Hey,

Im taking my first fourwheeler apart, it is an 86 lt250r, I got the top end off and I am wondering about the rod I think its called, (what the piton connects to), anyway how much play from side to side is allowable. On my lt, if you push the rod to one side there is about a 1/2 inch inch on the other side, but on my girlfreinds blaster, the rod barely moves at all. The next question is, If I port and polish, add a pipe and new reeds, would it gain me anything to add a bigger carb. If I do have to replace the rod is it a big project, consider that I am moderatly mechenical,(I can follow my clymer manuel pretty good) and have a limited amount of tools, (am willing to buy what I need when I can afford it). Is this something I can do or will I need to have someone else do it, and what will I need to replace. What does something like this cost to have done? Im sure i have more questions, ill keep thinking. Thanks in advance, you guys have been a huge help.

 

also the piston has 05 stamped on it, so what size do I need to order next?

thanks

 

the lower end of the con-rod on the LT's is considered a floating end( and thus will slide sideways about 1/2"), the top part should have thrust washers that help it locate close to the center of the crank. the way that you measure the wear on the lower con rod is by rocking it and measuring the ammount of play at the top end of the rod.
a larger carb is a must if you're porting the cylinder. as is an aftermarket pipe. cost of porting varies by who's doing it.
go to harborfreight.com and get a caliper.... they put a good digital one on sale occasionally for $20 and it is worth having. use that to measure your cylinder, depending on the condition of the cylinder walls you may need a bore, but usually just a hone job does the job. your pistion having 05 marked on it makes me belive that your bore is 0.050" over stock.... but you can't tell without a good caliper. here's the link to the caliper

are you just doing a top end or are you doing bottom end too? that question can only be answered by careful inspection of your con rod bearing and main bearings... also, the ammount of difficulty increases doing a bottom & top vs top end only... you have to split cases and deal with the transmission too.

 

Thanks for the info, just bought a caliper(thanks for the link) I am rebuilding a blaster to, so i needed one for that also. I would like to just do the top end, but I had read in the blaster manuel about clearences for the blaster rod, and my lt manuel doesnt say anything about it, only to check the bearing. so I wanted to check it out.

 

as a general rule, you can hold the crank still while pulling up & down on the rod... if there is any play you need a rod kit installed... which means splitting cases and pulling the crank, and if you're in that deep... put in new main bearings and seals as well as all new oil seals, gaskets & reeds.... then you have a strong motor top-to-bottom again

i've now done it on 3 '90-91 LT motors, and helped on a '86 LT motor... in the near future i'll be doing a couple more too.

 

ill be honest with you. if you dont know what a rod is your better off having someone else do your bottom end. there is going to be many things to screw up down there and after the 3rd time having to tear into it you will be wishing you let someone else do it [img]i/expressions/face-icon-small-smile.gif[/img]

 

86ltr

First off on the piston size. The numbers stamped into it could be as follows:
STD = stock bore
0.25 = 10 over (the 0.25 is mm's over stock size)
0.5 = is 20 over (this is what might be on yours)
0.75 = 30 over
1.0 = 40 over
1.25 = 50 over
1.5 = 60 over
2.0 = 80 over

Now as for the bottom end rebuild. If you feel it needs done I would have someone else do it or find a buddy that you trust and that has done it to help you. Splitting the case and having to deal with the transmission and all the other little things change be a big chore for someone how has done it before.

I think for now I would add the reeds and FMF Fatty pipe system and maybe a 34 to 36mm carb. If you have someone else do the bottom end of the quad go ahead and have them polish and port it. The bolt thing will give you a HP increase and the port and polish will help to make it more useable for the type of riding you do.