temp specs on exhaust manifold?

If it's broken or just needs tweaked

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kbailey
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Location: central Iowa USA

temp specs on exhaust manifold?

Postby kbailey » Sun Jun 04, 2006 2:30 pm

Interesting story, my brother-in-law is into small car racing. These are the little remote control cars that use small gasoline engines. and he has this little gadget that will tell you the temperature of anything just by pointing it at it. I assume it works by measuring the amount of infrared emitted. He uses it to keep tabs on how hot his little remote controled car engine gets. I used it to measure the temperature of my exhause manifolds. on three pipes the temperatures were 144-155 degrees F and on #4 it was only 98. obviously I have some work to do to figure out why #1 is not running. Also, is there a spec I can compare the other 3 to? what would you consider to be normal variation in the exhaust temp?

as an aside note, where can I get some of the little thread in vaccum ports so I can sync my carbs?

thanks guys.

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Ibsen
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Postby Ibsen » Mon Jun 05, 2006 2:09 am

I have no idea what the temperature should be on the headers.

But here is a couple of places to get the adapters.

http://www.motionpro.com/motorcycle/too ... _adapters/

http://www.carbtune.com/carbaccs.html

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Volker_P
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Re: temp specs on exhaust manifold?

Postby Volker_P » Tue Jun 06, 2006 1:32 am

Note that the original exhaust pipes are double walled, so they are usually colder than single walled ones. When you measured just after starting, do not worry. It runs quite smooth on 3 cylinders, you only notice the missing one with load. It may take some time until it runs on all four. If you measured after a ride, what did your #4 spark plug look like?
For the little threads, I think one can fit a bicycle tire valve (I used something like that but it has been some time).

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kbailey
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Location: central Iowa USA

Postby kbailey » Tue Jun 06, 2006 1:39 am

I measured after a short ride (5 minutes at freeway speed) the #4 spark plug looks to be running SLIGHTLY leaner that the other 4. It was not wet with fuel or burnt at all.

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Volker_P
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Re: temp specs on exhaust manifold?

Postby Volker_P » Tue Jun 06, 2006 2:22 am

Had a look, you have a Nighthawk, right? 5 minutes should be enough for a SOHC at summer temperatures, however as the plug did not look to bad or even fouled I would repeat the whole thing after a longer turn to be sure before looking for a problem. Other hints to a possible problem may be enhanced fuel consumption together with lower power.

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kbailey
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Location: central Iowa USA

Postby kbailey » Tue Jun 06, 2006 2:38 am

for a very long time I have thought that my fuel consumption has been too high. I have recently experience an unsmooth power curve. If you feel it while going through a tight corner or while cornering from a stop it can really throw you off. the power will dramatically and suddenly increase at about 3k RPM. it can for a short while vascillate dramatically and give a very jerky acceleration. I assume that this is due the the #4 cylinder cutting in and out of firing. I will do more investigating before putting much weight on any of my concusions.

I have a confession, I hope that it does not make me unwelcome in this forum. I have a DOHC. its an '84 nighthawk. its just that so much of what you guys discuss is still applicable to me. I hope you forgive.

thanks again.

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Volker_P
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Re: temp specs on exhaust manifold?

Postby Volker_P » Tue Jun 06, 2006 3:49 am

Oh, oh, there is no reason to excuse for a nighthawk. I am not aware this here is a SOHC only forum. Most topics are related to SOHC and so usually I assume it's a SOHC if nothing is specified and I correlated your name to a nighthawk a bit too late. So don't worry whether you are welcome here. I also think I remember there is at least one other nighthawk rider here. :D
From what you wrote now, I share your suspicion of a temporarily cut off cylinder. Most simple reason would be a damaged plug. Other options might be the carb diaphragm has a crack or maybe the carb piston it moves stucks a bit at some (low) position. Then the full power should stay until you close the throttle again. If the sudden power increase is only available for a very short time, consider also fuel transfer problems to the outermost #4 carb.


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