First off, sorry for the noob question. I'm nowhere near as knowledgeable as some of you and that's why I'm here. Anyway, here goes.
Ever since I bought my '83 vt500c, I've had a problem getting it to start once the engine is hot. Like if I stop somewhere and turn it off, I usually have to wait quite a while before I can get it to start again.
I'm pretty sure my problem is because it's running rich. I can start it pretty easily when it's cold, at stoplights I can smell excess fuel, it wants to stall if I leave the choke on too long. These are symptoms of running rich as is not wanting to start when hot, am I right?
Right now it's too cold to do anything in the garage, but as soon as it warms up a little, I was planning on playing with the carbs to see if I could lean it out a bit.
Then today, I read that running rich could be caused by a bad air filter. Is this true? I braved the cold and pulled the filter and to my untrained eye, it looks like it could stand to be replaced. It also smells heavily of fuel. At this point, I'm planning on changing it anyway, but I was just hoping for confirmation that this might have been my problem all along. When I bought it, the bike appeared stock and I've only made a few minor cosmetic modifications myself.
Also, would you recommend the K&N air filter? I've been having a hard time finding an oem filter.
Even a semi-clogged ( or saturated ) filter will cause a rich condition; yes.
Try that first.
I like K&N or Unifilters, because they can be cleaned and re-used. I like having that option.
I'd recommend those, especially after re-reading your last sentence.
Just my opinion.
If you have to choke it to get it to run during the hot condition, you could be vapor locking/boiling the fuel out of the lines from engine heat which my 1100 would do on a occasion. And yes a dirty filter can cause rich fuel thus I would use a Uni Filter to keep stock air flow so to speak.
1983-84 VT 500 C, FT - NU-4072 - 12.95
After reviewing a parts fische it seems you already have a foam reusable element. Just clean and re oil if the foam is in decent condition. A new element is $9 from Honda or buy the Uni at $12.
A hot motor that won't restart is also cause by bad coil(s), very true.. But the filter should be eliminated as a possible issue. It will run rich. 500s are pretty simplistic.
Agreed, this is a cheap and routine maintenance issue. If you do not know how old the filter is, replace it regardless of the bike performance. If it's even in question, replace it. If replacement doesn't help, so be it. At least you know the $10 air filter isn't the issue.
As for the temporary attempt, you're not going to damage anything with your idea. Give it a try! It might be better - might be worse. Don't base any further decisions on negative results, but if it helps ... well, that's awesome!
May I hijack this thread and ask a similar, yet opposite question? I've noticed the boot in the back of my air box is not connected all the way to my air box. So maybe it is allowing too much air into the air box??? Could that then cause a LEAN condition?? If a clogged up or partially clogged up air filter can cause a rich condition then can an improperly sealed air box cause a lean condition????
Yes a restricted air filter can cause rich condition. Easiest test to see if that is the problem is just take out the element and put the cover back in place for a hot restart test.
Do not use the choke for hot restart. If the bike runs excellent normally after warm up, I would not mess with the carbs. Maybe just adjust the mixture screws leaner to help some. Maybe it had been rejetted in the past and now a little richer but if it is running strong leave it alone until you need to work on the carbs. Too many problems result when a guy opens up the carbs. Like a can of worms at times.
Take a look at the plugs also to see how dark they are. Clean them and re-examine them after the air filter is replaced. That is an indicator of the mixture condition.
tbfoto, if the opening is before the filter element it probably won't effect running much at all. If it is a leaking inside the filter tube to the carb, dirt will get in the engine. Some guys open up their air boxes to do a air box mod with good results.
Someone on here had listed a NAPA thermostat that fits = NAPA Part 185, 180F Thermostat (UPC 0 23644 00185 1)
If you take you old one into Napa they should be able to match this up.
Okay, I have another stupid question. Don't laugh at me.
So I ordered a uni filter, unfortunately, it's not supposed to be here til the 22nd. I decided to try cleaning the filter that was in it. As soon as I did, it disintegrated in my hands. Meanwhile, tomorrow is supposed to be the first decent riding day since the snow flew. I called all the shops in the area and nobody has a replacement. What would be the feasibility of getting some open cell foam, oiling it, and wrapping it around the inner cage to use as a temporary filter?
Again, please don't laugh. I'm just really looking forward to getting back on two wheels.
For a temp fix just so you can ride now, I say yeah why not.
Btw. The only stupid ?s are the ones not asked. If you don't know the answer, its not a stupid ?
Not a stupid question, but this may sound like a stupid answer. Try the foam lightly oiled, and see if it flows enough air not to hinder the engine running good. Then if it doesn't work properly, since it is not dusty and dirty outside while it is wet and snowing, you could just leave the filter out so you could ride . Unless it leans it out so much as to cause lean problems. But it won't hurt the engine just because there is no filtration since there would be hardly any dust in the air. Better than that old filter particles being sucked into the engine.
I know, I know, that's a stupid idea !!! :shock:
Filters are cheap and easy to change. Buy a couple of them. Clean the old filter material out of the box and carb intake as best you can. I suspect running it w/o any filter will tell you a lot. Don't let how it runs with "foam and oil" temp filter influence your thinking , there is no way to "spec." that out. With dry cold snowy conditions you may not even need the temp filter if you don't get too carried away. But do put the cover back on.
If the new filter , and possibly some tweaking the R/L screw doesn't fix it do quick spark check. Short the plug to the cooling fins ...........fuel off and plug as far away from plug hole as can.....hit starter only very shortly.......see if spark color is bright white or yellowish. Yellowish indicates weak. Sometimes easier to see in the dark. Use rubber gloves or insulated pliers, or something. A good spark can give exciting jolt.
Rich running and dark looking plugs come primarily From restricted air , poor R/L setting (same thing) , weak spark , poor plugs / bad gaps . Those are the easy ones to check and fix.
How has the mileage been ? Have you had to add oil ? Are you hearing any valve clatter , cold or warmed up?
Any color to the exhaust ? Any "clean exhaust" devices ?
Anyway, I get ahead of myself..........
What ever you do start with the simple . That is usually where the problem is solved. The air filter is probably the villain given it fell apart in your hands. Hope none got into the carb.
SeaFoam spray into carb with filter off sometimes works wonders too.
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