So I have seen many posts on crank shaft issues when running a performance motor that has big torque. I am talking about welding the crank versus not doing so. Some here have stated that when you have a V-Twin putting out big torque, welding the crank should not be an issue, not necessary, simply an urban myth! Such as the 120r motor when the cam is upgraded that may produce ft. lb. of toque in the 120 plus range at low rpm's. Or if the crank is made by S&S, or in the case of the 120r is of tighter press fit..... no worries?. Now I have to disagree as the V-Twin, in the TC88 version, was making maybe 70 lb.ft. of torque in stock configuration. In the case of my 117" motor that makes 115 lb. ft from 2000 to 138 lb. ft. at around 2700 rpm's and up I should not have bothered welding the crank? If a 120r with a stock high reving cam that makes toque in the high rpm range maybe not.....but if you add a big torque cam that comes on in the low rpm range all should still be well??? I see comments on the 124" motor not needing to be welded.....how long are these motors going to last before crank issues surface? Unless you baby the hell out of them they are going to have issues and why would you go to the expense of such performance and not weld the crank? Pinch a few pennies? So my question is simply this.......what say you?

 

I guess a lot would have to do with how you ride, just because your bike produces high HP and TQ doesn't mean that its being used all the time? If your a red light racer or like burning up your tires all the time then it should be done, But even tough my bike can put down the power doesn't mean I use it all the time. If I'm touring two up and weighed down I like the extra power and torque to pass the logging truck in front of me on a two lane so I'm not getting blasted with tree bark!

I did lose the crank in my 106, so I can see getting it done on my 106 and my 120r but not until I start modding the 120r.

I'm riding the hell out of my 120, put about 10,000 miles on in the last 7 months I've had it put I ride it pretty normal. I plan to get another used touring bike and then I'll have the crank fixed in my 106 that's sitting in a crate in my garage and install that into the used bike. After that I'll think about having the crank done.

Having a crank pulled, done and reinstalled isn't "pinching pennies"! Its pretty costly for some of us that can't do that type of labor ourselves, I'll be pulling and reinstalling mine but I'm still in an unpacking phase from moving for now.

 

For a street bike...unnecessary! I have hung with many all out dragsters and any serious racer/builder has the crank welded, trued and balanced first thing. Just sayin'.

 

For a Twin Cam bike? Oh yes... on a 117, I would for sure weld the crank, and I would have Hoban Bros do the job, too. If you send them the cases... they will align bore the crank holes in the cases so that everything is nice and straight.

I have a 120r, and I did NOT weld that crank. New S&S cranks need NO welding. Both have different crank plugs than stock. If I was bagger class racing... I WOULD weld up the 4 5/8 SE crank. (120r crank).

If your crank is actually in decent shape and you wish to save some money... you could have Falicon weld it or have Randy from Hyperformance weld it. Randy does excellent work for a couple hundred.

Twin cams are pressed together as opposed to SHovel/Evo cranks. The weak point is the factory uses a crank plug that looks like a freeze plug. Good cranks use a solid plug instead. Once S&S went to solid plugs... is when I started to tell folks those are great cranks.

I twisted a crank to .0045 on a totally stock 09 bike with Andrews 26s. When I installed the 26s, the crank was at like .002

 

It might be an urban myth to some but not to me. Below was the result of not welding my 98" crank. From now on my motors are built from the bottom up. My 120 crank was sent out brand new to be plugged/welded.

Rick

 

So at what point is crank work necessary?

1. At a certain cubic inch size
2. At a certain Ft Lb level?
3. Dependent on street or race use?

I did a lot of research prior to my 107 build and while there is certainly a crank failure story to be found out there, the great majority of quality 107 builds without crank work are running strong 10, 20, 30k later.

 

rev performance ( a well known builder) recommends crank work for anything making over 120 foot #.i don't have the qualifications to argue with them.

 

If I touch it, I start a the bottom end, I had my S&S welded because I still have plans for a blower on my bike. but if I wasn't going to do a super charger I would have left it alone because I believe in S&S cranks. my moto is do it once and do it right.

even the Harley 110" I wouldn't buy unless I knew the crank runout.

 

How are you gonna know that by just accepting someone`s word, and Harley sure won`t tell `Ya.?

 

if you can , have it welded , if not hope for the best , my 07 stock 96'' twisted at 41000 , 07s had a history of bad cranks but it can happen