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Post by heathjl85 on May 20, 2020 23:39:18 GMT -6
Hey everyone. I have been working on a 1988 454 Ltd. I installed the new right master cylinder and hand brake yesterday. Today the new drive belt arrived. I installed the new belt and I took it for a run down I-35, but I didn’t have the throttle stop screw adjusted correctly and it died off after I got off the interstate at a stop sign. Seems like the interstate speed flooded the carburetor because I there was fuel in the air filters. I suspect don’t have the air/fuel mix right. That or maybe an issue with the carburetor itself. After hauling it home in my truck, I experimented in my neighborhood with the choke and throttle stop screw adjustments. This seemed to work, but the longer I rode in the neighborhood, the more I had to adjust the choke or throttle to keep the RPMs from going above 2000. I was trying to keep it in the 1200 range. Anyone have any suggestions? I’m still learning all of the part names, so I apologize for my ignorance ahead of time. I’m a noob.
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Post by Blaine on May 21, 2020 5:22:07 GMT -6
Sounds like a vacuum leak.
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Post by heathjl85 on May 21, 2020 6:24:00 GMT -6
Blaine,
I noticed there was some fuel dripping out around the petcock. Would that be a source of a vacuum leak?
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Post by Blaine on May 22, 2020 5:22:16 GMT -6
Blaine, I noticed there was some fuel dripping out around the petcock. Would that be a source of a vacuum leak? Answered your P.M.  |
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Post by heathjl85 on Jun 27, 2020 8:12:26 GMT -6
Just an update. I cleaned and rebuilt the carbs with a rebuild kit. I replaced the petcock. I put some clamps on the boots all the way around the carbs hoping to solve the vacuum issue. The throttle cables were gnarly and the the throttle was not snapping back in place so I replaced those as well. Great throttle response now, but idle issues and gas in the air box still happens. I’m going to adjust the float height but I’m waiting on a float level gauge. Thoughts/suggestions?
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Post by knoizy on Jun 27, 2020 8:57:47 GMT -6
How clean are these carbs? Not sure from your description if you've had them apart for a rebuild.
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Post by heathjl85 on Jun 27, 2020 8:59:22 GMT -6
Sorry for that oversight. I have cleaned the carbs and rebuilt them with a rebuild kit. I will correct my recent post.
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Post by knoizy on Jun 27, 2020 9:28:45 GMT -6
I'm 99% that's still a stuck float bowl and that's why I was asking about the rebuild. Worth setting the floats properly but my hunch is that even eyeballing with a ruler should be good enough to stop a fuel leak, not something I've put to the test though. Also if the carbs were gummed up it can take a fair bit more than carb cleaner to really get clean especially the passages. Worst set I've had needed a lemon boil, lots of careful scraping out with picks and thinners and plenty of compressed air, likewise with the jets you should be able to see daylight through all the holes.
You might have to keep checking through the variables for more info on the problem and there might be more than one fault. The carb has a separate idle circuit so keep the RPM in mind when testing, when you go up RPM on to the main jets that's no longer an idle/mix variable but the sync, floats and diaphragm will be factors. You could do all that and find there's an issue with the spark, trim back 1/4 inch of HT lead for clean copper on the caps and put new plugs on, check contacts are clean on the coils etc and fingers crossed the CDI is OK. Likewise with the air intake and exhaust, get new filters and check everything is 100% fitted to factory when testing as this engine is very sensitive to changes in airflow. Any of those things could present as idle problems and all be different under load, is everything in your fuel/air/spark factory stock?
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Post by heathjl85 on Jun 27, 2020 9:41:23 GMT -6
The Jets are new. Air filters are new. Everything is stock. The carbs Do not seem to show any gunk. They’re not shiny like brand new but they’re clean. I used a parts cleaner can and an air compressor. I am getting ready to buy a floor blast cabinet and ultrasonic machine for cleaning. I could replace the spark plugs. They haven’t been much action but they’ve been in the bike for at least four years
I was wondering if it was the float height itself. So I am waiting on a float height tool to arrive so I can check it and be as precise as possible.
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Post by heathjl85 on Jul 11, 2020 10:38:48 GMT -6
Update: I ordered a float height gauge and used it to set the float height to specs. A little tweaking of the idle screw and it seems to be good to go now!
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Post by adarngoodjoe on Aug 27, 2020 22:36:28 GMT -6
Back when I was refurbishing my carbs, I found the brass channels in the front throat of the carb were gunked up with something I can only describe as like caramelized gas. Carb cleaner and chem dip wouldn't touch it. I had to use torch tip cleaners and very carefully selected drill bits to physically scrape the junk off. I did not have a ultra sonic cleaner at the time. I'm not sure if that would've gotten the junk off with the right solution. It's an easy task to do if you're still experiencing any issues.
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