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Exhaust Temperatures

Discussion in 'The Garage' started by SoraXS400, Jul 8, 2017.

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  1. SoraXS400

    SoraXS400 1982 XS400

    Does anybody have stock exhaust temperatures for the '82 XS400 Maxim? (DOHC, YICS)

    I'm looking at new exhuasts and in the mean time also looking for my temperature probe and I was wondering what the difference between the stock pipes are and an almost straight pipe design would be.

    Also, has anybody compared these with the MAC 2-1 exhaust system?

  2. SoraXS400

    SoraXS400 1982 XS400

    Bought a new temp gauge. Running at about 370f right out of the pipe, about 280f at the weld in the middle. Going to order the jetting kit and check out temps when I cut the baffle.
  3. 16VGTIDave

    16VGTIDave XS400 Guru Top Contributor

    The DOHC pipes are double walled. You can't get an accurate temp reading from them.

    Have fun tuning for the "almost straight pipe" exhaust. FYI, I've recently added 19mm (3/4") restrictors to my HD Sportster mufflers and the bike is slightly quieter, pulls stronger, and is getting much better fuel mileage. All that suggests I'm making more power now. It is a well documented fact that "drag pipes" reduce power except in a very narrow range at high RPM. And they sound like crap because the engine is running like crap.
    xschris likes this.
  4. SoraXS400

    SoraXS400 1982 XS400

    I really give no shits about the actual temperatures, because they'll be consistent. I don't need real temps to tell if the temperature changes, and you have no idea if your bike is making any more power, you're basing it off anecdotal evidence?

    Also, why does every single person on this fucking website think people asked for their opinion? Every single thread on here has been a simple question and people think they have to put their 2cents in. Listen, I didn't ask if straight pipes or baffle removed pipes make the bike sound bad or lose a slight amount of power and that I shouldn't do it. If you understand how to tune carburetors, you can tune the bike to make power even with straight pipes and drags. You can make any modification and tune the carbs correctly.

    I'm sick and tired of reading the same shit over and over on this forum, 80% of the people here have never worked on other bikes or know what they're even talking about, and think that a stock bike makes the best power and everything.
  5. 16VGTIDave

    16VGTIDave XS400 Guru Top Contributor

    :laughing: That was a hysterical response. Not hysterically funny, hysterical like a 4 year old throwing a tantrum. Did you need to check your blood sugar? Or had you just chugged your 5th energy drink for the morning? I hadn't intended to get your panties in a bunch when I offered you that information. I was merely sharing facts with you, For Your Information and all. You asked the question and didn't like the ONLY reply you got. Well don't life suck. If you just wanted to be told you are doing a good job and have your ego boosted, maybe next time you'll post a picture on instagram.

    @SoraXS400, since you criticized the fine people here, let me ask you some critical questions. Who the heck are you and what makes you think you know anything? How many years of experience do you have working on bikes? How many bikes have you worked on? And how many were dyno tested after your expert manipulations? Any relevant education? I get the impression that you don't even know your level of ignorance. 95% of the motorcycle people I've met (here and on the road) with modified bikes don't know :poo:. They certainly can't tell the difference between marketing BS and practical application. And none, not a single person, has been able to discuss volumetric efficiency or pulse propagation tuning. All of the bike mechanics I've met were no different.

    Back to the temps you are trying to read. They are virtually useless because you don't know where the inner pipe is in relation to the outer, how much thermal energy is being transmitted or at what rate. Sure, you can read a change. But how long does it take to get that change? What is the ambient temperature, humidity and air speed and how are they effecting the reading? If you are such an expert, why don't you know all this?

