Sudden loss of power.

[inspectorcritic]

Ok, here's the run down and I apologize in advance for being long winded. My muffler pipe snapped and I got a flat within a week of each other. Needless to say, I had to park it while I waited for payday to arrive. I ordered a new muffler, new intake (not much room to do maintenance on the carb) bucking bar (I dropped and lost the original, please don't judge me), new rear tire with a smaller outer diameter than the factory tire, and a new chain tensioner pulley.
After reassembling everything and going for a maintenance ride, I discovered that I am only getting about half of the power and speed that I got previously. I did adjust the engine angle also to get the carb to set level, since the extended intake has an odd angle to it.
I have checked and found a vacuum leak where the intake mates to the engine head. Could this be the entire problem? or could the change in mounting angle also play into my massive reduction in power?
This is my first build (and like a moron I bought the cheapest engine available on amazon), it was listed as a british built engine, but after receiving it, I learned that it is a Chinese engine. The seller hasn't replied to email and Amazon isn't helping much either. I'm not even sure if it the 80 cc that it was sold as. I have it mounted to a Huffy Nel Lusso.

Also lubricate your chain and sprockets with WD White lithium Grease reduce friction and drag you pickup 2-3 MPH but you get a much smother performance.

 

[Gregory Neighbors]

I've been using 3-1 oil on my chain. Like I did my mini bike when I was a kid. It helps, but it also requires frequent application. How long does the lithium grease last on average? I honestly have only used lithium grease when storing guns for extended periods.

 

[FurryOnTheInside]

How have you changed the mounting angle? Surely that is entirely dependent on the angle of the seat tube of your frame.

If you're interested in getting more power and torque, and you're replacing the head gasket now, you might as well measure the clearance between piston and head to be sure you don't have huge excess clearance which would reduce compression.
I have a very sloppy engine, cheapest on eBay, and I was able to reduce the clearance from a huge 1.2mm to only 0.55mm without any modification of the cylinder or head, just by the use of a twisted Teflon tape gasket instead of the stock aluminium one.

After fitting a new gasket you should perform a compression test to see where you stand.

Also, call me a weirdo but I use actual bicycle chain lube on my motored bicycle's chains.
Chain lube is supposed to be able to flow enough to move the crap out from underneath the rollers so (after you have cycled the chain around a few times) you can wipe it off with the excess lube.

 

[Gregory Neighbors]

I wish I had a compression gauge, unfortunately I don't. I would love to know the technique you used to make the twisted teflon tape gasket. As for the engine angle. I purchased motor mounts which have limited vertical articulation. they allow me to tweak the angle by a few degrees, they have been very handy and are by and far superior to the stock mounts which didn't match my frame at all. If the rain ever quits I'll go pull my engine and bring it into my apartment to start taking measurements. I'll have to open the windows though, my girlfriend gets mad about the gasoline smell. lol.

 

[crassius]

many auto parts stores will loan a compression gauge for free

 

[Gregory Neighbors]

True, but the local bus system won't let me put my bike on the rack because it has an engine. Bike, feet, or bus are my options for transport. lol. I'll come up with something though. I am still pondering the teflon tape head gasket.

 

[FurryOnTheInside]

I wish I had a compression gauge, unfortunately I don't. I would love to know the technique you used to make the twisted teflon tape gasket

It's a very simple tool and should be cheap, tbh I wouldn't be without one for this hobby, even if you could borrow one it's nice to have it handy.

twisted Teflon tape gasket correctly

• FurryOnTheInside
• Sep 20, 2017

Correctly this time, I think! Crossed at a stud. Spots of grease on the outside of the loop hold...

The tTt gasket couldn't be easier. Take a length of the common PTFE Teflon tape (I think it was about 60cm) and double it then twist it up into a string. Slightly untwist a few millimetres close to one end and lay the string around the cylinder top, about a millimetre out from the bore, using a pointy tool like a dental pick or whatever to position it carefully and tiny spots of grease around the outside to steady it until you get the head on. Cross the untwisted bit in line with a stud and trim the excess.
The tTt gasket doesn't like a polished surface, it likes a few lines to grip, so you don't need finer than 320 or 400 grit paper to flat the mating surfaces.



I did it wrong the first time (although it probably would have worked)
View media item 60991

I like the sound of the adjustable mount!

 

[Gregory Neighbors]

Thanks for the pics and instructions. I was thinking along those lines, but I wanted to be sure. The mounts are great. Here's the manufacturer link for the mounts. http://www.cdhpower.cn/product/class/?125.html

 

[inspectorcritic]

Ya used

I've been using 3-1 oil on my chain. Like I did my mini bike when I was a kid. It helps, but it also requires frequent application. How long does the lithium grease last on average? I honestly have only used lithium grease when storing guns for extended periods.

Ya I used it as a kid too pretty light and messy the WD 40 lithium suppose to repel dirt. How often, your chain well tell you when it begins to clank and make noise suppose to be the indicator.

 

[crassius]

when they loan a gauge, you can take it with you & return it next day