Post by chanito on Oct 18, 2008 19:07:01 GMT -5
When i first started this about the big bore, i posted here for help and we decided to go all out for the big bore engine, and that means racing parts, i wrongly assumed that everyone would be familiar with techniques for assembling racing engines, or at least be savvy enough to put the engines together without trouble, but not everyone is on the same page, so i need to put some steps for DIYs to follow. I put an engine together for justintime and it did overheat, he send it back and allow me to figure out what was wrong, and i find out a lot of little things, the engine overheated due to a coolant leak, and then after replacing the head-gasket, the chain guide broke scratching the water pump. and it overheated again, so i got it back all the way from the northwest, and after taking it apart i ordered the water pump, the broken guide and some hose clamps. Put the engine back together, install it in Katrina and rode around, everything seem to be fine until i decided to do a load test, which is just getting to a tall bridge and cross it over and over about 5 times, after the 4 time the engine overheated, so it was back to the drawing board and a deeper inquire into the matter, and this are my findings1.- Just because a thermostat pass the opening test it does not mean it will open "all the way" serious overheating can cause the thermostat to suffer permanent damage and not open all the way, therefore restricting the flow of the coolant around the engine.
2.-Aftermarket radiator covers might look cool, but some of them are way too close to the radiator restricting fresh air flow to the radiator, installing some washers as spacers and separating the cover just a bit can increase flow to the radiator a "lot"
3.- Jetting can affect the temp specially after running at full for long, and now more than ever with the gasoline having alcohol on it (up to 10%) which make it even leaner
The radiator cover was one of those things i should have spot it since day one, but it took me a good week to figure out, why the temp was still hot if everything was OK, so one day i was checking the fluid level and a quick glance show that the bend on top of the cover was hitting the top tank in the radiator preventing the hot air from leaving the scene of the crime with the scooter standing still, after putting some washers it cool down nicely, and those oil caps with a thermometer are useless, the engine will over heat long before they show a hot oil readingThe high performance head gaskets can be great, but they require a very smooth surface, so decking (fine sanding) is a must, before you put the engine back together, get a piece of thick glass (i got mine from an old elevator they were taking apart) and 4 or 5 sheet of wet or dry 600 grit sandpaper, some dish-washing soap and a lot of patience, just keep sanding the sealing surfaces until the surfaces are smooth and there is no scratches of low spots on them, avoid the temptation to use a courser grit to make it faster, as it can take way too much material and make matters worst. using an inch/pound torque wrench and torquing the bolts in 3 steps on an spiral pattern, should be fine
For same reason this engine is not as peppy as mine, but is way stronger in the top end, climbing rpms with gusto way over 8500, i was thinking it had a special camshaft but not is just an rpm monster 
