My 83/250cr crankshaft

[Bigbill]

I sent my 83/250cr crankshaft to kem O’Connor racing to be assembled. I emailed him today and he had a question. He never seen so much play in the connecting rod in the crank. He wasn’t sure about the husky so he waited to be sure and ask me. I like that better to be safe than sorry. As we all know the thrust washers on the wrist pin keeps the lower rod journal centered on the crank pin. There’s a little extra clearence there for expansion and oil.
No copper or bronze washers on the crank pin. But I’m very happy that Ken waited to ask me. I have more husky cranks for him to install new HVA rods in.

I have a used 500cr crank where the lower rod makes 1/8 turn circular when you turn it. The bearing is probably shot. I have a new hva rod for that one too. Kens next job. He has a custom made fixture that presses them. Way faster than I could. He’s on you tube I’m very impressived with his work.

 

[hva-factory]

Correct. The 250s use a shim / washer either side of the small end to control rod float, but the 430 does not. Never did work that one out, but I am about to rebuild my 300 with no control washers - so the small end gets more oil...

Most engine manufacturers put bronze washers on the big end to control this - but Husky did it on the small end. I can see their thinking, as on the big end you have the possibility of friction through rotation where as on the small end the rod is only arcing back and forwards a little....

The 500 uses nothing - so my guess is that they are in the 250 as it is higher revving....

Andy.

 

[Bigbill]

The 390 uses the two spacers on the upper rod wrist pin bearing. I guess we could use a wider wrist pin bearing.

 

[grouty]

I use a Wossner piston that will not accept the small end spacer washers. So I use a Kawasaki small end bearing that is wider to make up the gap.

 

[jimspac]

The connecting rod is piston driven because the spacers in the piston center the rod within the crank. Crank driven rods(spacers within the crankcheeks) control the side to side float in the piston

 

[Bigbill]

Your right guys.

I finally purchased some good used cranks too that show how tight the rod was when they were new. This tells me it might not be fin ring we are hearing. I wonder if the 250 top rod spacers were left out by some owners. I have assembled basket cases were I had to add the thrust washers. Just another thing to lookout for.

 

[hva-factory]

The trouble with the small end spacers is that they seriously limit the amount of lubrication the small end bearing gets. The small end on one of my 300s has just failed due to lack of lubrication, so it is going back together with a wider small end bearing and no spacers....

Andy.

 

[Bigbill]

The 390 small end spacers are thin rings to keep the rod centered in the piston. I prelude everything with a moly paste and 2t oil. I believe in letting the choke stay on when warming it up to fog and mist the crankcase. I’m also planning on using a 20-1 castor oil mix too. I think not using the correct oil ratio is the problem to premature wear.

 

[GaryM]

If you want bean oil better to use Maxima 927. Cleaner blend but with bean oil molecles Now after Barber vintage festival seminars, I will always wnat to break
in any bike with standard not syntheic oil

Great experiance with good old oil Golden Spectro. Uses classic oil base stocks in making his oil. Upon two different after break inspections , surprised at coating of oil
all over the metal parts. Bearings, crank, cylnder walls. Yep it that base stock of oil creating a surface tension and clinging and coating the surfaces

Before was using super m. It was not coated the same as golden sprectro. ALmost like the syntheic was yes washing ovver the metal , doing its job , but weas not clinging
also kind of like water beading on frexh auto wax. Top two- golden sprctro, Maxima 927. 32 to 1 is much better that 20 to 1

Remenber goal of oil is to float and cling to surfaces. Noted at barber from two different semiars that rod bearings are like surf boards and ride on a wave of oil as they rotate
at speed. No metal to metal.

Why on ratio , gas is cooling as it flows through engine and lower end bearing and rod bearing too much oil is hotter. Bill watch the break video again from Ken O conner why do you think he is turning throule up and down so much , nice cool gas and nice rush of oil.

Of all things in the Barber basement , warming the bike did something smiliar each time old bikes were started. Nobody was idling them and before vintage races the same thing both four and two strokes

 

[Bigbill]

Maxima 927 is a blend of synthetic and castor oil. I was thinking about breaking in my new engines using castor 2t oil first. They recommend one tank of castor oil to break in the rings. Then switch to 927 at 20-1 mix.

