CM400A Engine very hot

Windmill John

Windmill John

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Location
East Sussex, England
Hi All,
Of course… hot… one could say that’s subjective, but I don’t recall an engine this hot before; not had a torque converter before. If this is normal, then fine.
Just had my third ride, only about 30 miles. Even half a hour after getting home and tapping the engine quickly with any part of hand is blooming hot; I mean VERY hot.
Okay, bike starts first kick, runs very well, idles well. In the olden days, retarding ignition helped starting, but could cause overheating. But these bikes are fixed CDI ignition.
Yes, we are in the 20s; Celsius.
Am I missing something?
 
Do you have a Laser Thermometer or access to one? That would really be the only way to tell is take a reading and then compare to what the operating temp should be. On Amazon there are a number of inexpensive one ones.
 
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Yeh I had thought of that. They’ve had them in Aldi for ages. Very cheap and every time I stare at it, I think I’ve done very well so far.
But… maybe now’s the time… Bet the buggers have sold out!
 
It could all be totally normal, but boy, it’s hotter than anything I’ve ever (almost) felt.
On other bikes, you could pat the engine (why?!) and yes they were were hot, but this just goes to the next level.
As mentioned above, the ride is excellent.
 
You have the oil cooler, so maybe its no flowing properly, i have manual version and for comparison, i measure temp on mine after long rides and one of them runs at 180f, and the other at 200f consitently, measured at the oil filter side of the oil pan, which always seems to be the warmest part. Converted for you at 82-93 ish celcius. That is with air temps upper 80's to low 90'sF. LDR responded to me once that 200F is not too bad if the air temp is in the 90'sF. See if you can get a laser thermometer, or borrow one. Or just ride over to someone that has one and take a quick temp.
 
Last edited:
esmith250624 said:
You have the oil cooler, so maybe its no flowing properly, i have manual version and for comparison, i measure temp on mine after long rides and one of them runs at 180f, and the other at 200f consitently, measured at the oil filter side of the oil pan, which always seems to be the warmest part. Converted for you at 82-93 ish celcius. That is with air temps upper 80's to low 90'sF. LDR responded to me once that 200F is not too bad if the air temp is in the 90'sF. See if you can get a laser thermometer, or borrow one. Or just ride over to someone that has one and take a quick temp.
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That's the ticket! Typically under $30 Canadian off Amazon or Princess Auto, Canadian Tire ect. Worth the low cost investment for an IR/Laser reader these days, if your going to be faffing around with this older stuff on more than one occasion. ;) Great for reading general exhaust pipe temps especially on bigger fours for a quick look at the pipe temps and and spark plug colouring.
 
Thanks both. I have often thought about one. I’ve had big fours before, but everything has always worked out when fiddling and luckily not needed to check an errant hotter or cooler cylinder before.
I’ll be wandering through the shops.
 
Just taken a reading. I remembered I have a, never used, temp probe for my multimeter; that was a waste of time, only showed 80 degrees C.
Then remembered I have a good quality thermometer. I installed that between the cylinder head fins and it climbed steadily to 180 degrees C, topping out very slowly at between 195 and 200 C.
I did a bit of Googling and that is on the high side, but not excessively so.
 
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