'05 Heat & Leaks!

I bought my son an '05 CRF450R a little over a month ago. The price was really good, but it was obvious that it was a bit of a fixer-upper (I know, not what you want in a used 4-stroke, but that's now irrelevant). The bike had obviously been neglected. Bolts were a mish-mash of stuff from the hardware store. Too many loose bolts to count (the rear sprocket was about ready to fall off). Missing spacers in the rear wheel. Leaking head gasket, etc, etc, etc. However, the valves had been done very recently along with a 13:1 high compression wiseco piston and a stage 1 hotcam. We've been through quite a bit of the bike so far (shimmed the valves, replaced the leaking head gasket, replaced and tightened numerous bolts, replaced fork seals, replaced clutch plates, filed out clutch basket notches). We still haven't greased the suspension, and we haven't been into the carb. The bike runs really, really strong and starts nearly every time on the first kick. It's much, much more powerful than my '02 CRF450R (which is in pristine condition, btw, with a new 12:1 OEM piston). But, we've still got a few issues we're dealing with.

#1 - Leaks. The left side cover is leaking at the front. You can see this by all the sand attached to the cover after the first ride at the sand dunes on Saturday:


I think this is an easy fix -- just replace the left side cover gasket. The next leak is a bit more challenging (maybe). The bike is leaking oil from the weep hole in the head on the right side of the bike. Here's a pic (again notice the sand that's stuck to the oil):


I'm not sure what this hole is for, but I believe it's simply a drain hole in case water gets into the spark plug hole. When we looked at the spark plug, it had oil all over the middle to top threads (but not on the bottom threads nearest the end of the plug in the head). So it appeared that somehow the bike was leaking oil into the top of the spark plug hole. Being curious, I pulled very lightly on the sleeve around the spark plug. Guess, what -- it wasn't hardly even attached and came off effortlessly:


Not a good sign, but this certainly seems to explain the leaking from the weep hole. I gently pushed the sleeve back into place, and tapped it gently with a rubber hammer. It feels fairly tight, and certainly seated much, much better than before. But I'm fairly certain this shouldn't come out. Anyone have suggestions here? I thought we'd try it as is for a ride and see if it still leaks. Should I try a bit of sealant around the bottom edge if this doesn't work? OK, leaks are the easier of our problems. On to the next one.

#2 - Heat. Definitely have a problem here. The bike looses coolant and within a few hours has drained the rads. It must be a pretty slow drain because we haven't noticed much coming out the overflow tube. We installed a 1.6 high pressure cap, which helped maybe a tad, but by the end of a days riding the rads were nearly empty. How do I know we have a heat problem? Take a look at the discoloration in the head:


There was some discoloration when be bought the bike, but it's definitely worse after 3 days of riding. Heat = Bad, and I'm sure we've shortened the life of the head. Is it warped? I dunno - maybe - as I indicated, the head gasket was blown when we bought the bike. But thus far after a new head gasket it's not leaking (knock on wood). But I don't think we've got many more rides with the bike running this hot before we kill it. Check out the discoloration on the cam sprocket (this was definitely not there when we bought the bike):


I originally thought we were leaking coolant into either the engine oil or tranny fluid. And we may well have leaking crank seals. Engine oil upon draining (no filter change) was 635 ml vs. 660 we added on last change. However, upon draining the sight glass was to the top, perhaps indicating that we picked up a bit of fluid from somewhere. However, there doesn't appear to be any coolant in the oil (based on taste, and based on a chocolate brown color). Tranny fluid was pretty low upon draining -- only got about 300 ml out vs. the 590 we added on last change. Color was more grey than the engine oil (Rotella T in both sides), but no metal shavings or other indication of problems other than the low level. Also, based on taste and sight, there doesn't seem to be any coolant in the tranny fluid. Bottom line -- we may be leaking a bit of tranny fluid into the engine oil, but I don't think we're getting coolant into either the tranny or engine oil.

So, what could be causing the excess heat? Due to the 13:1 wiseco piston, it may be that the gas we're using isn't acceptable. We're running Sinclair premium, 93 octane pump gas. I had thought this was OK for 13:1 and that race gas isn't required until you bump up to 13.5:1. Anyone know if this is correct? The only other thing that is suspect is jetting. This may well be the issue. As I mentioned, we haven't yet been into the carb, so I don't know whats in there as far as main and pilot jet sizes. The plug is a light brown (not white), so this is a bit inconclusive to me. My photo of this one doesn't capture it too well (sorry):


I run my '02 a bit rich, and the plug is usually a bit black. This is definitely not rich, but it doesn't look all that lean either from just looking at the plug. But the bike does pop on decel a bit more than it should, which indicates perhaps it's too lean. So my inclination is to go up one size on both the main an pilot jets. Other than the high comp piston and stage 1 hotcam, the bike has a DrD pipe and White Brothers muffler (could require a bit of jetting - don't know if jets have been changed from stock).

OK, guess that's about it. Leaks and heat -- both not good. Any insight or suggestions would be appreciated. As I mentioned, we're gonna kill the head and valves if we keep running it this hot (if we haven't already killed it!). So heat is first priority. But then we'll need to stop the leaks also.

Maybe a boysen water pump, engine ice for coolant and performance radiators, those can reduce engine heat by up to 30% so I've heard to keep things a bit cooler for your higher compression piston and higher octane fuel causing extra heat. After the gaskets, fork seals, and other crap you needed to replace the cheap price you purchased the bike for probably equals out to a well maintained bike? Sometimes it's better to spend a bit more and buy from an owner that takes preventative maintenance seriously? Good luck, sounds like quite a project you have on your hands but I'm sure with some time you'll get it all dialed in, CRF's are great bikes! :p


You have some gasket problems with the bike for sure.

I would start by taking off the cylinder (where the piston travels) and make sure the O ring and water pass colar is there! Buy a new base and head gasket. Also make sure the water pump is not leaking. Wouldnt hurt to buy a new seal for it and bearing.

But overheating, sounds like the issue is lack of coolant. Looks like it is getting into the motor with the discoloration. Might be better off pulling the motor and freshing up the crank, crank bearings, crank seals and all the gaskets.

I think we've finally resolved the overheating and leaking problems. For the leaking, we just replaced some gaskets. Also, we used a high temperature sealant to put the spark plug tube back in permanently. No more oil out of the weep hole.

The overheating was more difficult to solve. Tried a high pressure cap. Helped, but didn't solve. Added a turkey baster coolant reservoir. Also helped, but didn't resolve completely. Flushed coolant system, but didn't solve problem. Jetted a bit richer - helped but didn't resolve. Finally gave in and jerked out that Wiseco 13:1 piston and replaced it with OEM 12:1. Guess what? No more overheating. I know some of you guys are running these things without issue, but I couldn't seem to make it run cool enough for my liking (at least on 93 octane pump gas).

good information, excellent thread!

I was under the impression you could safely run pump gas with a high compression piston, guess not.

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