Trials Australia Forums

It was discussed in a different topic the possibility of fitting a DT175 head to the TY175.
The DT175 head bolts straight onto the TY175 barrel and although the fins are longer the exhaust header fits with about 4mm clearance.

Based on a quick ride around the front yard it is certainly more powerful off the bottom and that advantage continues through to the top end.
Interestingly the carburation was quite ok with no changes, I will have to take it for a proper ride and see how it goes.

Compression Ratios listed:
TY175 = 5.8:1
DT175 = 6.8:1

Bore and Strokes listed
TY175 = 66 X 55mm
DT175 = 66 X 50mm

Based on my calculations you would end up with a compression ratio of 7.5:1 if you added the DT175 head to the TY175.

Interesting. But as we all know, power is one thing, - more important is how it's delivered. More power CAN be a liability instead of an advantage.

Very true Jools, however from what I know of Kurt he's a pretty handy Trials rider and will give us an honest appraisal once he's had it out in the bush. I'm sure there's others out there maybe seeking a little more oomph from their TY175's, this mod might be what they're looking for.

I'll be looking out for Kurt's conclusions. My Miller TY175 is sweet, but nothing is beyond improvement eh?
I do know that my 175 is twice the machine that my TY250 was (If only it had the 250's forks!).

Kurt wrote:Bore and Strokes listed
TY175 = 66 X 55mm
DT175 = 66 X 50mm

Kurt I like what you are doing to that TY.
I'm also wondering if this post is a test to see if anyone fully reads the posts on here because the stroke is the same on both of those motors (50mm)

Typo, surely.

A typo in the manual I have which I then copied

Which makes the compression ratio the same as the DT175 = 6.8:1.

The power does not come in savagely but the port timing etc hasn't been effected as we have only increased the amount the gasses are compressed.
It is still smooth off the bottom and doesn't seem to want to stall with the extra compression.

Looking forward to taking it for a proper ride.

It's my RDO again so I'm having fun in the workshop today.
After chemically stripping off the black paint from this early 1970s headlight shell, I noticed that there are a few solid rivets in the shell, made from aluminium.
I want to get rid of the rust before painting it. I could have taken it to a local workshop for dry blasting but decided instead to use my bucket of acid to remove the rust.
At first I was going to remove the rivets before the acid treatment, but then thought it could be fun to see how much of the rivets are left by the time the rust is gone.
Does anyone want to make a prediction of the outcome
The acid bath is diluted molasses with some added phosphoric acid. I hung the parts in the acid bath at 8/1/2023 11:30

Looks like the sandblast would've been the better option?

Jools wrote:Looks like the sandblast would've been the better option?

Yes it is but where's the fun in that?