Welcome to Netrider ... Connecting Riders!

Interested in talking motorbikes with a terrific community of riders?
Signup (it's quick and free) to join the discussions and access the full suite of tools and information that Netrider has to offer.

Honda Spada rejetting required?

Discussion in 'Maintenance and Servicing' at netrider.net.au started by FrenchGrabber, Aug 20, 2012.

  1. Hey everyone,

    I just have a quick question regarding the Moriwaki Tourer full exhaust found here (http://japan.webike.net/products/1020013.html).

    Has anyone else purchased this for their Honda Spada? If so, did you have to change your main jet in your carb?

    I have contacted customer support, but their answer was kind of vague:
    > Basically, It is not need to change the main jets in your carb.
    > But as the case may be you can change the parts.

    If anyone has any experience with this exhaust and has changed the main jet, what size did you use?




    Thanks,

    Joel.
     
     Top
  2. Wow $700 for a Spada muffler? That's like 1/3 of the total value of the motorcycle. The extra power available after rejetting will be negligible. Definitely not worth the cost.

    If you must replace the exhaust try eBay. Just the can and adapters should be no more than $200. I doubt welding is necessary.

    I didn't imagine Spada's were in Canada. Oh and welcome to NR.
     
     Top

  3. They're normally not in Canada. I purchased it from a guy who imports Japanese bikes.

    I agree $700 for an exhaust is a little high, but I only paid $1400 for the bike so I can justify the extra for the exhaust. Especially since whoever did the exhaust on this one did a bit of a botch job on it.

    I'm not too concerned about the power when it comes to rejetting, I'm more worried about the bike running too lean with the muffler being removed. I've seen the results of a bike running too lean, the large hole in the top of the piston doesn't look fun to fix.


    Cheers,
    Joel.
     
     Top
  4. I would hate to be one of these people who tell others how to spend their money, it's your $$ after all and if you want it, go for it!

    But I would like to just mention a quick aside, you said the previous owner botched the exhaust? Did he screw up the whole system, heads and all? Because I must admit it does seem a little excessive to add a full exhaust system on a 22ish year old 250. Have you considered just the can?

    In regards to the jetting question, try the guys over at vtr250.org or vtr250.com, they have US version of the older VT250F and a couple have put on full systems if I remember correctly. They should also be able to talk to you about the correct jets and so on needed, including part numbers.

    I hate those carbs with a passion, I find them really difficult to get back into the rubber boots so changing the needles (pulling them on and off to play around) sounds like a nightmare. Good luck!

    Would love to see some photos if you do get the full exhaust!

    Cheers,
    John
     
     Top
  5. Unfortunately, they cut the original exhaust and put a straight pipe on it. When they installed the new straight pipe though, it was too short so they had to mount it on a really short tab that has left the exhaust pointing on a 60 deg. angle directly at the rear foot peg.

    This means the better half can't ride on the back. I'm not complaining too much as it's more fun to ride solo :p but it means less riding when she's around.

    On top of that mess, the rear exhaust outlet where it clamps on is so old it doesn't even clamp properly any more so I tend to get a little exhaust directed up at me when idling, which will probably make me start seeing things if I idle too long.

    Thanks for the tips with the other forum, I'll take a look and see if I can find something.


    I'll definitely post pics when I get it installed.


    Cheers,
    Joel.
     
     Top
  6. The stock pipe is welded on the Spada, so this is your only option.
    The rest of the job does sound like a botch, but the right slip-on can will fix all of it too, I'd say.
    Please post pics, regardless...
     
     Top
  7. I know it's almost 2 years later, but I finally got the time to install the Moriwaki exhaust! When given the choice between going for a ride or replacing the exhaust, I always chose to ride :p

    I love the new sound of the bike, and installation wasn't too bad. The biggest pain were the clamps around the can.

    After translating the instructions to English, I noticed it said that the exhaust was designed to run on the stock system and that the main jets are not required to be changed.

    I might have the jets checked anyway as I have to take it in to get the carbs properly balanced.

    Before and after pics are attached below:
    old_exhaust.
    new_exhaust.

    Cheers,
    Joel.
     
     Top
  8. The power and cost is not the point. If the changed flow conditions are large enough then it will effect the way the bike responds to throttle. The smaller the engine the more obvious it becomes. So whilst the economics might be more questionable smaller bike, the improvement to riding will actually be greater.

    Then there is the reliability side. A more free flowing exhaust can cause you burnt out exhaust valves and/or make the engine run hot.

    As to the benefit, a 5% improvement (for example) is 5% regardless of the capacity. I'd say that's more important on a 250 than it is on a 1000. This is because you can't use the last 5% on a 1000 (on the street) but you can on a250.

    All that aside, to the OP, if someone buggered with the exhaust that much, who knows what they did to the carbie. Get it cleaned, tuned and get it checked out. If the last owner didn't change jets, then it might be alright as it is. Honda do tend to run a bit rich, so opening up the exhaust flow brings it back closer to stoichiometric.
     
     Top
  9. Thanks for the info!

    When I first purchased the bike I completely stripped it down and cleaned out the carbs. I didn't really have a choice since they were completely gummed up and weren't letting any fuel through.

    On a side note ... does anyone know where the carb adjustment screws are located on the Spada? I was thinking of building a manometer and attempted to balance the carbs myself.


    Joel.
     
     Top
  10. There are three adjustments. One is to balance the two carbies. This will be located in the linkage. All you are doing with the balance process is getting the two butterflies synchronised. Phillips head screw with the rusty spring below.
    kusu2hiro2-img600x450-13112331301d9jap45966.
    Again, quite important on a small capacity bike.

    The next adjustment is an idle speed adjustment (or throttle stop). As you get the balance better you may need to reduce the idle speed. Black knobbed screw below

    kusu2hiro2-img600x450-1311233130flhfgw45966.
    The third adjustment is a idle mixture screw. This sets the mixture a idle, but also effects the way the bike responds to initial throttle input. If you get a hesitate when you open the throttle to accelerate (regardless of speed) or get popping on closing the throttle, then the problem may lay here. Again, it needs to be balanced with idle speed screw.

    This last screw was covered by a "plug" on some bikes, in some countries, for some years. look to a bike specific forum on how to get it out. Shouldn't be hard. The Spada carbs are a different arrangment, so I'd only be guessing about the location of the idle mixture screw,
     
     Top