ellwinger
New Member
My motorcycle runs like a raped ape! It's fast!
Posts: 34 
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Post by ellwinger on Apr 17, 2017 19:51:39 GMT -5
I finally decided to get my brother's old TX750 running this year. I had the gas tank sealed and rebuilt the petcocks. I replaced the entire ignition system and separated it from the original wire harness. I disassembled the carbs and cleaned them out, replaced the inlet needle and seat, set the float levels, and replaced the diaphragms. I also replaced the battery. It will start with starting fluid but once that's gone it quits. It sounds very strong when it starts. I'm thinking carburetors but I really don't know how these work. It's all together and ready to go but it just won't go! HELP!
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Post by don73tx750 on Apr 18, 2017 7:11:05 GMT -5
I'd start at the top of the fuel system and work down.
Check the gas cap vent isn't plugged. The cork gasket falls apart.
Check the petcocks for sufficient flow.
Now you should have fuel in the float bowls. Did you pull the jets when the carbs were cleaned?
If not, find a friend with an ultrasonic cleaner. Make sure the passages to the enricher plungers
are open. I'd probably get a pair of new Mikuni pilot jets. The jets that come in the aftermarket
carb kits don't work for me. Let us know how it goes.
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ellwinger
New Member
My motorcycle runs like a raped ape! It's fast!
Posts: 34
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Post by ellwinger on Apr 18, 2017 12:15:45 GMT -5
I tried to get the pilot jets out but they wouldn't budge. I pulled the plunger and cleaned it and it looked fine. Would that keep it from running?
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Post by don73tx750 on Apr 18, 2017 14:19:28 GMT -5
When I read it runs on starting fluid then quits, it tells me you have spark, compression, and air, but no fuel. After all that work on the tank and petcocks, are the float bowls full? Need to make sure you have fuel there first. After that, you will most likely be pulling and cleaning the carbs again. I've never got carbs to run right without pulling all the brass before cleaning.
To get stuck pilot jets out requires heat. Try a heat gun.
Did you spray carb cleaner thru all the passages to see if any were still plugged? You need to get the enricher circuit and pilot jet circuit sorted first.
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ellwinger
New Member
My motorcycle runs like a raped ape! It's fast!
Posts: 34
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Post by ellwinger on Apr 18, 2017 15:13:50 GMT -5
I'll get on that tomorrow. I really appreciate the input.
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ellwinger
New Member
My motorcycle runs like a raped ape! It's fast!
Posts: 34
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Post by ellwinger on Apr 24, 2017 11:12:58 GMT -5
The good news is that I have the carbs all cleaned and assembled and I got those pesky jets out; the bad news is.......  NOW WHAT?! |
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Post by don73tx750 on Apr 24, 2017 14:19:39 GMT -5
Now you're looking for a replacement float bowl.
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ellwinger
New Member
My motorcycle runs like a raped ape! It's fast!
Posts: 34
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Post by ellwinger on Apr 24, 2017 18:33:50 GMT -5
You are correct, sir.
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ellwinger
New Member
My motorcycle runs like a raped ape! It's fast!
Posts: 34
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Post by ellwinger on May 16, 2017 15:16:23 GMT -5
Got a parts carb on ebay and it had a good float bowl. Carbs: all the passages are clean and free in both carbs, installed NEW Mikuni main and pilot jets, set the float levels, synced the butterflys and set the idle screws. IT STARTS! It will sit and idle for a time and then it just quits. Any attempt at throttle is the same as turning it off. The diaphrams in the carbs are good and the timing is spot on. I would expect it to start easier than it does It takes a little cranking to make it go. When my brother had it it always started first kick. I'm growing weary.
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Post by don73tx750 on May 17, 2017 7:57:58 GMT -5
Look for an air leak. Symptoms of being lean. I'd spray some WD40 around the carb boots when it's idling.
If the RPM's pick up you found you're leak.
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ellwinger
New Member
My motorcycle runs like a raped ape! It's fast!
Posts: 34
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Post by ellwinger on May 17, 2017 9:40:22 GMT -5
OK, Don, I'm on it!
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Post by farmrjohn on May 17, 2017 9:52:37 GMT -5
It sounds like it could still be a fuel supply issue. Have you confirmed the flow out of the petcocks? The 650 forums have some good information on the BS38 carbs. The third link I've found to be especially helpful, and it took me a few attempts to get good running. "General Information" "operation" "Carb Guide"An air leak is also a possibility as mentioned. New aftermarket boots are available from "JBM" |
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ellwinger
New Member
My motorcycle runs like a raped ape! It's fast!
Posts: 34
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Post by ellwinger on May 17, 2017 17:08:38 GMT -5
Didn't want to idle today. I think I'll remove the carbs (again) and check the condition of those mounts. Tomorrow is another day.
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pewe
New Member
Posts: 29
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Post by pewe on May 21, 2017 11:51:04 GMT -5
How is starting/idling with choke ?
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ellwinger
New Member
My motorcycle runs like a raped ape! It's fast!
Posts: 34
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Post by ellwinger on May 22, 2017 19:51:32 GMT -5
Hard to start and occasionally idles for a short time. Choke valve is clean and clear and lines up properly with the inlet. Today I removed the carbs (again) and pulled the boots. The bolts came out nice and the right ones weren't all that tight. The boots are in excellent shape so I ordered new gaskets. Perhaps with new gaskets and tight bolts my leak problem might be solved. Thanks again, Don, for the input. Makes perfect sense. Thank goodness it doesn't need boots. JBM wants $75 for a pair of them.
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