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Post by oldgeek on Jan 16, 2020 6:33:48 GMT -5
At least look thru the exhaust port to see the rings condition. Good idea and I have done that before, but it won't really change anything. It is a cast iron bore, I will run it till it quits, hone it out if necessary, and put a new piston in if they are still available. This whole cylinder kit was $108. That is about as cheap as it gets for a 2T IMO. I am more concerned about the crank bearings when the pulley and belt came off, It had to hit 15K+ for a second or two! cant really do anything about that either.  |
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Post by oldgeek on Jan 16, 2020 6:41:56 GMT -5
You have it all going on! Blame your mate.  Variator nuts do stretch over time. It's supposed to be a service item. But nobody really changes them much. Yes Paul, you are so right. I have had that thin nut on and off hundreds of times! I should have replaced it long ago. I have a full width nut on there now, no need for the special thin nut since I dont run the kickstart components anyway. I bet I can get even more use out of this one. |
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Post by 2stroked on Jan 16, 2020 21:16:40 GMT -5
Just got caught back up with this build. Damn OG, you've done amazingly well, fabricating, and adjusting, thinking out of the box. Everything we all want to do, but only a few can. Nice.
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Post by oldgeek on Jan 16, 2020 21:35:27 GMT -5
Crazy nice weather today, as a result there is no job related work to do. So I got the new CHT sender installed, along with a new plug. I also swapped out the upper intake for another one I had that tilts the carb up a couple degrees, just enough to allow the carb to clear the CVT cover, so I put the cover back on. In the process of swapping out the upper intake I realized I had a 26mm stuffer in the top of the reed block, so I swapped it out for the 28mm one to match the 28mm carb. I also lightened up the sliders just a little bit, buttoned everything up and headed out for a ride. However I ended up turning back rather quickly as the temps started to skyrocket.
I now suspect the temps must have been high all along but the CHT gauge was not telling the truth do to it being damaged. The MJ was currently 118, the next largest size I could come up with was 132 so that's the one I used. The larger MJ seemed like it was enough to control the CHT's so I set out for another ride. Surprisingly to me, it still wanted to get hotter at WOT than I wanted it to, I had to reach down and pull the choke now and then to keep it from overheating. I saw 65mph at 9700 RPM a couple times, but did not want to push it too hard until I get the new carb figured out. Colder weather arrives tonight, so I dont know how much riding I will be doing anytime soon.
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Post by 190mech on Jan 17, 2020 4:57:48 GMT -5
I noticed in your pics there is no left cylinder shroud,,that would not allow the air to flow completely around the cooling fins and possibly cause hot running,,also the hot air is heating the reed box and carb which should stay cool...  |
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Post by oldgeek on Jan 17, 2020 6:52:29 GMT -5
I noticed in your pics there is no left cylinder shroud,,that would not allow the air to flow completely around the cooling fins and possibly cause hot running,,also the hot air is heating the reed box and carb which should stay cool... Quite a bit of heat pours out of the carb area, no doubt it can't be good to heat the intake and carb up. Maybe I should make up a diverter from sheet metal to direct the heat away from that area. It should be easier to do now that the carb sticks straight out the side of the motor. When I had the the 21mm carb dialed in the CHT temp was stable. I think when I get the 28mm jetted properly the CHT will be ok. I had a 118 MJ in there thinking it was ok because the CHT sensor was way off. I am up to a 142 mj and I think I am finally getting close LoL! |
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Post by oldgeek on Jan 21, 2020 12:40:14 GMT -5
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Post by repherence2 on Jan 21, 2020 20:29:36 GMT -5
Im glad you decided to unclamp the head/bore to visually inspect it.
Was the compression really high on that set up? That piston looks like it was ready to burn a hole in itself.
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Post by ryan_ott on Jan 21, 2020 22:08:28 GMT -5
Good thing you decided to pull it apart. That could of ended very badly.
