03 CR 250 Exhaust bridge/Porting

[sandflyz]

I called my local dealer today to get some advise on weather or not to hone my cylinder before replacing the piston and rings. My cylinder is Nickasil plated and you can see where there are shiny spots on both the exhaust and intake sides of the plating. I'm not sure if this is because i waited to long to replace the rings or not. Anyway, i asked my dealer how much to hone my cylinder to clean out the footprint of my old set of rings. He sais to me "don't bother". just throw in you new piston and tings and be on your way. You can still see the crosshatching all the way around, it just looks like there was a tiny bit of scuffing.
You know if i diden't spend so much time on Dirtrider.net, I probbly would have taken his advise. My cylinder does deffinitly need to be honed though before i put in a new set of rings. Anyway, I diden't think this was a very good peice of advise from a dealer that makes his living doing this sort of work.
I will be sending my cylinder and head off to Eric Gorr soon as i have heard nothing but good things about his work and figured i'd try the Mo-Betta porting. As well i will have him releve the exhaust bridge where there is a shiny spot on the lower third of the bridge where it looks like the rings have been rubbing. The plating is still there but it is shiny. I know Eric will releve this area when he ports my motor but doesn't this mean in order to do this he has to actually remove the Nickasil plating in this particular area. I guess it doesn't matter if the ring will not be touching the area there anyway.I wonder about the transition area between where he will remove the plating and where the plating resumes again. Could the plating begin to flake in that area? If theres no one that knows, i guess eric will answer theese questions himself when i send my parts in. What about the porting. Is there anyone on here that regrets having Eric port their Cr?
One other question. If Eric decides to take a bit of material off of my head or cylinder, will my top motor mount still fit properly cause the jug and head will be a little shorter?

Thanks
sandflyz

 

[oldfrt613]

Worry not, Eric will take care of everything - you'll find the best seat of the pants improvement you can make. As far as the head stay, you need not be concerned. There is quite a bit of play for alignment when you put it all back together. Don't be too hard on your dealer, they're only regurgitating what the factory training tells them. Better to not hone than to hone wrong !

 

[skipn8r]

As well i will have him releve the exhaust bridge where there is a shiny spot on the lower third of the bridge where it looks like the rings have been rubbing. The plating is still there but it is shiny.

Don't be worried about shiny plating near the exhaust bridge. My original cylinder had a similar looking spot. I bought a brand new cylinder for my '03 to send out for porting and it looked almost exactly like my original; shiny spot on the exhaust bridge. Below are two views of the exhaust ports on my brand new (unmodified) cylinder.

View 1

View 2

 

[sandflyz]

yeah thats exactly what mine looks like. I feel better now. Its the worst shiny spot in my cylinder so i guess i'm ok. I got worried a bit as my dealer said the plating was only .002" thick. So if the rings are rubbing a high spot or something you gotta know its not going to take long to rub through the plating or snag a ring. Did Eric Gorr do the porting? How did you like it? If he milled the head or cylinder did you have to round out the top motormount holes to get it to fit back together? Oldfrt613 above sais its not an issue. I put the JD kit in mine to clean up the jetting and bought a V-force2 reed block. Right now it runs strong everywhere. Actually i emailed jd jetting and told them i was using the leanest needle in the first clip position and wanted to get some porting done on my bike. I said that since I am already in the leanest position i was worried that porting my bike would render my jd kit useless if i had to lean out any further. I got an email back an hour later telling me they would send another leaner jet needle to me free of charge. Great service and a great product. The Mikuni is a handful otherwise. Anyway, I figured since i was putting a top end in and had it appart i might as well send it off to Eric for the Mo-Betta everywhere.
Thanks for the pics

sandflyz

 

[skipn8r]

I posted my porting experience over in the Mods & Performance section.

http://www.dirtrider.net/forums3/showthread.php?t=124875

 

[john3_16]

If Eric decides to take a bit of material off of my head or cylinder, will my top motor mount still fit properly cause the jug and head will be a little shorter?

I just had mine ported by Eric and just finished putting it back together(except for the top mount) the other day and the top mount needs a slight modification...We're talking a very small amount here...After examining and determining what needs to be done I came to the conclusion that you can either slightly elongate the hole that bolts to the cylinder or you can elongate one of the holes that connects to the frame...Most likely the top motor mount will need some extra space....But not even a mm.
I'm going to borrow my buddies drill tomorrow to make the mod...

He had his modded by Terry Varner and he had to the same issue...But he just hammered the one bolt in that connects to the frame and made that suggestion to me but I don't like trying to force things like that.

 

[skipn8r]

I just had mine ported by Eric and just finished putting it back together(except for the top mount) the other day and the top mount needs a slight modification...We're talking a very small amount here...After examining and determining what needs to be done I came to the conclusion that you can either slightly elongate the hole that bolts to the cylinder or you can elongate one of the holes that connects to the frame...Most likely the top motor mount will need some extra space....But not even a mm.
I'm going to borrow my buddies drill tomorrow to make the mod....

Mine needed more like 3 mm (~1/8") elongation, but I'm at altitude and mine was a tight fit before mods. I'd recommend elongating the engine side holes only. If you mock it all up, you can see how you should elongate it parallel to the axis of the cylinder.