top end swap

[caps 999]

question will a it175j top end bolt onto a yz100j bottom end

[Nathan S]

Pretty sure the 100s have a shorter stroke, which will bring you undone.

An IT175 top end will bolt onto a YZ125G bottom end (and presumably a YZ125H one too, if you can deal with the un-used water pump).

[caps 999]

according to climer the 125j 100j and it175 have the same stroke and use the same rod kit

[cyclegod]

question will a it175j top end bolt onto a yz100j bottom end

YES YES YES , but you have to change the rod as the pin size is different at the piston end or change the YZ100J crank for a YZ125G crank as they use the exact same crank parts (as YZ100J) but have the correct 175 rod for the conversion. If you look at a 175 barrel and compare it to the 100 you see that they are the same but that the 100 is massively sleeved down.

100J rod is  4V2-11651-00-00
175J rod is  3R2-11651-01-00 

Both those part numbers are for 100cc bike 4V2 is YZ100H and 3R2 is YZ100G

Heres what you need....
http://cgi.ebay.com/ebaymotors/Yamaha-YZ100-YZ125-MX125-YT175-Connecting-Rod-Kit-76-79_W0QQcmdZViewItemQQcategoryZ34284QQihZ004QQitemZ140221671536QQrdZ1QQsspagenameZWDVW

[caps 999]

in this case has any one got a it175 head and barrel ang a good 125g crank

[Tim754]

Check ebay item number 220228807615   Cheers Tim

[cyclegod]

If you're checking with the wreckers ask for prefix 5X8

[TT5 Matt]

beware of cut back gears [not full width gear teeth] just the differences i noticed between dt/it 175 gearboxes of the same era,could be abit much grunt for the box to handle

TT5 Matt

[caps 999]

should be rite i checked ypic and according to it the centre cases are the same part# for the yz and it

[cyclegod]

should be rite i checked ypic and according to it the centre cases are the same part# for the yz and it

Don't forget to post pics of the finished product (and your grin) after its ready

[caps 999]

wiil do ill post a before pic when i get home from work (shhhh)

[evo550]

Why stop there, why not just bolt a complete it200 motor into it.

[Hoony]

or just go and get a 500cc 2 stroke and be done with it. 

[caps 999]

i still wanna keep it lookin like a 100

[Tim754]

Hey Caps while your the little screamer was here at my place I did happen to measure it re fitting a real engine. Failures Honda 754, Honda XL350, Yamaha XS650, Kawasaki W1/2 650  Ducati 860  .. Kawasaki H2 750 and H1 500 triples. Possibles with a bit of work Kawasaki S2 350 triple, Yamaha RZ 250/350 (Mmmm  ) ,  Honda 500/550 4, Ossa 250, Victa 160cc . Easy fit Yamaha IT175/200 and easiest of Yamaha all YZ100.