Overall barrel dimensions for CR125 74/75 models

[suzuki27]

I have 2 barrels supposedly for 74/75 CR125. While both have the same bore, inlet and exhaust port dimensions ,one of the barrels has larger finning. Does anyone have an idea here?

[elsie 125]

larger finning is more likely a 76-77 cylinder

[suzuki27]

Thanks elsie.  I half suspected that. They look the same on the inside except for the larger finning.

[jimg1au]

i belive the 75 is different in the porting to the 74
cheers
jim

[dkupf]

The sleeve on the 76 is a lot thicker and won't go into 74/75 cases.Darcy

[ba-02-xr]

The 75 has a boost port above the inlet port. 73-74 does not.

[suzuki27]

Its looking very much like I bought a 76 engine in a 75 frame! The area where the engine number is supposed to be is blank. I thought it had a new left side engine case and replacements came un-stamped. It was advertised as a 75 model . Not happy.

[suzuki27]

Anyone know if a MR175 or anything Honda really has 'KT' stamped in the barrel beneath the exhaust outlet. After a bit more searching I found that the base gasket is the same for the CR125's- I looked from 75-78.
The larger OD sleeve in the barrel I have sits correctly in the cases- good fit. The 74/75 barrel I have fits on etc, but the OD of the sleeve being smaller leaves a pretty large gap between the sleeve and cases.
With no engine number to go on, I'm starting to think it might be a MR175 engine with a sleeved down barrel .
I checked some numbers and see the main bearings are the same in the MR175 and the CR125.

[elsie 125]

 you would most likely have 76, 77 78, cases, most likely your whole engine is 1976- 1978

[suzuki27]

Hi elsie, the KT has me stumped.The 76 and 77 barrels haven't got KT stamped on them- I believe
So is the sleeve a lot thicker (OD) on the 76-78 CR125's?

[Noel]

Bill
I doin't think the KT stamp is relavent to model, more likely a batch or manufacture code
I'll measure the OD of the sleeve tomorrow
Noel

[suzuki27]

Thanks Noel that would be good.

[Noel]

Hi Bill,
OD of sleeve where it enters the cases 76/77 is 72.90
Cheers
Noel

[suzuki27]

My one measures the same- 72.90 give or take.
The other CR barrel I have measures about 63.5 mm OD of the sleeve where it enters cases.
Interesting that the 74/75 case numbers supercede to the the later 76/7/8 numbers.
I believe all or most of the internals are the same.