Unwanted heat is troubling

Street Ryderz

Well-Known Member
Local time
7:30 AM
Joined
Oct 14, 2016
Messages
4,473
Location
Ft Erie Ont
This build has me confused in that it's engine is one of my Road Runner's ported for torque with no timming changes to the cylinder windows.Generic case halfs with quality bearings a Skyhawk crank with ZL rod and 40mm stroke and the high pinned piston,The crank gets trued so that the weights run verticaly straight then the horizontal through the shaft is trued then it's balenced.The jug isn't Grubee's it's a generic and the head is stock angle fire 6cc it has a good pipe(not great)in that it flows well and stages around 5,500 rpm just a bit loud.The stock gear out back and a 16mm CNS carb with a 72 jet in it and stock idle jet.It runs really strong in the bottom and midrange comes on the pipe breifly then gets fat and falls off not allowing a clean burn at wot and being rich on top shouldn't be getting as hot as it does.After a twenty to thirty min ride it's temp between the head and cylinder is around 320-330 f unacceptable for me.Especaily since I put another Road Runner engine in my sons current bike since his 50cc has to be rebuilt and it's spec's are identical to the engine above except for the jug is a Skyhawk but the port volumes are the same timmings are the same except for the intake witch is slightly lower in the Skyhawk jug the druations are close within 2 degrees but I dont see how that can cause so much heat when we run both together same 20-30 min run the first one is 80-100 degrees hotter last night both those bikes and mine did the same run together and it ran 100 degrees hoter than mine even I don't get it.
 

6blueoval9

Well-Known Member
Local time
6:30 AM
Joined
Aug 28, 2017
Messages
1,115
Location
Kansas
Possibly more compression with the generic head?..I'd do a compression check to see.
 

Street Ryderz

Well-Known Member
Local time
7:30 AM
Joined
Oct 14, 2016
Messages
4,473
Location
Ft Erie Ont
I took the exhaust from my sons bike and put it on the one running hot and it actualy got worse more heat and no balls in the bottom or middle compared to the previous pipe,it seems like every engine I've done lately requires custom fitted larger dia exhaust to see it's full potentail and run in the heat range I prefer to see. So now I have to make a couple custom pipes since I now also realized the one I took from my sons bike isn't flowing all that well either thou it was working on his for heat it's just a muffler not a tunned pipe so it's all engine doing the work and that engine would be even stronger with a real pipe.When we ran it with the muffler tonight the whole rpm range was also leaner not helping the heat issue but I guess that was the lack of return wave not getting a good cylinder fill.
 
Top