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View Full Version : Do you think I need an engine rebuild?



leprekawn114
03-22-2009, 06:22 PM
I have an 87 lt250 I picked up about a month ago. IT has an FMF pipe, bored to 260, and slightly new plastics. It usually runs good, but the past two weekends Ive taken it out I've barely been able to ride it. The seal around the foot shifter gave out and was shooting tranny fluid all over the place...I had just got that fixed Thursday then left for Glamis on Friday. After a few trips around, I came back and had coolant spitting out of the top of the jug (The bolt towards the front of the jug, all the bolts point up with nuts on them and this one points down). The coolant spits out when I give it gas. I tried tightening the bolt but it seams that the inside of the jug was stripped, and the bolt looked fine. Would it be safe to ream it out a couple mm or do I have to get a new jug? Should I rebuild my top end too? Should I rebuild the engine altogether? If I were to rebuild it, what all do I need for it?

LTandRaptorider
03-22-2009, 08:12 PM
The bolt you are referring to is the bleeder for the coolant. When you fill the radiator with coolant, you loosen this bolt to allow the coolant to fill rad and enter the engine water jackets. You say this doesn't tighten? Drain the coolant, bolt to do this is on the right lower side of the engine, under the water pump. After draining, remove the cylinder head only. Loosen the head nuts a little at a time, first one nut then across to the opposite and so on. After removing the head, check the threads in the head that the bleeder bolt goes into. If they are screwed up, then drill and tap to a larger size. Get a new bolt, fine thread and get the drill and tap to match. This will take care of the coolant leak. Do this first, see how the engine runs. But... Most likely this has been leaking for awhile. Previous owner may have run the engine without much coolant, over-heating the engine. So you may have to get it bored next size up. Do you know what over-bore it is on now? I believe bored .080 over is max on the LT250R.

Hope this helps. :cool:

leprekawn114
03-23-2009, 08:21 AM
That helps a lot, I really appreciate the input. Drilling and tapping it (if that is what needs to be done after I check it out) seemed like a good way to fix it, but I just wanted to make sure it was also a safe way to fix it. If I were to do that would I have to unbolt the whole top end and take it off to drill and tap? I know this is probably a stupid question but I've never taken a motor apart and want to make sure it runs when I put it back together. haha.

As for the over bore, to be honest I'm not completely sure what it is. The previous owner just told me it was bored out to a 260cc. I've also never dealt with a bored out motor. Is it usually pretty expensive to bore it out to the next size? I would have to get a new piston and what else? Thanks for the help!

LTandRaptorider
03-23-2009, 03:31 PM
Yes, remove the cylinder head (dome) to drill and tap the hole.

And yes, you will need a new piston for boring. Local shop would charge about $100 for boring. Make sure you send the piston along so they can check the piston to cylinder clearance.

I would fix the coolant leak first.