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Starting issues. New battery time?

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Hey there, I just rebuilt my engine with help from Mike over at Engine Dynamics with a 10.5:1 compression piston and it seems to be killing my battery.

I still have the O'reily's branded "SuperStart" AGM battery from when I bought it and it dies out within 10 seconds of cranking. Voltage on the battery drops to near 8 when cranking (Waaay too low to produce a spark from my experience.)  Although I did hear it run for 5 seconds before it died out.. I'm also running a HotCam and have about 120 psi compression

I want to put a Lithium battery in there for weight reduction, charge retention and cranking amps for the higher compression ratio. Which one would you choose? 


1: $150 Shorai https://shoraipower.com/lfx14a4-bs12-p70
2: $115 WPS http://www.santaclaracycle.com/wpsfelibayt.html
3: $75  Super Cheapo Lithium https://www.amazon.com/Lithium-Battery-Replaces-YTX9-BS-Motorcycle/dp/B078BCYJF9/ref=sr_1_6?s=automotive&rps=1&ie=UTF8&qid=1519399734&sr=1-6&keywords=YTX9-BS+12V+Lithium+Ion+Battery&refinements=p_85%3A2470955011
4: $50 Yuasa AGM http://www.yuasabatteries.com/battery.php?bID=B9&vID=3576

I'm leaning towards the WPS due to the price but I'd like to hear from some other guys who are running lithium batteries, or those who have higher compression pistons running on AGM batteries. 

 

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Get the Yuasa.  I just got one from 2wheel last week , they had the best price and I got it in three days. Other than the weight savings , the lithium batteries will leave you dead , sooner or later , with no warning.  They're finnickey about charging voltage and occasionally explode or burst into flames.

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you will save weight with a lithium battery.......but that`s it,.. get a Yuasa battery and be done with the cheap crap..

You are running a higher compression piston without decomp on the cam.....that puts extra strain on the starting system and a crappy battery is gonna make you swear..lol

 

 

B

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if it was only 120psi you`d have an issue,,,yip..lol

 

considering 199 is stock...but ...is decomp still active when it was tested,,there`s the question

 

B

Edited by brianhare

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18 hours ago, WvChamp said:

I am surely hoping "higher compression" is more than 120psi ? ;)

 

Couldn't fit a screw on compression tester in there so I went with rubber tip hand pressure thingy. 

I knew it was a brand new bore, new rings, newly lapped valves with a good seal so I had compression. :p

Went through testing coils and plugs etc all morning. Good ohms on the coil and plug lead. Voltage to the cdi but none out? Weird no voltage at the coil with the ignition on. Plug out = spark. Plug in = no spark. Lead on separate plug without a plug in the bike = spark. Lead on separate plug with spark plug in the bike = no spark. It was weird. But it works now. Ain't broke, don't fix it. 

Turned out it was battery not having enough UMPH to turn over that brand newly bored cylinder and overcome all that new machining friction. I tied on another battery and that gave some extra juice and it turned over and started right up. I let it warm up, checked for excess smoking or weird problems; none. 

Now I'm sitting here listening to it idle like a dream.  Changed the oil and pumped all that bad oil I could up out of the crankcase; thick bad black shit.

Now it starts just fine off that crappy SuperStart battery I have. :) But I'm still gonna get a Yuasa in the next couple days. 

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