Painted engine

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Greg58

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May 1, 2011
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If you want a painted engine do it yourself, don’t buy one already painted. I got a engine delivered Thursday that is painted, after taking it down to clean up the ports and true the head and cylinder I found paint everywhere. Paint was in every port, including the transfers, paint was on the piston too. The head of the piston was black along with the top edge of the cylinder above the top piston ring. I got it all cleaned up and back together and ready to install, on a future project.
 

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Greg58

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May 1, 2011
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I have been thinking of doing a girls bike conversation with a built in tank, I’ve also been thinking of a big bore conversion with a steel sleeve cylinder. No definite plan yet but I may put it on one of my bikes To see how it runs, it is a 40mm stroke engine, my other 47mm bore engine is a 38mm stroke, I’m curious to see if there’s much difference.
 
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curtisfox

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Dec 29, 2008
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Kool, sounds like fun, Mr B's build may give you a little help on tank build. Good luck..........Curt

 
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mapbike1

New Member
Aug 27, 2010
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I haven't bought a fully painted engine before Greg, but I have bought cylinders that were painted and they had paint all inside like you described lol..!

Have you ever tried to drill and balance the crank better?

Im gonna give that a try on an engine I have that I know has horrible vibes to see how much difference it makes.




If you want a painted engine do it yourself, don’t buy one already painted. I got a engine delivered Thursday that is painted, after taking it down to clean up the ports and true the head and cylinder I found paint everywhere. Paint was in every port, including the transfers, paint was on the piston too. The head of the piston was black along with the top edge of the cylinder above the top piston ring. I got it all cleaned up and back together and ready to install, on a future project.
 

Greg58

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May 1, 2011
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Newnan,Georgia
I remember a while back seeing the video you sent me the link to, I’m probably going to bolt this engine on a bike and try it. It has the open trench style transfer ports, They seem much better than the earlier style. If mine needs balancing I’ll take it down and give it a try.
 
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mapbike

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Mar 14, 2010
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thats a very nice clean looking engine sir.






I remember a while back seeing the video you sent me the link to, I’m probably going to bolt this engine on a bike and try it. It has the open trench style transfer ports, They seem much better than the earlier style. If mine needs balancing I’ll take it down and give it a try.
 
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Greg58

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I put the engine on the cranbrook I had a GT5 type 38mm stroke engine on, this 40mm stroke engine is very smooth. It gets into the 30’s straight out of the box with a 38t sprocket, should get better after a while. After it’s broken in I’ll be able to compare the two, right now the gt5 is much faster, but the new engine is much smoother. I’ll take smoothness over a couple of mph. I’ve already started taking the gt5 apart to balance the crankshaft, I’ll then install it on my main bike with the 44t sprocket and see what the vibration is like, I had it on that bike before and it was bad, I’ll know fairly quick if the balancing works. Since it’s on a cranbrook I set it up so my car makes it look better.
 

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mapbike

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Mar 14, 2010
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Look forward to hearing how the crank balance job worked out... I have a GT5 geometry engine on a "diamond" frame bike, basically like a MTB style frame and the engine has vibes out the wahzoo.
Not enjoyable to ride at all... top speed isnt very good either, maybe 30mph with a 40T sprocket.

If it would do a smoother 35mph Id be happy and it would be the best running GT5 engine Ive had out of 3 I tried to run and never liked them because they had bad vibes and not nearly the top speed as my PK80 engines.


I put the engine on the cranbrook I had a GT5 type 38mm stroke engine on, this 40mm stroke engine is very smooth. It gets into the 30’s straight out of the box with a 38t sprocket, should get better after a while. After it’s broken in I’ll be able to compare the two, right now the gt5 is much faster, but the new engine is much smoother. I’ll take smoothness over a couple of mph. I’ve already started taking the gt5 apart to balance the crankshaft, I’ll then install it on my main bike with the 44t sprocket and see what the vibration is like, I had it on that bike before and it was bad, I’ll know fairly quick if the balancing works. Since it’s on a cranbrook I set it up so my car makes it look better.
 

Greg58

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May 1, 2011
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Speed is not a problem with my gt5, it's the vibration. I've been 40 on it but hated ever second, the new 40mm stroke engine is so smooth, if it picks up a little more power after break in I'll be happy. 31-32 right out of the box with a stock gutted muffler and a bofeng carb.
 

Greg58

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May 1, 2011
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Hey MB I get 32 out of my best running 48cc on a 24" tire bike with a 41T sprocket, I've done a lot of porting and the port timing is real good. A lot of people don't like grubee engines but that one has been great, we'll see how these newer engines compare. By the way that black engine was $70 plus tax with free shipping.
 

Larry Trotter

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Nov 26, 2017
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Just finished pulling the head on a factory painted engine and it was spotless inside. It had clearly been painted when full assembled because there was a lack of paint on the underneath of the head.