Low RPMs on takeoff

Does your Spree/Elite already run great, and you're trying to make it quicker/faster? Need a monster motor swap? Discuss your ideas here.

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ansneds
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Low RPMs on takeoff

Post by ansneds » Tue Oct 17, 2017 9:33 am

I've been experiencing low RPMs on takeoff for awhile now and I can't seem to figure out why. I've read multiple posts saying that it's either the main or pilot jets. I am using the stock carb with a 78 main jet. Also have polini variator with unknown weights in it. Just put in 9:8:1 gears in too. Please let me know if there's anything else I should look into.
Currently own:
->1995 Honda Elite 50 (Derestricted)
Have previously owned:
->Multiple 94-01 Elite 50s
->1985 and 1986 Honda Sprees
->1985 Honda Aero 50

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Meatball
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Re: Low RPMs on takeoff

Post by Meatball » Tue Oct 17, 2017 9:56 am

Is your motor stock with a PG Short exhaust?
I need to find some new haters...the ones I have are starting to like me.

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ansneds
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Re: Low RPMs on takeoff

Post by ansneds » Tue Oct 17, 2017 10:06 am

Yeah it is
Currently own:
->1995 Honda Elite 50 (Derestricted)
Have previously owned:
->Multiple 94-01 Elite 50s
->1985 and 1986 Honda Sprees
->1985 Honda Aero 50

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Meatball
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Re: Low RPMs on takeoff

Post by Meatball » Tue Oct 17, 2017 10:49 am

That pipe likes 8k-10k rpm's....not 2k-6k....especially on a stock bore.

Tall gears are a trade-off as well. If your mountain bike was in a tall gear, it would be tough to pedal...until you get the RPM's up. Multiply this with an exhaust that has no power at low RPM's and you have a recipe for sluggish take-offs.

Stock bore + PG Short + Tall gears = slow take-offs.....add a BBK, Intake, Carb, etc and you'll fly.
I need to find some new haters...the ones I have are starting to like me.

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ansneds
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Re: Low RPMs on takeoff

Post by ansneds » Tue Oct 17, 2017 1:31 pm

Alright I'll try the stock exhaust to see if it's any better. Do you think I need to upjet?
Currently own:
->1995 Honda Elite 50 (Derestricted)
Have previously owned:
->Multiple 94-01 Elite 50s
->1985 and 1986 Honda Sprees
->1985 Honda Aero 50

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Meatball
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Re: Low RPMs on takeoff

Post by Meatball » Tue Oct 17, 2017 1:53 pm

Whenever you change exhaust you should re-jet. A higher flowing/revving exhaust would require an up-jet to normalize the additional air provided. Having changed ONLY the exhaust wouldnt require a very drastic jet change since the surrounding components (airbox, carb, intake, bore) are still in restrictive "stock" form, limiting the amount of additional flow your PG Short is capable of providing. Maybe only a few sizes up. Ultimately, you have to be realistic in your expectations of the stock bore. It can only give you what it has...which isnt much.

My suggestion: up-BORE!
I need to find some new haters...the ones I have are starting to like me.

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bonesv
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Re: Low RPMs on takeoff

Post by bonesv » Tue Oct 17, 2017 5:56 pm

Meatball gives good advice on this but you could first try changing the springs in the clutch and maybe a few total grams lighter roller weights to help the revs come up before the drive starts shifting and see if you can get the power of the stock bore to at least get you off the line better. I have a stock bore with 9:1's and clutch spring/roller weight mods and it gets me to the store economically and a little faster! You will need to practice tuning the drive system anyways if you go bbk so it could be good practice. It's cheaper than all the other stuff at least.
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Jonadz
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Re: Low RPMs on takeoff

Post by Jonadz » Tue Oct 17, 2017 6:10 pm

With the pg short I found 5g weights in the vari to be the game changer, yellow contra spring and shoe springs to launch at 4500-5000 rpms, also stock belt, not a malossi for some reason.

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ansneds
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Re: Low RPMs on takeoff

Post by ansneds » Tue Oct 17, 2017 9:51 pm

Jonadz wrote:With the pg short I found 5g weights in the vari to be the game changer, yellow contra spring and shoe springs to launch at 4500-5000 rpms, also stock belt, not a malossi for some reason.
Is that all on a stock bore or bbk?
Currently own:
->1995 Honda Elite 50 (Derestricted)
Have previously owned:
->Multiple 94-01 Elite 50s
->1985 and 1986 Honda Sprees
->1985 Honda Aero 50

Jonadz
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Location: Pacific Northwest

Re: Low RPMs on takeoff

Post by Jonadz » Tue Oct 17, 2017 10:56 pm

That was on stock! I can dig out my carb tomorrow to check jetting but itÔÇÖs really an individual number, MeatballÔÇÖs ran great and I tried to mimic his, ended up being different by at least 5 sizes but IÔÇÖm pretty sure I had I mean air leak back then. Regardless rode it 69 miles a day in hilly terrain for a month and pulled on everything.

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ansneds
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Re: Low RPMs on takeoff

Post by ansneds » Tue Oct 17, 2017 11:17 pm

Dang, what did you top it out at?
Currently own:
->1995 Honda Elite 50 (Derestricted)
Have previously owned:
->Multiple 94-01 Elite 50s
->1985 and 1986 Honda Sprees
->1985 Honda Aero 50

Jonadz
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Posts: 198
Joined: Wed May 10, 2017 12:19 pm
Location: Pacific Northwest

Re: Low RPMs on takeoff

Post by Jonadz » Tue Oct 17, 2017 11:55 pm

My highest gps reading was 67, granted it was on a spree swap but still a stock elite bore.

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ansneds
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Re: Low RPMs on takeoff

Post by ansneds » Wed Oct 18, 2017 9:33 am

And you didn't have any issues with the yellow contra spring on the stock pulley?
Currently own:
->1995 Honda Elite 50 (Derestricted)
Have previously owned:
->Multiple 94-01 Elite 50s
->1985 and 1986 Honda Sprees
->1985 Honda Aero 50

Jonadz
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Posts: 198
Joined: Wed May 10, 2017 12:19 pm
Location: Pacific Northwest

Re: Low RPMs on takeoff

Post by Jonadz » Wed Oct 18, 2017 10:17 am

Red contra is the only one IÔÇÖve read about that presented issues with the stock pulley, I believe most with stock pulleys run a yellow and have yet to hear of failure myself.

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bonesv
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Re: Low RPMs on takeoff

Post by bonesv » Wed Oct 18, 2017 2:12 pm

Jonadz wrote:My highest gps reading was 67, granted it was on a spree swap but still a stock elite bore.
You need to get a new gps :roll:
Honda Elite SR
Honda Elite-Dio ZX

Dio ZX Headlight/Disc Brake Mod: http://hondaspree.net/phpBB3/viewtopic.php?t=30861

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