DT175 engines/conrods...

[Nathan S]

The wife has an 88 DT175 - this is the safety-seat/boost-bottle model, basically the same as you can buy new. It was bought rattly and low on compression, so we knew it was up for a rebuild.

Well, it sure needs a rebuild! The rod has over 1mm of up-and-down movement in the big end (!), the rings were sooooo thin it was remarkable that it ran...
Shit! This was supposed to be going to the Vinduro on the weekend!

Anyhow, my questions are:

Does the 'late model' DT175 motor run the 66x50 motor (like the earlier monoshock ones), or the 64.5x54 motor (like the RT180)? (Our bike is on 66.50mm which means it could have started life as either bore size).

Are the conrods the same as the earlier bikes, or a different part?

Anyone got a spare motor/bike...

[Noel]

Hi Nathan,
drop the TY motor in,  it was running before I pulled it out
Noel

[Lozza]

No spares, I would doubt very much if the dimensions of the humble DT have ever changed.Better factor in a set of bearings in the rebuild.

[Nathan S]

TY engine might get me out of trouble for the weekend... Why didn't I think of that?

Lozza, it surprised the crap out of me, but there's quite a lot of differences between it and the earlier monoshock motor. Piston height, reed block, port lay-out, blah blah.

[Freakshow]

thought by 88 they were 200's ?

[Nathan S]

They ran in parallel.
The 200R (and the rare, earlier 200N) were the all-singing, all dancing water cooled, power valved, semi-YZ replicas, but the humble old 175 was kept in production as the cheap, simple, unpretentious beginner's/farmer's bike.
My nearest dealer still has a couple of 2006 model DT175s on the floor - apart from the front disc and the paint job, they're the same bike as Anna's 88 model.

Yamaha did the same with the single cam XT250K - kept making and selling them for years, in parallel with the disc braked, twin cam XT250N.

[cyclegod]

You can modify DT175's with a lot of the stuff they use in Blaster quad engines, you could probably make your 175 into a 200 quite easily as they share cases & bottom end parts 

[Lozza]

Going massively oversquare in dimensions compromises transfer duct areas in a serious way.The big bore banshee/rd/rz engines never see thier true potential because of it.

[Tex]

Based on the fact that the RT180 shares the same styling as the later DTs, I'd think that the motors are the same. I don't think the RT180 was ever sold here though.

Tex

[Noel]

IT175 rod kit on ebay at the moment
Noel