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Old 03-27-2013, 01:27 AM
bairdco's Avatar
bairdco bairdco is offline
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Default Re: 2-stroke 'over heating' myth...

the main point norm is making is that there's no need to stop and rest your motor after 20 minutes during break-in, or whatever the manual says, so it can cool down.

this question comes up a lot from new members worried about destroying their new engine on the way to the store or something.

the generic term "overheating" doesn't cover piston meltdowns due to lean conditions, air leaks, blown headgaskets, etc.

all these things can and will happen to the HT motors, but they're caused by other problems, not just long running times.

every motor i've destroyed had a root problem, such as too high compression, weak pistons, rings, bearings, ring clips and pins, etc.

an air leak, poorly tuned expansion chamber, warped head, lean fuel, etc, can overheat an engine and burn up a piston or fry a bearing, but a tuned engine can run all day as long as no other harmful conditions are in play.
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Old 03-27-2013, 01:40 AM
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Goat Herder Goat Herder is offline
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Join Date: Apr 2008
Location: N.M.
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Default Re: 2-stroke 'over heating' myth...

Originally Posted by 16v4nrbrgr View Post
There's also a way you gotta ride them, blip the throttle a lot to keep it oiled on downhills, light load cruises, things where the motor would otherwise be spinning with only idle fuel flow going though at higher crank speeds. Maybe that's where the heat problem is arising, people are going along with steady throttle never giving the engine its oil, with cylinder and head temps fluctuating like 50 degrees between going at speed and idle, this can cause all sorts of weird issues. I have to conciously think to blip the throttle on long braking zones even though there's no downshifts, to prevent bad stuff. If you've ever seen the clip of James May wide eyed on the brakes hard and blipping the gas on an old Saab going down a steep hill, nearly crapping himself, you'll know what I'm talking about. Fortunately for us there's manual clutches and centrifugal clutches so its not an issue, its just a habit to form.

That must mean my lapped head is around 16+:1 because I had to take off a lot to get the lathe faced head to true out flat. Wow, that's crazy, 91 octane always it is!

I was thinking maybe carbon deposits or irregularities in the heads in HT's could cause hot spots in the cylinder if running lean already that could really turn into a predetonation meltdown situation, maybe that's what the deal is, and why some have had problems, others not, there's like 10 heads out there for HT's.
My Morini exept for the 5.8 s6t and smaller models needed to be blipped on the throttle in my experience because the carb loads the engine up. I have gone for extended periods of time in many positions. If I idle for very long with my bigger carbs they try to load up. That personality changes with the season too and sometimes I re-tune for it as well. Despite getting a clutch that would crawl gingerly around and rip!

Small price to pay for a tiny bit more power. Its like a little dragster engine

I concur with Bairdco as he said it right. This was pretty much the point.
Still gotta have a since of humor.

Last edited by Goat Herder; 03-27-2013 at 01:42 AM.
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Old 03-27-2013, 01:49 AM
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16v4nrbrgr 16v4nrbrgr is offline
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Join Date: Mar 2012
Location: North Bay
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Default Re: 2-stroke 'over heating' myth...

Yeah mine loads up too, I set the idle screw high sometimes to make it easier, then dial it down once its warmed up. It still needs the typical two stroke brapp every once in a while to clear it out. I'm glad the stock jetting is rich, I'm gonna keep it that way, its safe and the air can be really cold and wet here, need lots of gas to compensate.
KTM50 Schwinn Chopper - 6000W E-Motard - 52cc Auger BMX - 9sp+CVT 52cc Cagllari Moped
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