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  #41  
Old 12-08-2019, 03:08 PM
Mrmonk7663 Mrmonk7663 is offline
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Ok y’all. Still waiting on 22lb valve springs. However I put the 7” driven on, Middle hole, 265 cam and pink garter springs. Took it for a test. Jetting is a bit off in mid and top but that will be fine tuned.

Previously with the 6” driven I was hitting 41mph no matter what changed I made.

New setup without final tuning I am hitting 53mph at 61xx rpm when I ran out of space

With a 160 main I was at 50. 145 main 53. Gonna try a 140 next. Needle clip needs adjusted as well as it has one flat spot in midrange.

Bike pulls like a freight train it is noticeably faster not just in speed but acceleration. Engagement is quick Right around 2700-2800 rpms with aluminum weights/pink springs. . No useless belt slipping prior to engagement.

Need to swap the ngk plug in and take out the 3910x.

Things just got real!!!
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  #42  
Old 12-08-2019, 10:08 PM
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amazing ...

Now I cannot help but wonder if that gear ratio benefit
you gained with the 7" would help moving the 6" as quickly..
No, no need to test that just for my curiosities sake, but I still wonder

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  #43  
Old 12-08-2019, 10:59 PM
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I don’t know haha. When I had the 6” driven I tried everything from 7.2:1 down to 5.5:1....and multiples in between and nothing would work. I believe, and it’s just my belief, that the engine’s power forced the bike into overdrive way too fast. That’s why the racers try to lock it out I imagine.

But I’m headed in the right direction for sure. 50-9 was my gearing today. I will try 50-10 and see if I continue to gain speed or if the 50-9 will be optimal. I can potentially still test out the third hole on the driven road see if anything is gained or lost there. But after that and the valve spring upgrade I’m done with the exception of fine tuning carb. I am much happier with the bike now than I was last week. That’s for sure.
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Old 12-15-2019, 05:46 PM
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Little update. Swapped in the 22lb springs. The 18lb were not holding me back but the 22lb are better suited to the 265 cam. I’m going to try stock comet blue springs next. The Chinese stock springs were stiffer than they should have been. The pink springs are working well at 2800 rpms but I feel 3300 might be ideal. We will see.
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Old 12-16-2019, 08:14 AM
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One thing I am considering is tires. Not many options but Kenda has an 18” tire. At 1” shorter it might make it easier to rev out on the tav.

Another question. Endplay. Could this effect the tav? Perhaps make belt contact less than ideal? I need to tighten endplay in the crank, just waiting for the shims.
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  #46  
Old 12-16-2019, 09:30 AM
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You know, I just realized something. It's either the tav springs or the engine. I have a baja warrior with a 196cc engine, a 30 series and a 9/50 (5.5:1). The only thing that's been done to the engine is a governor removal and an upgraded carb (bigger bore rui xing). That thing hits a gps confirmed 57mph before valve float. Have you thought about a billet flywheel? I think that I read that they have a stronger magnet, which would help with spark. Also, I wouldn't trust a stock flywheel over 6k rpm.
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  #47  
Old 12-16-2019, 12:45 PM
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My flywheel is not the stock iron flywheel. Anyway I’m sure the bike will go faster as is if I had space. My testing is done at the same place and all mph referenced are in the same place for consistency. The engine is fine. The bike is a rocket. It’s simply I’m trying to make a part designed for stock power levels to function at almost double the power.
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Old 12-16-2019, 01:11 PM
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How well are the driver and driven lined up? The driver's stationary sheave should be directly in front of the driven stationary. Couldn't that be causing more drag than there should be, and more belt wear.
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  #49  
Old 12-16-2019, 07:11 PM
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They are aligned perfectly. From what I can tell it’s the power level of the engine that’s the problem. It’s too much. Drag racers have suggested it’s the asymmetric design that holds the higher power builds back. Some even use a 29 series with the v-belt to overcome the problem. My belt is brand new. The Chinese belt I took off was fine as well, just sub par material. I guess it’s possible the belt is slipping at higher rpms but no way I can tell.

What is happening is the driven opens up fully very fast as it is overpowered. The 7” helped tremendously. If I can get some stronger snap ring pliers I’ll see if the third hole helps. The 6” driven was utterly useless regardless of hole position.

