went down to 10g sliders, wow!

davelhunter · Post by **davelhunter** » Mon Aug 17, 2009 5:45 pm

As many of you know, I have been woriking on my project Blur, which included 63mm big bore, forged piston, stroker crank, port & polished head, A9 race cam, increased the compression slightly, etc.
I discovered something very interesting playing with my slider weights. I had purchased sliders in 10,11,12,&14gr weights to experiment with and do some GPS testing.
Upon getting my motor back from K7S Power, who did an excellent job, I left in my 12 gr sliders which I had used previous to getting my motor built. I then switched to 14 gr. weights. These seemed to drop my rps's from about 8,000 on takeoff to about 6,000 with what I thought was maybe 1mph more on the top speed, so I kept in the 14g weights since I like to do a lot of freeway riding.
Last week I purchased a dr pulley variator. I wasn't really impressed with a difference in performance. It seemed like there was a slight difference in performance, but nothing much. This was with using the 12 gr weights and then the 14's.
Yesterday I decided to take out my variator and look at the ramps to compare to the stock variator. I decided to see what would happen if I put in the 10 gr weights. Wow! I immediately rev to a little over 8,000 rps's. The bike just pulls at the same rate all the way up to about 75 mph indicated and then keeps pulling up to about 83-84mph indicated on the dash! (77mph) I had no trouble passing cars on the 405 freeway in Los Angeles! I was actually able to drive in the left lane on the freeway.
I would have thought that the lighter weights would have not pushed the variator all the way out, but I guess the lighter weights do the job and put less strain on the engine then the heavier weights. This is all with stock gearing! If I could only find aftermarket gearing that will fit the Blur, there would be no reason to buy a 220i when it comes out.

* I noticed that I still have about 1/8" on the outside of the variator even with the heavier weights & the 10g weights so I am in the process of ordering a longer belt and will post results when installed.

To summarize, I would highly recommend the big bore kit with stroker crank & A9 cam. It really takes this bike from an in town scooter to a highway motorcycle like machine.

santa · Post by **santa** » Mon Aug 17, 2009 10:39 pm

Sorry I got a little lost.

I got that the 10g weights gave you the best results. However I would be concerned that the increased revs could be somewhat detrimental to the longevity of the engine. What do you think.

But from what you said it sounds like that nothing else really made much of an improvement. Am I missing something?

I have been strongly thinking of selling my Blur since living on the edge of the suburbs means that getting around usually means trying to survive the freeway for short bursts. If this works I can keep my Blur.

davelhunter · Post by **davelhunter** » Tue Aug 18, 2009 5:25 am

Basically what I meant was that if someone is thinking of selling their Blur for a 200cc scooter or a small motorcycle, I would recommend going with a big bore kit, stroker crank, A9 race cam, port & polish on the head and you have an awesome freeway capable machine. On our rpm gauges, the red line is not until 9k or 10k if I remember correctly, so I assume you can ride all day at 8,000 to 8,500 rpm's. I recall somewhere reading that the gy6 is capable of running to 12,000rpm's? If I am wrong, please let me know.
Regarding the slider weights, I was stating that I had assumed that going heavier was going to increase my top speed, but all it did was slow down my takeoff by "lugging" the engine. The 10 gr. variator weights are enough to get the variator all the way out for the belt to ride just as high as it does with the heavier weights, so the heavier weights are unnecessary. Now I know it may be different for a stock motor, I am stating these findings based on my motor which has the mods stated above which puts the powerband in a higher rpm range than a stock motor I believe.

beeboytroy · Post by **beeboytroy** » Tue Aug 18, 2009 7:12 am

Now I know you have new Mikuni carb. Is that also in your machine?

bikebuda · Post by **bikebuda** » Tue Aug 18, 2009 9:04 pm

you said you put in a A9 cam this is a 9000 rpm powerband cam

by using the heavier weights you were keeping it from getting into the designed rpm power range
by going lighter you allowed the engine to rev into its (now designed for ) power range

davelhunter · Post by **davelhunter** » Wed Aug 19, 2009 12:08 am

Bikebuda,
Thanks. This is probably a stupid question, but does the # after the A on the cam mean this is where the powerband is for that particular cam? Ex. A8 cam = 8,000rpm powerband, A12 cam = 12,000rpm powerband?

Regarding the Mikuni carb, no I am still using the stock carb, intake, and pipe. The stock pipe makes more torque than the aftermarket pipes from my experience. I do not believe an aftermarket pipe is of any benefit.
The mikuni carb would not fit properly, so I didn't keep it. I just could not get it to fit. The top was too high so I could not get the seat on without cutting into the storage, which I did not want to do. In addition, the bottom of the carb had these little metal fins on the sides that held the vent hoses. They got in the way and I could not get the carb to lay flat. It was hitting where the timing chain tensioner was. I may try a 30mm cvk carb, but the flat side carbs don't appear to fit, at least not the mikuni. I am wandering if a bigger carb will do much. The motor is running so well right now.

babblefish · Post by **babblefish** » Mon Sep 14, 2009 1:19 pm

Question: did you change the rear variator spring (not clutch springs) to a lighter one or is it still stock? If so, which one did you install? Thanks.

KS Power Nick · Post by **KS Power Nick** » Mon Sep 14, 2009 9:38 pm

Dave

Have not been in this forum for awhile now. (I broke my finger and can not do to much shop work so I will sit in front of the computer for the next week or so.)

I am REALLY glad to hear you got the motor to spin up higher. FYI David engine has the GOOD valve springs and Titanium retianers in it, so it can handle the rpms (just keep an eye on the engine temp for long distances). The stock intake on the blur is a VERY nice design.

Do you access to a GPS? I would love to hear what your top speed is now!!

Enjoy!!