250SL pipe mod

[racerclam]

I'm doing something I have wanted to do for along time after Harry Taylor told me about all the garbage I the stock 175SL pipe as well as later combat wombat pipes. Two layers of wire screen mesh sound deadener, when removed he said that the stock pipe worked pretty good , so away I go. Here is pics of the inner workings. I got it all ready to weld together I'm about 5hours into it at this point.
I will keep you updated on progress and outcome.

Rich

[Bullfrog]

FYI - I did this same operation (internal screen-ectomy) on a Wombat 03 pipe once. Felt no difference by the seat of the pants and identified no difference on slightly uphill, 1/8th mile acceleration runs on a hard packed dirt/gravel road using a stop watch to time the runs. The Wombat 94A and 03 pipes are essentially the same pipe and I can't say that I'd recommend this operation on either of those pipes.

250 SL pipe is a different animal, it will be interesting to hear how the bike feels after the "screen-ectomy".

Ed

[racerclam]

Well Ed if it don't work at least I got to practice butchering and welding 8o)

Rich

[Bullfrog]

It is an interesting project in craftsmanship . . . and the specs on the 250 pipe could be bunches better than the specs on the 125 pipe.
Ed

[Darrell]

It is an interesting project in craftsmanship . . . and the specs on the 250 pipe could be bunches better than the specs on the 125 pipe.
Ed

This procedure is beyond the scope of 250SL owners that only have rocks and sticks in their toolbox, and the corresponding level of skill to use them.

Anyway, I'm wondering how many other ways the 250SL pipe is deficient -- and if there are any easy fixes to improve it.

For instance, at one point in its length the inner pipe has a short (about 3") section of fiberglass packing -- I don't know what the designers thought they would gain by working that token packed section of inner pipe into the design. Could anything be gained by unpacking the fiberglass and modifying the inner pipe to a straight-through design? Conversely, what about drilling more and larger holes in the in that section?

And this is just an observation, but I believe the SkyWay silencer has its own, independent from the main exhaust, spark arrester function. If the main and/or inner pipe also has a stand-alone spark arresting design, then you should be able to make modifications to the main exhaust -- and still stay on the good side of Smokey the Bear(?).

[racerclam]

Pipe Is welded back together now and painted , today I will reinstall and give the report on if it was a waste of many hours or not.

Rich

[racerclam]

YEA!! Got the pipe back on and tested , significant difference it even has a hit now . I'm glad that I didn't waste 10 hours cant say it was fun to do. Sounds like a 2 stroke now its not loud out the back but very dingy.

Rich

[hodakamax]

Rich, good job, experiments are creativity, sometimes they work, sometimes they don't. Not time wasted but time thinking and doing. The project looks good!

Max

[rtboone]

Greetings Rich

Congratulations on proving Harry's theory. Nice work. I'm glad that you didn't waste your time.

Do you think that this mod would work as well on a 250 SL with the stock piston port? It appears that you have a reed intake.

Did you need to alter the jetting to compensate for the less restrictive exhaust?

Did you modify the inner muffler pipe?

Do you expect the engine to run cooler as a result ?

Thanks ( I hope that's not too many questions )

Tom
P.S. One more question--- What work needs to be done to install a reed valve on this engine?

[racerclam]

I had to re adjust the idle speed and mixture the rest seems good, Should still work with a piston port just fine. The pipe with the spark arrestor that goes in the main pipe is still in tact and I'm sure it will run cooler,

Rich

[Hodaka250SL]

What adjustmentshould did ya do to the idle and mixture