Keeping my new Helix running...

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Keeping my new Helix running...

Postby K-9 » Thu Apr 04, 2019 6:44 pm

OK...two days ago I picked up a 1986 that could use some TLC. The person I bought it from got it from a friend of his 4 years ago and never drove it, and it had a lot of storage time before that.

Apparently when he decided to sell it a month or so ago, it wouldn't start and he expected a fuel problem based on what he did to it.

He did a new battery, plug, fuel filter, fresh gas, and a carburetor.

It starts, but doesn't start in high-idle mode I thought it was supposed to. It runs for about 10 seconds and runs out of gas.

In my research, I read there is a chamber in the carburetor, Something about an auto bystarter? I have the owner's and service manual. The service manual also mentions the auto bystarter as a potential problem, as well as the fuel pump, but since it is getting gas, it seems to be something else. After it has died, if you wait a short while, you can start it again and the same thing happens.

So what I read about gas leaking from one chamber to another makes sense as it can slowly fill back up.

Since he put on a brand new carb, I shouldn't be dealing with varnish issues like maybe the original carb had.

Also, when it dies, I get a sound, perhaps from the starter? something like i have heard from a bad solenoid.

I am so anxious for my first ride....am hoping I can get clarification on the bystarter if that is the issue.

Thanks so much!
Lew
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Re: Keeping my new Helix running...

Postby K-9 » Tue Apr 30, 2019 9:22 pm

Was hoping to hear from someone. Working my way from bottom up...emptied gas tank, refilled with fresh gas, he had replaced the filter, I tested the fuel pump and it pumped fine.

He had replaced the original car with a chinese clone but had saved the old one. I threw it in my ultrasonic but it wasn't really that bad.

I did notice some cracking in the intake manifold gasket and ordered another one, but I can't get the bolts out. I am only willing to put so much pressure on the wrench.

Since the rubberized mount blocks access to the threads, I don't know if Liquid Wrench is even getting to the threads.

I also have one of those hand impact drivers, you twist when hitting with the hammer which has been my standby since the 60s, but with some tapping, nothing on either bolt.

Any other solutions for removing the bolts?

Thanks
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Re: Keeping my new Helix running...

Postby birdmannn101 » Wed May 01, 2019 2:48 am

K-9 wrote:
Any other solutions for removing the bolts?

Thanks


I would use a pair of vice grips and buy some new bolts from Honda.

Oh, if your not getting fuel from the line to the carb I would use a cheap manual vacuum pump from Harbor Freight to get the fuel up to the carb.
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Re: Keeping my new Helix running...

Postby GrahamH » Wed May 01, 2019 9:32 am

Assuming the bolt heads are in good condition then find a well fitting ring wrench or socket, ideally with a six sided fit rather that the 12 point type.

Now apply heat to the aluminium around the bolt, aluminium expands more that steel so hopefully will break the stiction. To be really careful cycle the heat several times before pulling on the wrench. I use a hot air gun designed for paint stripping, be careful as they are very hot! Or maybe pour boiled water over it.

The bolt is likely to make a cracking noise as it breaks free. Now if it is still tight don't just unscrew it in one but work the bolt back and forth and try to get some lubricant onto the threads.

And most important.....be brave and don't allow the bolt to know you are frightened of it!

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Re: Keeping my new Helix running...

Postby K-9 » Wed May 01, 2019 11:47 am

"I would use a pair of vice grips and buy some new bolts from Honda.

Oh, if your not getting fuel from the line to the carb I would use a cheap manual vacuum pump from Harbor Freight to get the fuel up to the carb."

Guess I wasn't clear...the bolts are still intact...when they didn't want to turn, I didn't proceed. All I did so far was Liquid Wrench.

I am getting gas to the carb, the fuel pump is working fine, it appears. I was only saying that it seemed like it was running out of gas. My latest guess is that the float bowl gets gas, lets me drive a short distance, and then runs out, as if they needle valve wasn't letting in fuel as fast as was needed. By the time you roll over to the shoulder, and start it again, there is more gas in the bowl and it runs a short distance, repeat.

This is why I was trying to put back the original carb instead of fiddling with the Chinese one the seller installed.

Thanks!
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Re: Keeping my new Helix running...

Postby K-9 » Wed May 01, 2019 11:53 am

GrahamH wrote:Assuming the bolt heads are in good condition then find a well fitting ring wrench or socket, ideally with a six sided fit rather that the 12 point type.

Now apply heat to the aluminium around the bolt, aluminium expands more that steel so hopefully will break the stiction. To be really careful cycle the heat several times before pulling on the wrench. I use a hot air gun designed for paint stripping, be careful as they are very hot! Or maybe pour boiled water over it.

