Marbling = overheating? - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 6 (permalink) Old 05-25-2007, 07:10 PM Thread Starter
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Marbling = overheating?

My bike has been backfiring from the rear cylinder like crazy.

I couldn't find the right sized marbles or copper fittings, so I ended up buying 4 5/8 rubber chair legs. What I did was remove the hoses altogether, and put a stopper on each cylinder nipple and also on the two nipples under the seat. There was also another big hose and a small hose on that thing under the seat, but I left them as-is.

Anyway, the backfiring didn't get any better. So I fiddled with the carb screws a little more. I found that 3 turns on the rear cylinder and about 1 1/2 on the front seemed to stop the backfire.

Problem is, now the bike seems to be running hot. The temperature was just slightly above the middle of the gauge. Not into the red, but a little above the tiny thermometer symbol. There was also a small amount of smoke coming out from behind the engine when I stopped. Could marbling cause it to overheat?

It always ran pretty cool before, about 1/3 up on the gauge. Maybe its just warmer out today (almost 90), but the gauge creeping up above half freaked me out a bit. And the smoke didn't help. The bike had been sitting for pretty long before I bought it, maybe it was just burning off some grease or something. Either way, is it possible marbling could cause this problem?
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post #2 of 6 (permalink) Old 05-25-2007, 07:39 PM
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Thats strange, I marbled years ago and have not had a problem.

Chad Falstad "Hawk"
Vroc #17649
2011 HD Ultra Classic "angel"
2001 Nomad 1500 Sold March 2012
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post #3 of 6 (permalink) Old 05-25-2007, 07:57 PM
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About you adjusting your carb screws. One 3 Turns and one 1 1/2 turns. Your carbs are more than likely out of sync. I'd try to clean them and sync them. It just may help... Plus the bike sitting for a while you prob have varnish in the carbs.....

'92 Vn750

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post #4 of 6 (permalink) Old 05-25-2007, 10:02 PM
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If you haven't already you should check for exhaust leak on the pipe that is backfiring. A leak can cause backfiring pretty easy.
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post #5 of 6 (permalink) Old 05-29-2007, 08:07 PM Thread Starter
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Thanks -- I'm going to give the exhaust a good check and see if I can get the screws a little closer in tune. I think I might have overreacted to the "overheating" since normally the bike runs so cool. Today it was warm and I went on a pretty long ride (for me at least, maybe 20 miles) and the bike was fine. I think the overheating might have been from letting it idle for a minute or two while fiddling with the carb screws. It wasn't sitting long, but it was very hot and stagnent out. Might have caused the engine to get warmer than normal.
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post #6 of 6 (permalink) Old 05-29-2007, 11:03 PM
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I'm finding that I tend to pucker more these days when stopped in traffic with the bike. Overheated once, now I am constantly watching the temp gauge.

I would be willing to bet it all boils down to this; Our bikes generate no more heat than any other water cooled (or air-cooled, for that matter) bike. We just happen to have a little temperature gauge that lets us see the typical heat buildup so we get to begin fretting when everyone else is happy as a lark.


SW Ohio

'02 VN750
Pipes drilled
Spline lubed
R/R relocated
AGM batteried
Iridium equipped
LED tail lighted
8000-ish miled
Soon to be MCCTed

Lovin Life.
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