I picked up an 07 Raptor that had run low on oil and trashed the motor. So the kid repaired it with a big bore and stroker kit making it a 379 cc. When I went to pick it up it would not hardly run and he said it was because he hadn't re-jetted the carb for the additional CC.
Here's the new 07
I got it home and noticed it was running very lean as expected. I kept upping the jets, mostly the main jet till I pretty much had it maxed out but the quad started running decent. I took it out for a test drive (16 acres at a buddy's house) and noticed it was getting really hot. I was not hammering on it, just cruising around. We have several warrior/raptor 350s out there so I had a lot of references. I grabbed my IR temp gun and the others show approximately 240F on the front right side of the head. This 07 was showing more like 340+ and even 360F and I'd shut it down and just let it sit.
Out doing some testing
So at this point I'm thinking the quad is still running very lean. So I decided to put a wideband in instead of trying to read plugs and keep guessing because it wasn't tuning in like they normally do. Also installed a whole new exhaust since the stock one was trash.
Almost immediately after that I notice the head gasket was blown. Ugg. I thought I saw it blow smoke when I went to look at it but then couldn't get it to replicate so thought I was going crazy but no it was blown lol.
So pulled it apart and got head to machine shop
Machine shop had to take off .004 to straighten head and had to order custom sized commetic MLS head gasket since it has an over size bore.
All back together. Now with the head gasket fixed I see it's pig rich. I had to jet it way back down to more expected jets. Turns out the blown head gasket was creating the super lean condition the whole time.
Heading out for another test drive.
Loan behold the dang thing still runs hot. How confusing. I know the A/F is spot on now due to the wideband yet in a few laps around the property I notice it's up to 365F + and you can smell burning. The engine eventually just shutdown from over heating. I let it sit and cool and confirmed it fired back up and was not completely seized.
Now I'm wondering about oil in this thing so I start googling and find how you can remove a bolt on the top of the head that opens up an oil port and confirm oil pressure. Sure enough I get nothing. So I pull the oil filter cover and oil filter itself and fire it up and not a drop comes out. Ugg so the dang oil pump has been trashed since the previous guy broke it and rebuilt the motor with the same old trashed oil pump.
Tear down again
Sure enough oil pump was completely trashed and locked up with metal shavings from the original motor failure. I removed it and got a new one in there.
So now I have oil pressure, verified on port. Air fuel ratio is in check, verified on wideband. Fins on engine are clear of dirt and have good access for air flow. Yet the dang thing still over heats like crazy. I'm out of ideas? What would still cause this thing to be getting so incredibly hot?
Any pointers or experience with over heating like this is greatly appreciated.