The bolt is likely to make a cracking noise as it breaks free. Now if it is still tight don't just unscrew it in one but work the bolt back and forth and try to get some lubricant onto the threads.

And most important.....be brave and don't allow the bolt to know you are frightened of it!

GrahamH


When seeking an answer I found a couple people mentioned using heat. In one case, for exhaust manifold bolts, the guy suggested running the engine to get it heated up. I guess I could install the carb back, run the engine, then pull the carb off while the engine was still hot as I don't have a hot air gun. The closest I have would be a hair dryer.

Since the liquid cooling is intended to keep the engine cool, would that part of the cylinder head get hot? Or should I say really hot, hotter than what a hair dryer could make it? I could pour gas on it and light it :)

Since I don't think the manifold has split through, maybe I should skip the manifold for now, put back the original carb and see if that fixes the problem of it not continuing to run. I am so anxious to be able to drive it further than 2-500' at a time.

Thanks
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Re: Keeping my new Helix running...

Postby zozman » Thu May 02, 2019 2:16 pm

See Tech Tip #3 Starting and Driveability Problems

Any of you who have a CN250 Honda Helix with any miles on them undoubtedly will have, at some time, hard starting characteristics. Assuming you have good fuel, battery, starter, fuel tank ventilation, and fuel shut-off valve operation, cleaning the carb and servicing the choke will give you enhanced startability.

Honda uses the Japanese Keihin Constant Velocity (CV) carburetor with a starter valve set or electric choke. This carburetor is unique as it has the ability to compensate itself at higher altitudes. On conventional carburetors, the throttle cable is connected directly to the throttle slide. When you twist the throttle, this lifts the slide and immediately increases the size of the carb opening letting in more air/fuel mix and increasing the speed of the motor. On CV carburetors, the throttle cable actuates a butterfly valve and, as the throttle is opened, the air pressure difference between the sealed chamber above the vacuum slide and the inside of the carb venturi forces the slide up and down.

On the upside, this carb adapts greatly to altitude changes and touring but, on the downside, exhibits lack of immediate throttle response and leisurely acceleration compared to a conventional carb. The amount of hoses Honda likes to attach to their carburetors and accessibility to it is astounding. Once removed, the carb is quite easy to service. On the bottom of the carb is the float bowl held by four screws. Removing the bowl gives access to the plastic float and valve, main jet and the jet holder. Higher than expected gas consumption or dripping gas mean the float valve needs replacement. Brand new, the main jet and jet holder looked like a shiny penny. Tarnish and poor fuel probably has darkened and possibly closed the tiny holes in each. Clean the jets with 0000 steel wool and open the holes with a fine sewing needle or piano wire.

Next to these jets is the slow jet which has very tiny openings. If your idle over time has deteriorated, this is usually the culprit and if any replacement jets were considered, this would be the one. On the top of the carb is the vacuum slide and diaphragm. Your finger should be able to move the slide up and down. The only resistance is the spring in the diaphragm chamber. Once disassembled, the diaphragm has a rubber sheath around it and should be free from tears. On the backside of the carb is the air cut-off valve held together by two screws. Inside is a vacuum piston and a tiny rubber o-ring. Check to be sure the vacuum piston rubber sheath also has no tears. I like to clean the carb parts in diluted ZEP or CLR calcium/lime/rust remover and dry with compressed air prior to assembly.

Without doubt, the best enhancement to startability is to replace your starter valve set. The autobystarter, as it’s sometimes called, is the black tubular shaped thing with the wires coming out on the left side top of the carb. Held by two screws and a plate, its job is to enrich the carb upon cold start. When cold, its needle piston is retracted cutting off the air mixture circuit. After a few minutes, it electrically extends its needle into the valve body opening up the air circuit. Regardless of how nice it looks, over time, electrical resistance builds and the valve piston looses its effectiveness giving you hard cold starting. To measure the resistance of the bystarter, place an ohmmeter between the two wires. A new bystarter reads almost zero ohms. A bystarter with a reading of 7.0 ohms is weak and may give poor performance. Replace any bystarter with an ohm reading near 10.0 ohms.

The valve starter plates (autobystarter) for the CN250 Helix is PN #16046-KS4-840 and is about $55. Once you have a clean carburetor and a fully functional electric choke, starting your scoot will be a push button away.

Randy Pozzi (Rev. 11/2007)
Copyright 2009, all rights reserved.
Used with permission Honda Helix Discussion Board
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Re: Keeping my new Helix running...

Postby K-9 » Fri May 03, 2019 11:16 am

I am aware of that article, but nothing is relevant to my issue. He neglects to mention the pilot? valve that needs an elevation adjustment for high altitude, i.e. 6500'.

I am going to get a heat gun in homes that will help loosen the intake manifold bolts. They are stuck and am hoping heat will be the solution.

Thanks
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