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Post by philip on Oct 15, 2012 12:17:24 GMT 1
Is it worth while boring out my barrels to fit DT175 Pistons in my Yamaha RD350LC and due I need to machine the heads to suit?
Thank you
Philip
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Post by billbott on Oct 15, 2012 12:46:21 GMT 1
I'm no expert but think you will have to machine the base of the barrels because the pin height is different.
I'm sure an expert will be along tonight to clarify.
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Post by marddy on Oct 15, 2012 13:54:00 GMT 1
Yes, I too tend to think so. The Cylinders need to be shaved by a few MM to suit the height of the pistons.
There is a concept called Long Rod Motors where-in they use a longer con rod on a RD 350 crank and use DT pistons. We get a swept volume of almost 400cc + a lighter crank that revs more than the 400s.
I am unsure the exact specs but am sure you will be able to get to the bottom of it.
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Post by Norbo on Oct 15, 2012 15:26:50 GMT 1
You are both corect yopu do need to shave the barrels when fitting DT175 pistons . and the use of 115 mm rods is all so a good mod insted of the standard 110 mm rod . it gives more torke to the motor but sp[acers need to go under the barrels . I am talking to a place now that im asking to make some 4mm stroked cranks with the 5mm longer rods as well to give the very best performance you can get from a crank in standard cassings
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Post by marddy on Oct 16, 2012 16:58:54 GMT 1
Nice to know that Norbo. I would like to try this set up too.
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Deleted
Deleted Member
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Post by Deleted on Oct 16, 2012 17:15:37 GMT 1
remember norbo i amyour long term tester, banshee racing coils still running fine
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Post by rich on Oct 16, 2012 19:27:23 GMT 1
i may be mistaken but don't you bore 250 heads etc to fit the dt 175 kit  No but you can bore 250 barrels to '275' using a/c DT125 pistons. The barrels don't need shortening like the 375 either. I had a 275LC with a proddy tune and it went like sh1t off a shovel  oops, sorry I just re-read and realised you were talking heads and not barrels. Not sure about the 375 but I have heard that 250 heads can be reprofiled and used on a 350 as there is more meat to machine and you get more compression due to the smaller combustion chamber. |
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yaddy
L plate rider.
Posts: 26
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Post by yaddy on Oct 16, 2012 21:52:31 GMT 1
If using a standard crank with dt175 pistons, you will need to shorten the cylinders as suggested. Take off the bottom, not the top!
Also, you do need to re-profile the head for best performance. It's a better option to re-work the 250lc head to fit the 375lc cylinders.
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Post by lckid on Oct 16, 2012 22:17:54 GMT 1
If using a standard crank with dt175 pistons, you will need to shorten the cylinders as suggested. Take off the bottom, not the top! Also, you do need to re-profile the head for best performance. It's a better option to re-work the 250lc head to fit the 375lc cylinders. prob right there best bet is to call Fahron racing they do the conversions (I have one on my 250LC) but i thought you can only do the 375cc conversion with 250 barrels and not 350 but im not 100% on this?  |
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Post by Norbo on Oct 17, 2012 8:47:12 GMT 1
350 just get bored out and 250 get relined and shortened frankly Its far better tio use IT pistons not DT any way . 350s get very thing when you bore them the apsoloot best thing do is
250 barrels relined rinning IT175 pistons reprofile the head
Put an O ring in both barrels to take a TZ750 O rings and instent gasket for the water jacket.
All so you will need to grined out the top casing so the ports flow and dont ghit a ridge
That is for a standatd set up after that to get more cc and extra power but a ofset 4mm crank with a 115mm rod and a spacer under the barrels but be shure you tell who ever is doing the relining if the barrels waht tyou are doing so the ports can all be matched up .
These things tend to blow if you dont ajust the port timings after fitting a stroker crank as the ports go to high with the spacer you need. It all has to be done at the same time .
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