Solo 471 KAT hard starting when hot

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For those that don't know, Solo 471 KAT is a German Backpack blower with a catalytic converter. This is not a well supported brand in US. I have been using it for 10 years and did change plug due to hard starting when hot. I still have the problem. It starts after about 3 pulls first start of the day. After running it for a while and trying to start it hot it seems flooded. Basically I have had to let it get cold to start it. Local shops do not work on these. Parts are like unobatinium. I am not even able to find a fuel filter replacement on Solo's website. It has a foam air filter which is clean. I have used Echo mix or Homelite mix at 50:1. I add an ounce of Seafoam per gallon of gas also. I will be getting fresh gas, but would a different oil mix help with starting? I found Homelite mix helped with a sputtering Echo trimmer compared to Echo mix. It takes a Bosch WSR6F plug, Champion RCJ-6Y or comparable. I am considering an E3 or First Fire plug but they have mixed to no reviews. I have had great results with NGK so that is another option. It takes an NGK BPMR7A. It does have some carb adjustments in manual (intended for service personnel only). But my carb has only one screw to open or close throttle for idle speed. I requires at least 91 octane gas. Would 93 octane tend to make it easier to start when hot or harder? Thanks in advance!
 
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You have described the exact symptoms of a 2-cycle engine that is low on compression (either it is worn-out or has a scored piston/cylinder).
 
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Sometimes heat can have an effect on the electrics. Before you start the machine up, turn the on switch to on, pull the spark plug and ground it on the cylinder, take it into a dark area and pull the starter. Watch closely for spark and make note how bright and blue it is. Put the plug back in, fire it up and go to work. Once it's hot, repeat the above process and look to see if the spark is the same or not. If it's not as bright and blue, there's a chance the electrics might be going. If the CDI is shot, you're probably better off scrapping it, if parts are that hard to find. You can also do a compression test to see if it's low. Not sure what the specs would be for that machine. I'd say if it's better than 100 psi. It, probably good. If the electrics are shot, get yourself an Echo. Good price, great machines.
 

MONKEYMAN

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Originally Posted By: wag123
You have described the exact symptoms of a 2-cycle engine that is low on compression (either it is worn-out or has a scored piston/cylinder).
Interesting that you say that. The blower runs super strong once started. It has a terrible design for air filter. It has bolt with plastic coated wing nut but other end screws into aluminum. The aluminum tends to fall into area where air filter mounts. I could see some small pieces of metal being sucked up. I am not using this commercially. I have around 100 bags/trash cans of leave to process. The mower man grind leaves I blow into yard. Last two years I am blowing leaves to street 3 times per year. Maybe will use this unit 15 hours a year or so. It runs great when started so it does not seem ready for scrap yard yet. I did pick up an NGK plug to see if that helps with hot starts. As far as compression test my time is short and knowledge is shorter. I need to blow leaves this weekend. I re-read manual. I think I was overusing choke for 10 years. It says "engine attempts to start (engine fires)" "immediately open choke shutter with choke lever and re-start. I am used to leaving choke on until engine starts, running it a little, then turning off the choke. Maybe my problem is more user error? I agree with Echo. I love their products. My Solo is over $500 new. A comparable Echo is $400 new. Right now a $4.00 spark plug and fresh gas seems more cost effective even if I have to keep it idling instead of restarting once she is hot. I would like to get another season out of her.
 
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The choke should not be used when restarting a hot engine. Hold the throttle wide open when pulling it. If it runs at all, the spark plug is good. Bad magnetos are relatively rare on small 2-cycle engines. If a customer came into my shop with this complaint, the first thing I would do is pull the muffler and have a look at the piston and cylinder through the exhaust port. If both were smooth and shiny, then I would get it hot and check for spark. If it had good spark when hot, then I would do a hot compression test. Anything much less than 100 PSI hot and the engine is toast. A small 2-cycle engine that is low on compression will start fine when it is cold and run fairly good, until it is shut off. Then, after it is hot, it will be a bear to restart (if you can even get it restarted).
 

MONKEYMAN

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Originally Posted By: wag123
A small 2-cycle engine that is low on compression will start fine when it is cold and run fairly good, until it is shut off. Then, after it is hot, it will be a bear to restart (if you can even get it restarted).
That pretty much describes it. I have used the choke when I thought it was cold. Big mistake. Was even having problems getting it started after installing dry spark plug. It has always had problems starting when warm if choke was used, but is worse with age. Even starting hot without using choke just was not happening sometimes. I bought this online as a demonstrator model. So maybe it was used more than I thought? I installed NGK plug. I could see oil leaking from muffler pipe that attaches to the engine at the flange. That got me thinking of the catalytic converter and what role it may play in my hard starting issue? Maybe I can pull the back cover and check it out and tighten the bolts where it is leaking at the muffler. At this time I do not have money to replace it. The leaves just are not coming down much yet. Monday I will get fresh gas and see how she is running. I just need to blow into big piles so I can tarp and drag to front.
 

MONKEYMAN

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Update: Took back cover off. Nuts were loose where exhaust flange mounted to motor. I have limited 9 mm tools and no replacement gasket, so I just tightened them. Would the exhaust leak contribute to hard starting? It has been getting progressively worse over the years. So could it be as exhaust leaked more it would cause more hard starting when hot? My experience with exhaust leaks is they get worse when hot. When I purchased unit the fuel lines leaked. I shipped it back to Solo under warranty and they updated the fuel lines. They also tightened nut for impeller. Maybe when this unit was built some things were not torqued properly or maybe it is the nature of dampening system for vibration? I may call Solo and see if they can send me a gasket and make sure I have proper tools to access things better. I did find adjustment screws on carb, but they do have plastic limiter caps. You can only turn them 1/2 turn.
 

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Fixed: Was able to order exhaust gasket from Solo USA. Installed today. Started first pull. Started when warm after 1st pull. Thanks for everyones input!
 
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