Edelbrock carb + stock exahust = heat

8 replies to this topic
  • saunan

Posted May 20, 2007 - 07:33 PM


My 2001 XR650R has been uncorked, but has a stock exhaust and an HRC tip. I usually ride above 2500 feet. After installing an Edelbrock carb, the bike is running over 220 degrees in 1st and 2nd gear (TrailTech Vapor installed).

Carb Idle to Mid-Range adjustment: If I go two clicks toward rich, the temp drops back to 195 or so, but it starts hard and gets poor gas mileage. I've had the carb on for three rides, and there's not much else I can do with this adjustment.

Should I change the Mid-Range to Full throttle adjustment with a smaller needle (#17) and then richen the low end?

Would that help with the overheating, or do I need an aftermarket exhaust?

  • XRR-kat

Posted May 21, 2007 - 05:58 AM


It's been speculated before that the Trail Tech temp sensor would reduce flow in cooling system - looks like as much as 50% from size and why I won't use that feature of the TT on my BRP (need to get a oil fill analog temp guage).

I had your setup, less the TT in-line temp sensor - HRC tip, uncorked, 175 main, 68s but without your over-heating concerns. Granted, I didn't have a thermometer, but it never boiled over like when it was corked - 3-4 minutes idleing parked and boil-over.

Don't see how aftermarket exhaust will cool the engine down since you have the HRC tip which flows a bunch. If you want aftermarket exhaust go for it, but don't expect it to solve your overheating.

Check/replace your coolant, maybe add water wetter to the Honda product and all this assumes you have cooling system in good working condition. The carb questions would best be answered by Edelbrock or Barnum's if you bought it there, but I still think it is the TT temp sensor - it is the bottle neck in your cooling system.

  • Agent2

Posted May 21, 2007 - 07:58 AM


I ride about the same elevation, uncorked 650R, running a 19e needle and about 12 - 13 clicks out. Never had an overheating problem with the stock exhaust or the XR's exhaust I have on now. I agree with XRR-kat, check your cooling system - water pump, replace the coolant.

  • saunan

Posted May 21, 2007 - 03:34 PM


Thanks for the suggestions. I'll check the water pump. The coolant is brand new 100% Engine Ice. What I don't get is why the temp is so high with just a slightly leaner mixture. Two clicks toward rich, and the temp drops back down. :)

The reason I asked about the exhaust is because the Edelbrock manual says the carb is designed for an aftermarket can ... I couldn't see paying another $300-$400 for THAT. Yikes!

A riding buddy of mine has an '00 BRP with stock carb (175 main, 68s), FMF exhaust, TT Vapor and his bike runs around 190 F at the same time mine's up at 220.

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  • XRR-kat

Posted May 22, 2007 - 04:20 AM


More info - good
I have the stock carb on mine with jetting and comments mentioned above. I've got an "Edie" waiting to be installed and would not expect it is that far off any range on it's fuel/air-rpm curve though I am aware that the Edie does not allow for as accurate as stock carb adjustments.

Does your buddy have a TT installed as well with the huge in line temp sensor? How do you measure his temp? Analog guage or TT sensor? Haven't heard your response on that item.

I still say pull the TT temp in-line temp sensor and see what your temps are like. Or, you could swap carbs with your buddy?-)

  • vaughn

Posted May 22, 2007 - 06:09 AM


A riding buddy of mine has an '00 BRP with stock carb (175 main, 68s), FMF exhaust, TT Vapor and his bike runs around 190 F at the same time mine's up at 220.

Just a thought. Is your buddy running synthetic motor oil and you are not? Lower temp w/synthetic.

  • saunan

Posted May 22, 2007 - 02:24 PM


About the TT Vapor: We both have the in-line temp sensor in the same place (the larger radiator hose on the left side).

Oil type: I'm running Shell Rotella 15W40 diesel oil, my buddy uses 20W50 Royal Purple synthetic. How much lower temp with synthetic?

Today I adjusted the idle to mid-range mixture one more click toward rich. The exhaust was popping on deceleration anyway, meaning too lean (right?) ... That should shave a few degrees off the temp.

  • XRR-kat

Posted May 23, 2007 - 04:55 AM


So you and your buddy have similar bikes with you having the "Edie" and him having the stock carb....then swap carbs to see if that is the difference. I suspect that is not the cause of the diff temps. Still think it is systemic..your cooling system is not working as good as his. Wonder if you have an obstruction in your plumbing?

Otherwise, start removing ballast to stay afloat...remove the TT sensor and replace with an analog dipstick guage.

vaughn's suggestion on motor oil sounds good too...lighten your motor oil and go synthetic.

  • saunan

Posted May 23, 2007 - 01:43 PM


Excellent suggestions... thanks! :) I'll do one thing at a time and find out what the problem is...

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