Author Topic: Starting Trouble When Hot  (Read 260 times)

Jack Straw

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Starting Trouble When Hot
« on: September 15, 2020, 05:26:12 pm »
My bike starts easily with little or no choke in the hot weather here in Arizona.  Runs perfectly, pulls strong, feels totally normal.   After riding at normal temp for a few miles it won't re-start.   

I pulled the choke plungers out for inspection and they look fine.   A former American Honda tech suggested that one or more of the plungers might be leaking leaking or not seating properly causing over-rich condition when hot. 

The fuel cap is venting normally, fuel is fresh.  Battery has 12.7 volts.   I'll check the coil resistance but I'm not sure what the ohm values should be.  I'll research that on line.

Anyway, that's my life with the VT at the moment.  I'd appreciate any advice.

triguyracer

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Re: Starting Trouble When Hot
« Reply #1 on: September 16, 2020, 05:18:16 pm »
Check your valve clearance, tight valves can cause hot start problems

Jack Straw

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Re: Starting Trouble When Hot
« Reply #2 on: September 17, 2020, 12:01:53 pm »
Thanks for the suggestion on checking the tappet clearance. :D

Bucko

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Re: Starting Trouble When Hot
« Reply #3 on: September 17, 2020, 02:14:08 pm »
A 'Hot, no-start condition' is very common with these bikes.  Typical symptom: go out for a ride, stop for gas, after which the bike won't re-start until the motor cools down.  Popular opinion is the problem is faulty coils which don't show a problem until they're hot.

Jack Straw

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Re: Starting Trouble When Hot
« Reply #4 on: September 21, 2020, 06:00:02 pm »
Yep, my problem exactly, It failed to start after a gas station stop.   I checked the primary and secondary resistance on the coils both cold and hot they read 2.5 ohms each, hot and cold primary and about 35K secondary.   These figures are within tolerance according to the Clymer manual.   

In the meantime I received a new pair of coils from Rick's Motorsport Electric and they check out the same primary ohms as the stockers.  I've not installed them yet as that will kill my return privilege.

I'm suspicious of the choke plungers perhaps not closing fully and causing over richness when hot.   That mickey mouse one into two cable doesn't inspire confidence.

Oh, I checked the valve cleances and they're spot on.   

I know there's a solution but I want to fix it myself.  Taking it to the local shop is admitting defeat, silly, but that's the way I see it.

Bucko

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Re: Starting Trouble When Hot
« Reply #5 on: September 22, 2020, 01:26:58 am »
Although replacement" Choke plungers" are no longer available from Honda, there are "stand-alone" aftermarket ones (two required - one for each carb) that screw right in.  Not sure how to operate them since you'd need 3 hands but it's a possible option if the OEM ones are buggered. I recently bought a set just to see if they would fit and they do but I haven't actually installed them as there's nothing wrong with my OEM setup at this point.

Jack Straw

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Re: Starting Trouble When Hot
« Reply #6 on: September 22, 2020, 12:38:03 pm »
When I install the three handed plungers I'll post results.

My other bike is an '08 KLR which uses a Keihin carb with a similar choke set-up.   Changing to the button plunger is a fairly common mod on these bikes.

in the meantime it's back to the hot start troubleshooting.   Pray for me.

Jack Straw

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Re: Starting Trouble When Hot
« Reply #7 on: September 22, 2020, 06:57:51 pm »
Victory is mine.   Two new coils did the job. 8)

Bucko

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Re: Starting Trouble When Hot
« Reply #8 on: September 23, 2020, 02:54:06 pm »
 :) :)

Jack Straw

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Re: Starting Trouble When Hot
« Reply #9 on: September 28, 2020, 10:59:10 am »
The button plungers for the choke work perfectly and they have a detent to hold them open so "three hands needed" is not an issue.   The stock cable on my bike was kinked and corroded so the button gizmos are a worthwhile change.

Now that the hot starting problem is fixed and I trust the chokes to close properly I can begin to take some shakedown cruises and simply enjoy the bike. 8)

Bucko

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Re: Starting Trouble When Hot
« Reply #10 on: September 29, 2020, 02:25:04 pm »
You'll enjoy it.  It's a very fun bike to ride.