facebook1 youtube1 twitter1 instagram linkedin1 pinterest1

NOTICE:  If you are not a free registered member of the site, you will not see the photos in the forum, and you won't be able to access our premium member content. Please consider joining our community! REGISTER AND MAKE THIS BOX DISAPPEAR!

×

Pictures Posting Not Working (12 Jun 2023)

Picture uploads is again unavailable. We are working on the problem. Thanks for your patience.

Makotosun

Substitute pistons for DT360

  • turbodan
  • turbodan's Avatar Topic Author
  • Offline
  • Site Supporter
  • Site Supporter
  • Posts: 423
  • Likes received: 346

Substitute pistons for DT360 was created by turbodan

I have whittled the list down to two prospective candidates, I was curious if anyone had tried them. Option number one is the Honda FL350R, bore size and wrist pin diameter is correct. Crown height may be a little higher. The dome height looks pretty close, though I don't have one in hand yet. This one is also intended for an air cooled engine, and I suspect this factors into the taper. Option number two is a Polaris Trail Boss 350, same bore sizes and same wristpin. I believe this is a water cooled engine though.

I see some people using a YZ400 piston but these start at 82mm I believe, would be a shame to bore that much meat out of this thing unless its necessary.

Any thoughts? There are few NOS pistons still available but probably not for long. Might as well solve this issue sooner than later.
The following user(s) Liked this Post: MarkT, mdscott, Snglsmkr
10 Jul 2020 13:13 #1

Please Log in or Create an account to join the conversation.

  • Posts: 2141
  • Likes received: 1412

Replied by mdscott on topic Substitute pistons for DT360

If you find a good replacement you will be forever remembered, we will erect a statue and promise not to tear it down. :ROFLOL
Keep us updated.
I have a DT360, MX360 guys will love you too.

Your next mission, turbodan, should you choose to accept , is to find a substitute for a SC500
Thanks Mark
Roseville, Ca.

'03 ST1300
'75 Norton
'73 CB500K
'81 Honda CT110
'87 PW50
'64 McClane Edger
'02 Honda XR70R
The following user(s) Liked this Post: Enduronut, MarkT, Snglsmkr
Last edit: 10 Jul 2020 20:06 by mdscott.
10 Jul 2020 20:05 #2

Please Log in or Create an account to join the conversation.

  • turbodan
  • turbodan's Avatar Topic Author
  • Offline
  • Site Supporter
  • Site Supporter
  • Posts: 423
  • Likes received: 346

Replied by turbodan on topic Substitute pistons for DT360

I think the SC500 guys are up shit creek. There are 90mm CR500 pistons available, surely someone has looked at those already though. Slim pickins in terms of two stroke pistons at that bore size.

I have the FL350 top end on the way. The only question is if it will require a spacer under the cylinder or some trimming of the skirts. Everything else looks good. I'll know next week.
10 Jul 2020 21:11 #3

Please Log in or Create an account to join the conversation.

  • Posts: 915
  • Likes received: 1252

Replied by Enduronut on topic Substitute pistons for DT360

.

"Necessity is the mother of invention" . . . so I applaud your efforts to search for a suitable replacement. :likey

That said . . . what size, and how many do you want?
For about the same price as a set of Wiseco FL350, you can get whatever Genuine Yamaha set you want from me!
I've been selling dozens of DT360 sets to forum members here for many years now, and still have plenty to go around.

But some day, you're right ... they WILL dry up.

oh btw, I have some SC500 sets as well ... but rest assured, you'll pay the fiddler for those.

.
Control your thoughts . . . or your thoughts will control you!.!
Don't aim . . . and you'll hit your target every time!
A wise man knows . . . he isn't!
Failure squared . . . equals success!
The following user(s) Liked this Post: MarkT, swm, Swoop56, Snglsmkr, Pedalcrazy, turbodan, cullyklyde
Last edit: 10 Jul 2020 21:37 by Enduronut.
10 Jul 2020 21:34 #4

Please Log in or Create an account to join the conversation.

