1979 IT400F. I need a 2X5 connecting rod. Anyone have one?

I bought a kit from England that has a rod that is supposed to be the same dimensions. I had my crank rebuilt by Bill Bune. Got the cases back together tonight and the rod contacts the case at the bottom of the stroke.

Just trying to think how you mean it contacts the case.
Do you mean the bigend eye is fatter diameter on the outside of the bigend so scrapes the case where the cases seal together in the centre.
Be unusual for that happening so must be me misunderstanding.
Just wondering if you mean when at bdc the piston underside contacts the wheels, like the rod is shorter.
Yamaha seem to change lengths in 5mm differences with conrods. I'll go study.

Not sure how i found this page or if it's up to date & relevant but says conrod length is 137mm.
But that's no help if its touching the case a bdc?.


dirtbikestore.co.uk/products/yamaha-it-4...cting-rod-conrod-kit

That's funny because that's where I bought the rod from but on Ebay. That listing has it listed as a 2X7, not a 2X5 which is weird. The big end of the rod does make contact with the case in several places during the rotation and stops dead at bdc.

I've talked to the guy from Dirtbikestore via email and he says he's sold 33 of the kits and only had one problem other than mine. He suggests getting the .7mm machined off the rod. The pic on the website you linked to shows the rod being machined but the one I got isn't. He said the pic is just a representation and not actual.

Very odd problem. 

2X7 is the IT250F

I'm going to clean up the stock rod and post some pictures tonight to see if you all think it is usable. The engine was locked up when I got it (had been sitting 25 years). Piston was stuck by corrosion, crank wouldn't spin as the main bearings were all bound up and the rod was really stiff. I've replaced the piston, had cylinder bored to match, replaced the main bearings, and had the crank rebuilt. Looks like I'll be sending the crank off to be rebuilt again.

If there was even a spec of corrosion on any of the rod bearing surfaces, it's likely to go bad quickly.  And best practice is to always replace races and bearings as a set...   Again, life might be shortened, possibly significantly, if you don't.

Might be best to use a belt sander or something and take a little off the OD of the new rod?  Maybe Bill Bune has some ideas.

I just emailed Josh at Bill Bune to see if they could do this. Would probably be the cheapest option. Thanks for the suggestion.

Great idea MarkT if you don’t have a belt grinder take it to a machine shop with your old rod and they could do it probably while you wait 

I cleaned up the stock rod at lunch. Too my plating gone from the bottom end. Waiting to hear back from Bill Bune.