2003 KX 250 SF Conversion

[umberto]

I never thought about wider, but always felt like my 07 was just longer than my 03s and my 04.  I may be wrong, but it sure looked and felt like it was.  You're absolutely right about the handling.  My 04 would turn circles around my 07.

[zz3gmc]

Ive fiddled with my 07 and have come to terms with its handling. I like it a lot in tight, technical terrain (does great pivot turns) but when riding in more open terrain I just dont trust the front end. Likes to knife and wash at times. There is a fix on here that involves changing the steering head angle by cutting and rewelding it. I have thought about doing it in the future. Im still faster on the 500 hybrid! It handles great!

[umberto]

I measured the 1988 head that I got off eBay, and the bore is 88 mm.  The head that came with the motor is 86 mm, so if I want to use the eBay head I will obviously need a new piston (Wossner makes one).  The engine displacement calculator I found online said this combo would give me 523 cc.  Do you guys think I should go that route (my life insurance is paid up), or should I try to find an 86 mm bore 1988 head on eBay?  I think the sleeve on the eBay head is okay, but I don't have that much experience with non-coated cylinders.  Is there anywhere I can send the cylinder to that can evaluate it?  Thank you for the advice!

[dave916]

I measured the 1988 head that I got off eBay, and the bore is 88 mm.  The head that came with the motor is 86 mm, so if I want to use the eBay head I will obviously need a new piston (Wossner makes one).  The engine displacement calculator I found online said this combo would give me 523 cc.  Do you guys think I should go that route (my life insurance is paid up), or should I try to find an 86 mm bore 1988 head on eBay?  I think the sleeve on the eBay head is okay, but I don't have that much experience with non-coated cylinders.  Is there anywhere I can send the cylinder to that can evaluate it?  Thank you for the advice!

I would u the ebay cylinder {if there is wear u would feel with your nail on Exhaust side /3mm below TDC where the rings stop
May be better to use a 88mm head gasket as well
The old wiseco with the cut out at the side are the lightest piston u can get
not sure if this is a old one are not but pretty cheap
http://www.ebay.com/itm/WISECO-PISTON-BIG-BORE-KIT-1988-2004-KX-500-88MM-/271802068221?hash=item3f48aa6cfd&vxp=mtr

[umberto]

The cylinder has some light marking, but no grooves at all.  I think I should be okay.  I am going to try a Wossner piston, Foxx and Sandblaster seem to really like them. 

[umberto]

Luckily, there was no side to side either.   All in all it seems to be a very solid motor. 

I wasn't that impressed with the 88 KIPS valves, they seem to be made of some pretty cheap metal. I wasn't able to locate any 86 valves.  Do you know if the later model valves will work?

All the KIPPS  valve 86/88 will interchange/ alloy and steel {
IF  You had a steel set i think the should last for ever
The steel one have a narrower stem than the alloy ones

I took your advice and found a set of 86 steel valves on eBay.  I hope to have them installed in the cylinder head this week.  Sandblaster was nice enough to help me with getting an 88 mm Wossner and goodies so I can start putting the motor back together, which I hope to do this weekend.  I'm heading to my parents for Labor Day, and there are a ton of places to ride in Southeastern Oklahoma.  525, here I come!   

[umberto]

Got the exhaust valves cleaned up and installed.  They fit without any issues and work very smoothly. Now I'm just waiting on the rest of the parts to arrive.  Thanks for the tip Dave916, I feel a lot better about the steel valves in there. 

[sandblaster]

It shipped to me so hopefully I'll have it SOON!

[umberto]

I can't wait to see a Wossner piston first hand, they look like works of art.  Thank you again for your help in getting all that stuff ordered, Sandblaster!

[umberto]

Got some goodies from Sandblaster Claus today.  Ready to start assembling the 525!!

[zz3gmc]

I have a 87mm weisco, what size would that be? Its not in the bike, Im running the oem piston in mine.

[umberto]

It's an 88 mm.  It fits the head I bought on eBay that was sleeved.

[alexander-vmann]

I have a 87mm weisco, what size would that be? Its not in the bike, Im running the oem piston in mine.

i think 87 is stock (check your manual)

[DoldGuy]

I have a 87mm weisco, what size would that be? Its not in the bike, Im running the oem piston in mine.

KX511.24

[DoldGuy]

I have a 87mm weisco, what size would that be? Its not in the bike, Im running the oem piston in mine.

i think 87 is stock (check your manual)

86mm is Stock...