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Thread: gs300l engine swap

  1. #1
    james750tz Guest

    Default gs300l engine swap

    I have a 1982 GS300 with a bad motor. What other motors will bolt in and be an easy/safe swap. As most of you know it is an inline twin TSCC. It's in reasonably good shape, but I don't want to put a bunch of money into it. I'd like to find a complete parts bike to do the swap with, but I need to know what to look for. I saw some 250 TSCC engines that look very similar as well as a 450 nonTSCC that looks like it might work. Any help is appreciated.

  2. #2
    mriddle Guest


    First I have ever heard the question . . you may be the pioneer here ..

    The frame of a GS300L is beefier than that of a 250 so my inclination would be to look for a 450 engine to initially.

    Does anyone here think that a more modern GS500 twin would work ?

  3. #3
    Join Date
    Jan 2006
    Near South Park


    I am sure someone here with a 425 or 450 could measure everything you need to see how easily it will fit.
    I would not go smaller, it's just wrong.

    Life is too short to ride an L.

  4. #4
    james750tz Guest


    This article is what made me think that it would work. It came from Other than the side covers on the early models, the bikes look identical. After about 1983 or so, the side covers even look the same. I found a 450 motor on ebay for $150, so I want to make sure it will fit. BTW, I only considered a 250 motor, because you can tell it is identical physically, so I know it will fit. I also found a 300L motor that I am going to pick up next week, but I am still trying to keep my options open.

    Last edited by james750tz; 01-19-2009 at 04:56 PM.

  5. #5
    james750tz Guest


    Look at this and see what you think. Note the starter and cam tensioner is missing off of the 300. The mounts look the same don't they?


  6. #6
    mriddle Guest


    I think if you can find a 300L engine that would be the simplest and keep the bike stock.

    Next I would try the 450 (after getting some measurements).

    My 2 cents

  7. #7
    makenzie71 Guest


    Depends on what you want...if you want to keep it simple, stick with the 300 motor. A 450 might work, but you're in for more effort and potential much more money making it work.

    If you want something crazy, while remaining relatively inexpensive, throw in a CR500R engine.

  8. #8
    SqDancerLynn1 Guest


    It is my understanding the later GS500 will not fit unless you use the older 450 style head because of the ex port spacing

  9. #9
    james750tz Guest


    Honestly, I'd be okay with the 450 motor if I knew for sure it would fit. I have looked at the documentation, as well as pictures of both motors. It sure looks like to me to be the same thing from a fit standpoint. According to the article, they are identical, but I'd hate to buy this motor and it not fit. It would be nice to use the 450s brakes too. I'd like to get rid of the crappy drum brakes on the front too.


  10. #10
    focus frenzy Guest


    Quote Originally Posted by SqDancerLynn1 View Post
    It is my understanding the later GS500 will not fit unless you use the older 450 style head because of the ex port spacing
    correct! it is the one problem as Suzuki moved the exhaust ports to clear a perimeter type frame, the ports point right at the front down tubes on the 400/450 frame. it is possible to use a 500 engine but it requires a custome made exhaust system.

    the 250 engine is a drop in fit.

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