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Discussion Starter · #1 ·
after the 11:1 piston and cam swap my xx is hard to start, im thinking the decomp mechanism is not working properly but i wanted to know if anybody else is having a problem starting thiers? and i have no idea why the decompression mechanism would not work..
 

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I remember reading about getting a better batery for more cranking amps on higher comp engines.
 

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I would look into you decomp mechinism....I know of bikes running 14:1 still on stock starter and battery and turn over fine.
 

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I had a hard start problem when I first installed my 11:1 and stage 2 Web cam. I did find that the de-compressor was not working. I got it working again. Here is what I got for cranking compression; 100 psi with de-compressor inop, 75 psi with the de-compressor working. I did update to the higher cranking amp CBR battery. The CBR battery (YTZ10S) in a AGM type which is physically smaller than the stock battery, but more amps. I actually think that the YTX14S battery will fit for even more cranking amps.
 

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Discussion Starter · #5 ·
how did you get the decomp mechanism working? mine seems like it is hanging up in the disengaged position but it has alot of side to side slack, its the little bar type pin that it gets caight on on the cam, i really hate this design.
 

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how did you get the decomp mechanism working? mine seems like it is hanging up in the disengaged position but it has alot of side to side slack, its the little bar type pin that it gets caight on on the cam, i really hate this design.
I installed everything and it worked for the first few starts, then no crank. The next day I went to adjust the valves after my intial run in and I couldn't hear the exhust valve snap when turning it over by hand. Ran a comp test got 100 psi. I took the valve cover off and just checked to see if it was jammed or something I didn't find anything obvious. I cleaned it with brake clean, put some engine oil on it and reinstalled the valve cover. I turned the engine by hand and I could hear the exhaust valve snap again. Ran a comp check and it was 75psi. I am thinking that perhaps the cam lube that I used may have caused it to malfunction. I think it may have hung up a few times after that. I rode it for a weekend at the dunes and had no more problems. I hope it doesn't come back to haunt me.
 

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I put in the new battery and it fixed my problem
 

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I put in the new battery and it fixed my problem

I installed a CBR battery , if that decompressor is not working it still won't crank with a new/bigger battery.
 

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Discussion Starter · #9 ·
mine was hard to start the first time, i put as charger on it and it cranked fine,i killed it a few times and started it but it was hesitant every time, the next day it wouldnt start with a charger, put thebattery out of my gsxr in it and it does the same thing, took the valve cover off and hit thekey and it spins perfect with the spark plug in and all valves closed. i have a 180 CCA battery on the way to replace the stock 120 CCA but id like to know if it is releasing the compression.
 

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mine was hard to start the first time, i put as charger on it and it cranked fine,i killed it a few times and started it but it was hesitant every time, the next day it wouldnt start with a charger, put thebattery out of my gsxr in it and it does the same thing, took the valve cover off and hit thekey and it spins perfect with the spark plug in and all valves closed. i have a 180 CCA battery on the way to replace the stock 120 CCA but id like to know if it is releasing the compression.

Check your cranking compression, read my first post. It maybe a little different than mine because of cam differences but more than 70-80 psi I would say is too much(de-compressor not working).
 

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Discussion Starter · #11 ·
im pretty sure its not working, the problem is figuring out how to fix it.
 

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It's weird though that it works with the charger on though.
 

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recheck exhaust valve lash... too loose and it won engage the decomp

I was wondering if incorrect valve lash could cause the de-compressor to not work.:nuts: Although mine was in spec when it was inop.
 

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what did u set your at? and how did u set it?

@ tdc I set them @ .006 intake and .008 exhaust I believe, whatever the spec is with the camshaft.
 

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Discussion Starter · #18 ·
it may be my exhaust lash then, hotcams wanted something like .010 exhaust .020 intake, i set it a little looser to let the new valve job set in, now that it got hot and ran for a while, ill try setting it closer to stock and see how it works.thanks for the help, that makes more sense than anything.
 

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mine did the same thing, first start up was very hard then I checked my compression and was at 105psi then had an issue with my sleeve(not related)and redone the assembly and the decomp was working ... now compression is at 80psi and start like a new bike...The only different thing I made is use assembling moly first time and second time engine oil only. Maybe the moly got it stuck. Also noticed the ticking noise when the decomp act the second time. check the spring action on the decomp if it is working freely.
 

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Hotcam stage 1 should be set at 0.2 intake and 0.15 exhaust IN MILLIMETERS. Thats like 0.006" and 0.008" in inches. If your set at 0.01" and 0.02" thats really loose.
 
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