GT750 Crank Rebuild (bill bune, miss matched rods), issue?

[JSJamboree]

Just got my crank back from bill bune. One of the rods were bent on the old crank, so they needed to replace it. I got it back yesterday and they replaced the bad rod with an old version rod. Its in the middle of the crank so the different in weight wont matter, and its not 'correct' but will it really cause any other issues? Its going to be a fiasco to get them to take it back and swap out to a correct rod im sure. The sucky thing is that i even called to ensure they used the correct rod and they said they did..

[pearljam724]

Hold them accountable. They are responsible for using correct parts. You even warned them of it. Be kind and try to get them to work it out for you. If not, you may have to take further actions. Which is a pain too. But, these things aren't cheap. I was told on here, the rods are no longer available. So, what is the deal with that ? I'm guessing, it won't cause a problem though. As you stated, it's centered in the middle. But, why should you take that expensive risk ? If you insall it, then the accountability is out from underneath them. Tough decisions.

[GT750Battleship]

Absolutely,stand you ground totally unexceptable,I'm sure the weight difference would cause a "headache" of some description I'd also be worried about lubrication to the little end bearing without the eyelet
Sorry to here this,
Cheers,
Roger

[pearljam724]

If they were stuck with using an odd ball rod. Then they were still responsible for letting you know prior.

[pearljam724]

Roger, made an outstanding point. I'm sure, that was the whole idea of changing the design in the rods in the first place. But, let's give them the benefit of the doubt in that perhaps that was the only rod they could obtain. It's still there responsibility to notify you of that circumstance, first. You could have had a decision of going with 3 matching rods. I wouldn't worry too much about the crank balance. I know they balanced it. I know they knew of the part discrepancy. I would only worry about the end bearing as Roger stated. Knowing your dedication involved. I wouldn't let that pass. If you install it and the piston seizes a few years later as a result of the bearing. Their hands are clean. You deserve what you payed for.

[tz375]

The issue is not weight, even though the crank was not balanced at the factory or when rebuilt. The issue is that the rod design changed slightly to improve lubrication.

Early rods were 22mm wide at the big end and had thrust washers
Late rods were 21mm wide at the big end and did not have B/E thrust washers

Late rods have Small end thrust washers and they were changed to have an oil slot and 2 holes to get oil mist into the little end.

Small end on early rods is 22.01mm and later rod is 21.79

Q: What year is you crank and what rods were on it when it was shipped to BB? I don't recall seeing a picture of it.
Q: Does it have big end thrust washers on all three rods or just the center one or not at all?
Q: How wide are all 6 crank wheels - 28.5mm or 27.5mm? They should All be the same.

[Suzukidave]

I am surprised at Bills shop for making a mistake like that .. i am sure they will fix what they did wrong , still the hassle of sending it back

[tz375]

To be fair to Bill Bune's guys, the crank they were sent for spare parts had been rebuild previously and had two old rods and one new one so they probably just chose the best of the three. They probably also assumed, incorrectly, that either rod design was OK to use.

On the flip side, they should have known that the rod design changed and are not readily interchangeable.

The question is really will it work with small end thrust washers and if so will that significantly restrict oil mist to the pin.

[pearljam724]

To be fair to Bill Bune's guys, the crank they were sent for spare parts had been rebuild previously and had two old rods and one new one so they probably just chose the best of the three. They probably also assumed, incorrectly, that either rod design was OK to use.

On the flip side, they should have known that the rod design changed and are not readily interchangeable.

The question is really will it work with small end thrust washers and if so will that significantly restrict oil mist to the pin.

They work with cranks everyday, all day. Regardless, of knowing a rod design changed or available. They knew that one rod simply did not match. Under all of those circumstances. The customer should have at the very least been warned of it prior. Sounds like, he wasn't and even went to lengths to warn them of this. Unless, the customer told them specifically to use what ever they needed from the spare crank to save money. Which may have happened. But, he makes it sound as a surprise.