At 4500 rpms the driven is fully open right now.
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Old 12-16-2019, 07:43 PM
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I'd try Kentucky Boy's suggestion. If you still have the original jackshaft throw it on temporarily, and try running a centrifugal clutch.
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  #51  
Old 12-16-2019, 09:49 PM
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Quote:
Originally Posted by itsid View Post
hmm MrMonk's got his head shaved (tonsure so to speak )
And Joe's was likely not exactly stock either
(going by what engines Joe usually present to us.. it likely qualifies as a racing engine I'd say)

And if it doesn't run right on any of Joe's engines (as I read his initial comment)...
chances are it's indeed not as good of a plug (neither for racing) as one might think when reading "racing plug" ...

Going out on a limb here, but let's say I keep note of
"3910 plug... be aware of it might be causing problems..avoid if possible"

Just to be prepared for the next soul having a weird engine not revving issue.

'sid
Mine was a bone stock 420cc powerland engine with a cam and matching valve springs , exhaust , billet long rod (shaved the piston myself with a grinder to clear the stock head even) , and a carburetor
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  #52  
Old 12-17-2019, 07:46 AM
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If it's not the stock flywheel, and it's not billet, I'm guessing a PVL flywheel??
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  #53  
Old 12-17-2019, 08:04 AM
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I just got done watching a RBG video on the street legal minibike, and He's having the same problem as you. Built 212 tillotson, stock tire sprocket, and a 30 series. His bike won't go past 43ish mph, and the engine won't get out of the 4k rpm range (it sounds like 4500 ish, maybe 4600). So it might very well be the 30 series.

One thing that has me stumped is why are your and red beards bikes stuck there, while mine is free to rev? Maybe it's the power that your engines are putting out, that the 30 series doesn't like. I mean, I have 30 series on the middle spring setting on the driven, 9t TC sprocket, 50t axle sprocket, and an engine that only has the governor removed, yet it'll rev to valve float (5200-5500 ish iirc). And mine will still rev to valve float with a 10t TC sprocket, it's just a bit too fast for me (she'll almost keep up with traffic on 19, which has a 60mph speed limit, though people usually do 65mph).
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  #54  
Old 12-17-2019, 07:05 PM
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It’s the power level. I believe it’s just too much for the 30 series. I’m fairly confident that if this was a stage 1 build it would rev fine. My stage 1 kart with 7@ and 30 series floats the valves no problem.

My bike is far from slow. It accelerates incredible...but at 4500rpm it starts to struggle. With the 6” I could get it to 5krpms only. The 7” helped a lot and will get me to 6k rpms...but I can feel that the bike should be accelerating faster from 4500-6000...and should be revving closer to 7k.

Only thing left to do is put the 7” in the third hole. After that there is no more testing I can really do aside from investing in an 18” tire...which may or may not help. I’m not aware of any 16 or 17” options that fit the 8” wheel.

This is all just my theories, but I know I’m not the first one to suggest the power level is simply too much for the unit. It’s a somewhat common issue with drag bikes...the solution being a clutch. Problem is I don’t want a drag bike...Perhaps a 40’series is the solution. I have been told by a couple of sources that the 20 series is also a solution which obviously I can’t confirm.

Oh and flywheel..it’s a 3.1lb aluminum flywheel. Not PVL. It’s a factory flywheel off a Honda engine that was sourced from a kart racing company.



I
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Old 12-18-2019, 08:11 AM
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For the sake of being thorough I ordered a yellow driven spring last night.
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  #56  
Old 12-20-2019, 08:10 PM
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So I’m not crazy after all . GPS just released a new driver called “the juggernaut” it specifically addressed the rpm limitation the normal 30 series imposed on higher powered builds. I purchased 2 and will be installing one on the bike in this thread. I’ll take the aluminum weight driver unit and put it on a small tire bike and see if it works better on that.
https://www.gopowersports.com/super-...he-juggernaut/
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  #57  
Old 12-21-2019, 05:03 AM
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that looks like a comet 500..

Also I don't quite understand that line:
Quote:
Originally Posted by GPS
Limits/Eliminates belt slippage
if the belt slips, the engine will rev up no problem
(the kart/bike won't move any faster .. but a slipping belt is not rev limiting)
Ah well if it works, that's all that counts..

I just hope it's not another series40 backplate brainfart

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  #58  
Old 12-21-2019, 08:09 AM
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Lol. I hear ya sid. I’ll find out next week I guess. They shipped this morning.
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Old 12-21-2019, 09:32 AM
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Hope that works. I’ve been forgetting to ask, when you installed the 72t sprocket did you have to buy a longer chain, or just move the axle forward and engine back?
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Old 12-21-2019, 02:09 PM
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I bought a longer chain. I need to sell the 72tooth and chain actually. It’s just collecting dust now.
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