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Post by duosport on Jun 20, 2010 11:00:27 GMT -5
Maybe I can upjet a little without changing my airbox at all.
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Post by duosport on Jun 20, 2010 11:25:03 GMT -5
The stock main jet on the Gurtner carb is a #62 or 64. What do you think would happen if I put a slightly larger jet in and did not change the airbox at all? Maybe just a #66 or a #68?
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Post by 90GTVert on Jun 20, 2010 11:52:14 GMT -5
The idea is actually to increase fuel wthout increasing airflow at this point. Some others are saying they are jetted too lean stock. If you increase airflow then you need to increase the jetting even more. I think trying those alrger jets would be a good idea. If it speeds up you know you are on the right track and you need to evaluate your tune more.
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Post by duosport on Jun 20, 2010 12:05:58 GMT -5
That makes sense because if I leave the rubber connector from the carb to the airbox only slightly, slightly not completly connected the engine bogs. So just letting a little more air overwhelms the mixture. Yes I have the carb adjusted pretty lean right now, but still it clearly needs more gas. I should get a range of jets probably. If I got three I wonder what would be a good range to pick?
66, 68, 70?
68, 70, 72?
Higher still?
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Post by 90GTVert on Jun 20, 2010 13:38:18 GMT -5
Either of those 2 ranges would be a good start. Just a reminder, if you can get more jets at once it's cheaper than ordering multiple times because of the shipping charges. ou've had the carb apart but since you don't know the jet size I guess it wasn't marked? If you knew what it was for sure it would make the choice easier. another thing to consider would be ordering every other size. So if you think it's 62 stock, get 66, 70, 74. If you get equal results with say the 70 and 74, stay with the 74 to be on the safe side and then you can order a 72 later to see if it's just right if you so desire.
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Post by duosport on Jun 20, 2010 16:22:36 GMT -5
Yes I will order atleast 3 jets. Thank you for the info, much appreciated.
So I simply enjoyed riding around on my scoot all day today. As I rode it off and on today it seemed to me that it was picking up acceleration. The weather here was just as yesterday hot humid and little to no wind, so the comparison of todays performance should be the same as yesterday's. I have been testing my top speed on the flat from one stop sign on a long flat road Yesterday was a top speed of between 35 and 36 nph. The electronic gage flashed back and forth between these two numbers. At the end of the day today I tested on this testing ground and received a top speed between 37 and 38 mph. So I had a 2 mile increase in top end. On my way home I wend over a manhole cover and it was a bit of a thunk. I thought to myself "You idiot, you did not check the air in your tires." I went ti the filling station and my rear tire was quite a bit low. After the inflation of the tires I went back to the test track. I got a solid result of 40 mph!. Just goes to show how on a 50cc these little things all add up.
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Post by 90GTVert on Jun 20, 2010 19:31:12 GMT -5
Getting closer anyway. I don't think you are gonna pick up a great deal of speed with a jet change, but maybe you can get a couple more MPH and better acceleration if it works out well.
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Post by duosport on Jun 20, 2010 21:16:42 GMT -5
Well a bit more power I guess I can play with to make either acceration or top end. Frankly at 40mph I am on the edge of a acceptability. A couple of more miles and I will be very happy.
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Post by duosport on Jun 27, 2010 11:31:48 GMT -5
Well here is where I am at on it now:
I had removed the washer before and then after I tried that I had ground down the sleeve about the thickness of the washer and had tried that. I did not get any increase in top end. I did the marker test on the sheave. with the washer out I was a little more than a 1/4" from the edge. With the sleeve ground down and no washer I had a 1/4" to the edge. The amound of increased travel on the variator was minimal. Obviously I did not grind away much material on the sleeve.
I think I did a bad thing with the grinding though. When I went to disassemble the unit I had a little trouble removing the sleeve from the shaft. The was some buring ar the end of the shaft. This was caused by the outside nut and washer coming in contact with the wider burled edge of the shaft. Only slightly contacting this shoulder but still cause=ing distortion. clearly the whole unit was not tighhtening down properly because of it. So now I have placed the washer back in and this has brought the whole thing out equal to what it would be with no grinding and no washer. The amount I had ground off was equal to the washer. The washer is very thin, just over 1/32" thinck.
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Post by duosport on Jun 27, 2010 11:35:32 GMT -5
So with the sleeve ground and the washer in I tried putting the original (worn) heavier weights in to see what would happen. I did my test track controlled run and received similar performance on the top end. I believe the low end pick up was reduced.
So I have room to increase the travel of the belt on my variator. Is this what I need to affect? What are my options?
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Post by 90GTVert on Jun 27, 2010 11:50:33 GMT -5
Take the belt out and leave the rollers out of your variator. Slide the movable face as far closed as you can, so it's resting against the fixed half of the variator. Make sure the variator's back plate is still in it's original position. If you still have room left for the variator's "rails" to stay withing the guides on the ramp plate you may be able to file the center of the face of the variator and allow them to come a little closer together and push the belt higher. Sorry if this is confusing. i've been meaning to do a little write up about this with pics, but my computer has been less than cooperative over he last few days and I'm on my 2nd windows re-install. :bfg: Get kinda tired at staring at the screen after a while.
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Post by duosport on Jun 27, 2010 11:58:50 GMT -5
I think I understand but that is a bit extreme for me. Frankly I am OK with losing a little off the start to add to the top end. Perhaps simply a slightly wider belt is a posibility?
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Post by 90GTVert on Jun 27, 2010 13:51:35 GMT -5
A wider belt might do it, or it may not wanna travel into the rear pulley as far and you may not get anywhere.
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Post by duosport on Jun 27, 2010 13:56:56 GMT -5
So this morning I did a test run with the washer out (remember I ground down my sleeve a little). The run yielded a top end of 42mph. I just did a test run with the washer back in and the top end was 40-41. So there was a loss of about a mile and a half. Even though the amount of belt travel was hard to tell the difference on the mark, there was obviously some change. Just not enough. The problem is with the washer out the variator nut on starts to hit the shoulder of the shaft. The outside sheave is not relly being held flat and solid because of it. Also the contact of the nut and outside washer on the shoulder is causing some deformation of the shoulder cauing the sleeve to have a hard time comming off.
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Post by duosport on Jun 27, 2010 13:59:16 GMT -5
A wider belt might do it, or it may not wanna travel into the rear pulley as far and you may not get anywhere. ahh! I did not think about the rear pulley. I understand what you are saying about grinding the Sheave. it just is a little radical for me. I am not wanting to do anything to the original equipment. Maybe this is where a performance variator comes into play? |
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