Engine Bogs Down Under Load.

Sitherus

Active Member
Joined
Apr 4, 2016
Messages
252
My bike only cold starts with starter fluid. I found this engine on the side of the road originally and so far i've replaced all mechanical, electrical parts, and gaskets except piston head and its rings. I have 2 rt carbs 1 walbro carb and 1 delarto all of them do the same thing. When I get on it, it runs slow, It runs happily of flat land but Roanoke is all hills, much like the terrain of San Francisco. Someone told me "it sounds like its pushing air up" from browsing and reading on this forum the common suggestions are compression test which I did and got 124 psi, spark plug check and I have checked and cleaned the one I was using (NGK BR7HS), but just in case that was bad, I switched to another cheaper lawn mower plug, and replacing the piston rings. I own the stinger engine which as I've been told is the GT5 engine so would this part work for my application?

The other thing is, I could buy jets to help with performance which I know i need to do because of my altitude (1,381 ft above sea level). Which jet should I use?
 


crassius

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Jul 23, 2012
Messages
4,575
with 124 compression, I'd be looking for a nice NT carb before a piston

also, if you have hills and a 36T rear sprocket, you'll never be happy
 

Sitherus

Active Member
Joined
Apr 4, 2016
Messages
252
with 124 compression, I'd be looking for a nice NT carb before a piston

also, if you have hills and a 36T rear sprocket, you'll never be happy
I have a 7 speed bike with a jack shaft. The nt carb and rt carb have the same internals so what makes them different?
 

Sitherus

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Apr 4, 2016
Messages
252
I just went out on flat land. I made it up to maybe 15mph I could be passed by other bicycles without motors. I crave power because my first engine and my friends engine ran great. I was able to make it up to 30mph on that and 25 up step hills on his. So i want to be able to do that on an engine with so many modifications that's supposed to be built better than the one I bought on eBay for $80.00.
 

crassius

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Jul 23, 2012
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4,575
pic looks like some type of 'speed' carb - these often run rich, but yours sounds more like a serious problem

clogged muffler or major lack of fuel
 

Sitherus

Active Member
Joined
Apr 4, 2016
Messages
252
okay, so, I got allot more torque and top end but the bottom end is still much too slow. when on a flat, if I start on a hill I get a top speed of 25. I don't have a speedometer because I lost my magnet but I was keeping up with traffic, in my neighborhood and the speed limit is 25. I noticed there was allot of unburned oil/gas (little black dots), and when I held my hand in front of the exhaust my hand was painted black. I can build a functioning bike with an nt carb and a basic head and normal restrictive exhaust but I want something fast.
 
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