rebuilding RM250

[rippedrm250]

undefined The riding season is almost back for the Northeast and I want to completely check my engine top to bottom. I was looking at EricGorrs to maybe send it in to him but w/ everything Im wanting done would cost close to 1,000$(top/bottomend+overbore) this leaves me with basically one choice try it myself w/ the help of a manual. how hard would this task be on a scale of 1-10? would it be better to send in just the bottomend and do the top myself to save money? also when i called a local shop they told me the '98 (nikasil plated) cannot be bored only replated i hope this is just a bunch of BS

 

[Chili]

It can be bored and then replated.

 

[snb73]

rippedrm250,

I am pretty mechanically inclined. I removed, rebuilt and installed the motor in my 73 vette. When my RM250 engine started to seize, I chose to send the whole thing to Eric. Since this was the first bottom end done on this motor, I wanted to make sure it was done right. Their are some specialized tools needed sometimes. For me the aggrivation factor wasn't worth saving a few hundred dollars. 4 weeks and $700 dollars later, I bolted it back in. It ran great. It sounded and felt much "tighter". Keep in mind, I asked Eric to do a basic rebuild with no performance mods.

My suggestion would be to save up the money and have Eric do the whole thing. Definately the easier way to go.

Hope this helps, Steve.

 

[blanc]

My advise would be to do the oppostie....rebuild the bottom end yourself with the manual. Get EG to do the topend....clean powervalves.Overbore, prob better off with porting if racing and renickelseal!!!

 

[rippedrm250]

i have a few more weeks to decide how i want to go about this before it needs to be started so im going to keep asking/looking around for the best way to go about it. my dad is the head machinest/engineer at a molding factory so if theres no speacial chemical to strip the nikasil im going to have him do the top end and install a sleeve from la or advanced sleeves.. think i might just call eric and see what he has to say about it all

 

[nickyd]

dude, what are you talking about stripping the nikasil? is something wrong with it? ONE of the main reasons its there is b/c it will make the cylinder last longer (ie, old cast cylinders used to wear AND the piston would wear) - now with the plating, the wear will be on the piston - and IN MOST cases, not the cylinder....so that when you rebuild, you are simply replacing the piston and not worrying about the cylinder being out of round, worn past specs, FORCING you to bore, etc...NOW if you really want to do a larger bore take the cylinder to a machine shop - they will bore out what you have and then either replate or sleeve the cylinder

pull the top end and inspect it...plating still there and in good shape? if so, clean the p-valve and order a STOCK sized piston.....of course measure the bore and make sure its good.

while you are there, check the crank - measure for side deflection and MOST importantly, up and down play....if its TIGHT, try rocking it by grabbing the flywheel - if there is not rocking, the bearings are fine. If they check out, ride the bike....bikes are like anything mechanical - if they are in spec, they are in spec....if not, fix what's wrong. hope that helps...

what the shop told you was correct - you don't bore a plated cylinder as part of routine rebuilds..if you want to step up the motor size - different story.