Don't know if u guys can help me trouble-shoot this one - any ideas r good ones.
K. I needed to scrap my bike and do another one. In doing this, some changes were made. I noticed my old cylinder was shot (had scratch marks all over -- I think the chrome was almost gone), so I got a cylinder rebuild kit. This new cylinder came from the same place my original cylinder came from. On my old bike, I was hitting 67-68 km/hr (8050-8100 rpm) givin my 26" wheels and 36 tooth sprocket. Oh yeah -- my motor is standard HT (China Gurl) 66cc, but with Flying Horse bottom end and grubee top end -- this is how my original configuation was as well -- but -- my older setup I made a 3mm spacer shim under the jug, and was RS reed-valved, and I had what I assume much better breathing in the transfers bcause I opened them up at the base and tapered them towards the port entrance to accelerate the incoming charge. The exhaust port of the older cylinder was enlarged -- I think my port timing was about 176 exh., 12X transfer, and intake roughly 180*, if I remember somewhat correctly. I also had an expansion (torque) pipe made to Jaguar's specs, but for a 6000 or 6500 rpm max. The motor worked beautifully, but was worn out. So in my new build (the cylinder is now broken in I'm sure), i went w/out the reed valve cause I needed the offset intake to run the dax RT carb -- the stock one fits with the reed valve, but the unit sits in such a fasion that the float bowl starves the motor at high revs. I had the RT carb on the motor before -- delivering 8000 + rpm. I have down-jetted to the 0.7 jet, but read a post about more of the story being dilution of intake. I am currently running a 'stockish' exhaust - 3/4" emt about 1' into a muffler. So I put on the torque pipe -- and the problem became much worse -- was 4 stroking at a much lower RPM.
I switched my new BPR7HIX plug to a stock one thinking maybe it was the temp range, this 'helped' the 4-stroking as I could barely get enough RPM to get to the 4-stroking point, but when I did -- it did happen. I am also now running a stock CDI (have the jaguar one) if u think that is making a difference. The thing that baffles me is that the torque pipe I made was for 6000-6500 (header is rougly 16 1/4" long) with port timing around the 140 exh/ 11X transfer) and it made things worse here.
Should I just down jet another size (this will be .65 (i think the smallest one I have)) and am at about 800 feet @ 75* F, and 65%-85% humidity. I am at about Or do I need to shim the jug up 3 mm, mill off the top and re-port the motor. The thing is if I use the reed valve (and the valves don't seal all the way any more -- if u suck on the entrance it makes a kazoo noise), and will have to cinch an adapter to get a carb away from the seatpost. Also noticed how much the extra piston slap chewed up the insides.
Was hoping to get decent speed with the piston port this time -- not just cause I like to go fast -- to get around these areas on higher speed roads, its just safer when cars aren't trying to pass -- u can keep up with traffic -- so I'm aiming for about 70 kph / 42 mph -- I had 68 before, with the restriction of the reed valve in the intake, and on this frame (disc brakes, compliant suspension, nice heavier more stable steel frame), I just cant fit the RT carb or the stock one at an angle that doesn't starve gas).
Long winded, i know, but I figure the more info I give, the more precise the trouble shooting. Oh yeah, b4 i was running about 170 psi, and now I am about 150.
Any suggestions would be greatly appreciated. Thanx in advance.
K. I needed to scrap my bike and do another one. In doing this, some changes were made. I noticed my old cylinder was shot (had scratch marks all over -- I think the chrome was almost gone), so I got a cylinder rebuild kit. This new cylinder came from the same place my original cylinder came from. On my old bike, I was hitting 67-68 km/hr (8050-8100 rpm) givin my 26" wheels and 36 tooth sprocket. Oh yeah -- my motor is standard HT (China Gurl) 66cc, but with Flying Horse bottom end and grubee top end -- this is how my original configuation was as well -- but -- my older setup I made a 3mm spacer shim under the jug, and was RS reed-valved, and I had what I assume much better breathing in the transfers bcause I opened them up at the base and tapered them towards the port entrance to accelerate the incoming charge. The exhaust port of the older cylinder was enlarged -- I think my port timing was about 176 exh., 12X transfer, and intake roughly 180*, if I remember somewhat correctly. I also had an expansion (torque) pipe made to Jaguar's specs, but for a 6000 or 6500 rpm max. The motor worked beautifully, but was worn out. So in my new build (the cylinder is now broken in I'm sure), i went w/out the reed valve cause I needed the offset intake to run the dax RT carb -- the stock one fits with the reed valve, but the unit sits in such a fasion that the float bowl starves the motor at high revs. I had the RT carb on the motor before -- delivering 8000 + rpm. I have down-jetted to the 0.7 jet, but read a post about more of the story being dilution of intake. I am currently running a 'stockish' exhaust - 3/4" emt about 1' into a muffler. So I put on the torque pipe -- and the problem became much worse -- was 4 stroking at a much lower RPM.
I switched my new BPR7HIX plug to a stock one thinking maybe it was the temp range, this 'helped' the 4-stroking as I could barely get enough RPM to get to the 4-stroking point, but when I did -- it did happen. I am also now running a stock CDI (have the jaguar one) if u think that is making a difference. The thing that baffles me is that the torque pipe I made was for 6000-6500 (header is rougly 16 1/4" long) with port timing around the 140 exh/ 11X transfer) and it made things worse here.
Should I just down jet another size (this will be .65 (i think the smallest one I have)) and am at about 800 feet @ 75* F, and 65%-85% humidity. I am at about Or do I need to shim the jug up 3 mm, mill off the top and re-port the motor. The thing is if I use the reed valve (and the valves don't seal all the way any more -- if u suck on the entrance it makes a kazoo noise), and will have to cinch an adapter to get a carb away from the seatpost. Also noticed how much the extra piston slap chewed up the insides.
Was hoping to get decent speed with the piston port this time -- not just cause I like to go fast -- to get around these areas on higher speed roads, its just safer when cars aren't trying to pass -- u can keep up with traffic -- so I'm aiming for about 70 kph / 42 mph -- I had 68 before, with the restriction of the reed valve in the intake, and on this frame (disc brakes, compliant suspension, nice heavier more stable steel frame), I just cant fit the RT carb or the stock one at an angle that doesn't starve gas).
Long winded, i know, but I figure the more info I give, the more precise the trouble shooting. Oh yeah, b4 i was running about 170 psi, and now I am about 150.
Any suggestions would be greatly appreciated. Thanx in advance.
