Engine Trouble Minarelli Progress/Friends BMW

[CrispyLeaves98]

If you’re running a 36 try a 38 or 40T sprocket. The sport Athena will still get you close to 50 mph on a 40T. I don’t think any of these engines are gonna hold up running them WOT for long periods lots of times. My temps run a consistent 180-190 the way I ride.
Anything over 35-40 mph is way too fast for a motorized bicycle unless you’re competing in competition sports with all the protective gear to support you anyway.

My cast iron top end did have a good bit more low end torque over the sport Athena on a 38T but not so much that I felt the Athena was no good. I prefer the Athena but I cruise up to 25-30 mph gently and do not rip up fast a lot. It does run superb though for my style.
My Athena sport really doesn’t come to life for abrupt torque until around 7,500 rpm’s. It’ll jump from 40 to 50+ in a blink.

the cast iron is the seizing issue thats why I wanted the aluminium cylinder. I wish I could get one with normal port sizes but with the style of how I ride, nah. I have the 36t to keep me at a constant 30mph crusing speed, but the minarelli cylinder gives me that low end power because i dont have functioning pedals, its all on the clutch. I wish I did. If I end up trying the athena it will be with a 38 or a 40t, but with my new minarelli, I feel like it will be a preformance increase somewhat. No more extremely cheap cylinder, piston, and rings. Going top notch on this engine, wish I could afford a smolikhead for even better cooling and they also look really cool.

 

[CrispyLeaves98]

another thing to keep my engine from overheating, how are the gauges from trail tech? I want something that gives me RPM's, Temperature, and speed. Also, how would you go about hooking something like that up?

If there is anything out there that shows me my RPMS in a cool way not a 14 dollar tachometer thats cheaper than a trail tech lmk

 

[ImpulseRocket]

If you monitor temps, you can prevent this kind of crap by simply... slowing down/stopping for a while.

$35.00 of prevention ...

Same with the genius who took LA Hoverbikes Phantom 85 and decided to run WOT for extended periods... on a 20" wheel... 44T sprocket.

That motor didn't die... it was killed.

Any of these higher powered engines in particular don't like to be run hard for extended periods of time. Both the Phantom and the Minarelli cylinder designs came from forced air cooling applications. They don't do well when pushed hard. They also don't do well with low speed and high RPM when pushed either - aka your 20" wheel with a 44t sprocket.

I can't speak for the Minarelli directly but the Phantom thrives with a smaller rear sprocket on a larger wheel. It has the grunt to pull it and the air speed relative to throttle position and RPM helps stop it from having a meltdown.

 

[ImpulseRocket]

another thing to keep my engine from overheating, how are the gauges from trail tech? I want something that gives me RPM's, Temperature, and speed. Also, how would you go about hooking something like that up?

If there is anything out there that shows me my RPMS in a cool way not a 14 dollar tachometer thats cheaper than a trail tech lmk

Not familiar with the trailtech stuff but if it is battery operated the rest of it is going to be simple to hook up. Most 1cyl tachs are just a inductance wire coiled over the plug wire. The sensors are just thermocouples that require being bolted to the head. The speed sensor would probably be the one unique thing but they usually come with instructions for that setup anyway.

As far as showing you the RPM... who cares how cool it is.

 

[Nickt919]

…. I have the 36t to keep me at a constant 30mph crusing speed, but the minarelli cylinder gives me that low end power because i dont have functioning pedals, its all on the clutch…..

No pedal assist and a 36T could be putting an unnecessary load on your engine…especially if there’s lots of stop n go…leading to heat issues.

The single speed engines we use are comparable to taking off in 3rd gear on a shift engine and staying there. Take off is hard on our engines as well as winding up to 10k-12k rpm’s for extended periods.

The shift engine on a motorcycle keeps the excessive load and rpm’s off their engine..
We do not have the luxury of a transmission so it’s up to us to recognize the limitations and work within it.

 

[CrispyLeaves98]

No pedal assist and a 36T could be putting an unnecessary load on your engine…especially if there’s lots of stop n go…leading to heat issues.

The single speed engines we use are comparable to taking off in 3rd gear on a shift engine and staying there. Take off is hard on our engines as well as winding up to 10k-12k rpm’s for extended periods.

The shift engine on a motorcycle keeps the excessive load and rpm’s off their engine..
We do not have the luxury of a transmission so it’s up to us to recognize the limitations and work within it.

Not too late to make something. Til then I'll see what I can do. Just wish eBay shipped faster

 

[noah9988]

Not familiar with the trailtech stuff but if it is battery operated the rest of it is going to be simple to hook up. Most 1cyl tachs are just a inductance wire coiled over the plug wire. The sensors are just thermocouples that require being bolted to the head. The speed sensor would probably be the one unique thing but they usually come with instructions for that setup anyway.

As far as showing you the RPM... who cares how cool it is.

Question, if you use a small sprocket and large wheel it will allow you to cruise at higher speeds at lower rpm, but does running a low gear ratio like that put extra strain on the engine or other components when accelerating?

 

[CrispyLeaves98]

Question, if you use a small sprocket and large wheel it will allow you to cruise at higher speeds at lower rpm, but does running a low gear ratio like that put extra strain on the engine or other components when accelerating?

You go faster at lower rpm's and have less torque, it's harder for the engine to accelerate

 

[ImpulseRocket]

Question, if you use a small sprocket and large wheel it will allow you to cruise at higher speeds at lower rpm, but does running a low gear ratio like that put extra strain on the engine or other components when accelerating?

No, not on its own. It depends on a number of factors. In the case of an engine like the Phantom, or most larger saw based hybrids, they make a ton of low end and mid range power. It's what they were designed for, being bogged down chewing through trees and logs. Ask anybody here with a Phantom or hybrid about how these pull away on a 36t sprocket on a 26" wheel. Doesn't phase it at all and it will pull to 8-9k rpm effortlessly.

The Minarelli hybrids are a very different animal. They seem to be a lot peakier and will definitely rev higher. Probably making more HP at the end of the day.

Since the Phantom so efficient in terms of power in the lower revs it doesn't really need to be lugged to get up to speed.

 

[CrispyLeaves98]

The rebuild has begun, gonna use stock head for a while any objections? Just too lazy to take the engine back off to put on a bigger head cause of the tight space. I know cooling and all that but it can wait in my opinion. This engine is gonna be babied til it's done broken in. Just waiting for a magneto from Amazon