IT125 interchangeability of parts question

[LWC82PE]

Does anyone know what engine parts are common to IT125 and YZ125? What is the IT motor based on, is it just a YZ motor? Looking for 1980 IT125 piston and rod etc and need to know if they are unique to the IT only or if bits from YZ fit? Is there a 175 top end that just bolts onto the 125 cases? Not many places list stuff specifically for IT 125 so I’m wondering if other YZ/IT stuff is the same? Thanks

[dave]

I'm pretty certain after selling Yamaha parts for years that IT125's derived their parts from earlier YZ125E - I just checked the crankcase No's and crank part No's which are the same as the 'E'! http://www.partforyamaha.com/pages/parts/viewbybrand/2/Yamaha.aspx here's the site if you want to check other bits yourself. Dave

[LWC82PE]

Thanks for that site. Has anyone got a Yamaha Zedder cross reference and can check what these part numbers are common to
It will save looking though a ton of different parts books online.

3R2-11651-01-00 – rod
3R9-11631-00-96 – std piston
3R9-11610-00-00 – standard rings
18G-11351-01-00 – base gasket


also what is the standard bore size for the IT125? Is there 2 sizes of YZ pistons from 76-82?

[Burgo68]

Hey, jump on this forum and all IT / YZ questions will be answered.
http://www.yamahait.com.au/

Cheers

[Nathan S]

Pistons are a bit confusing, but the short version is that they're all interchangable from 1974 to 1985 (even the DT125 and AT2 pistons will work, but they have a full skirt on the intake, with windows, rather than the MX/YZ cut away skirt).
The reason Yamaha has different part numbers for every year of YZ125 piston is because they were forever tweaking with the ring thickness and number of rings (and sometimes minor tweaks to the intake cut-away).
This means that you need to match the ring to the piston, but then they'll all go into any cylinder without worry - well, watch out for the YZ125A with the chrome bore, but otherwsie all interchangable.

Rods are much the same story. Some are beefier, some have a bigger slot in the big end, but they're all the same length until the YZ125H. The earleir YZ and IT part numbers were supersceded to the YZ125G's 3R2 ages ago.

The IT125 is a parts bin special, in the best Yamaha tradition.
Most of the bike is based on the IT175D (which is basically the same bike as the YZ125D). The front wheel is an AT1 hub with an alloy rim (like a YZ100 has), the side covers are IT175G, etc.
As far as I can tell, the only bits that are unique to the IT125 are:
Barrell and head;
Exhaust pipe;
Frame (just because it has different mounting points for the IT175G side covers).

[frostype400]

I have a zedder for yamaha Leith I will punch those numbers in.

[frostype400]

Rod
Part # = 3R2-11651-01-00
Part Description = ROD,CONNECTING
Model Count = 15
AT2 1972 125 AT2 Enduro Dual-Purpose
AT3 1973 125 AT3 Enduro Dual-Purpose
CT1 1969 175 CT1 Dual Purpose
CT2 1972 175 CT2 Dual Purpose
CT3 1973 175 CT3 Dual Purpose
IT175J 1982 175 IT175 Dual-Purpose
IT175K 1983 175 IT175 Dual-Purpose
YT175J 1982 175 YT175 ATV
YZ100C 1976 100 YZ100 Competition Motocross
YZ100D 1977 100 YZ100 Competition Motocross
YZ100G 1980 100 YZ100 Competition Motocross
YZ100H 1981 100 YZ100 Competition Motocross
YZ125E 1978 125 YZ125 Competition Motocross
YZ125F 1979 125 YZ125 Competition Motocross
YZ125X 1976 125 YZ125X Competition Motocross

[frostype400]

Piston std

Part # = 3R9-11631-00-96
Part Description = PISTON (STD)
Model Count = 2
IT125G 1980 125 IT125 Dual-Purpose
IT125H 1981 125 IT125 Dual-Purpose

Rings std

Part # = 3R9-11610-00-00
Part Description = PISTON RING (STD)
Model Count = 2
IT125G 1980 125 IT125 Dual-Purpose
IT125H 1981 125 IT125 Dual-Purpose

[frostype400]

no records on base gasket but couldnt you make one?

[LWC82PE]

No probs on the gasket, i just wanted to see if its common to something else which would then mean that a different barrel may fit. I will have a read of what Nathan says.

So basically i just need to order a piston and ring set for a YZ125 G and i would be right? does it have the same cutaways/skirt etc as the IT piston? Are they available in Wiseco brand?

And any 3R2 rod will be alright?

[frostype400]

yz125e head gasket came back as this

2X3-11181-00-00

Part # = 2X3-11181-00-00
Part Description = GASKET,CYLINDER HEAD
Model Count = 3
IT125G 1980 125 IT125 Dual-Purpose
IT125H 1981 125 IT125 Dual-Purpose
YZ125F 1979 125 YZ125 Competition Motocross

[frostype400]

IT175 and yz100 look a no go for the barrel to fit going on there head gaskets coming up in the zedder as it175 only suits it175 as yz100 only suits yz100.

[mainline]

Don't suppose you need a brake pedal do you? I bought a NOS one thinking it would fit my 125F, given the IT's being 1yr behind the YZ's idea, and it doesn't fit.

Also the parts manual (genuine) has a f***kup when it comes to the diagram of the brake/frame area, so that didn't help.

[metalskin]

dt125/175 gasket should work. i was looking into the interchangeability of parts for my dt, one thing i have learned
about it175's is the barrel/piston is a tiny bit taller than other yamaha 125/175 top ends but the stroke is the same.
(on the 175, dunno about the 125). cheers, metalskin.

[Nathan S]

There's three basic types of Yamaha 125/175 air-cooled top ends. Beware the 100 motors which have a shorter stroke, and consequently aren't directly interchangable with the 125/175 motors.

1. Early, with four long 8mm studs coming out of the cases. The barrel is sandwiched between the head and cases. All twin shock bikes and YZ125C/X and YZ175C have this set-up.
The YZ175 top ends may not fit on the others though, as apparently the studs are further apart to allow for both the larger bore and decent sized transfer ports.

2. Middle. Four short 10m studs out of the cases, that hold the barrel to the cases. Then there's 8mm studs out of the top of the barrel to hold the head on (125s have four 8mm studs, 175s have six).
All monoshock DT125/175s, YZ125D/E/F, IT125, IT175D/E/F have this set-up.
Beware the 85+ DT175 top ends - they run a shorter rod and different piston.

3. Late. Five 8mm studs out of the head. Fitted to all of the bikes with the engine with the chain on the RHS - IT175G+, YZ125G.
IT200 is similar but different - their longer stroke means that they're not a bolt-on fit. Also beware the change-over from offset exhaust port to centre port, begining with the IT175J.

Within the groups, you can mix and match top ends as you see fit - but watch out for stuff like exhaust pipe clearance against the cylinder head, exhaust pipe mounting to the barrel, and intake boot/reed block size etc. I can give you more detail on this if you've got a specific question.
Within the groups, the base gaskets are all the same.
The head gaskest are all the same as other bikes of the same capacity, within the same group.
Most of the bikes mentioned have interchangable conrods. The exception is the 85+ DT175 (as metioned). The water cooled YZ125s ran a slightly shorter 'rod (not sure if its the same as the 85+ DT175 rod - will check tomorrow).