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Post by spudsmckinsey on Feb 9, 2015 17:32:15 GMT -5
I recently installed an 83cc BBK from 02Starrider (ebay). Kit was great. New head but regular size valves. Stock exhaust. Stock cam. New, 8gr rollers. New Clutch (stock), new Variator (stock). But now, with about 100 miles on it, I'm finding that it seems to be considerably slower than most 72cc BBK's. The initial take off is better for sure. But after that, pretty much the same as when it was 49cc. Top speed is 38mph Main Jet size is  (was  ) but seemed even slower with the . Compression is 150 psi. Needle position is midway. Fuel - Fresh Premium from Mobil Air filter is new but I removed to to see it it was restricted and performance was about the same. Tried removing entire intake air box....no change. Truth be told - I was expecting at least about 45mph top speed with the 83mm piston. Any suggestions? |
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Post by alleyoop on Feb 9, 2015 17:49:44 GMT -5
What speeds was it getting before the BBK, normally a stock 50 are good for 30-35mph most stock 50s will not get to 35 maybe 32mph and I am talking real mph not what the speedo says because they are off up to 20 percent. Also what are your RPMS that will help determine what you may need to get more speed. But just so you know putting in a BBK will usually not give you much on the top end, what it will do is give you low end torque and power . But now that your motor has more power you can do things to get more top end speed. You may want to get a little bigger Variator so that the belt can climb higher and or put in taller gears. Also Mark your Variator like this and run it at WOT and see how high the belt is climbing. Alleyoop  |
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Post by spudsmckinsey on Feb 9, 2015 18:58:18 GMT -5
Thanks Alleyoop.
I was getting approximately the same speeds as before but it does get to 35 much quicker than it did before so there is definitely some low end improvement.
I'm going to buy one of those digital hand held RPM meters off ebay to determine the RPMs
Do the Big Valve heads do much for top end?
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Post by JerryScript on Feb 9, 2015 22:44:17 GMT -5
The only thing that will help your top end is changing your final drive gears. You can gain maybe 2mph with CVT weights, but that's it, drive gears make all the difference in top end, so long as you have the power to use them, which is what your BBK does for you. You also need to tune your carb appropriately. Changing or removing or altering the air box without re-tuning your carb is just an exercise in frustration. Grab a couple of spark plugs, put one in and do a 2 mile ride at WOT, then turn your engine off and pull the plug to check the ceramic color. You want a nice coffee-chocolate color brown, white is lean and dangerous, dark brown to black is rich and will foul everything up over time. Follow alleyoop's 4TS Carb Tuning Guide and you'll probably gain a bit more power right off the bat! |
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Post by spudsmckinsey on Feb 9, 2015 23:05:31 GMT -5
Jerry,
If the engine is not reving past say, 6,000 rpm wouldn't that affect top end speed too?
I'm not sure what RPM my motor is reaching yet. I'm getting a tach. But it sounds like it is not reving very well. Like it's held back.
I wonder if my exhaust is clogged?
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Post by alleyoop on Feb 9, 2015 23:14:20 GMT -5
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Post by JerryScript on Feb 10, 2015 1:44:12 GMT -5
Jerry, If the engine is not reving past say, 6,000 rpm wouldn't that affect top end speed too? I'm not sure what RPM my motor is reaching yet. I'm getting a tach. But it sounds like it is not reving very well. Like it's held back. I wonder if my exhaust is clogged? Possibly, knowing the actual engine speed under different conditions will help to determine if it's the engine, or those 8 gram weights. You should also follow alleyoop's advice and mark your variator with a marker, then run to top speed and see if the mark is mostly rubbed off, shouldn't be more than 1/8-1/4" remaining if your engine is taking full advantage of the CVT setup. Do this while riding, if you do it on the center stand you won't know how a load affects it. |
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Post by rcq92130 on Feb 10, 2015 1:51:29 GMT -5
It's been a couple of weeks now .... how do you like your pacifica?
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Post by spudsmckinsey on Feb 10, 2015 7:45:56 GMT -5
Thanks Jerry and Alleyopp. Good advice that will be followed.
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Post by JerryScript on Feb 10, 2015 16:15:35 GMT -5
It's been a couple of weeks now .... how do you like your pacifica? LOVE IT! Windy the the last few days, much more stable in the wind, and so much smoother with the 16" wheels! |
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Post by spudsmckinsey on Feb 10, 2015 18:38:53 GMT -5
It's been a couple of weeks now .... how do you like your pacifica?   |
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Post by rcq92130 on Feb 10, 2015 18:48:51 GMT -5
Chill, dude. Really! You (and the thread) will survive!
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Post by JerryScript on Feb 10, 2015 21:06:07 GMT -5
It's been a couple of weeks now .... how do you like your pacifica? True, we do seem to have threads hijacked a bit from time to time. It would be best to post these sort of queries in the appropriate thread. I apologize! |
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Post by spudsmckinsey on Feb 10, 2015 23:48:43 GMT -5
True, we do seem to have threads hijacked a bit from time to time. It would be best to post these sort of queries in the appropriate thread. I apologize! Thank you sir. I put the little icon underneath the Hijack warning to show it was posted with levity. I was kind of expecting a laugh from rcq...not so much a reprimand. You sir are a fair moderator. |
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Post by jerseyboy on Feb 11, 2015 10:54:44 GMT -5
The only way too get full benefits from the BBK is to get more air in and more air out as well...free flow exhaust,up jet,UNI pod,bigger ports in head,intake, bigger valves,better springs,cam.That bigger bore needs more air and fuel brother...its not like a 150cc where you only gain a couple mm or cc,,the 50 BBK's are more of a change,,unless you are doing a 230cc on a 150.
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(was 
) but seemed even slower with the 
..BAD TO THE BONE..
