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New cam, lower CR, or be ready to push start?

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Well it’s close to decision time;

Current setup; 90mm bore, 13.5 CR, Hot Cams In and EX. Runs very well, but starting is a bit iffy. Battery is brand new and fully charged, starter is good, and been swapped with a known good one for double check.

Cold, she starts just fine.. But hot start, as in dump, or quick map check, instruction moment or lending a hand for a fellow rider,, right back on the bike, it will stall the starter.. Several attempts will get it going,, but it is going to bite me in the butt one of these times.. I now try and roll/push button start it when I can,, and that is a sure fire way to kick it over,, but kind of a pain. Letting it cool down just 5~8 minutes will also allow it to turn over and start no problem... All this is with the headlight off, no heated grips, no helmet light. It is only going to get worse from here.

So several courses of possible action.

1: Leave it,, it works mostly now...

2; Add a kick starter,, uuuugg, more weight, and will it even work at my CR and no auto decomp on the ex cam

3: use a S base gasket to drop the CR to 12.6

4: Use an E EX cam

Those are the options as I see them, and the decisions on which one is proving hard

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I have a head that I'm sure would drop your compression ratio :thumbsup:

You're more than welcome to use my exhaust cam, I don't see any use for it in the near future. And if one does come up it won't be a quick need anyway. If it would make you feel better I'd even sell it to you. I have a sneaky suspesion that when I get around to putting that other engine together I won't be using it anyway. Or we could use it as a partial trade other parts.

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do this next time the starter stalls.put the bike in gear.pull it backward till it stops.put it back in nuetral.hit button.should fire everytime.

that puts the piston just after tdc.

im not sure what i would do in that situation.....

i would lean toward lowering the comp ratio if you like the way it pulls at high rpm.other wise i would got E ex cam if you want more bottom. :thumbsup:

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I vote for changing out the EX cam for an E cam, that is the simple solution while tiring to keep the power of high CR. There are several manufactures of small engines (Onan, Kohler, Honda, etc) that use about the same type of compression release on there singles.

I have thought about having my stock S ex cam reground just for this reason. I like the button that much :thumbsup:. If I'm going to kick start something, it will be a light weight smoker!

Just my two cents.

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Couldn't he use that to get the starter spinning? Pull the lever, hit the magic button, release the lever. I used to bump start my old YZF like that, hold in the decompression lever, get rolling in gear, then let go of the lever to light the fire.

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would it be possible to get the head machined? i've seen the boss casted in with no hole, is it just a through hole and a threaded hole? :thumbsup:

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no threads besides retaining bolts.its a stepped bore.a seal bore and the bore the shaft rides in.possible yes,cost effective....not sure.

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