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Won't start after carb rebuild

Fuel System: Gas (Petrol) tanks, Carburators
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ELMST616
honda305.com Member
Posts: 4
Joined: Sat Jan 04, 2020 11:14 pm
Location: Redmond, WA. USA

Won't start after carb rebuild

Post by ELMST616 » Mon Sep 07, 2020 5:57 pm

Hey all, I'm a newbie trying to rebuild a 1964 305 dream.

I got the bike last fall and it ran pretty well. Most times the bike fired right up or needed just a few trys. But it definitely needs work. So I rebuilt the carburetor and got replacement throttle cables, etc. Then COVID hit, I lost my job, found a new job and started a new life, but my attention was pretty much anywhere but hobbies. So the bike sat all winter and spring.

Fast forward to today, I've adjusted and installed the rebuilt carb and throttle but the thing won't start.

Here are my carb setting and what I've done:
  • 130 main jet and 40 slow jet;
    Jet needle on 4th ring down / or second from bottom
    Checked that throttle slide would fully seat with throttle screw out and throttle cable loosely adjusted
    Float adjusted to recommended height
    Air screw loosely tightened and backed off 1.5 turns
    Throttle screw lightly seated
    New plugs
    Ensured I've got spark on both spark plugs (albeit a visually weak spark)
    Healthy dose of starter fluid
    Confirmed petcock is working
    New battery that is on tinder when not in use
So with the above steps completed im at a loss. I'm not confident the throttle cable is routed and adjusted perfectly but it seems to be in fine working order. Maybe my spark is too weak? Not sure how my compression is looking but again it did run pretty well last fall and not sure it sitting for several months would reduce compression but I don't know

The starter sounds strong and after spraying starter fluid it sounded like it wanted to turn over for a second but then no.

Any recommendations would be highly appreciated.
Thanks,

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garncarz
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Posts: 207
Joined: Thu Oct 31, 2013 7:44 am
Location: York, PA

Re: Won't start after carb rebuild

Post by garncarz » Mon Sep 07, 2020 6:13 pm

Have you set your points, valves?
See my post about Honda carburetor settings. Your set up isn't exactly stock, which may be an issue too.

ELMST616
honda305.com Member
Posts: 4
Joined: Sat Jan 04, 2020 11:14 pm
Location: Redmond, WA. USA

Re: Won't start after carb rebuild

Post by ELMST616 » Mon Sep 07, 2020 9:25 pm

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Last edited by ELMST616 on Mon Sep 07, 2020 9:27 pm, edited 1 time in total.

ELMST616
honda305.com Member
Posts: 4
Joined: Sat Jan 04, 2020 11:14 pm
Location: Redmond, WA. USA

Re: Won't start after carb rebuild

Post by ELMST616 » Mon Sep 07, 2020 9:26 pm

garncarz wrote:
Mon Sep 07, 2020 6:13 pm
Have you set your points, valves?
See my post about Honda carburetor settings. Your set up isn't exactly stock, which may be an issue too.
Thanks for the reply.
I have not touched my points and valves. Would I need to adjust those just because I rebuilt the carburetor? How do I find your post about the carburetor settings?

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garncarz
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Posts: 207
Joined: Thu Oct 31, 2013 7:44 am
Location: York, PA

Re: Won't start after carb rebuild

Post by garncarz » Tue Sep 08, 2020 5:40 am

You said that it wasn't running well before the rebuild. Valves, points, carb. Typically in that order.
Honda carburetor settings guide2.jpg

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garncarz
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Posts: 207
Joined: Thu Oct 31, 2013 7:44 am
Location: York, PA

Re: Won't start after carb rebuild

Post by garncarz » Tue Sep 08, 2020 5:43 am

Honda carburetor settings guide2.jpg
A wise man once said: "Most carb problems are electrical". Set the valves and the points, eliminate the easy variables.

DJM
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Posts: 544
Joined: Thu Oct 09, 2003 1:54 pm
Location: Chesterfield UK

Re: Won't start after carb rebuild

Post by DJM » Tue Sep 08, 2020 7:58 am

Best thing is to set the carb to stock setting first, it may not be perfect that way but at least it should start on stock settings.

If it still doesn't start and as the bike has been standing through the winter it may be nothing more that stale fuel.

Drain the float bowl and put in some clean new gas and see what happens. If it starts, the fuel in the tank may be OK, in my experience fuel tends to go stale in the float bowls much quicker that it does in the tank.

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