Advice on Rebuild

[RockefellerGG]

2005 EC250
3 parts are damaged and I need some advice on the path forward.

1. Crankshaft - Needs to be rebuilt. The needle bearing, and inner washers are in bad shape/destroyed. I can pull off the inner bearing ring and order the rod rebuild parts. I've seen companies like R-B Designs will rebuild the crank for $60. It looks like they get it balanced and run-out minimized. Is this necessary?

2. The cylinder has a good gouge in it. I'm not sure that it can be repaired. Sleeve it? Replate? The rest of the cylinder looks to be in good shape.


3. The head has some gouges too. Replace with a used head? Wait until the end of the rebuild and have it machined and do squish mods at the same time?

 

[RockefellerGG]

FYI - I have a press and I can press apart the crank. It is the reassembly I'm worried about.

 

[RockefellerGG]

I started watching videos of reassembly and the jigs used... for $60-100, having it rebuilt professionally sounds best.

 

[coopernicus]

The cylinder and head are repairable for good shop. Buying a used head looks to cost the same or so as getting one fixed. I've seen the work by PowerSeal USA (Pennsylvania) and it was very good. I've heard good things (and some other things) about Millennium Technologies so they would be worth a shot, too. It would be nice if you could figure out a way to get the squish checked before you sent the head off as that would save you some time and money. I've heard that if you balance your crank, that it can be a very good thing (most good MXers I knew back in the day used to do it when they got their motors modded). I would certainly get a 300 crank balanced! On a final note, you may want ask if they could mod the head to match the dome of the piston. Colorado has a 2T great tuner (Bruce Sass) who recommended and performed the work for me and I was very happy with the results. When done, this mod re-shapes the combustion chamber and removes the "step" that is in the stock head and, when completed, the shape resembles an MX head. Please note, however, this may entail a complete "re-jetting event" to match any work you have done. Good luck and keep us posted!

Eric

 

[hadfield4wd]

I've used powersealusa many times and am pleased. They have done great work. Out local race shop uses them exclusively. Powerseal can do the head as well.

Also for cranks have a professional do it. I've used mrcrankshaft.com and have been pleased. He's done 6 cranks for me and friends.

 

[Jakobi]

I'd pay to have the crank trued. I'd even consider paying a little more for someone to really see if they can get it dialled in.

Biggest challenge will be getting the base stack, cylinder, piston and head all matched up for a nice tight tolerance.

 

[RockefellerGG]

Thanks guys.

I'll be sending them out this week. There's no way to do squish measurements at this point.

It sounds like a great option as long as there is some money in the budget.

 

[Zman]

You can do the bottom end and cylinder first and after they are finished you can measure the squish and get the head done.