Super Jet Servicing a 701 crankshaft

[1579]

Just curious, has anyone ever serviced there own crankshaft? I have a couple of spare cranks (one 650/701 and one 1100/1200) with dead rod bearings on the coupler side. I see I can buy the rod, bearing and pin only on ebay. Does anyone have a replacement how to? How do you go about "Truing" the crank?

I know I am going to get told to send these in to the machine shop, but I'm more interested in the process. Didnt see much on youtube.

I have acess to a 50 ton press and torches... Can I do it myself?

thanks
brandon

 

[Matt_E]

This requires very specialized tools and knowledge. I would not recommend it.

 

[1579]

Hey, just wanted to say thanks for your case porting thread, planning on porting some 1200 cases I just picked. Up. Great thread.

Did yamaha ever provide any service information on crankshaft rebuilding? In the shop manuals I see nothing, some specs and that is it. "Replace" only. I realize this is probably because of the special tools and knowledge that is required to do the job properly. Still, yamaha must have provided some information on the process somewhere, no?

thanks
Brandon

 

[Andrew1289]

You can do it. If your have access to the strong enough press I'd imagine you have access to people with the knowledge to disassemble and press a crank. Sounds like you just want to get the broken crank to work.

You might be better with just a used crankshaft, financially and mechanically.

You need the press as well as V blocks and micrometers to help with balancing the crank correctly. To be honest it kind of a crude process but the end result (checked with micrometer and v block) is very precise.

 

[WFO Speedracer]

I have done it numerous times before, by the time you buy the parts, even if you already have the tools its not worth it.

 

[BruceSki]

I had Patch motors (moto360) do my crank. All pro-x bearings and rods. It was about 450 in parts alone. He does great job though. Send him the parts and let him do the labor.

You can buy cheaper bearings and rods, but I wanted to go with as close to OEM spec as I could. I don't trust WSM stuff.

 

[WFO Speedracer]

I had Patch motors (moto360) do my crank. All pro-x bearings and rods. It was about 450 in parts alone. He does great job though. Send him the parts and let him do the labor.

You can buy cheaper bearings and rods, but I wanted to go with as close to OEM spec as I could. I don't trust WSM stuff.

Funny thing there , back when I first got into business I used to buy engine a lot of engines from SBT, I had quite a few failures, I switched over to USA short block which used all WSM components, never had a single engine failure, I also got quite a few cranks from Nancy @ Playtime power sports, they use all WSM components same deal, no failures.

 

[1579]

Hey guys

What I am really trying to get an idea of is the process. I have a small machine shop down the street that will service the crank for a reasonable price. I am trying to understand what is involved in case I get the chance to watch him while he works(this was the case with some cylinder heads he rebuilt for me and a crank he polished for me a few years back). I would love to gain some knowledge out of this rather then just sending my crank off in a box and getting it back ready to rock. Plus shipping over the boarder always costs extra, so I'm going to try to buy parts/service locally.

thanks for the replies/thoughts so far.

Seems that the special tools needed so far are

Shop Press - Min 20 ton
V Block set
Dial indicator

What am I missing?

Thanks
Brandon

 

[WFO Speedracer]

You are missing the jig to re-index the cranks with, the pullers to remove the bearings, the jig to hold the crank true while you press it together, the spreader to go in between the crank webs while you install the new bearings, a crank truing stand (you can do it on vee blocks but its not nearly as accurate) and a set of dial indicators and stands, (you can do it with one dial indicator and stand, again not nearly as accurate) and last but not least a good selection of brass hammers to true the crank with. Now someone with the proper experience may be able to rebuild your crank without all those fancy tools but (refer to vid)

 

[1579]

Haha so now we are getting into the good stuff. Still doing my homework, but so far a "trued" crank is one that is in proper alignment as per FSM specs? And a trued and welded crank simply has the rod bearing "pins" welded to the throw, or counterweight part of the crankshaft?

To assemble, thee crank is pressed together and then beaten into spec with brass hammers? Am i close?

Sincere thanks for the info so far.

 

[WFO Speedracer]

Haha so now we are getting into the good stuff. Still doing my homework, but so far a "trued" crank is one that is in proper alignment as per FSM specs? And a trued and welded crank simply has the rod bearing "pins" welded to the throw, or counterweight part of the crankshaft?

To assemble, thee crank is pressed together and then beaten into spec with brass hammers? Am i close?

Sincere thanks for the info so far.

Yes but its much easier to pres the crank together in a jig than to have to try to get it straight after you press it, I have literally spent hours beating cranks into submission

 

[1579]

Heated alot I'm sure? This is pretty interesting. My hats go off to the crank builders out there. That sounds like a pain...!

 

[#ZERO]

Some PWC engine remanufacturer had a video of the crank truing a while ago and it revealed a special hand operated tool that was placed between the crank webs to properly phase them before welding the pins instead of using the brass hammer method for a making slight adjustments. If you don't have a granite flat surface used for measuring the crank with the v-block method you can use a lathe with precision live centers to check all the tolerances and deflection points.

 

[Andrew1289]

An axe.