Engine difficult to start - bad running at high speed.

[romancustom]

Dear Friends,
It's great to find a Website dedicated to this wonderful engine.
Thanks a lot Howard!!

I'm trying to fine tuning the engine.
Right now I've found that maybe the mixture is too rich. When I remove the spark plugs, they look dark, like carbon.
Is it possible to make the mixture leaner?

Does moving the timing advance or adjusting the float level make any difference?

Thank you in advance and sorry about my English.

Kind Regards

Román

[Howard]

Roman

Hi, and thanks it’s good to know it’s valued.


Rich mixture, yes it sounds like that is your problem. The choke cable could be in need of adjustment not closing completely (most likely) or if not then the carburetor may need to be looked at. The level of the float should be checked and the seating on the float valve should be sound. These are the most likely causes of your problem. I would recommend that you remove the choke cable to start with once you have the engine warm and check that the choke is closed. Then se if it runs better.

Hope this helps, please let me (& other users) know how you get on, Howard

[romancustom]

Thank you for your answer, Howard!

Recently I bought a brand new carburetor from Honda. (Boxed and sealed)
When just installed, the engine started perfectly and run like a charm.
Idling was perfect and the engine accelerated like a Honda motorcycle =).
I never touched this carburetor because it looks that cames synchronized from factory.

Right now, I've the same rich mixture problem, with both carburetors, the old and the new one. I'm testing without the choke cable attached.
After reading a post here, I've move the timing advance a little, CW. Now, it seems that starts better.

Adjusting the float level, doesn't makes a big change. (I'm messing with the old Carb =)..)

When working with the transmission pulley, noticed that the "punch" is located exactly a half turn where it should be. (page 13 manual).
If I align the punch as indicated, the window in the pulley, doesn't align with the timing advance mechanism.

The engine seems with plenty of compression and the sparks looks OK.

My question is, how can I modify the Air / Gas mixture? Does the float level, or the (A) air mixing screw, change this?.

Any help would be much appreciated.
Regards
Román

PS: did you ever tried a Colortune Spark Plug?

Howard Wrote:Roman

Hi, and thanks it’s good to know it’s valued.


Rich mixture, yes it sounds like that is your problem. The choke cable could be in need of adjustment not closing completely (most likely) or if not then the carburetor may need to be looked at. The level of the float should be checked and the seating on the float valve should be sound. These are the most likely causes of your problem. I would recommend that you remove the choke cable to start with once you have the engine warm and check that the choke is closed. Then se if it runs better.

Hope this helps, please let me (& other users) know how you get on, Howard

[Ciao Bye]

Hi Roman

Place the throttle at 3/4 full to start it and reduce the speed after it is started. Full choke when cold and none when it is warm.

It should do the trick perfectly.

Cheers.

John
Quebec
Canada

[Howard]

You have made me think hard. I had a similar problem when I first bought my boat. I tried changing carbs and this improved things for a while but then it got worse again until I realized that the fuel had a lot of contamination in it. I cleaned out the whole fuel system and installed a new inline filter after that the I never had a repeat of the problem. It is always hard to diagnose remotely but it seems now that you might have the same problem. It is possible that you have a timing or electronics issues with the ignition system but I would look into the fuel system first. I would be interested to know if you have any contamination in your float bowl when you take it off, Howard

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