Author Topic: 175 Overheating  (Read 782 times)

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Offline alexm846

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175 Overheating
« on: August 10, 2017, 07:10:03 AM »
Hey there,

I've got a '68 175DT that's recently made it out on the road for the first time in decades (it had been someones parts bike).  Runs pretty good at higher rpms and goes up to about 60MPH, but a little sloggy in the lower/acceleration. 

Anyway, after a 25 min ride, BOTH headers measured up to 250 degrees F.  Now I don't know what they should be, but I'm assuming that's considered very hot as the exhaust connectors burned up.  Why question is, what could cause this amount of overheating?  Is it possible for mixture, or clutch to do this, or are we talking something more?

Next question, I don't think related, although I had that it was until I realized both sides were heating up:

It's leaking gearbox oil from the drain hole behind the left cover.  For people who know these things inside and out: Is there something other than a case half leak that this could be?

Thanks for listening!!

Offline OldSwartout

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Re: 175 Overheating
« Reply #1 on: August 10, 2017, 08:43:25 AM »

It's leaking gearbox oil from the drain hole behind the left cover.  For people who know these things inside and out: Is there something other than a case half leak that this could be?

Gearbox oil is collected and funneled into the oil pump drive case on the left rotary valve cover.  There is also a fill screw in the oil pump drive case below the oil pump.  Either the fill screw, one or both of the oil pump mounting screws or the oil pump drive case mounting bolts could be missing/loose or one of the gaskets could be damaged.
Karl Swartout
Mooresville, IN
BS175 Roadracer
BS350 GTR

Offline BRT-GTR

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Re: 175 Overheating
« Reply #2 on: August 10, 2017, 03:51:01 PM »
             Two main causes of overheating are ;- 1) Weak mixture - main jet too small or partially blocked, carb needle in wrong slot, dirt in carb, float level too low, poor fuel flow from tank..
  2) Ignition timing too far advanced - adjust points gap and reset timimg to indent marks on the crank flywheel.

   Could be either cause, there are others as shown in the service manual. You were lucky you didn't melt a piston

     
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Offline alexm846

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Re: 175 Overheating
« Reply #3 on: August 10, 2017, 09:09:12 PM »
Thanks for the responses.  That's good news to me about the oil leak.  I'll have to probably do some trial and error with the overheating.  It's been a a while since I adjusted the timing and carbs.  I remember being pretty confident with the timing, because I re-did it several times, although I did not replace the points.  Thought I adjusted the carbs to spec, but I may try raising the floats or needles and see how that goes.

 


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