1992 jog bbk build

[nelson]

Ok, this is the finished product of my 90cc + build. I still have some tuning to do on the cvt and it likely I will build a pipe and port a cylinder for it in the future, but for now its done. It is pretty quick but I am sure I want to take it to the 1/8 and see what she will do. I wanted it to appear as stock as possible.

[nelson]

Do you guys think would benefit more from a hoca 54mm cylinder or getting a 90 degree head to fit my dremmel and extending the durations a bit? I guess this would be determined on if I want to use n street or race only?

[nelson]

Is that on the long case? Because I see for the jog they are 780 16.5 30?


quote author="90GTVert" source="/post/124514/thread" timestamp="1403837177"]788 17 28 has worked alright for me up till all the Hoca variator was used and then it snapped belts. If you're getting a big vari like the Malossi OR then it will need a longer belt for full travel.[/quote]

[90GTVert]

I use 788 17 28 on short and long case clones. The angle will be OK and the 1/2mm of width may cause you to need extra spacing till it wears for the same take off but most likely the extra 8mm of length will be fine for it and hopefully improve launch and maybe top end a little.

You can increase durations without buying a 90 degree head. I still don't have any tools that let me port from inside the cylinder. The exhaust port can be opened up all the way through from the flange/header side and the easiest way to pick up transfer duration without expensive tools is to file the piston crown at the edges in the transfer area.

49ccscoot.proboards.com/thread/1304/filing-pistons-increase-port-duration

Fromm seeing how much power it appears to have taking off and how it maxes out quickly, I still think your best gains right now will come from getting the CVT to work better.

[nelson]

I have already taken some off of the piston crown. I just did a quick job of it so I assume I could get a bit more with attention to detail. And what would you suggest as for the width on exhaust port?

[nelson]

I guess I can just fnd your research page, I know it has all that info

[2strokd]

If its shifting well and getting good power down i bet you can get into the 10,s pretty easy with a Jog platform! Im glad to hear you are going to make some passes with it
Best of luck and keep us posted! Get some vids if you can?..

I think 60% of the bore width is what Bell suggest for ex port width?.

[90GTVert]

Here's a bunch of porting info.
49ccscoot.proboards.com/post/30229

[craisin]

martysgarage.info/manuals/bell2ttuning.pdf

this maybe of use

[nelson]

m.youtube.com/watch?v=g-vfPkx-lMs
Another short vid I made. This one isn't so shaky at somewhere point in vid yyou can see the seconds it takes to get from 0-53 mph. I did some cvt tuning when I got home but it isn't what I'm looking for. I shaved down some of front pully but the belt still does not ride down in there. A bit more tuning to come..what is weird is even with a tuned cvt on my 70 top speed is the same as my 90, 52-53 mph and theu jave different gearing. The 90 gets there a lot faster but I dont see it going much more than 56-60 with stock cvt. The emgine pulls hard. I have a larger than stock diameter front pully just have to get to the edge. I smoothed the cone down so belt could ride lower in take off and they can get closer together for top speed. Just needs a bit more taken off. Thoughts?

[90GTVert]

I'm guessing the 70 revs higher but has deeper gears and the 90 revs less and has taller gears so the speeds come out about the same. The 90 doesn't seem to be lacking the power to go faster, but probably needs the RPM to stay steady for longer to get more speed out of it.

[nelson]

I saw 10,500 rpm on the 90 yesterday on the tto when i shut it down. I noticed on th front pully the belt has been riding about 2 mm from the edge. With the 8:1 gears you'd think I would have a hhu ghost top speed. Need to read some more on subject

[90GTVert]

2mm from the edge does sound pretty good. Are you sure the rear pulley opens all the way? The easiest way to check it out is to take out the contra spring and set the clutch in place. Set the assembly down with the clutch facing up and see if it opens as far as it can without contacting the clutch and trying to push it up. Sometimes a lip on a pulley hits or the way the TD is made it's taller than needed and hits. If that's good then make sure the grooves in the torque driver extend to the edge so the pulley can open as far as possible. Some leave a pretty good gap between the end of the groove and the seal and others run right down to the seal (what you want for max travel). Can't remember if you checked this before, so sorry if it was already done.

[nelson]

No, that has not been done on the rear pully. thank u for the heads up. It was making so noise back there when I got home, the clutch felt like it was engaging at 1-2k rpm. I thought maybe the stock shoe springs were failing after all they are from 2001 atv! No telling how many hours on them put I could have almost pulled them off by hand! I put new 1k sprigs in. I am understanding the way rear works now. The forward motion of the belt twist the td open but have to see if all the way. Anyway, I pulled the clutch cover and my big nut that holds shoe to td had come a bit loose. Ok, well I guess it is just as important to get the belt down in the back as it is out on the front. I sanded the face of the front pully but didn't take the edge off so belt wouldn't drop all the way in

[nelson]

What do u think a reasonable top speed goal should be? I would like to be able to hit 70 if I wanted. with a larger diameter front pulley the a 90/90/10 tire (I think) and 8:1 gears and it pulls to 10k.plus I only weigh 145 on a jog