Exhausting Muffler Debates and Dyno Data
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  1. #1
    Senior Member Malkop's Avatar
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    Tinkering with my new Honda 1985 XL250 led me to this interesting source. It's the first time I've had a stock pipe on a bike since they are normally rusted and replaced by louder stainless pipes by the time I lay my hands on them. The XL250 led the way for all the 4T dual sports to come and back then they were doing pipe mods to up the HP. I am not changing from stock since I love the bike's quietness and are reconditioning her totally stock so she has that classic 80s look that matches the hairstyles and moustaches of the day. Andy showed me a bike magazine article from the 80s about the bikers in my city and how we had more bike shops per-capita than anywhere else in the country back then. I digress - have a look at the 1972 expriments, nice to have some science and the dyno data is interesting. If one is fitting one of those pipes would the carb have to be reset? I imagine so.



    http://www.oldrice.com/HondaXL250Dyno.htm

  2. #2
    Banned qwerty's Avatar
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    I have MUCH experience with early XL250s and exhausts. I raced enduros, flat and dirt tracks, MX, TT, and scrambles with XL250s, and rode one from Tennessee to Alaska and back. The first XL250 carbs were pre-EPA and were 2-3 mains richer than what is sold today, but any of those pipes would have required rejetting, maybe richening the midrange, but definately leaning the top end. Note that ALL the aftermarket pipes peaked and were losing horsepower at 7000rpm, and the stock pipe was still gaining at 7000 rpm. The red zone on these bikes started at 8000rpm. Extrapolate the horsepower curves and the clear horsepower winner is, drumroll please, the stock pipe. Make even moderate performance upgrades to the engine, and the difference would be even more apparent because all the aftermarket pipes in this test were already used up.



    Anything close to street legal with a USDA spark arrestor took weight off but made little difference in performance, or were worse than stock performance-wise. The only two aftermarket pipes that could hang with the stocker on a modified engine were from Kerker and Rocky. Both were virtually identical to the stocker with their baffles installed, but made definite gains on top when the baffles were removed. Both also saved about 8 pounds of weight. Take an XL250 out to 340cc with a Powroll stroker and big bore kit, port and polish the head with oversize valves, good carb and cam, and the Rocky without baffles walked the dog. 4 good 'ol boys on 4 XL340s took top 4 places in 4 dirttrack races on 4 consecutive Fridays, 4 Enduros on 4 consecutive Saturdays, and 4 MX races on 4 consecutive Sundays, and the local sanctioning organization banned stroker cranks.




  3. #3
    Senior Member Malkop's Avatar
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    Yup. I wish I could lay my hands on a stocker for my TW. Instead I might buy one of these kits and try and get some more horses and a longer life as claimed. What do you think of this deal qwerty? It's not so cheap for a TW but the price is the same for multi-carb bikes.



    http://www.ebay.com/itm/Yamaha-TW200...item35b5c550bd

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  5. #4
    Senior Member lizrdbrth's Avatar
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    I propose that as a gesture of international good will we exchange perfectly good Tw parts for perfectly good AG parts



    Edit: UPS and Fedex want $326-$370 USD to ship you a free muffler? So much for international good will....



    I can explain it to you, but I can't understand it for you.

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  6. #5
    Banned qwerty's Avatar
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    Quote Originally Posted by Big Torque View Post
    Yup. I wish I could lay my hands on a stocker for my TW. Instead I might buy one of these kits and try and get some more horses and a longer life as claimed. What do you think of this deal qwerty? It's not so cheap for a TW but the price is the same for multi-carb bikes.



    http://www.ebay.com/itm/Yamaha-TW200...item35b5c550bd


    I think you'll need some Vaseline. I've not seen any evidence the jet kits for TWs are any more effective than using jets from Yamaha and a washer under the needle. Oh, you get instructions for drilling the slide and a drill bit, but do so at risk of having to replace a $50 slide. Not to mention your OEM parts might be the good parts already--depends on the market. Depending on the year and market, stock TW200 jetting could have been #114, #116, or #118 for the early models, or #125, #126, #128, or #132.5 for the late models. Early models tend to like a #118, later models tend to like a #130 for most folks, with those riding at high elevations tending towards one size smaller.




  7. #6
    Senior Member Malkop's Avatar
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    Thank qwerty. I would leave it the way it was made and intended to be except that they reckon that the aftermarket mufflers with a bigger flow make the engine run lean and shorten its life. Is this so or is it hype? If its hype I'll leave well alone and not mess with it. It will not result in more speed anyhow.



    Hey Lzrd thanks for checking. Yeah there are some AGs going pretty cheap here and you could fly over and ride one home and write a book about it. You could get qwerty and a few hot babes to join to make a TV series. You might have to fit it to a boat to run an outboard for some of the journey. When I went to pick up some oil the other day the mechanics at Honda are complaining about the amount of stuff that has to go onto the Bushlander since they are selling like hotcakes with the current price $1000 less than their Yamaha and Suzuki competitors. I asked at Yamaha in Durban about used TWs and they said hen's teeth. They are on the farms and estates where they stay until they die and are not selling any new ones.



    Looking at price lists of stock muffler for my XL250R, it would cost nearly as much as I paid for the bike without shipping. Then looking at the prices of the German guy who advertised himself earlier on another thread for aftermarket pipes, I shake my head. Much more than i paid for a bike without shipping.



    Anyhow, my stock XL pipe is painted and looks and sounds like new. In fact even smells new. The only trouble is getting that secondary card to kick in now its back together after tearing down, rust blasting and painting. That's another story but maybe a good thing the TW's only got one.

  8. #7
    Banned qwerty's Avatar
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    Aftermarket pipes and mufflers may or may not require rejetting. Depends on the pipe, operating parameters, riding style, fuel quality, etc. Improper jetting can ruin throttle response, reduce acceleration, and cost several kph in top speed. TW jets are about $3.50 in the U. S. of A., and all North American market TWs are tuned poorly out of the box to appease the tre-hugging nazis. Rejetting is the best bang for the buck there is.




  9. #8
    Senior Member Malkop's Avatar
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    Thanks qwerty. I need to do a float needle job on the TW so will pull my jet out at the same time and report back with numbers when the XL project is finished.

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