Carb issues.

A place to discuss matters related to Honda Helix scooters.

Carb issues.

Postby Phil » Sun Jan 26, 2020 3:31 pm

I've had 3k mile of trouble free riding. But on my last ride up to San Simion to see the elephant seals. Hearst Castle. As I affectionately refer to her as "Hawg". She left me stranded. Has to call a friend to load it up. Only to have to call AAA for a flat tire on the rescue truck.

I rode about 45 trouble free miles to stop and get gas . No issues. Then rode the final 5 miles to my destination. Pulled in and the bike immediately died. Wouldn't start , nothing. So I go check out seals for 45 minutes. Come back and the bike starts right up. Comes to a high idle. Thought great. I'm on my way. Nope. It idles. But as soon as you give it gas. It bogs, and sounds terrible.

I get it home and remove the seat , and air intake. Noticed the bottom of the carb looked wet. And below it. I removed the carb. And took it over to my buddy Alex @ Perfomance Marine. Hes the one who worked on it last. Pulled the bowl. Still absolutely spotless inside. Removed the vacuum piston diagram. Soft and pliable. No apparent holes. Inspected the needle and seat. Then applied a pressure pump to the fuel inlet. And the needle and seat was holding 10psi no problems. Fuel level was about half way up the bowl. Alex said that was about right.

The starting enrichment valve was replaced 2k miles ago. Should be good. Page 4-4 The air cut off valve. I applied vacuum to it on the hose feeding the valve off the manifold. Applied 20hg of vacuum. And it would slowly bleed down over time. I then blew back threw the air vent tube that feed to the side of the carb. No vacuum, I could blow back threw the thermal valve. I then slowly watched the vacuum guage as blew. Then at 16hg it closed off. And I could no longer blow threw it. You could very slight suck backwards. Held pressure, but would slowly drop off.

My seam to think it's the air cut off valve from reading other threads. I did notice also when it was it was bugging. It I was to manually open slide. It would clean up and rev to the moon. Release, back to the same problem at hand.

What am I missing, and what is your diagnosis? Thank you. Sincerely Phil. Opps 1987 Helix. Just shy of 9k original miles.
Phil
 
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Re: Carb issues.

Postby Phil » Sun Jan 26, 2020 3:41 pm

My next question then. If I'm ordering parts. I should get 115/38 jets for it? 220 lbs guy. Seams to be riding close to ti wot or pinned. Crushing at 70 mph. I myself prefer denso plugs. Every since denso plugs fixed my high speed miss on my volvo. I'm sold. The stock denso plug is a x20epr-u9. For extended high speed riding, a denso x22epr-u9. 3-1 Would that be advisable to go to a slightly colder plug?
Phil
 
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Re: Carb issues. ANSWER

Postby zozman » Mon Jan 27, 2020 6:42 am

Hi Phil.

I recommend updating your main jet to #115. The slow #38 is OK. Replace your air valve (16510-KS4-753) as it fails to hold vacuum. Run a resistance check on the bystarter and replace it if it"s too high. If it's the original one, replace it anyway.

Check that you do not have a cracked intake tube. Tighten all the hoses.

Report back.

zoz
87 & 98 Helix
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Re: Carb issues. ANSWER

Postby Dan_Lockwood » Tue Jan 28, 2020 11:50 am

zozman wrote:Hi Phil.

I recommend updating your main jet to #115. The slow #38 is OK. Replace your air valve (16510-KS4-753) as it fails to hold vacuum. Run a resistance check on the bystarter and replace it if it"s too high. If it's the original one, replace it anyway.

Check that you do not have a cracked intake tube. Tighten all the hoses.

Report back.

zoz


ZOZ,

I have a question about your suggestions.

You recommend that he change out the jets, but this is alone not his issue as it was running well prior with the original jets. Your other suggestions about checks etc seem to be along the familiar lines of diagnosing etc.

So the jet change is ONLY to maybe make it run better "after" the original non-running condition is fixed, correct?

I'm sure everyone here appreciates your incite and experience on the Hondas. I have yet to get my Helix home in my garage as I'm still not cleaned out in my garage with projects to have enough room for it. I do remember working on this Helix about 12 years ago when it would not run for the guy I purchased it from. I did a complete carb cleaning and was able to get it starting and running quite well. It has remained running off and on for the many years afterwards, but VERY few miles still on the scoot. Just 603 miles on my '98. Hope to have it home in the spring and then may have some of my own questions to ask. But I've started reading all of your posts on the other forum and as you state, many overlap with the Helix.

Thanks for all the support you've given everyone here and hope you're here for many more years!

Have a great week!
Dan

3 Harleys
'98 Red Helix
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Re: Carb issues.

Postby Phil » Tue Jan 28, 2020 1:45 pm

My first bit of info to report back on by starter resistance is measured at 4.2k between the yellow wire and the solid green wire. 4-4 . The by starter was replaced about 2k miles ago. Purchased from partzilla. Coolant temp guage indicated 59 degrees. Installed an aftermarket digital guage by Trail Tech. Very nice addition.

The changing of the jet question was only for better drivability and performance. Nothing to do with my current issue.

Report back on other item to check as requested
Phil
 
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Re: Carb issues.

Postby Phil » Tue Jan 28, 2020 2:35 pm

More to report. Double checked all vacuum line and fuel lines. All were replaced about 3k miles ago . Nothing to report. Triple checked to make sure the carb was installed properly in to the intake boot. Between carb and head. It was replace as well 3k ago. Bike fires up very easily.and idles. I also took carb spray to look for a vacuum leak. Everything seamed fine until I got a indication of one from the throttle shaft on the right side. Able to get the straw close to it sprayed a slight amount and you can notice a drop or a stumble. Then a generous spray. Kills the bike.
Phil
 
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Re: Carb issues.