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Post by aeroxbud on Jan 22, 2020 4:20:15 GMT -5
Looks like you caught it just in time. Shame your temperature gauge messed up, or you could of saved it. Mind you pete130 would of got at least another 500 miles out of that piston! Must try harder. 👍 😉 |
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Post by oldgeek on Jan 22, 2020 8:23:23 GMT -5
Im glad you decided to unclamp the head/bore to visually inspect it.Was the compression really high on that set up? That piston looks like it was ready to burn a hole in itself. I had to look back to find the #'s uncorrected compression ratio = 14.49:1 and corrected compression ratio = 8.16:1 Actual compression tester came out to around 185 after the rings seated. It was very hard to start using the kicker, felt like something was going to break with every kick. I am so glad the high torque E-start and big battery starts it easily. That piston was definitely on the edge of failure. Looks like it had been running that way for some time. |
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Post by oldgeek on Jan 25, 2020 22:59:02 GMT -5
I finished the prep work and put everything back together yesterday evening. Since I had the pipe off and out of the way while redoing the piston, I decided to test fit the mini rotor ignition I picked up a while back. I discovered that the mini rotor flywheel was keyed in the proper place for this motor, which simplifies the mini rotor iggy installation.  I decided to go ahead and try the mini rotor iggy since it seemed to be a wire for wire swap. At the end of the night it fired right up and seemed to run fine with the mini rotor iggy, but I didn't get far before it was acting like it was running out of gas. I was tired so I said screw it and went home for the night. I did some checking today and could not find anything definite that would cause it, but I went ahead and installed a new plug just in case. The scoot started back up and it ran fine  I heat cycled it good a couple times, up and down the road close to the warehouse, enjoying the added snappiness of the mini rotor iggy. The third time I went out to heat cycle it, it started and idled ok for about 3 min, but as soon as I tried to ride, it acted like it was running out of gas again. I put it back on the lift and went through the PWK carb, but I could not find anything wrong in the carb. Feeling unsure of my tuning experience with the PWK carb, I decided I should put the Dellorto 21mm carb back on to rule out carb issues. I finished the carb swap this evening and it started right up, but that is as far as I got, it is a little chilly to be riding this evening so it sits till tomorrow. |
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Post by 190mech on Jan 26, 2020 1:37:33 GMT -5
It may be running out of spark instead of gas,,Had the same issue with my AF16 project,tried 2 different carbs,revised the fuel feed,still did it..Found the CDI unit flaming out at 9000 rpm when I ran it on the iggy test machine,which lead to testing a bunch of other 'spark boxes' for several weeks(I get side tracked on projects!),put on a known/tested flat line unit and no more "running out of gas"!!
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Post by oldgeek on Jan 26, 2020 11:47:32 GMT -5
It may be running out of spark instead of gas,,Had the same issue with my AF16 project,tried 2 different carbs,revised the fuel feed,still did it..Found the CDI unit flaming out at 9000 rpm when I ran it on the iggy test machine,which lead to testing a bunch of other 'spark boxes' for several weeks(I get side tracked on projects!),put on a known/tested flat line unit and no more "running out of gas"!! The new mini rotor and stator setup and its mystery circuit board was the immediate suspect, but when I checked the next morning I had spark. I am using a stock Kymco CDI with the rev limit removed. It may be that the mini rotor and the CDI do not play well together. I think you are right John, it really does not feel like a carb issue, but I had to start somewhere. Come to think of it, I had a weird no start condition a couple months ago that may have been CDI related. That time I checked all the wiring and it still would not start, so I swapped out the CDI for another one and it started fine. Then I put the original CDI back in and it still started and ran fine. |
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Post by oldgeek on Jan 26, 2020 20:37:59 GMT -5
Changing carbs did not fix anything. So I changed the mini rotor iggy out for the stock setup that I know is good. It started right up the moment I bumped the starter, and runs perfect.
As I swapped the iggy's out, I made a comparison between the stock flywheel and the mini rotor FW. They look to be timed the same but apparently there is something different because the motor would not run right with the mini rotor setup..
I pulled the air shroud off so I could see the timing marks on the stock FW, and hooked up a timing light. This is the first time I have used a timing light on a 2T, so this is all kinda new to me despite having watched countless videos trying to understand it all.
The published specification for my motor is 15.5°±2°BTDC/2000rpm. Using the timing light I can see the "F" mark lines up with the indicator at any RPM. Does this mean my base timing is around 15.5° and is flat?
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I decided to go ahead and try the mini rotor iggy since it seemed to be a wire for wire swap.
I heat cycled it good a couple times, up and down the road close to the warehouse, enjoying the added snappiness of the mini rotor iggy. The third time I went out to heat cycle it, it started and idled ok for about 3 min, but as soon as I tried to ride, it acted like it was running out of gas again. I put it back on the lift and went through the PWK carb, but I could not find anything wrong in the carb. Feeling unsure of my tuning experience with the PWK carb, I decided I should put the Dellorto 21mm carb back on to rule out carb issues. I finished the carb swap this evening and it started right up, but that is as far as I got, it is a little chilly to be riding this evening so it sits till tomorrow.