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Thread: bike update !!!!!! let me know what you think? Reply to Thread
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  Topic Review (Newest First)
03-17-2015 03:08 AM
Originally Posted by hawkinscjr View Post
Ok put stock jets back in and it idles great now but when I rev it it back fires and blowed black smoke
Backfires when you let off, or gas it?

Black smoke means flooding/rich. Could be a float problem. But also make sure the oil isn't overfilled, riding with the big jets could have filled the oil with gas. That could make it overfull and the gassy oil can get to the cylinders. It can also fill up with gas from the float problems.

Does the oil smell like gas? Change oil.

Had a car flooding out once. I was all over the carb. Ended up being a bad fuel pump that filled the oil pan with gas. Oily gas shot across the garage when I pulled the drain plug. All that oily gas was getting past the rings into the cylinders and it blew black smoke like a wicked-up Cummins..
03-16-2015 11:02 PM
vndiana maybe I missed it but any pics of the the entire bike? Looks good to me. I always have liked blacked out bikes.
03-16-2015 10:33 PM
hawkinscjr Ok put stock jets back in and it idles great now but when I rev it it back fires and blowed black smoke
03-16-2015 07:27 PM
smltownr Your very welcome Bordo.
03-16-2015 05:22 PM
bordolover I just finished the ear shave on mine and went the 140/40 with 2 shims route. However, at the altitudes I ride here in Colorado the bike was running way too rich and would stumble, stutter, burble and lose power in the 3000 to 4000 RPM range at steady throttle settings. So, I went back to the stock 132/38 jets and added another shim under the needle for a total of 3 so the taper would allow more gas in during the 3/4 to WOT settings.

Just finished a test ride and I am completely confident it is now squared away. She pulls hard up to redline and at intermediate throttle settings simply purrs like a kitten and has zero loss of power at any RPM setting. But of course I am at 6200 feet and run up to 10000 feet on our weekend runs so the stock jets make sense after reading a few articles on CV carb tuning...thanks smltownr...as well as this article:


148/48 does seem a bit large for this engine as well and is more than likely running really rich when the throttle is twisted and the needle raises up and lets in even more fuel to the carbs. The 750 Virago might be out accelerating you because you are running too rich...
03-16-2015 01:59 AM
OleDirtyDoc I ran 140/40,2 shims under needles in mine with pods and earshave and degoated with Harley screaming eagle mufflers
03-16-2015 01:54 AM
OleDirtyDoc What exact mods ya got?earshave and straight pipes?148/48 seems too big
03-16-2015 01:01 AM
smltownr Opps... after "try looking at this" should have been a link. Here it is http://motorcyclecarbs.com/Motorcycl...etting__W7.cfm
03-16-2015 01:01 AM
smltownr Try looking at this. It gives a starting point for rejeting. I've always thought the main jet was for 3/4 to full throttle. My bike cruises 70mph below 1/2 throttle. This is the area governed by the pilot and needle. I'm with Spockster, keep the OEM jets and if tweeking is needed small shims first.
03-15-2015 08:24 PM
Spockster I always suggest trying the stock jets, that's what I'm running with never a problem. (shaved with stock pipes)

140/40 is what was used originally for the shave, but double check that.

I'd think your bike should be putting out some bad fumes, and black smoke at some point.
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