toharsu crank problem

[leehall91]

Anyone ever see a crank do this ?



http://hallenbeckracing.webs.com/app...toid=111982356

[Mark75H]

Can't figure out what the pic is supposed to show Lee

[leehall91]

The space between the rod and throw! It has spread apart .

[dave dalton]

Crank is ' spreading" at pin ,from hi rpm's. 20 yrs. ago worked on buddys rz350(390cc)
motor was running up 10,000 rpm's m/c roadracing.It was doing same thing.
You need to rebuild crank & weld rod pins, problem will go away!!!..DD

[leehall91]

It is or was welded .

[Mike Schmidt]

Not wanting to cause problems, but PM me who did the crank. I might be able to shed some light on the problem if it who I think it is.

Michael D-1

[leehall91]

Mike pm sent . Anyone know a good "crank"guy ?

[Mike Schmidt]

Got your PM. Alex Policoff up in Richmond Maine has a real good crank guy near him that has done a bunch of Tohatsu cranks. Pete Nydhal is also real good. Rex Hall also does a ton of cranks. Any one of these three can help.

There is a very fine line when welding crankshafts. To much filler rod / heat input and the crank moves. Not enough of either and the weld breaks just like yours did. I like to use a small (3/16") rotary file and weld prep the pin / disk and then use 312 ss wire.

Welding a crank is a band aid for either a worn out crank or a crank that your trying to use for something that it was not designed to do. A good example is the Konig four cylinder crank. As a 350 or a 500 it works great. When you make it a 700 or an 1100 welding is almost always required to keep it from twisting.

Loctite also works on cranks pins that are marginal.

The reason I asked who did the crank is because a well known shop likes to hone the disk to make it easier to align the crank then they weld the snot out of the crank to keep it straight. Sure glad that these butchers did not do yours....

Hope this helps.

Michael D-1