Engine temp, 878 + Kent cams

HansJ · Post by **HansJ** » Mon Jun 04, 2007 11:09 pm

I am probably just worrying too much, but please bear with me...

My engine has, before I started tuning it, only kicked in the electrical fan once. That was in the beginning of my TRX days when I provoked it by running at idle for a long time on a hot day, just to see it was working.
Last winter I changed piston rings and had the head flowed. After this, the engine was running warmer. As long as I was able to go 50 kph, the temp was 'normal' i.e. ca 65 degrees. Any slower than that,the temp was rising. 8000 kms later, this winter, I wanted to ceck valve clearances, and found out that the inlet cam had worn down the 'bearings'. Close to disaster, but the cam nevr stuck.

This winter I have renewed the head, cam clearances well over maximum allowed play, ca 0,07 mm, and the cams rotated freely. I have also bored to 878 cc and fitted Kent cams. New cam chain, new crankshaft, new main and conrod bearings etc. started for the first time yesterday, breaking in with mineral oil, and have by now 400 kms. Engine seems to rn fine, feels punchy, and does not sound unnormal, but the engine temp... Same as after last winter, even more prone to run warm. Just came home, and we have ca 15 degrees outside, and temp gauge goes from 65 towards 90 in just one or two minutes...

You guys with 878 and hotter cams, what are Your experiences, are Your engines more easily running hotter?
I can understand the engine changes behaviour due to other cams, thinner cylinder sleeves, higher compression, I am just worried because of last season's experiences, I don't want spoil the new parts...

haggisbash · Post by **haggisbash** » Tue Jun 05, 2007 9:33 am

Have you checked the other possibilities?
Thermostat opening ok?
Water pump ok?
Engine running too lean?
I had an engine once that consistently ran hot (not TRX) with no obvious reason why. Turned out the crankshaft was bent

slow codger · Post by **slow codger** » Tue Jun 05, 2007 9:58 am

Hans if your happy that the engine is ok, then look at the cooling system, as haggis says, sticking thermostat was always a favorite, stick it in a pot of boiling water with a thermometer, also check that water pump is working correctly. Secondly. air in the system would cause the temperature to rise rapidly at a standstill.

Dave E

HansJ · Post by **HansJ** » Tue Jun 05, 2007 11:50 am

I am pretty certain the waterpump is working, I have dismantled the engine completely, and put it together again, and no obvious errors. The crank plus all bearings are new, incl. oilpump. New pistons/rings from JE, cams from Kent (one was slightly bent, but within tolerances). Cam bearings have been worked on, the clearnces are bigger than recommended.

I have just run the engine with some cooler cleaning, and no obvious pollution in the water.

I also checked the oil temp in the oiltank (Mrs is away, so I borrowed an electronical meat thermometer

), and although the fan kicks in after 4-5 minutes of idle with warm engine, the oil in the tank was not getting hotter than 72ish. Does even sound a wee low?

Maybe the porting has thinned out the material in the head, and thus heating the cooling liquid quicker?
BR,
Hans

HansJ · Post by **HansJ** » Tue Jun 05, 2007 12:10 pm

with air in the system, would the temp gauge really show normal temperatures while riding. Coz mine shows normal TRX readings while driving plus 50 kph, but starts to run hotert as soon as traffic is slower (70ish). cools down though when I go faster.

Thing is, I am concerned re the engine, as the overheating last season might have been a sign of the cams wearing down. I'll lift the valve cover now to see if I can see any problems.
cheers,
Hans

trixynut · Post by **trixynut** » Tue Jun 05, 2007 12:11 pm

Maybe the porting has thinned out the material in the head, and thus heating the cooling liquid quicker?

..following this thinking, wouldn't boring out the cylinders to 878 make the metal between the cylinder/pistons and the water jacket thinner so will heat it up quicker?

Plus, a motor spinning bigger pistons and fancy cams etc is bound to be under bigger load than it was before, so will generate more heat. Thinner/cheap mineral oil for running in will probably make this worse.

If it's not overheating i.e. the fan's doing it's job, then it shouldn't be anything to worry about IMHO.

Dave

HansJ · Post by **HansJ** » Tue Jun 05, 2007 12:34 pm

trixynut wrote:
Maybe the porting has thinned out the material in the head, and thus heating the cooling liquid quicker?
..following this thinking, wouldn't boring out the cylinders to 878 make the metal between the cylinder/pistons and the water jacket thinner so will heat it up quicker?

Plus, a motor spinning bigger pistons and fancy cams etc is bound to be under bigger load than it was before, so will generate more heat. Thinner/cheap mineral oil for running in will probably make this worse.

If it's not overheating i.e. the fan's doing it's job, then it shouldn't be anything to worry about IMHO.

Dave

exactly my thoughts, but I want to be as certain as I can. I am off to a 3 day trackday on an island on Thursday, with little hope of finding spares or repair possibilities. I have PM:ed Honk and Phuk to hear their experiences from Kent cams and 878 kit.

Post by **phuk72** » Wed Jun 06, 2007 10:50 am

It's fine

Have PM'd you BTW

HansJ · Post by **HansJ** » Wed Jun 06, 2007 11:38 am

Thannks for the input guys!

There seems to be something magic with my engine, for some reason my cam lobes had unnormal pitting after only 400 kms. Tony at Kentcams was very service-minded though, so I'll send them to him for fixing. Seems like the surface hardening wasn't enough. Have to put in a pair of standard cams now.

Killerwhale · Post by **Killerwhale** » Wed Jun 06, 2007 11:45 am

HansJ wrote:Thannks for the input guys!

There seems to be something magic with my engine, for some reason my cam lobes had unnormal pitting after only 400 kms. Tony at Kentcams was very service-minded though, so I'll send them to him for fixing. Seems like the surface hardening wasn't enough. Have to put in a pair of standard cams now.

Hmmm....we bought at somewhat same time...should i check Ãƒâ€šÃ‚Â´em out perhaps!?

dandywarhol · Post by **dandywarhol** » Wed Jun 06, 2007 6:51 pm

Probably a long shot but is there any chance the hoses for the carb heaters and the overflow to the expansion tank are mixed up??????

That would mean the coolant couldn't pressurise and would overheat...........