler), probably due to a different cam and set-up for low end torque. I have a stage 3 jet kit and K+N filters on my bike now. They seemed to work out OK on my bike with an after market pipe, but faded quick in the higher RPMs. Now that I've done a bunch of engine Mods, I'm trying to come up with a solution to the potential carb prtoblem, as I'm not totally convinced that dual cr 33mm carbs is the best solution. seems like too much carb, lots of flow, but no velocity. I was thinking one Mikuni flat slide, or an edelbrock qwik silver.

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