Postby zozman » Wed Jan 29, 2020 12:04 am

So apparently you have an intake hose clamp loose either front of or rear of the carburetor or a crack in the intake boot itself.

zoz
87 & 98 Helix
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Re: Carb issues.

Postby Phil » Fri Feb 07, 2020 6:54 pm

Zoz, thank you for all your help. I will agree that a cracked intake boot or loose or improperly installed carb will cause the bog described. I had it happen when I first started to work on the bike awhile back. I loosened up the clamp reset the carb, tightened it down and it ran like a champ.

Like I said I replaced the booth less then 6-8 months ago. soft and pliable. no cracks. Took it off cleaned the head, installed a new O-rings. Reinstalled the carb , multiple time checked and retightened the band clamp. Fires up, idles fine cold. But as soon as you hit it with carb cleaner, it effects the idle. Big blast directly on the throttle shaft. It will kill the motor.

Talking to the motorcycle mechanic who is fairly familiar with the Helix. He mentioned that there are O-rings on the throttle shaft to seal them. He mentioned you can put silicon on it to temporally fix it. But its not a cure. He said its common with age and ethanol fuel. Every heard of that, and is there a fix?

I also am ordering the back fire diaphragm here in the next week or two. I will also trailer the bike to my buddies shop. cap the throat of the carb. Make sure the intake valve is closed . Then hook up the smoke machine for be 1005 sure where the vacuum leak is coming from.

any insight would be appreciated Zoz. Thank you !!!
Phil
 
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Re: Carb issues.

Postby Phil » Fri Feb 07, 2020 7:05 pm

Replacing the air valve wont fix my bog issue. These are two different issues. Correct?
Phil
 
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Re: Carb issues.

Postby zozman » Fri Feb 07, 2020 7:33 pm

This is exciting! Some one to talk with in the Winter!

On the back side of the intake boot there is an o-ring. It is a #21 on the parts diagram. I'd look at it and replace it. #91304-KM1-003, 91304-MCA-A02.

You do not need to replace your autobystarter as it is in specification. The jet replacement is for added acceleration response not for the issues you are experiencing.

The air valve is not within specs. You do not NEED to replace it as racers seldom do but those baby farts on decel will get noticeably louder if you don't.

There are no replaceable o-rings in the parts diagram for the throttle shaft on the carburetor. Like I told others, once you reach the cost of a bystarter and a air valve plus a bowl gasket kit, just buy a new carburetor.

Report back what happens.

This is exciting!

zoz
87 & 98 Helix
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Re: Carb issues.

Postby Phil » Fri Feb 07, 2020 7:48 pm

With all that said, what is a suitable replacement carb for my Helix? I've looked on line for a factory carb. I,ll I have found is NLA. Where would you recommend me to get one. I've thought about buying a cheap one off eBay for just the body, and transfer the factory parts to the Chinese body? I could be dreaming. what would you recommend? Carb off a different bike ? Thanks for your input!!!! The weather is nice and I would like to be riding my "Hawg". I couldn't imagine having to get a newer bike.
Last edited by Phil on Fri Feb 07, 2020 8:20 pm, edited 1 time in total.
Phil
 
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Re: Carb issues.

Postby Phil » Fri Feb 07, 2020 8:16 pm

Phil wrote:My next question then. If I'm ordering parts. I should get 115/38 jets for it? 220 lbs guy. Seams to be riding close to ti wot or pinned. Crushing at 70 mph. I myself prefer denso plugs. Every since denso plugs fixed my high speed miss on my volvo. I'm sold. The stock denso plug is a x20epr-u9. For extended high speed riding, a denso x22epr-u9. 3-1 Would that be advisable to go to a slightly colder plug?



Zoz I didn't hear any comments about what choice of spark plug I should use. I'm a denso man. What do they consider to be extended high speed cruising? What are your thoughts on that.

thank you my friend !
Phil
 
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Re: Carb issues.

Postby zozman » Sun Feb 09, 2020 2:25 pm

Hi Phil.

Your choice of carbs is an OEM one from Honda for the 2004-07, 16100-KFR-842, $233. They used either a #108 main for California or #110 for everybody else. Replace the main with your #115. The slow is the same at #38.

I regard to spark plugs, the Denso plug for your bike recommended x20EPR-U9 as you stated. The NGK is a DPRSEA-9. A heat range of "9" in a NGK plug is more toward the cold range. To find one comperable, it would be in the "27" range for Denso. For Denso, the larger the numbers, the colder the plug.

To find the middle of the road temperature range for NGK it would be 6,7. For the Denso, it would be 22.

A good rule of thumb for spark plugs is to stay cool enough to avoid pre-ignition and stay hot enough to burn off combustion deposits. When in doubt, lean toward a colder plug as its insulator is relatively short and thusly remove heat from the combustion area quite fast. (source: BriskUSA.com)


zoz
87 & 98 Helix
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Re: Carb issues.

Postby Phil » Mon Feb 10, 2020 7:46 pm

Question for you, I went to order the carb. $210 threw partzilla. For the llife of me, I cant find the part number for the 115 main jet. Plus I used the search engine on here. Thanks !!!
Phil
 
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Re: Carb issues.

Postby Phil » Mon Feb 10, 2020 7:56 pm

I found these two different 115 jet numbers 99101-393-1150 or 99101-393-1150 ?
Phil
 
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