engine stumble problem

A place to discuss matters related to Honda Helix scooters.

engine stumble problem

Postby Buffalo Sam » Tue Aug 27, 2019 3:49 pm

I have a recently developed problem with my 1986 Honda Helix. It has a stumble in the firing up at highway speeds when more throttle is applied to accelerate or to maintain speed going uphill. Cruises at neutral throttle just fine and accelerates from a stop up to 40 mph without problem. Stumble and lack of power happen at the higher speeds. So far I have done some easy and cheap things. New spark plug, new air filter, fuel filter is clean, fuel pump works fine, adjusted valves, cleaned contacts of plug-ins on ignition module. Currently I've added carb cleaner to the gas and run it around a bunch. Before I try to order up expensive or no longer OEM parts hoping something will fix it, do any of you forum members have suggestions what I should do to fix this?
Buffalo Sam
 
Posts: 2
Joined: Fri Aug 23, 2019 1:08 pm

Re: engine stumble problem

Postby scootcat » Tue Aug 27, 2019 5:35 pm

A lot of things can do this, what is the history of bike, how many miles? Old gas? Gas cap not venting good, Chinese carb? What size jets?,water in gas? Air box leak?, What cooler is spark plug?, How is compression?
scootcat
 
Posts: 40
Joined: Sat Jul 21, 2018 12:21 pm

Re: engine stumble problem

Postby Buffalo Sam » Tue Aug 27, 2019 11:01 pm

Shop manual suggests a fault with the ignition module, which is no longer available from Honda. Aftermarket one in Australia on Ebay. Another possibility suggested by a bike mechanic friend suspects diaphragm in carb. 2 month backorder from Honda and expensive. Still have to test for air leak between carb and motor. Also pull airbox and check that carb slide is moving as it should with engine running. Been told that removing top cap to check diaphragm could wreck it so, I'd like one on hand in case that happens. Still looking for aftermarket one. All original parts-no Chinese stuff yet.
Buffalo Sam
 
Posts: 2
Joined: Fri Aug 23, 2019 1:08 pm

Re: engine stumble problem

Postby scootcat » Wed Aug 28, 2019 5:30 am

Someone on this forum may have parts in the buy and sell area, I think you have to make five post before you can use it.
scootcat
 
Posts: 40
Joined: Sat Jul 21, 2018 12:21 pm

Re: engine stumble problem

Postby zozman » Fri Sep 06, 2019 6:32 pm

I would disassemble the carburetor and clean or replace the jets. While it is unnecessary to fatten the jet needle for anything other than competition performance, fattening the main jet from a #110 or #112 to a #115 or #118 has shown significant improvement in the high speed range.


zoz
87 & 98 Helix
zozman
 
Posts: 514
Joined: Sat Aug 01, 2009 10:59 am


Return to Honda Helix

Who is online

Users browsing this forum: No registered users and 1 guest

cron