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#2271892 - 05/26/11 09:59 PM Cylinder not firing? 2002 Honda Shadow 750
kevinf Offline


Registered: 05/08/09
Posts: 137
Loc: Virginia
I'm trying to get a motorcycle back in service. I've cleaned the carb jets once already. The front cylinder appears to not be firing based on the amount of heat I feel in the exhaust pipe(hmmmm),compared to what's coming out the rear exhaust pipe (yeeeouch!). I switched the coils, front to back, and it ran the same way. I checked the float bowl in the front carb, and it had fuel in it. What are the next steps I should take to diagnose the problem?
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'01 Toyota Sienna - PP 5W30
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#2271896 - 05/26/11 10:12 PM Re: Cylinder not firing? 2002 Honda Shadow 750 [Re: kevinf]
Chris142 Offline


Registered: 06/05/03
Posts: 11471
Loc: apple valley, ca
Did you actully ck for spark?
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#2271950 - 05/26/11 11:26 PM Re: Cylinder not firing? 2002 Honda Shadow 750 [Re: Chris142]
kevinf Offline


Registered: 05/08/09
Posts: 137
Loc: Virginia
No, how do I do that safely? I was going to buy an extra plug and tape it to the cylinder head so that it's grounded.
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---
'07 Toyota Sienna - Castrol GTX 5W30
'01 Toyota Sienna - PP 5W30
'98 Acura CL 3.0 - G-Oil 5W30
'02 Honda Shadow ACE - Valvoline 10W40 Motorcycle oil

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#2272047 - 05/27/11 07:07 AM Re: Cylinder not firing? 2002 Honda Shadow 750 [Re: kevinf]
Trav Offline


Registered: 11/20/06
Posts: 9987
Loc: MA, Mittelfranken.de
Did you try a new plug?
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#2272095 - 05/27/11 08:22 AM Re: Cylinder not firing? 2002 Honda Shadow 750 [Re: kevinf]
meep Offline


Registered: 02/20/07
Posts: 2497
Loc: Southeast
you need, spark, fuel, and compression.

pull the plug, tape, lay, tie, it to something and crank. look for spark.

sniff the tailpipe for fuel. don't stick your nose in it, use your hand to waft the fumes towards you. you can also try a squirt of starter fluid.

I love the older shadows. first bike I ever rode was a 500 shaft drive, a wonderful, wonderful machine.
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#2272183 - 05/27/11 09:55 AM Re: Cylinder not firing? 2002 Honda Shadow 750 [Re: kevinf]
Bladecutter Offline


Registered: 02/21/11
Posts: 881
Loc: Arvada, CO
Did you pull the pilot jets, and run a copper strand through it to make sure they weren't plugged?

Have you pulled the non-firing spark plugs to see if they are fouled or dry? Switch the plugs between the two cylinders. Should be a 2 plug per cylinder setup for the Honda 52 degree V-Twin.

Here's what I would do if it were my bike, in order:

Pull carbs, and recheck the pilot jets for clogs, and reset the mixture screws to 2.5 turns out. Might be worth the $20 to replace both pilot jets with new ones.

Check the spark plugs for fouled or dry condition.
Replace if fouled.

Check valve clearances (too tight valves lead to idle issues).

I work on lots of motorcycles, and see your symptoms on a regular basis every spring. Chances are your bike sat over the winter. New (or properly cleaned) pilot jets should get you up and running right quick.

BC.
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#2272229 - 05/27/11 10:37 AM Re: Cylinder not firing? 2002 Honda Shadow 750 [Re: kevinf]
mechtech2 Offline


Registered: 09/05/06
Posts: 19479
Loc: Chicago Area
I'm with Blade.
It's probably fuel related. There are all sorts of jets and passages besides the main jet. Amateurs concentrate on the main only.
Fresh plugs Are always smart in a scooter, esp after misfiring for whatever reason.

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#2272347 - 05/27/11 12:02 PM Re: Cylinder not firing? 2002 Honda Shadow 750 [Re: kevinf]
dwendt44 Offline


Registered: 05/17/06
Posts: 3571
Loc: Central Wisconsin
Ya, the carb is still plugged.

Resurrected an old Suzuki twin. First time I cleaned the carbs, it would only run on one cylinder. Cleaned them again(they are bracketed together) with a stronger carb cleaner. Then it ran fine.
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#2272372 - 05/27/11 12:37 PM Re: Cylinder not firing? 2002 Honda Shadow 750 [Re: dwendt44]
kevinf Offline


Registered: 05/08/09
Posts: 137
Loc: Virginia
Thanks for the input so far. I bought two new plugs for that cylinder, now I'll check spark to rule that problem out definitively.

Based on the response posts, now I'm thinking that I didn't get that front carb clean enough. It was the first one I worked on and I may have been too careful with it and not clean agressively enough. It is a real pita to get those joined carbs off and on in that teeny space. I think I'll video record how I remove them this time so I can get them back on easier.

I have a compression tester for my car. Do they sell adapters for it to work on a motorcycle, the spark plug is narrower, no?
_________________________
---
'07 Toyota Sienna - Castrol GTX 5W30
'01 Toyota Sienna - PP 5W30
'98 Acura CL 3.0 - G-Oil 5W30
'02 Honda Shadow ACE - Valvoline 10W40 Motorcycle oil

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#2272585 - 05/27/11 05:25 PM Re: Cylinder not firing? 2002 Honda Shadow 750 [Re: kevinf]
Bladecutter Offline


Registered: 02/21/11
Posts: 881
Loc: Arvada, CO
Yes, compression testers have adapters to work on the smaller spark plug holes. The kit I bought many years ago came with several fittings, one of which works with just about every motorcycle I've ever used it on.

A tip for narrow angle v engines is to remove one intake boot with the carbs, while leaving the second one still attached with the engine. Makes life much, much easier. Just be grateful you aren't doing the carbs on a Honda Interceptor with the V-4 engine. That's a royal pain in the bum getting them on and off.

Make sure when you remove the carbs from the bike, and are working on cleaning them, that you unscrew the pilot jets (#40 size for your bike), and hold them up to the light to see through them. If you can't see through it, its clogged. You should see light coming through.

BC.
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2014 Mazda CX-5 Touring (Soul Red)
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#2272686 - 05/27/11 08:12 PM Re: Cylinder not firing? 2002 Honda Shadow 750 [Re: Bladecutter]
kevinf Offline


Registered: 05/08/09
Posts: 137
Loc: Virginia
Thanks everyone - update

OK, it has spark, and now it has two new plugs in the front cylinder.

I'll pull the carbs again when I get time.

Here's something I thought was bizarre, I called Actron and they were out of 12mm adapters for their compression testers. Part is 0180-000-0894. How does a manufacturer run out of a simple component they sell on a regular basis? I may buy a cheap compression tester kit from Harbor Freight just to get the adapters.
_________________________
---
'07 Toyota Sienna - Castrol GTX 5W30
'01 Toyota Sienna - PP 5W30
'98 Acura CL 3.0 - G-Oil 5W30
'02 Honda Shadow ACE - Valvoline 10W40 Motorcycle oil

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#2273226 - 05/28/11 01:33 PM Re: Cylinder not firing? 2002 Honda Shadow 750 [Re: kevinf]
mechtech2 Offline


Registered: 09/05/06
Posts: 19479
Loc: Chicago Area
If it ran OK before it was stored, the engine probably is did not break mechanically when sitting.

It's the carb[s].

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