    @SoraXS400 do you really think that carb tuning is the answer for every engine modification or mistake? If so, you know even less than I thought you did. The fact that you are ordering a jetting kit demonstrates your knowledge. :thumbsdown:

    As for how my bike is running, I have over 57,000 km (35,500 mi) of documented records. I log everything done to the bike. I keep notes on how the bike is running and the weather at the time. So when I say I'm getting better fuel economy, I am. 4.1 l/100km (24.4 km/l, 57.3 MPG US, 68.9 MPG UK) is hard to argue with and certainly not anecdotal evidence. I often ride the same roads with the same loads. I know what gear and how much throttle it takes to climb a certain hill without loosing speed. When I say the results indicate the bike is making more power, they do. Installing the restrictors in my mufflers, with no other changes, increased the fuel economy from just over 5 l/100km (45 MPG US) to 4.7 l/100km (50 MPG US). @SoraXS400, you know that power and economy are the same thing, right?. With further tuning (reduced jetting) the economy has increased and so has the power. I still haven't been able to tune out the stumble I get around 7000 RPM, but I'll live with it. Unless you @SoraXS400 can tell me, with your infinite tuning wisdom, what the problem is and how to tune it out?

    Now, do you want to swear at us some more? Are you going to send me nasty PM's? Or are you going to be polite?
    buztabuzt likes this.
  6. SoraXS400

    SoraXS400 1982 XS400

    Simple solution for your 7k rpm stumbles, either it's your float bowl adjustment or your fuel adjustment.

    Also, when I say that carb tuning is the solution to every engine modification, it essentially is, for all intensive purposes. When you change out an air filter for a higher air-flow filter you have to jet accordingly, when you get a new exhaust, you have to jet differently, when you get anything with airflow or any change to fuel or how the bike would run, the carburetor is in charge of fuel distribution, and you said
    which obviously shows you're way in over your head - You can't tell me exactly what jet I will need with a removed baffle, or even with just straight pipes. Right now, I run about 55MPG Stock, and I'm not going to go on about exact numbers, because no matter how much you think you know the exact amount of power to give it, you ride differently every day. I ride pretty aggressively some days and sometimes not and I still get around 50MPG every single time I fill up.

    Also, in the first comment you should have simply provided evidence, instead of just saying "oh I get better performance too"

    I asked for temperature differences between the stock pipes and removed baffle pipes, and you decided to tell me that the exhaust is double piped so I would not get an accurate reading, and then proceeded to say that everything else would be majorly different in the next test.

    Even if the rate of change of temperature was slowed after removing the baffle and allowing more airflow, the end result would still be a different temperature and would be consistent. You would be taking a reading from the difference between the baffle in after x amount of minutes and then when the baffle was removed you would take that same x amount of minutes to check the temperatures again, or until the bike was at operating temperatures.

    You cannot just by looking at the bike, calculate the rate of change of airflow from the removed baffle to the stock pipes, you can't. There are imperfections in the manufacturing process and no bike here acts the same.
  7. 16VGTIDave

    16VGTIDave XS400 Guru Top Contributor

    That is the response of an amateur. The float levels are a minor factor at that RPM. What fuel adjustment? Pilot Screws? Pilot Jets? Pilot Air Jets? Needle Jets? Jet Needles? Main Jets? Air Jets? What about the transfer passage in the slides?
    Rank amateur! Carb tuning can't resolve mechanical or dynamic engine performance issues. For example, reduced port velocity caused by excessive porting, cam phasing, ignition timing, or exhaust reversion as caused by open pipes or straight through mufflers. Bad design can't be tuned out.
    Of course not, nor would I try. I KNOW better.
    When most people's eyes glaze over as soon as technical discussions begin, why would I waste the effort? It's not like 95% would comprehend any of it. You apparently don't.
    I gave you the information you didn't even know to ask for. And you failed to comprehend that or the rest.

    To repeat myself:
  8. SoraXS400

    SoraXS400 1982 XS400

    You can't say anything further then, because you clearly have nothing to add to the conversation.
  9. Travis

    Travis Staff Member Staff Member

    This thread went to shit, so I closed it.
    buztabuzt, BBS360 and xschris like this.
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