 

[GaryM]

may be too much oil at 20 to 1 re read the kleem page. Again talked about at Barber - you want what is a called a dry break in.

That does not mean no oil on piston and bearings but oil just enongh not to stop break in. Remenber the reving of engine that ken does that also
brings in a fresh charge of clean gas and oil. If too much oil on cylinder can linger , get hot, gum wall, piston can start too have small
fretting lines. Thats why new feedback has us reving up and down. Now Ken has us doing 3 temp cycles with full cooling.
You know what the rep from wiseco said to me he wanted up to six cycles. ? Less time on each run at first, complete cooling. Then cycle
again WOW I said ? Why does not anyone tell us this. This is how i got on this kick asking why i have some small fretting lines on my pistion from those
first break in with lots of oil. I did just a few years ago.

I removed fretting lines on pistion with mico shotpeening after break in. I sent this out to be done. This has no dimensional pistion material removed , just the fret lines.

Oh, those lines are small melting points on a new pistion. I still believe the lack of lead in gas is a major reason in the old days i did not see this.

This is not me making this up, comes from other engine builders with years of experiance, ken s you tube video, kleems site. etc. And asking a lot of questions.
Some dumbs ones too. LOL

 

[suprize]

ran in a new kato 300 on 75:1 full sunthetic Motorex (thats nuw Zuland for synthetic ) with no probs, changed to 100:1 and ran 50 hrs. piston was within limits and clean as. put new rings in to be sure. dont get to excited about oils..
ps dont do this with an aircooled engine......

 

[Bigbill]

That’s a nikasil cylinder(chrome) with chrome rings. The synthetic 2t oils are a very good lubricate.

There’s a gas station that sells the older blend of gas non ethanol.

https://www.pure-gas.org/index.jsp?stateprov=CT

 

[squid on a 300]

The trouble with the small end spacers is that they seriously limit the amount of lubrication the small end bearing gets. The small end on one of my 300s has just failed due to lack of lubrication, so it is going back together with a wider small end bearing and no spacers....

Andy.

Andy or anyone else..i'm going to be putting a Wossner in my 79 CR...it had a Mahle with the spacers in it...what size small end bearing should i use without the spacers on a 250 with the Wossner?
thanks
Bob

 

[Bigbill]

The trouble with the small end spacers is that they seriously limit the amount of lubrication the small end bearing gets. The small end on one of my 300s has just failed due to lack of lubrication, so it is going back together with a wider small end bearing and no spacers....

Andy.

Theses spacers have been in these bikes since they were built. My84/250wr is runs like a new bike but I’m not sure how long it was in the barn. These spacers center the lower rod journal on the crank. Less frictionand less wear.

 

[grouty]

Andy or anyone else..i'm going to be putting a Wossner in my 79 CR...it had a Mahle with the spacers in it...what size small end bearing should i use without the spacers on a 250 with the Wossner?
thanks
Bob

The reason I use a Kawasaki bearing on my 390 with the Wossner piston is that the bosses where the rod and alloy spacers go is narrower than it used to be. I have this bearing in both my 390's without any issues. It does allow more oil to get to the small end, which is greatly needed. The gap between the ends of the bearing and the piston are the same as it was with the ORIGINAL Husky pistons and the older Wossner.

Bill ..... pistons have changed over the years. They are way more advanced than they were when they were new. I saw a problem, and solved it.

 

[Bigbill]

It’s narrower in the after market piston than the orginal. Oh crap the new pistons aren’t the same. Do you have a measurement of the wider bearing or part number.?

 

[Bigbill]

The trouble with the small end spacers is that they seriously limit the amount of lubrication the small end bearing gets. The small end on one of my 300s has just failed due to lack of lubrication, so it is going back together with a wider small end bearing and no spacers....

Andy.

Your right Andy.

 

[grouty]

Bill, I had a quick look earlier, but could not find the part number. It is a common KX250 small end. I'll try tomorrow.

 

[Action Jonny]

I get the argument that pistons have improved in 35 years, but so has bearing quality. When Husqvarna designed these engines, surely they must have anticipated the lubrication problem, but thought that keeping the con rod centred was more important. I've just built mine up with spacers so I'm hoping they were right!