  • Posts: 2141
  • Likes received: 1412

Replied by mdscott on topic Substitute pistons for DT360

Yes Enduronut, the SC500 pistons are at a premium. I sold mine a few years back, thank God.
Thanks Mark
Roseville, Ca.

'03 ST1300
'75 Norton
'73 CB500K
'81 Honda CT110
'87 PW50
'64 McClane Edger
'02 Honda XR70R
11 Jul 2020 07:55 #5

Please Log in or Create an account to join the conversation.

  • turbodan
  • turbodan's Avatar Topic Author
  • Offline
  • Site Supporter
  • Site Supporter
  • Posts: 423
  • Likes received: 346

Replied by turbodan on topic Substitute pistons for DT360

The Honda FL350 piston will require a 4mm thick spacer under the cylinder base and an additional base gasket. A shorter rod would work too. For now, I will make a spacer. Same thing I had to do with my KE250.

The Honda piston does not come with any boost ports in the intake skirt which is actually fine. You can put them where ever you want or leave them out entirely. This opens up some options with porting.
15 Jul 2020 21:11 #6

Please Log in or Create an account to join the conversation.

  • turbodan
  • turbodan's Avatar Topic Author
  • Offline
  • Site Supporter
  • Site Supporter
  • Posts: 423
  • Likes received: 346

Replied by turbodan on topic Substitute pistons for DT360

I will probably have this on the bike in the next few days. Deck height looks great.
The following user(s) Liked this Post: shyted
05 Aug 2020 20:34 #7

This message has attachments images.
Please log in or register to see it.

Please Log in or Create an account to join the conversation.

  • Posts: 9639
  • Likes received: 3915

Replied by RT325 on topic Substitute pistons for DT360

Looks like ya snuck some holes through into the transfers unless i need better glasses lol.
The 82mm YZ piston was one year only "79 long stroke motor & a good one too!!. prior to that all 400's were 85mm YZ & DT400. Actualy i think YZ465G in "80 was still 85mm just loger stroke, then 490 went to 87mm--by long term memory at the moment.
06 Aug 2020 15:42 #8

Please Log in or Create an account to join the conversation.

  • turbodan
  • turbodan's Avatar Topic Author
  • Offline
  • Site Supporter
  • Site Supporter
  • Posts: 423
  • Likes received: 346

Replied by turbodan on topic Substitute pistons for DT360

Your eyes do not decieve you. The intake port area seemed insufficient for a 351cc single so I added some boost ports in this jug. In addition to increased port area, these also allow the intake to respond to a pressure differential in the crankcase at any time, even BDC where the stock piston closes the intake port completely. If I were to install a good expansion chamber, this would be significantly beneficial.

Then again, I have begun to wonder if this motor would benefit from increasing primary compression, in which case I should have left the intake port stock and also omitted the windows from the intake side of the skirt. This is a potential advantage of the FL350 piston. Comes with no windows or boost ports. This would increase primary compression by isolating everything upstream of the piston skirt from the crankcase by 75 or 80 degrees ATDC.

I may order up another one of them in 80mm and try it in the stock jug I have on the bike currently. That would be easier than splitting cases just for an experiment in stuffing the crank and epoxying the cases. I'd be happy to do that though if the results are good.
The following user(s) Liked this Post: Snglsmkr
06 Aug 2020 20:39 #9

Please Log in or Create an account to join the conversation.

  • Posts: 138
  • Likes received: 198

Replied by YZBill on topic Substitute pistons for DT360


That is correct. When I got the 79 YZ400 I was told there were a few combinations of pistons/shims that would work. However I never heard concrete information on what to use. Luckily the bore was within spec and I was able to source a new IT piston and ring set from eBay. The 1980 IT425 uses an 85mm piston and has the same stroke as the 79 YZ and IT400.
08 Aug 2020 17:39 #10

Please Log in or Create an account to join the conversation.

Moderators: yamadminMakotosunDEETVinnieJames Hart