[tz375]

In this case, the added complication is that the donor crank that was sent so they could harvest a rod and main bearings was a hybrid and had both types of rods on the same crank. That crank was supposedly rebuilt by someone in Michigan and not only did it have one odd rod, but it also had damage to one oil slinger from the stripping process and several of the crank wheels were badly rusted where the seals run.

Most of that was not visible and the crank had not been run since it was "rebuilt" with two old seals and three new seals.

My guess is that they saw that crank and assumed it was OK to mix and match. We know it's not OK to mix old and new style con rods but I would venture to suggest that very few of us here knew that a few days ago. But BB are professionals - they are supposed to know.

The point of this thread is not for the OP to work out how pissed off he is with the world, but to determine what needs to be done - if anything. He will probably call BB and talk to them and work out a solution.

[JSJamboree]

Thanks for the help up to this point guys, what im trying to ensure here is that I get a good reconditioned crank that will work properly in my bike. Per TZ i went and took some measurements.

L 21.8 (upper) 20.5 (lower)
C 22 (upper) 22.5 (lower)
R 21.8 (upper) 20.5 (lower)

Now, I went to look for thrust washers (my spare 72 crank as thrust washers) I didn't find any on the lower ends. To make it worse, there is CRAZY SIGNIFICANT PLAY side to side with the rods. I took a video to show this, I'm not motor expert, but Ive never seen a crank do this, and it seems to me this could cause some major issues down the road. https://www.youtube.com/watch?v=nTzH1HHnq34.

EDIT: I measured the gap between the two counter weights on the one bill built and are between 10.6-10.9, I measured the distance on my 74 crank (the one thats rusted into a single piece) and they measured 10.5-11. I cant see any washers on the 74, but they could just be hidden under all the nasty. Maybe the play is expected in a later model crank then. Is anyone able to remember theirs, or have one they can check? The distance on my 72 crank is only 8.8-9.1, and includes thrust washers. There is 0 slide back and forth in the 72, but again, maybe that was a change for the later model cranks that is expected. So there is no confusion, this is going into a 75 motor, the 72 is a spare I have laying around.

They also seemed to use some sort of grease on the bearings, Ive always been told never to use grease like that in a 2stroke chamber as it'll just gunk up and ruin everything.

I don't have a good picture of it prior to going off, this is the best I have which doesn't provide much. The crank I sent was a 75 crank, and it had all new style rods. I should have paid more attention to it, but I didn't expect to need to.

[Suzukidave]

72 & 73 cranks have thrust washers on the big end and none on the small end , also the pistons will be more narrow at the small end . 74 and later.. no thrust washers on the big end and thrust washers on the small end with matching wider gap pistons .

[tz375]

Dave did a nice job of posting pictures of what I was trying to describe in words.

Your measurements are spot on and correct. So is the crazy amount of side to side play at the big end. They returned all 6 big end thrust washers from the 73 crank and have used the later style big end spacers, so that is all spot on.

The only open issue is how to lubricate the small end of that center rod. With thrust washers in place at the small end and without the slot or two holes in the small end of the rod, there is no easy way to get oil mist into the little end bearing.

The question for BB is whether they think that will be fine or if they recommend a change to later rod or can they drill the holes and gut a slot in the small end to get oil mist into the bearing. Or would they prefer to get the crank back and re-do it with a later style rod.

[dyrberg123]

Hi guys.

Look the small end trust washers for the later style rods, is that common? I have had 2 gt 750 previously 75 and 77 and both where without those washers, and i didnt know..

Not sure if the pistons where suitable for them either.. will mitaka and cruzins pistons have the correct 21,79mm width?

So are you all using those washers, and where can i get them if needed on my new gt 750?

[Suzukidave]

If your later ( 74 and later ) engine has the proper crank without the thrust washers on the crank end of the rod there should be thrust washers on the rod small end . You just have to be sure there is the extra space in the piston for the thrust washers , if someone had fitted up early style pistons there wouldnt be space . The thrust washes are available from Suzuki .