I'm getting ready to do the top end on my 1989 Suzuki LT250R Quadracer. Well I am trying to do my first top end rebuild and took it in to see if they could bore it out or hone it or what it needed. He said he would go ahead and bore it after looking at it. Then I mentioned the piston had cracked and he said that if they are too loose in there they will crack exactly like I described so basically I would have to bore it out to get it the correct size. Well he said it looked like it had been bored a time or two already but still could be done a few more times before I had to worry about problems. Well people on another forum tell me that they wouldn't do it and think I might have to change the air box and carb to feed power to it. Is this true? They were saying it would probably also put more stress on the whole engine. Is this true should I worry about it? Basically I think my options are new cylinder or boring. What would you guys do?

 

First off you never bore until you have your new piston. You must take measurements of it to know how far to bore. Anybody that wants to bore first you better run. Also first measure to see what your current bore is and order the next size piston and take it somewhere reputible and have them bore it should be around fifty bucks.

 

Yup they said they had to have the piston first but would measure to see what size I needed to order and it was $50 to bore. Another place quoted me $75 but that sounded way too high to me and another $42 but was an hour drive so not really worth it to save $8. What all do I need just the piston kit and gasket kit? This is my first top end. He said something about a bearing what do I do with that? I don't remember seeing any when I took it apart.

 

the piston kit comes with a new bearing and c-clip and stuff.

 

It is very easy to do a top end. I will run you through it first order a piston kit make sure your kit includes wiesco piston, top end gasket kit a new bearing not all kits will have a bearing make sure you get one also should have new pin and clips. after you have your cylinder bored. clean away all old gasket material and put on your new base gasket. I always apply a thin coat rtv sealant on the gasket with my finger dont run a bead just lightly wipe a thin layer. Assemble your piston on the rod make sure the arrow is facing towards the front of the engine. Make sure you put the rings on the right way they have a beveled edge and line up the rings where they belong on the piston and compress them, An extra hand is a big help here. lower down the cylinder and tighten bolts to spec I think the cylinder bolts are 6mm 6 to 8 ftlbs 8mm 19 to 22 ftlbs head nuts are 19 to 22 ftlbs I also always apply a thin layer of rtv on the head gasket as well again make sure you just spread it with you finger very light coat. Tighten everything to spec and fire it up. Give the bike a good break in time before you hit the throttle

 

make sure you replace the 2 wrist pin washers too!!

 

Ok shop called and told me they would bore it and get the piston kit and bearing and gasket kit for $195 that was only slightly more than Rockymountainatv.com I don't know if it has a Weisco piston but I sure hope so I probably should have asked but oh well. He said he would have to bore it I think he said .68 or .068 whatever it is over and I didn't see a piston that size on Rockymountain anyway so I'm not sure but he said it still has room to bore more and will be fine at that bore. Anyone know how many CC's I'll be looking at with that bore?

 

Do not use rtv or other sealants on the gaskets. it is not necessary and just creates problems when you have to rebuild the top end again. just make sure you get the gasket surfaces very clean. a sharp puddy knife will do just fine. i have see too many stupid people using files and such cleaning gaskets and ruining the jug or case.

 

you can buy gasket remover and it will take all the crud off the top end from burt gaskets

 

Yeah stock bore is 67mm if your at 68mm he should get you a 68.50mm or 60 over and that should leave two more bores Good Luck