Custom exhaust problem

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Custom exhaust problem

Postby Trung Đào Jr » Thu Nov 19, 2015 3:50 am

Hi, i'm 19 years old and i'm from VietNam. I have a 2004 VTR250. I have just installed a custom exhaust ( just the terminal not the whole system). Then some of my friend say that it could damage the engine in the future. So what problems and how bad they are? If there are problems, what can i do to prevent them? I need advises, please help me !

P/s : my English is pretty bad , sorry abt that.
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Re: Custom exhaust problem

Postby spotthedogg » Thu Nov 19, 2015 6:17 am

I can't see any reason to think a slip on exhaust would damage the engine... What exactly have they said is the problem?
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Re: Custom exhaust problem

Postby John Hilmer » Thu Nov 19, 2015 5:27 pm

I'll just GUESS at what his friends might think the problem might be.

Let's assume that the free flowing muffler mounted after the collector changes the back pressure in the system enough that the engine is running too lean. This might explain the friends concerns. A lean running engine can cause high exhaust temperatures and hence exhaust valve damage. Again, this is an assumption, and it should be able to be checked by pulling the plugs to see if in fact the combustion is too lean, showing white deposits rather than tan to light brown in color which would be normal.

I would do this, checking the plug color in any case; muffler change or not, just to see how the air/fuel ratio is working. It would be easy to reverse this test and put the original muffler back on, install new plugs and run the engine for some time. Then compare the two sets of plugs for color.

The big part of this problem is knowing how to read the plugs for color and this depends upon the fuel used. If the fuel is laced with ethanol the results will be quite different from straight gas. Searching on line will provide the means of knowing how to test and read the plugs

I'm well impressed with your abilities using English rather than your native language. I have no such ability.

Welcome aboard to our forum, we are very pleased that you have joined us,

John
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Re: Custom exhaust problem

Postby Trung Đào Jr » Fri Nov 20, 2015 12:25 am

Well i'm very happy that you guys can understand my English :D so, back to the question, now i need to check the plugs color right ? I will do it now . thanks for your help John
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Re: Custom exhaust problem

Postby squirrelman » Fri Nov 20, 2015 4:56 pm

Does your bike have fuel injection or carbs ?? If FI, it should adjust itself for the exhaust change. :? ;) ;)
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Re: Custom exhaust problem

Postby VTRamen » Fri Nov 20, 2015 8:18 pm

According to Wikipedia, the 2003–2008 models all have EFI.
- 1988 VTR 250
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Re: Custom exhaust problem

Postby Trung Đào Jr » Sat Nov 21, 2015 2:53 am

My bike have carbs not FI so.......
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Re: Custom exhaust problem

Postby spotthedogg » Sat Nov 21, 2015 8:16 am

Interesting, I too was assuming it had EFI
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Re: Custom exhaust problem

Postby John Hilmer » Sat Nov 21, 2015 11:59 am

Trung,

I'm not at all familiar with your bike or the fuel system, but the plug reading is a fool proof way to determine if the air/fuel ratio is close to correct regardless of which system it uses, carbs or EFI.

The fear about changing the muffler is that a free flowing exhaust may reduce the back pressure that the system is designed to have. This in turn could cause the engine to run lean. If this is sever enough there could be excessive heat on the exhaust valves which could be damaged.

Do you have a manual for your bike? It would be good to have one if you don't have it.

Have you pulled the plugs to see what their colors look like?

John
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Re: Custom exhaust problem

Postby Trung Đào Jr » Sun Nov 22, 2015 10:30 pm

Hi John, i had opened the plugs, both of them are in good condition ( brown with a little red, i don't know how to discribe the color, wish that i could sent you images of the plugs )
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