04 400-S Cold Start killing battery

I have an 04 S-Model with Head & Can pipe mod, air box mod tuned to perfection.

The bike is eating batteries on a cold start situation.

Every 6th cold start or so, it locks-up and shorts out the system with the battery getting the worst of it.

It has never blow a fuse on this.

What I think it happening is that the battery plates are getting stressed until the battery won’t hold an adequate charge any more. You need a solid 11.4 volts to get the Ignition to fire.

I have been through several batteries with this.

I have found that on a cold start, If I put it in gear and rock it a bit, moving the piston up and down in the bore, that it relieves this lock-up on cold start.

it does not do this on a warm start.

I was wondering if the bike has a compression release that may be malfunctioning.

What else might be going on here?

Try a LFP battery from Shorai or www.turntechbattery.com Something in a 5Ah or larger will have a way higher peak than the lead acid battery and be lighter too.

If it has stock cams there should be an auto compression release built into the exhaust cam on the right side. Take off the valve cover and have a look.

It won't blow a fuse because the high current through the starter relay is not fused.

Are you sure you don't have a leaking float valve leading to hydro-lock?

Hmmmmm. Damn good points there SlowRider.

Ill check on that right side exhaust cam and see if im getting any lift.

Ill pull the plug and see if any gas is leaking in, but I doubt it. I replaced the vacuum PetCock with a standard unit. It is doing this on both units. Reason I went with the old school is that it takes to many strokes to get some gas to flow, especially if it has been sitting and the float bowl dries up. That takes a lot off the battery. I guess there are safety issue with that but it helps allot. Ive had to may problems with those vacuum units.

Fuze . . . . Dughhhhh . . .


checked an exploded parts view of the valve train, no compression release to malfunction. almost 100% on the vapor lock. is there any history of this problem?

The float-valve-needle getting worn and not sealing or the o-ring that seals the float-valve-seat to the carb body are not rare. If they leak the fuel can bubble out the jets and run downhill into the intake runners, past the open valves, past the rings, and into the oil. It can also cause hydrolock on the way.

Usually shows up as a bike that stalls at idle as it warms up as the fumes from the oil separator get sucked into the intake making it rich. It will run at revs ok because the higher airflow dilutes the fumes.

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