Hi, I have a 1976 YZ125 with a 1976 DT175 engine. I was wondering if a YZ left hand side case/ignition cover fits the DT engine casings? Thanks Justin.

What are you trying to accomplish? 

The 76 YZ125 ignition cover will not fit a 76 DT175 but there could be other options that do.   

Ok cheers Mark, I have a YZ cover on the right side and was hoping to match it on the left. Does the later one piece cover fit. See attached.

I'm not clear on what you're trying to "match"?

I'm pretty sure that you have to go back in time...  74-75 YZ125 ignition cover should bolt on to 1976 DT175 cases...  but the early YZ125 cover might not fit over ignition if you're using the larger DT175 ignition system.

 

Hi Mark, To cut to the chase. I just got hold of a YZ125X (European spec chassis 1J8-001480) somebody put a DT175 engine in it (1G1-102043). I think its 1977. I want to build up a period (1976 YZ125) engine once I get the correct main cases and was hoping to use some of the DT bits. IE: the crank etc. What if any of these engines share the same internal bits. Cheers

Unfortunately we never got the 1G1 but from what I've seen it is very much the same as a 1976 US DT175 engine. 

I would not be surprised if nearly every part from the DT could be used in the YZ engine if you tried hard enough.  The biggest challenge might be the shift drum and trans...  YZ had a 6 speed and I'm not sure if it was 76 or 77 YZ where they went to the big hole in the left case for the shift drum?  If so, then you'll need a 6 speed YZ trans and shift drum for the YZ cases.

The other thing is you can just bolt a 76 YZ top end onto your DT175 cases since you swapped the right side cover already!.  The ignition cover might be different (76 YZ and TY for some reason were) as we discussed. 

But if you want to use most of the DT parts you have for sure you could just use the whole DT bottom end and just get the YZ top end.

(The DT175 in a YZ is a pretty fun bike...  I'd try a top end swap before spending too much...  You might decide to stay with the DT175 top end?)

As a final note, from 69 to 81 the 125/175 kept the same shaft spacing etc.  With not very much fabrication I was able to install a 6 speed trans into 1970 CT1 cases...  I mixed and matched parts from several years and had to manufacture a couple pieces (getting the 6 speed drum to fit was the most challenging... I'm pretty sure I used a 1G8 YZ drum I machined and added a shaft to)

Biggie on the crank is early models were splined, later were keyed...  but the DT175 engine you have should actually have the same crank as the 76 YZ125 with the exception that the DT175 takes a wider small end rod bearing than the 125's... crank and rod should be the same though. 

Thanks Mark, great stuff, very useful info. I'll keep you posted on my progress.